Nail, Wood Screw, and Staple Fastener Connections

Transcription

1 CUREE Publication No. W-16 Nail, Wood Screw, and Staple Fastener Connections Fernando S. Fonseca Sterling K. Rose Scott H. Campbell Brigham Young University 22

2 Disclaimer The information in this publication is presented as a public service by California Institute of Technology and the Consortium of Universities for Research in Earthquake Engineering. No liability for the accuracy or adequacy of this information is assumed by them, nor by the Federal Emergency Management Agency and the California Governor s Office of Emergency Services, which provide funding for this project. the CUREE-Caltech Woodframe Project The CUREE-Caltech Woodframe Project is funded by the Federal Emergency Management Agency (FEMA) through a Hazard Mitigation Grant Program award administered by the California Governor s Office of Emergency Services (OES) and is supported by non-federal sources from industry, academia, and state and local government. California Institute of Technology (Caltech) is the prime contractor to OES. The Consortium of Universities for Research in Earthquake Engineering (CUREE) organizes and carries out under subcontract to Caltech the tasks involving other universities, practicing engineers, and industry. CUREE

3 CUREE Publication No. W-16 Nail, Wood Screw, and Staple Fastener Connections Fernando S. Fonseca Sterling K. Rose Scott H. Campbell Brigham Young University Provo, Utah 22 CUREE Consortium of Universities for Research in Earthquake Engineering 131 S. 46th Street Richmond, CA 9484 tel.: fax: website:

4 ISBN First Printing: August 22 Printed in the United States of America CUREE Published by Consortium of Universities for Research in Earthquake Engineering (CUREE) 131 S. 46th Street - Richmond, CA (CUREE Worldwide Website)

5 Preface The CUREE-Caltech Woodframe Project originated in the need for a combined research and implementation project to improve the seismic performance of woodframe buildings, a need which was brought to light by the January 17, 1994 Northridge, California Earthquake in the Los Angeles metropolitan region. Damage to woodframe construction predominated in all three basic categories of earthquake loss in that disaster: Casualties: 24 of the 25 fatalities in the Northridge Earthquake that were caused by building damage occurred in woodframe buildings (1); Property Loss: Half or more of the $4 billion in property damage was due to damage to woodframe construction (2); Functionality: 48, housing units, almost all of them in woodframe buildings, were rendered uninhabitable by the earthquake (3). Woodframe construction represents one of society s largest investments in the built environment, and the common woodframe house is usually an individual s largest single asset. In California, 99% of all residences are of woodframe construction, and even considering occupancies other than residential, such as commercial and industrial uses, 96% of all buildings in Los Angeles County are built of wood. In other regions of the country, woodframe construction is still extremely prevalent, constituting, for example, 89% of all buildings in Memphis, Tennessee and 87% in Wichita, Kansas, with "the general range of the fraction of wood structures to total structures...between 8% and 9% in all regions of the US. (4). Funding for the Woodframe Project is provided primarily by the Federal Emergency Management Agency (FEMA) under the Stafford Act (Public Law ). The federal funding comes to the project through a California Governor s Office of Emergency Services (OES) Hazard Mitigation Grant Program award to the California Institute of Technology (Caltech). The Project Manager is Professor John Hall of Caltech. The Consortium of Universities for Research in Earthquake Engineering (CUREE), as subcontractor to Caltech, with Robert Reitherman as Project Director, manages the subcontracted work to various universities, along with the work of consulting engineers, government agencies, trade groups, and others. CUREE is a non-profit corporation devoted to the advancement of earthquake engineering research, education, and implementation. Cost-sharing contributions to the Project come from a large number of practicing engineers, universities, companies, local and state agencies, and others. The project has five main Elements, which together with a management element are designed to make the engineering of woodframe buildings more scientific and their construction technology more efficient. The project s Elements and their managers are: 1. Testing and Analysis: Prof. André Filiatrault, University of California, San Diego, Manager; Prof. Frieder Seible and Prof. Chia-Ming Uang, Assistant Managers 2. Field Investigations: Prof. G. G. Schierle, University of Southern California, Manager 3. Building Codes and Standards: Kelly Cobeen, GFDS Engineers, Manager; John Coil and James Russell, Assistant Managers 4. Economic Aspects: Tom Tobin, Tobin Associates, Manager 5. Education and Outreach: Jill Andrews, Southern California Earthquake Center, Manager Preface iii

6 The Testing and Analysis Element of the CUREE-Caltech Woodframe Project consists of 23 different investigations carried out by 16 different organizations (13 universities, three consulting engineering firms). This tabulation includes an independent but closely coordinated project conducted at the University of British Columbia under separate funding than that which the Federal Emergency Management Agency (FEMA) has provided to the Woodframe Project. Approximately half the total $6.9 million budget of the CUREE-Caltech Woodframe Project is devoted to its Testing and Analysis tasks, which is the primary source of new knowledge developed in the Project. Woodframe Project Testing and Analysis Investigations Task # Investigator Topic André Filiatrault, UC San Diego Kelly Cobeen, GFDS Engineers Project-Wide Topics and System-level Experiments Khalid Mosalam, Stephen Mahin, UC Berkeley Bret Lizundia, Rutherford & Chekene Two-Story House (testing, analysis) Two-Story House (design) Three-Story Apt. Building (testing, analysis) Three-Story Apt. Building (design) Frank Lam et al., U. of British Columbia Multiple Houses (independent project funded separately in Canada with liaison to CUREE- Caltech Project) 1.2 Bryan Folz, UC San Diego International Benchmark (analysis contest) Chia-Ming Uang, UC San Diego Rate of Loading and Loading Protocol Effects Helmut Krawinkler, Stanford University Testing Protocol James Beck, Caltech Dynamic Characteristics Component-Level Investigations James Mahaney; Wiss, Janney, Elstner Assoc. Anchorage (in-plane wall loads) Yan Xiao, University of Southern California Anchorage (hillside house diaphragm tie-back) James Dolan, Virginia Polytechnic Institute Diaphragms Rob Chai, UC Davis Cripple Walls Gerard Pardoen, UC Irvine Shearwalls Kurt McMullin, San Jose State University Wall Finish Materials (lab testing) Gregory Deierlein, Stanford University Wall Finish Materials (analysis) Michael Symans, Washington State University Energy-Dissipating Fluid Dampers Fernando Fonseca, Brigham Young University Nail and Screw Fastener Connections Kenneth Fridley, Washington State University Inter-Story Shear Transfer Connections Gerard Pardoen, UC Irvine Shearwall-Diaphragm Connections Analytical Investigations Bryan Folz, UC San Diego Analysis Software Development Helmut Krawinkler, Stanford University Demand Aspects David Rosowsky, Oregon State University Reliability of Shearwalls iv Nail, Wood Screw, and Staple Fastener Connections

7 Not shown in the tabulation is the essential task of managing this element of the Project to keep the numerous investigations on track and to integrate the results. The lead management role for the Testing and Analysis Element has been carried out by Professor André Filiatrault, along with Professor Chia- Ming Uang and Professor Frieder Seible, of the Department of Structural Engineering at the University of California at San Diego. The type of construction that is the subject of the investigation reported in this document is typical twoby-four frame construction as developed and commonly built in the United States. (Outside the scope of this Project are the many kinds of construction in which there are one or more timber components, but which cannot be described as having a timber structural system, e.g., the roof of a typical concrete tilt-up building). In contrast to steel, masonry, and concrete construction, woodframe construction is much more commonly built under conventional (i.e., non-engineered) building code provisions. Also notable is the fact that even in the case of engineered wood buildings, structural engineering analysis and design procedures, as well as building code requirements, are more based on traditional practice and experience than on precise methods founded on a well-established engineering rationale. Dangerous damage to US woodframe construction has been rare, but there is still considerable room for improvement. To increase the effectiveness of earthquake-resistant design and construction with regard to woodframe construction, two primary aims of the Project are: 1. Make the design and analysis more scientific, i.e., more directly founded on experimentally and theoretically validated engineering methods and more precise in the resulting quantitative results. 2. Make the construction more efficient, i.e., reduce construction or other costs where possible, increasing seismic performance while respecting the practical aspects associated with this type of construction and its associated decentralized building construction industry. The initial planning for the Testing and Analysis tasks evolved from a workshop that was primarily devoted to obtaining input from practitioners (engineers, building code officials, architects, builders) concerning questions to which they need answers if they are to implement practical ways of reducing earthquake losses in their work. (Frieder Seible, André Filiatrault, and Chia-Ming Uang, Proceedings of the Invitational Workshop on Seismic Testing, Analysis and Design of Woodframe Construction, CUREE Publication No. W-1, 1999.) As the Testing and Analysis tasks reported in this CUREE report series were undertaken, each was assigned a designated role in providing results that would support the development of improved codes and standards, engineering procedures, or construction practices, thus completing the circle back to practitioners. The other elements of the Project essential to that overall process are briefly described below. To readers unfamiliar with structural engineering research based on laboratory work, the term testing may have a too narrow a connotation. Only in limited cases did investigations carried out in this Project put to the test a particular code provision or construction feature to see if it passed the test. That narrow usage of testing is more applicable to the certification of specific models and brands of products to declare their acceptability under a particular product standard. In this Project, more commonly the experimentation produced a range of results that are used to calibrate analytical models, so that relatively expensive laboratory research can be applicable to a wider array of conditions than the single example that was subjected to simulated earthquake loading. To a non-engineering bystander, a failure or unacceptable damage in a specimen is in fact an instance of successful experimentation if it provides a valid set of data that builds up the basis for quantitatively predicting how wood components and systems of a wide variety will perform under real earthquakes. Experimentation has also been conducted to improve the starting point for this kind of research: To better define what specific kinds of simulation in the laboratory best represent the real conditions of actual buildings subjected to earthquakes, and to develop protocols that ensure data are produced that serve the analytical needs of researchers and design engineers. Preface v

8 Notes (1) EQE International and the Governor s Office of Emergency Services, The Northridge Earthquake of January 17, 1994: Report of Data Collection and Analysis, Part A, p (Sacramento, CA: Office of Emergency Services, 1995). (2) Charles Kircher, Robert Reitherman, Robert Whitman, and Christopher Arnold, Estimation of Earthquake Losses to Buildings, Earthquake Spectra, Vol. 13, No. 4, November 1997, p. 714, and Robert Reitherman, Overview of the Northridge Earthquake, Proceedings of the NEHRP Conference and Workshop on Research on the Northridge, California Earthquake of January 17, 1994, Vol. I, p. I-1 (Richmond, CA: California Universities for Research in Earthquake Engineering, 1998). (3) Jeanne B. Perkins, John Boatwright, and Ben Chaqui, Housing Damage and Resulting Shelter Needs: Model Testing and Refinement Using Northridge Data, Proceedings of the NEHRP Conference and Workshop on Research on the Northridge, California Earthquake of January 17, 1994, Vol. IV, p. IV-135 (Richmond, CA: California Universities for Research in Earthquake Engineering, 1998). (4) Ajay Malik, Estimating Building Stocks for Earthquake Mitigation and Recovery Planning, Cornell Institute for Social and Economic Research, vi Nail, Wood Screw, and Staple Fastener Connections

9 Acknowledgments The authors would like to thank FEMA for providing funding through the California OES and the Civil and Environmental Engineering Department at Brigham Young University for providing matching funds for this research project. Thanks to Mr. Robert Reitherman, CUREE Executive Director for coordinating the overall project. Thanks to Professor John Hall (California Institute of Technology), manager of the CUREE-Caltech Woodframe Project; Professors André Filiatrault, Frieder Seible and Chia-Ming Uang (University of California, San Diego), managers of the Testing and Analysis element; and Ms. Kelly Cobeen (GFDS Engineers), Mr. John Coil (Thoron-Tomassetti / Coil & Welsh), and Mr. James Russell, managers of the Building Codes and Standards element for their guidance, support, and comments throughout this research task. Thanks to Professor James Beck and Ms. Vanessa Camelo (California Institute of Technology); Professor Rob Chai and Mrs. Tara Hutchinson (Univesity of California, Davis); Professors William Cofer, Ken Fridley, and Michael Symans (Washington State University); Professor Greg Deierlein and Helmut Krawingler (Stanford University); Professor Dan Dolan (Virginia Polytechnic Institute and State University); Mr. Seb Ficadente (F&W Inc.); Dr. Bryan Folz (University of California, San Diego); Professor Frank Lam (University of British Columbia); Mr. Philip Line (American Forest & Paper Association); Mr. James Mahaney (WJE Associates); Professor Kurt McMullin (San Jose State University); Professor Khalid Mosalam (University of California, Berkeley); Professor Gerry Pardon (University of California, Irvine); Mr. Steve Pryor (Simpson Strong-Tie); Professor David Rosowsky (Oregon State University); Professor Yan Xiao (University of Southern California) for their many questions, comments, suggestions, and assistance during and after each research meeting. Thanks to Mr. Tom Skaggs (APA The Engineering Wood Association); Mr. Ed Diekmann; Mr. John Kurtz (ISANTA); and Ms. Kelly Cobeen (GFDS Engineers) for providing some of the materials used in the testing program. Also, Mr. Darius Campbell for donating the staples and staple gun. Thanks to Mr. Justin Rabe, a former graduate student in the Civil and Engineering Department at Brigham Young University, for designing and constructing the testing apparatus. Also, Curt McDonald, Paul Lattin, and Holly Rose graduate students that assisted during assembling and testing. Thanks to Mr. David Anderson, the technician in the Civil and Environmental Engineering Department at Brigham Young University, for his assistance during initial setup and data acquisition. Preface vii

10 viii Nail, Wood Screw, and Staple Fastener Connections

11 Nail, Wood Screw, and Staple Fastener Connections Fernando S. Fonseca, Ph.D., P.E. Brigham Young University Provo, Utah Sterling K. Rose and Scott H. Campbell Brigham Young University Provo, Utah Summary Testing of several sheathing-to-wood connection types in lateral bearing under fully reversed cyclic loading was conducted under Task Nail, Wood Screw and Staple Fastener Connections. Task is one of the tasks of the Testing and Analysis element of the CUREE-Caltech Woodframe Project. The purpose of the testing was to obtain load-slip curves for each connection type so that a database could be compiled. The database consists of a set of ten parameters for each connection type. For each connection type, a group of ten specimens were tested. The parameters were extracted from the load-slip curve of each specimen and averaged for the ten specimens of each group. The database will be integrated into the 3- Dimensional Seismic Analysis Software for Woodframe Construction developed in Task Analysis Software. Specimens were assembled by attaching a piece of sheathing panel to a wood member. Different thicknesses of oriented strand board and plywood were used as sheathing panels. All specimens were assembled using the same type of wood member except two test groups. Several types and sizes of nails, wood screws, and staples were used as fasteners to attach the sheathing panel to the wood member. Specimens were assembled such that load could be applied perpendicular and parallel to the grain of the wood member. To characterize the materials used, the density of the oriented strand boards was obtained, the moisture content of the wood members was measured, and the bending yield strength of the fasteners was determined. A fixture was designed and constructed for the testing of the specimens. The design was aimed at making the fixture easy to use and more efficient without compromising the results. The main advantage of the fixture is the clamping system that allows for quick setup. The clamps are also beneficial because they provide a consistent clamping force. There are no bolts to be tightened, so forces applied by the clamps to secure the specimen during testing are similar from test to test. As a specimen was tested, however, the sheathing panel came in contact with parts of the fixture. A study was therefore conducted to determine the magnitude of the friction between the sheathing panel and the fixture. Study results indicate that the friction between the specimen and the fixture is negligible. Preface ix

12 Testing was accomplished using the simplified basic loading history developed in Task Testing Protocol. A study was conducted to determine, which is the reference deformation that defines the variations in deformation amplitude of the loading history. Concurrently, a study was conducted involving the recommended loading histories that may represent the seismic demands imposed on the connections due to ordinary ground motion. The simplified basic loading history was selected because there were no significant differences between the behavior of the tested specimens and because the extraction of the database parameters from the load-slip curves would be significantly simpler without compromising the results. A reference deformation value was determined for each of the three types of connectors to be tested. The frequency for testing all specimens was.5 Hz. Testing was conducted on an INSTRON universal testing machine. The testing machine was controlled by the MTS Teststar II software, which has data acquisition features. Connector slip was measured by two-cable extension linear position transducers mounted at the base of the testing apparatus. To measure the applied load, a load cell was installed between the testing machine and the testing apparatus. Data were recorded at a rate of 2 points per second. A data reduction program was written to extract the database parameters from the load-slip curves. Ten parameters are required for modeling the hysteretic behavior of the connections in the analysis software developed in Task The program extracted the parameters for each load-slip curve, which were then averaged for the ten curves for each connection group. The parameters and, which represent the strength degradation and stiffness degradation, respectively, within cycles of same displacement amplitude were maintained constant. A parametric study was conducted using and ; the results show that the model was not sensitive to either one of them. The study showed that a value of.6 for and a value of 1.1 for would yield satisfactorily result. The database was assembled and is available from CUREE on a CD-Rom. The CD-Rom was set up with a data viewer and contains a simple search engine. The parameters for each connection group as well as the parameters for each specimen tested are presented in a tabular form. In addition, the measured data of each test, a picture of each specimen taken right after completion of the test, and the mode of failure of each specimen are included in the data viewer. Furthermore, the data viewer includes theoretical strength values for each connection type. The data viewer is expandable and can be updated to include data from existing as well as future sheathing-to-wood connection tests. x Nail, Wood Screw, and Staple Fastener Connections

13 Table of Contents Preface... iii Acknowledgements... vii Summary... ix Table of Contents... xi Index of Figures... xii Index of Tables... xiv Introduction...1 Specimens...2 Test Matrix...3 Materials and Material Properties...4 Sheathing Panels...4 Wood Members...5 Fasteners...8 Specimen Assembly...11 Testing Setup...13 Testing Apparatus...13 Load Cell...14 Position Transducers...14 Testing Machine...15 Data Acquisition...15 Loading Protocol...16 Determination of the Reference Deformation...16 Reference Deformation for Nails...17 Reference Deformation for Wood Screws...19 Reference Deformation for Staples...2 Loading Rate...21 Preliminary Studies...22 Loading History...22 Friction...23 Simple Analysis...25 Data Reduction and Viewer...26 Stiffness and Strength Degradation Parameters...28 Load-Slip Curves...29 Data Viewer...29 References...31 Table of Contents xi

14 Index of Figures Figure 1: Typical Specimens...8 Figure 2: Schematic Representation of the Specimens Figure 3: Type and Thickness of Sheathing Panels...82 Figure 4: Wood Member...83 Figure 5: Fasteners...84 Figure 6: Fastener Edge Distance...85 Figure 7: Fastener Driven Depths...86 Figure 8: Stamps on Sheathing Panels...87 Figure 9: Moisture Box...88 Figure 1: Moisture Meter...89 Figure 11: Specimens Drying....9 Figure 12: Time Required for Specimens to Achieve a Dry Condition Figure 13: Testing Apparatus for Determining Bending Yield Strength of Fasteners Figure 14: Bending Yield Strength Test in Progress...93 Figure 15: Typical Load-Slip Response of a Fastener to the Bending Yield Strength Test...94 Figure 16: Locations Along a Screw Where the Bending Yield Strength Can Be Determined...95 Figure 17: Specimen Assembly Apparatus...96 Figure 18: Punches for Nails...97 Figure 19: Punches for Staples...98 Figure 2: Testing Apparatus...99 Figure 21: Testing Apparatus Parts...1 Figure 22: Frictionless Rolling System...12 Figure 23: Testing Apparatus Load Cell...13 Figure 24: Testing Apparatus String Pots...14 Figure 25: Overall Testing Setup...15 Figure 26: Simplified Basic Loading History...16 Figure 27: Typical Monotonic Load-Slip Response of a Specimen...17 Figure 28: Typical Perpendicular Specimen with an Offset Fastener...18 Figure 29: Typical Perpendicular Specimen with a Center Fastener...19 Figure 3: Typical Parallel Specimen with a Center Fastener...11 Figure 31: Load-Slip Response to the Simplified Basic Loading History, Perpendicular =.17 in Figure 32: Load-Slip Response to the Simplified Basic Loading History, Perpendicular =.2 in Figure 33: Load-Slip Response to the Simplified Basic Loading History, Parallel =.17 in Figure 34: Load-Slip Response to the Simplified Basic Loading History, Parallel =.2 in Figure 35: Load-Slip Response to the Simplified Basic Loading History, Perpendicular =.12 in xii Nail, Wood Screw, and Staple Fastener Connections

15 Figure 36: Load-Slip Response to the Simplified Basic Loading History, Perpendicular =.17 in Figure 37: Load-Slip Response to the Simplified Basic Loading History, Specimen with Staple, Perpendicular =.17 in Figure 38: Load-Slip Response to the Simplified Basic Loading History, Specimen with Staple, Perpendicular =.2 in Figure 39: Load-Slip Response to the Simplified Basic Loading History, Specimen with Staple, Parallel =.17 in Figure 4: Loading Rate Corresponding to Loading Frequency Figure 41: Load-Slip Response to the Basic Loading History, Perpendicular =.17 in Figure 42: Load-Slip Response to the Simplified Basic Loading History, Perpendicular =.17 in Figure 43: Rolling System and Sources of Friction Figure 44: Testing Apparatus Setup for Friction Study Figure 45: Load-Slip Response to the Simplified Basic Loading History, Perpendicular =.17 in Figure 46: Load-Slip Response for Connection Type No Figure 47: Load-Slip Response for Connection Type No Figure 48: Average Results for Connections Type No.3 and Figure 49: Parameters for Modeling Load-Slip Curves Figure 5: Range Used for Extraction of Initial Stiffness Parameter Figure 51: Range Used for Extraction of Parameter r 1 and F Figure 52: Range Used for Extraction of Parameter r Figure 53: Range Used for Extraction of Parameter r Figure 54: Range Used for Extraction of Parameter r 4 and F Figure 55: Sensitivity of a Load-Slip Curve to the Stiffness Degradation Parameter Figure 56: The Measured and the Calculated Load-Slip Curve for a Nail Specimen Figure 57: The Measured and the Calculated Load-Slip Curve for a Wood Screw Specimen Figure 58: The Measured and the Calculated Load-Slip Curve for a Staple Specimen..16 Figure 59: The Measured and the Average Calculated Load-Slip Curve for a Nail Specimen Index of Figures xiii

16 Index of Tables Table 1: Test Matrix...34 Table 2: Sheathing Panel Manufacturers...4 Table 3: Density of the Oriented Strand Board Sheathing Panels...41 Table 4: Lumber Moisture Content at Assembly...43 Table 5: Lumber Moisture Content at Testing...45 Table 6: Results of the Study Validating the Moisture Meter Table 7: Lumber Moisture Content at Assembly (Corrected) Table 8: Lumber Moisture Content at Testing (Corrected) Table 9: Dimensions of the Fasteners Table 1: Nail Bending Yield Strength...65 Table 11: Wood Screw Bending Yield Strength...66 Table 12: Reference Deformations...67 Table 13: Monotonic Loading Results for Perpendicular Loaded Specimens Assembled with Nails...68 Table 14: Monotonic Loading Results for Parallel Loaded Specimens Assembled with Nails...69 Table 15: Monotonic Loading Results for Perpendicular Loaded Specimens Assembled with Screws...7 Table 16: Monotonic Loading Results for Perpendicular Loaded Specimens Assembled with Staples...71 Table 17: Property Summary for the Basic Loading History Connection Type...72 Table 18: Property Summary for the Simplified Basic Loading History Connection Type...73 Table 19: Variable and Property Summary for Connection Type No Table 2: Variable and Property Summary for Connection Type No xiv Nail, Wood Screw, and Staple Fastener Connections

17 Introduction The objective of the CUREE-Caltech Woodframe Project is to significantly reduce earthquake losses in woodframe construction. The project is divided into five elements: Testing and Analysis, Field Investigations, Building Codes and Standards, Economic Aspects, and Education and Outreach. Task Nail, Screw and Staple Fastener Connections is one of the twentyone interrelated tasks of the Testing and Analysis element. The objective of Task was to establish a parameter database for sheathing-to-wood connections tested in lateral bearing under fully reversed cyclic loading. The database is comprised of a set of ten parameters for each connection type. The objective was accomplished by testing several sheathing-to-wood connection types. For each connection type, ten specimens were tested. The parameters were extracted from the load-slip curve of each specimen and averaged for the ten specimens of each group. The database will be integrated into the 3- Dimensional Seismic Analysis Software for Woodframe Construction developed in Task Analysis Software. Introduction 1

18 Specimens Figure 1 shows a typical specimen, assembled by attaching a piece of a sheathing panel to a wood member. Two types of specimens, according to the direction of the applied load, were tested: parallel and perpendicular. Parallel specimens had the grain of the wood member parallel to the direction of the applied load, while perpendicular specimens had the grain of the wood member perpendicular to the direction of the applied load. Figure 2 shows the overall dimensions of the specimens. Specimens were constructed by attaching a nominal 2 by 4 in wood member, 6 in long, to a 12 by 4 in piece of a sheathing panel. For the perpendicular specimens, the length of the wood member was parallel to the smaller dimension of the sheathing panel. The sheathing panel was attached to the smaller crosssectional dimension of the wood member, and the connector was inserted in the center of the wood member. The length of the wood member for the parallel specimens was turned 9 degrees with respect to that of the perpendicular specimens. The connector, however, was still inserted in the center of the wood member. Specimen configurations used in this research were selected to represent limiting bounds for both the perpendicular and parallel specimens. The lower bound was caused by the sheathing panel bearing on the fastener against the 3/8 in sheathing panel edge. This situation caused a worstcase scenario, whereas the upper bound represented a best-case scenario. This was formed when the fastener boar against the full side of the sheathing panel. These configurations were selected for testing limiting bounds and do not represent specific locations in a shear wall. 2 Nail, Wood Screw, and Staple Fastener Connections

19 Test Matrix Table 1 summarizes the tests conducted and the variables of each test group. For each test group, a total of ten specimens were tested. The variables of the testing program are briefly described below: The type and thickness of the sheathing panel (see Figure 3). Two types of sheathing panels were used: oriented strand board (OSB) and plywood. Several OSB panel thicknesses were tested: 3/8, 7/16, 15/32, and 19/32 in. Only 15/32 in plywood was used. The type of wood member (see Figure 4). Douglas Fir-Larch (DF-L) was used for all specimens except for two test groups that were assembled with pressure treated Hem-Fir (PT HF). The moisture condition of the wood member at assembling and testing time. Most coupons were assembled with green or wet wood, which is defined as having a moisture content greater than 19 percent. Few coupons were assembled with dry wood, which is defined as having a moisture content less than 12 percent. All specimens were tested with the wood member in a dry condition. The type and size of fastener (see Figure 5). Three types of fasteners were used: nails, wood screws, and staples. Nails used were 8d cooler (2 3/8 in long by.113 in diameter), 8d common (2 1/2 in long by.131 in diameter), 1d framing (3 in long by.131 in diameter), 1d common (3 in long by.148 in diameter) and 1d common short (2 1/8 in long by.148 in diameter). Limited nail penetration tests were also conducted. For those tests, three nail lengths were used. The shorter 8d cooler nail lengths were 1 11/16 and 2 in; the shorter 8d common nail lengths were 1 13/16 and 2 in. Wood screws used were No. 8 (2 in long by.164 in diameter), No. 8 (3 in long by.164 in diameter), and No. 1 (3 in long by.19 in diameter). All wood screws used in this research were rolled threadhardened. Staples used were 16 gage (1 3/4 in long, 1/2 in crown). The edge distance (see Figure 6). Edge distance is defined as the distance from the center of the connector to the nearest edge of the sheathing panel. Most specimens were assembled with 3/8 in edge distance, which was the control edge distance. To determine the effects of edge distance, four other distances were used: 2, 1/4, 3/16, and 1/8 in. The depth to which the head of the nail is driven past the surface of the sheathing panel (see Figure 7). This depth is commonly known as overdriven depth. In addition to the flush-driven condition, which was the reference, four overdriven depths were considered: -1/16, +1/16, +1/8, and +3/16 in. The negative sign means that the head of the nail was above the surface of the sheathing panel, while the positive sign means that the head of the nail was below the surface of the sheathing panel. The direction of loading with respect to the direction of the grain of the wood member. Two directions were considered: parallel and perpendicular. Parallel specimens were assembled with the grain of the wood member parallel to the direction of the applied load, while perpendicular specimens were assembled with the grain of the wood member perpendicular to the direction of the applied load. Introduction 3

20 Materials and Material Properties Sheathing Panels Sheathing panels were obtained from three different sources. The APA The Engineered Wood Association donated the 3/8, 7/16, 15/32, and 19/32 in OSB as well as the 15/32 in plywood. A sheet of 19/32 in OSB was purchased locally, and a sheet of 3/8 in OSB was obtained through direct contact with Louisiana Pacific. Table 2 summarizes the manufacturer of each sheathing panel; Figure 8 shows the rating stamp on each of the sheathing panels. Theoretically, there should be no difference in specimen response due to the manufacturer of the sheathing panel. To quantify any difference in response that might exist, however, 3/8 and 19/32 in OSB panels were obtained from three different manufacturers, and 7/16 in OSB panels were obtained from two different manufacturers. The 15/32 in plywood was donated and was not a full panel; because of that, it lacked the manufacturer stamp. The density of the OSB panels was determined according to the guidelines for common testing items of Element 1 Testing and Analysis. Several standards from the American Society for Testing and Materials were referenced directly or indirectly including ASTM D137 96a (1996a); ASTM D (1993); ASTM D (1992); and ASTM D (1996b). The samples for determining the density of the OSB panels were obtained from the interior of the panel. OSB panels are usually denser around the edges due to the pressing. The samples were obtained from at least 2 in away from the edges of the panel. Three samples 3 in wide by 6 in long were obtained from each OSB panel. Several intermediate steps were necessary in order to determine the density of the OSB panels. The following is an outline of the procedure used: The moisture content of a sample was determined using Method B Oven-Drying (Secondary) as specified in ASTM D (1992) and Sections 119 and 12 Moisture Content and Specific Gravity from ASTM D137 96a (1996a). Equation 1 was used to compute the moisture content of the sample. M 1 [ ( W F) / F ] (1) where M is the moisture content (percent), W is the initial weight (g), and F is the final oven-dry weight (g). The initial weight of the sample was obtained at the beginning of the test using an electronic scale. The sample was then placed in a drying oven at 13 C until a constant weight was attained, which took approximately 48 hours. To insure that the sample had reached constant weight, measurements were taken at least two hours apart of each other. The final weight was determined using the same electronic scale. 4 Nail, Wood Screw, and Staple Fastener Connections

21 The specific gravity of a sample was determined using Equation 2 (1996, 1993). sp gr ( K F) / ( L w t) (2) where sp gr is the specific gravity, K is a conversion factor (.61), and L, w, and t are the length, width, and thickness, respectively, of the sample (in). The specific weight or density of the sample was then determined by multiplying the specific gravity of the sample (sp gr) by the specific weight of water (62.4 lb/ft 3 ). Table 3 summarizes the density of the OSB panels used in this research. The intermediate values necessary to determine the density are also presented. A target density between 38 and 4 lb/ft 3 was suggested in the guidelines for common testing items of Element 1 Testing and Analysis. There is very small variance in OSB panel density between manufacturers. One panel thickness, 15/32 in, was slightly above; and one panel thickness, 19/32 in, was slightly under the suggested target density. Wood Members Wood members or lumber were standard 2 by 4 in Douglas Fir-Larch No. 2 or better. Two test groups were assembled with pressure-treated Hem-Fir (PT HF). The lumber used in this research complied with the guidelines for common testing items for Element 1 Testing and Analysis. One of the variables of the testing program was the lumber moisture condition. A significant number of wood structures in California are built with green or wet lumber, which statistically will not be the condition of the lumber during an earthquake. Thus, the specimens were required to be constructed with green lumber (except for two test groups) and to be tested after the lumber reached a dry condition. According to the National Design Specifications (NDS) for Wood Construction (1997a), green or wet lumber has moisture content of at least 19 percent, and dry lumber has maximum moisture content of 12 percent. The lumber was obtained from Pinnacle Lumber of Tacoma, Washington. Measurements indicated that the lumber, at the time of purchase, had moisture content of at least 19 percent. The lumber was stamped green and Douglas Fir-Larch No. 2 or better. Several months were required to complete testing. Retaining the lumber moisture during those months was, therefore, necessary if all specimens were to be assembled with green lumber. To maintain the moisture content of the lumber as close as possible to that at the time of purchase, plastic wrapping was used during transportation, and a moisture box was constructed for the lumber storage. Figure 9 shows the moisture box. The box was composed of a framed bin 4 ft wide, 3 ft tall, and just over 8 ft long. The box was sealed with plastic in an attempt to maintain the moisture of the lumber. Also, a storage rack, providing a clearance of approximately 2 in between the bottom of the box and the bottom of the lumber, was constructed and placed at the bottom of the moisture box. That space was filled with approximately 1 in of water in an attempt to keep the humidity constant. Introduction 5

22 Because of the large number of specimens, moisture content was measured using a Delmhorst R- 2 wood moisture meter. Figure 1 shows the moisture meter. The Delmhorst R-2 is a resistance type meter with insulated pins that gives quickly and accurately the moisture gradient (the difference between the shell and core moisture), an estimate of the average moisture content, and the range of moisture content. The Delmhorst R-2 measures moisture content over the range of 6 to 6 percent. A moisture test is conducted by inserting the prongs of the moisture meter into the center of the lumber to about 1/4 of the member thickness. The moisture content of the lumber was checked at the time of purchase to confirm that it met the testing program specifications. Several measurements were made on different lumber members to ensure proper moisture content. Most of the measurements were between 3 and 4 percent with some as high as 5 percent. All measurements were higher than the threshold for green lumber. The records of the measurements unfortunately were lost. The moisture content of the lumber was measured during assembly; those readings are summarized in Table 4. The following general procedure was used to measure the moisture content of the lumber: randomly choose a wood member from the lumber pile; cut the wood into 6 in long pieces; randomly select a sample; measure the moisture content in the center of the sample. The Delmhorst R-2 wood moisture meter has the capability of reading and storing up to ten readings. The average reading can then be retrieved. Table 4 gives the average reading made for each wood member; individual sample readings were not recorded. The results show that the moisture content of the lumber at assembly is higher than the required minimum. These results confirm that the lumber was green at purchase time since there should not have been any change in moisture content from purchase to assembly time because the lumber was stored in a moisture box. Prior to assembling and testing the specimens, a simple study was conducted to determine how long it would take for the wood members to reach a dry condition. The motivation for the study was to minimize the sporadic checking of moisture content of the large number of specimens. For this study, ten specimens were used. After assembly, the specimens were left to dry in a climate-controlled room (see Figure 11) that was maintained between 68 and 7 F; the ambient air moisture, however, was not recorded. Measurements were made every day for twenty consecutive days. Figure 12 shows the results of the study, indicating that the wood members reached a dry condition within approximately 11 days. Testing of the specimens was conducted approximately 14 days after assembly. This time frame was used because it best fit the testing schedule. Final moisture content measurements were made right after testing. Table 5 gives the average moisture content reading for each wood member right after testing. Measurements were taken at the center of each wood member. The results show that the moisture content of the wood member at testing time was lower than the threshold specified for dry lumber for all specimens except for two of them specimens 35-5 and 9-2 (the first number corresponds to the test group and the second number corresponds to the specimen number within the group). A simple study was conducted to validate the measurements made with the moisture meter. The readings from the moisture meter were compared to the moisture content as determined using 6 Nail, Wood Screw, and Staple Fastener Connections

23 Method B Oven-Drying (Secondary) as specified in ASTM D (1992). Table 6 summarizes the results of the study. Three wet wood samples were considered in the study. For one of those samples, however, the moisture content as determined using Method B was lower than the threshold for wet wood. Thus, three more samples were added to the original set. For the six wet wood samples, the average moisture content as determined using Method B was 2.5 percent and as measured by the moisture meter was 27.8 percent. The average reading from the moisture meter for the wet wood samples was approximately 36 percent higher than the measurements as determined using Method B. If a reduction of 36 percent is applied to the readings summarized in Table 4 (see Table 7), any reading below 25.8 percent violates the moisture content threshold for wet lumber. For wood member Nos. 16, 23, 31, 32, 34, 57 and 59 the moisture content after applying the correction factor is 17.9, 18.7, 16.5, 17.6, 17.8, 18.8, and 18.2 percent, respectively. These measurements are slightly lower than the threshold of 19 percent specified for wet lumber. Three dry wood samples were also considered. The average moisture content as determined using Method B was 6.2 percent and as measured by the moisture meter was 8.2 percent. The average reading from the moisture meter for the dry wood samples was approximately 33 percent higher than the measurements as determined using Method B. If a reduction of 33 percent is applied to the readings summarized in Table 5 (see Table 8), the moisture content of all specimens at testing time is below the maximum 12 percent specified for dry lumber. The validation of the measurements made using the moisture meter should have been accomplished prior to assembling and testing the specimens. Because the Delmhorst R-2 wood moisture meter has a microcontroller circuit that corrects for individual species and is widely used, the accuracy of the readings was never questioned. Questions about the accuracy of the measurements were raised, however, after the testing was complete. Those questions prompted the aforementioned study. To determine the effects of construction with dry versus wet lumber, 2 specimens were assembled with dry lumber. These specimens were assembled with the same wet wood except that the wood was let to dry to below 12 percent moisture content prior to assembly. The process of drying was accomplished by simply letting the wood dry in a climate controlled room. As shown in Table 7, those specimens were assembled with wood member No. 48, which had a corrected moisture content of less than 6 percent. Before assembly of the specimens, the lumber was cut to 6 in lengths. A few specimens were then assembled (with green wood) and tested after the wood dried. During those preliminary tests, it was observed that the testing fixture and consequently the response of the specimens were very sensitive to imperfections in the lumber. The specimens with significant bowed lumber (cupping) could not be placed flush within the fixture and would rock during testing. Cupping is a common side effect of curing small-dimension lumber, which causes the wood to bend away from the center of the pith. Because specimens were assembled with a small piece of wet lumber and let to dry, significant cupping was observed in a few specimens. Thus, the specimens that showed significant cupping were discarded. Overall, very few specimens were rejected; thus, it is believed that bias was not introduced in the testing program. Introduction 7

24 Fasteners Table 9 summarizes the dimensions and Figure 5 shows the various fasteners used in this testing program. Several sizes of nails were used in this testing program. Nails used were 8d cooler (2 3/8 in long by.113 in diameter), 8d common (2 1/2 in long by.131 in diameter), 1d framing (3 in long by.131 in diameter), 1d common (3 in long by.148 in diameter), and 1d common short (2 1/8 in long by.148 in diameter). Limited nail penetration tests were also conducted. For those tests, three nail lengths were used. These shorter nails were manufactured from full-length nails by cutting them with shears to the specified lengths. The ends of the nails were pointed with a grinder. Care was taken to control the nail temperature during the grinding process to minimize any possible changes in the properties of the nail. The lengths for the shorter 8d cooler nails were 1 11/16 and 2 in, while the lengths for the shorter 8d common nails were 1 13/16 and 2 in. Halsteel manufactured all nails used in this research except the 1d common short nails. The 8d cooler nails and the 1d framing nails were provided by the managers of Element 1 Testing and Analysis. The 1d framing nails provided, however, were collated at a 3 angle, which did not match the angle of the nail gun. Therefore, the 1d framing nails used in this research were purchased locally. The International Staple, Nail and Tool Association (ISANTA) provided the 8d and the 1d common nails except the 1d common short nails, which were provided by Mr. Ed Diekmann. All nails were coated with a proprietary thermal plastic resin with adhesive properties. The bending yield strength of the nails was determined according to ASTM F (1995a). Figure 13 shows the testing apparatus. The apparatus consists of a base and two blocks. The base has a steel rod that is gripped by the testing machine. The two blocks are attached to the base by two screws. The base is fitted with a set of holes such that the blocks can be moved further apart or close together depending on the length of the nail being tested. The blocks have cylindrical bearing points that allow the sample to rotate freely. A steel rod with an end cylindrical point is used to apply the load to the specimen. The diameter of the cylindrical bearing points and cylindrical loading point is 3/8 in. Testing was conducted on an INSTRON universal testing machine. Figure 14 shows the apparatus in the INSTRON machine. The load and displacement were measured using the internal machine load cell and displacement transducer. The INSTRON machine was controlled by the MTS Teststar II software, which has data acquisition capabilities. Data were recorded at a rate of 2 points per second. ASTM F (1995a) does not specify the number of samples to be tested. Fifteen replicates, as suggested by ICBO criterion AC95 Acceptance Criteria for Test Method to Determine Bending Yield Moment of Nails (1996c), were used to determine the bending yield strength of the nails. The samples were selected randomly from the nail box. Figure 15 shows typical test results used to calculate the bending yield strength of a specimen. The bending yield strength is calculated from the bending yield moment, M y, according to Equation 3: 8 Nail, Wood Screw, and Staple Fastener Connections

25 M y Fyb (3) Z where F yb is the nominal fastener bending yield strength (psi) and Z is the effective plastic section modulus (in 3 ) for full plastic hinge (for circular, prismatic nails, Z = d 3 /6, where d is the nail diameter). The bending yield moment, M y, is calculated according to Equation 4: P sbp M y (4) 4 where P is the yield load determined from the load-displacement curve and s bp is the spacing between the cylindrical points of the testing apparatus. The yield load corresponds to the load for the 5 percent diameter displacement offset from the initial stiffness (see Figure 15). The initial stiffness was determined by fitting a straight line through the initial linear portion of the load-displacement curve up to the load corresponding to approximately 5 percent of the maximum load. Table 1 summarizes the results of the bending yield tests for the nails. ASTM F (1995a) does not specify a minimum bending yield strength. According to the NDS (1997a) and report No. NER-272 from the National Evaluation Service Committee (1997b), however, the minimum average bending yield strength is 1 ksi for nails with a diameter less than or equal to.135 in (3.429 mm) and 9 ksi for nails with a diameter greater than.135 in (3.429 mm). As shown in Table 1, the nails used in this research meet these minimum requirements. Three wood screw sizes were used in this testing program. Wood screws used were No. 8 (2 in long by.164 in diameter), No. 8 (3 in long by.164 in diameter), and No. 1 (3 in long by.19 in diameter). The managers of Element 3 Building Codes & Standards provided 5 No. 8 (2 in long), 2 No. 8 (3 in long), and 5 No. 1 (3 in long) wood screws. These wood screws were bought at Home Depot and manufactured by Crown Bolt. Because the number of wood screws was not enough, additional No. 8 (2 in long) and No. 8 (3 in long) wood screws, also manufactured by Crown Bolt, were purchased at a local Home Depot. All wood screws used in this research were flathead rolled thread-hardened coated with zinc. There is no standard for determining the bending yield strength of wood screws. According to ICBO criterion AC12 Acceptance Criteria for Wood Screws (1996d), tests must be in accordance with ICBO criterion AC95 (1996c), which in turn references ASTM F (1995a). The procedure outlined in ASTM F (1995a), which is for nails, was therefore used. The major drawback is that ASTM F (1995a) does not specify the location along the length of the wood screw to apply the load, since location along the length is irrelevant for nails. As shown in Figure 16 there are two possibilities: mid-length, which includes the threads, or at the transition zone, which is the location of the transition from smooth shank to threaded shank. A few tests were conducted by applying the load at the transition zone; however, the calculated bending yield strength was significantly higher than that specified by the NDS (1997a). All wood screws were, therefore, tested at mid-length because such an approach would yield slightly more conservative results. No crushing of the threads was observed during testing. Introduction 9

26 Table 11 summarizes the results of the bending yield tests for the wood screws. ASTM F (1995a) does not specify a minimum bending yield strength. According to the NDS (1997a), design values for wood screws are based on estimated bending yield strength for common wire nails of same diameter, which corresponds to a minimum average bending yield strength of 1 ksi for 6g screws; 9 ksi for 7g, 8g, and 9g screws; 8 ksi for 1g and 12g screws; 7 ksi for 14g and 16g screws; 6 ksi for 18g and 2g screws; and 45 ksi for 24g screws. As shown in Table 11, the wood screws used in this research meet these minimum requirements. Staples used in this testing program were 16 gage. As specified in NER-272 (1997a), staples should have a 7/16 in minimum outside dimension crown width. Furthermore, for Group II wood species the minimum penetration for staples is 1 in (NER-272). The staples used in this research were 1 3/4 in long and had a 1/2 in outside crown, complying with the minimum requirements. The staples were purchased locally. Paslode manufactured the staples used in this research. Staples were coated with a proprietary thermal plastic resin with adhesive properties. Similar to wood screws, there is no standard for determining the bending yield strength of staples. ASTM F (1995a) allows the bending yield strength of smooth shank nails to be determined from either finished nails or specimens of drawn wire stock from which the nails would be manufactured. The bending yield strength of the staples could therefore have been determined from the wire the staples were manufactured. Because the staples were purchased locally, wire samples were not available. The bending yield strength of the staples was therefore not determined. 1 Nail, Wood Screw, and Staple Fastener Connections

27 Specimen Assembly The specimens were assembled using the wooden apparatus shown in Figure 17. The simple wooden apparatus was constructed to secure the longer cross-section dimension of the wood member in an upright position while aligning the fastener at the specified edge distance for the sheathing panel. The fastener was driven in the center of the smaller cross section dimension of the wood member. Such a procedure allowed for uniformity in constructing the specimens. A Porter Cable model FR 35 pneumatic framing nailer was used to drive the nails. The nail gun was set using an adjustable nosepiece to slightly underdrive the nails. The slightly underdriven nails were set to their proper depth using a hammer for the flush-driven nails. Once a specimen was assembled, the nail was examined to make sure it was flush with the surface of the sheathing panel. The specimens with overdriven or underdriven nails were set to their proper depth using a hammer and special punches. The punches are shown in Figure 18. The body of a punch is 3/4 in round mild steel. The drive pin is pressed fit into the punch body and protrudes from the end of the punch the exact length of the final desired overdriven depth. The punches for the underdriven nails were also constructed of mild steel; however, a hole was milled into the end of the punch to the desired underdriven depth. The ends of the punches were heat-treated. Using the same nail gun setting as before, the nails were slightly underdriven. They were then set to their proper depth using a hammer and the corresponding punch. The specimens with staples were constructed using the same wooden apparatus. The staples were inserted with the crown parallel to the long dimension of the wood member. ASTM D (1988) specifies that the staple shall be inserted with its crown at a 45 ( 1 ) angle to the grain direction of the wood member. Two geometric restrictions, however, existed that prevented the staples from being inserted as per ASTM D (1988): the width of the wood member and the edge distance specified for the sheathing panel. The staples were therefore inserted according to NER-272 (1997b), which specifies that staples attaching diaphragms and non-diaphragm structural-use panels shall be installed with their crowns parallel to the long dimension of the wood member, and shall be driven flush with the surface of the sheathing panel. A Paslode 32/5 S16 pneumatic stapler was used to drive the staples. The specimens with staples were assembled using the same procedure as that used to assemble specimens with nails except that a different set of punches were used. The punches for the staples are shown in Figure 19. Measurements taken prior to and following the construction of several specimens indicate that there was neither shortening of the pins nor increase in the depth of the holes. Nails and staples overdriven and underdriven by the described method were usually within 1/64 in of the desired depth. The specimens with wood screws were also assembled using the wooden apparatus. The main difference is that a lead hole was drilled prior to construction of the specimens. The NDS (1997a) specifies that for wood with specific gravity less than.6, the part of the lead hole Introduction 11

28 receiving the shank shall be approximately 7/8 the diameter of the shank and that part receiving the threaded portion shall be 7/8 the diameter of the wood screw at the root of the thread (1997a). For the No. 8 wood screws, a lead hole of 1/8 in (3.175 mm) diameter was drilled; for the No. 1 wood screws the diameter of the lead hole was 5/32 in (3.969 mm). The same size hole was drilled through the sheathing panel and into the wood member for the entire length of the wood screw. Wood screws were driven using a Makita 14 volt cordless drill. The wood screws were examined to ensure that they were flush with the sheathing panels. Neither overdriven nor underdriven specimens with wood screws were tested. 12 Nail, Wood Screw, and Staple Fastener Connections

29 Testing Setup Testing for this research initative was conducted on an INSTRON universal testing machine. The testing machine was controlled by the MTS Teststar II software, which has data acquisition features. Connector slip was measured by two cable extension linear position transducers mounted at the base of the testing apparatus. To measure the applied load, a load cell was installed between the testing machine and the testing apparatus. The testing apparatus used was specially designed and constructed to handle a large quantities of specimens quickly and easily without comperming accuracy. Testing Apparatus ASTM D (1988) details the testing of a single fastener connection. This standard, however, is used to test the fastener in simple, monotonic shear. There have been several concerns raised about the prescribed setup. Several testing devices have been proposed to remedy the various shortcomings, but the proposed devices require significant setup time and have made the specimen setup very difficult. A new testing apparatus was designed and constructed for this research (2). The apparatus is shown in Figure 2. With the prospect of testing close to one thousand specimens, a simple and rapidly changeable apparatus was required. The new testing apparatus incorporates the main properties of the standard testing apparatus and some properties of alternative testing devices. The principal design modifications were aimed at making the fixture easy to use and more efficient without sacrificing accuracy. The main improvement of the apparatus is a new clamping system. A clamping system was designed and engineered so that the apparatus would firmly secure the specimen and yet would allow rapid change of specimens. Two clamps secure the specimen in place by clamping down the wood member as shown in Figure 21(a). Two other clamps are used to secure the sliding backside of the apparatus. The reason for this sliding backside is that the apparatus can then be used to test different sheathing panel thickness. Figure 21(b) shows the sliding backside away from the specimen; Figure 21(c) shows the sliding backside at the final position. Another clamp, shown in Figure 21(d), is used to firmly grab the sheathing panel. Although the clamping system allows for rapid change of specimens, there was a potential for specimen rocking. To minimize the potential for rocking, the plate used to clamp down the wood member has four corner tabs. These tabs allow specimens with reasonable cupped wood members to be tested. Extreme amounts of cupping also interfere with the movement of the sheathing panel. The sheathing panel must move parallel to the face of the wood member. The cupping shape of the wood member makes it impossible to mount the specimen in the testing apparatus while maintaining a planar relationship between the sheathing panel and the wood member. As previously mentioned, specimens with large amounts of cupping were discarded because they could not be tested. Very few specimens were rejected; thus, it is believed that bias was not introduced in the testing program. Introduction 13

30 A more important reason for the four corner tabs is to eliminate a compressive stress state on the wood member. If a flat plate were used, the clamping force necessary to secure the specimen firmly in the testing apparatus would also cause compression parallel to grain in the wood member. This compression could, among other things, restrain the withdrawal of the fastener, especially during monotonic loading, increase the lateral resistance of the fastener, increase the stiffness of the connection, and increase the occurrence of fatigue failure. There was also a potential for slip between the clamp and the sheathing panel. Several testing apparatuses use bolts to secure the sheathing panel, thus eliminating the slip between the apparatus and the sheathing panel. These apparatuses, however, are cumbersome, requiring significant amounts of time during setup. The apparatus used in this research relied on friction between the clamp and the sheathing panel because the force applied to the sheathing panel through the clamp was perpendicular to the force applied during testing. To minimize the slip potential, the clamp was chosen so that a large contact area between the face of the clamp and the sheathing panel would exist. That measure was sufficient to prevent slip between the clamp and the sheathing panel. In addition to the new clamping system, the testing apparatus has the frictionless rolling system shown in Figure 22. As a specimen is loaded, the sheathing panel must move parallel to the face of the wood member (in plane) without moving out of plane. The sliding backside of the apparatus shown in Figures 21(b) and 21(c) prevents any out-of-plane movement, while the frictionless rolling system allows the sheathing panel to freely move in plane. Load Cell For accuracy purposes, the testing apparatus has its own load cell, as shown in Figure 23. The load cell manufactured by Sensotec, model number 41/571-7, has a range of plus or minus five hundred pounds and is accurate to the nearest hundredth of a pound. Position Transducers Figure 24 shows the instruments used to measure the fastener slip. Displacements were measured by linear position transducers mounted at the base of the testing fixture. The transducers were mounted leveled as closely as possible to the fastener to improve the accuracy of the measurements. The displacements measured correspond to the slip in the fastener. Two LX-PA cable extension transducers (string pots) were used. UniMeasure, Inc. manufactured the transducers, which have a range of 3.8 in, have essentially infinite resolution, and are linear to ± 1 percent of the full range. 14 Nail, Wood Screw, and Staple Fastener Connections

31 Testing Machine Testing was conducted in an INSTRON universal testing machine model The testing apparatus including the load cell and string pots were attached to the testing machine as shown in Figure 25. The INSTRON machine is capable of cycling at 5 Hz and has an axial load capacity of 2, lb. For this research initiative, the load range was set to of 5, lb. The INSTRON machine is outfitted with an internal load cell and a Linear Variable Displacement Transformer (LVDT) transducer. Data Acquisition The MTS Teststar II software, which has data acquisition capabilities, controlled the INSTRON machine. Data were recorded at a rate of 2 points per second. The following data were recorded: Applied displacement. This is the displacement as specified by the loading protocol. String pots displacement. This is the displacement measured at the fastener location, which corresponds to the fastener slip. Theoretically, this displacement should be exactly equal to the applied displacement. Due to elongation of the sheathing panel, slip at the grips, and relaxation of the specimen, however, there may exist a small difference between the fastener slip and the applied displacement. Load from the internal machine load cell. This is the load corresponding to the applied displacement as measured by the internal load cell. Load from the loading apparatus load cell. The load cell attached to the loading apparatus has less signal noise than the internal load cell. Theoretically, load readings from both load cells should be equal; due to signal noise, however, there may exist a small difference between the measurements. The redundancy in the data acquisition procedure was chosen for safeguard reasons. Introduction 15

32 Loading Protocol Testing was accomplished using the simplified basic loading history developed in Task Testing Protocol. One of the main reasons for this selection was that this protocol is particularly useful for the development of analytical models. The loading history is defined by variations in deformation amplitudes, using the reference deformation as the absolute measure of deformation amplitude. The simplified basic loading history is shown in Figure 26. The protocol consists of initiation cycles and primary cycles. All cycles have identical positive and negative amplitudes. Initiation cycles are executed at the beginning of the loading history; they serve to check the loading equipment, measuring devices, and the response at small amplitudes. There are six initiation cycles with amplitude of.5. Seven primary cycles follow with amplitude of.75. The amplitude of the primary cycle is then increased to.1, and seven cycles are completed. The procedure is repeated for amplitudes of primary cycles equal to.2 and.3, and four cycles are completed for each one of these amplitudes. Then the procedure is repeated for amplitudes of primary cycles equal to.4,.7 and 1., each having only three total cycles. After 1., the amplitude is increased by.5, each having also three total cycles, i.e., three cycles of 1.5, three cycles of 2.. The loading protocol stops after the three cycles of amplitude equal to 3.5 are completed. Deformation control was used throughout the testing. Determination of the Reference Deformation The loading history is defined by variations in deformation amplitudes, using the reference deformation as the absolute measure of deformation amplitude. The reference deformation is defined as the maximum deformation the test specimen is expected to sustain according to a prescribed acceptance criterion and assuming that the proposed loading history has been applied to the test specimen. Therefore, it was necessary to estimate the deformation capacity of the specimens prior to cyclic testing. The general guidelines to determine the deformation are as follows: Conduct a monotonic test, which provides data on the monotonic deformation capacity, m. This capacity is defined as the deformation at which the applied load drops, for the first time, below 8 percent of the maximum load that was applied to the specimen. Figure 27 shows the load-deformation response of a typical monotonic test, including the maximum load and monotonic deformation capacity. Use a specific fraction of m as the reference deformation for the cyclic load test. A value of =.6 m has been suggested. The reference deformation is also highlighted in Figure 27. Table 12 summarizes the values of the reference deformation used for the loading protocol. Several sizes and types of fasteners and sheathing panels will be tested in this research initiative. Because the deformation capacity will be determined empirically, a different value for was 16 Nail, Wood Screw, and Staple Fastener Connections

33 expected for each different specimen configuration. Mainly for simplicity, a reference deformation was selected for each loading protocol, depending on the type of fastener used, i.e., only one value for all specimens assembled with nails. Furthermore, a lower bound value was selected because of normal variation in material and the desire to test specimens with weaker configuration than the baseline configuration. For those specimens, a lower bound value for the reference deformation could yield a full-spectrum load-slip curve, in other words a curve with post-peak response. A full-spectrum curve was necessary to extract the parameters necessary for modeling. Reference Deformation for Nails Several perpendicular-to-grain specimens were tested using a monotonic loading protocol. The results of those tests are summarized in Table 13. Two sets of specimens were tested: the first set had eleven specimens assembled to represent a possible general worst-case scenario. This was accomplished by offsetting the nail 7/16 in from the center of the smaller cross-sectional dimension of the wood member, as shown in Figure 28. The offset distance was determined by offsetting the edge of the sheathing panel 1/16 in from the center of the wood member and at the same time maintaining the minimum 3/8 in edge distance for the nail. The 1/16 in distance was determined by assuming a 1/8 in gap between sheathing panels. The other set only had four specimens and was assembled with the nail driven in the center of the smaller cross-sectional dimension of the wood member as shown in Figure 29. The value for as determined from the first set of results was.17 in, while the value for as determined from the second set of results was.22 in. The results from several specimens within the first set were disregarded. The last column in Table 13 briefly describes the reason those results were not included in the determination of the reference deformation. Preliminary cyclic tests were also conducted to help establish a reasonable value for the reference deformation. Six specimens were assembled with the nail offset as described above and tested using the simplified basic loading protocol with the reference deformation equal to.17 in. The load-slip curves of all six specimens are shown in Figure 31. Consideration was given only to the positive load-and-slip portion of the curves, because this portion of the curve contains the limiting information needed for modeling purposes. The behavior of specimens No. 2 and 3 was significantly different from the others due to the mode of failure. The wood member of specimens No. 2 and 3 split, while the other four specimens failed because the nail tore through the sheathing panel edge. Also, specimen No. 4 failed prematurely, as is evident by the lack of post-peak response. The load-slip curves of the other three specimens exhibit the desired behavior for modeling purposes. The curves have full envelopes with considerable post-peak response. In addition, three specimens were assembled with the fastener driven in the center of the wood member. These specimens were also tested using the simplified basic loading protocol. The reference deformation, however, was equal to.2 in. According to the monotonic test results, the reference deformation should have been.22 in. The value.2 in was selected for testing simply because the previous set of tests conducted with equal to.17 in resulted in good Introduction 17

34 overall response, and an increase from.17 to.2 in was thought to be more reasonable. The load-slip curves of all three specimens are shown in Figure 32. Consideration was given only to the positive load-and-slip portion of the curves, because this portion of the curve contains the limiting information needed for modeling purposes. All three specimens failed because the nail tore through the sheathing panel edge. Specimen No. 1 failed somewhat prematurely, as is evident by the lack of post-peak response. The load-slip curves of the other two specimens exhibit the desired behavior for modeling purposes. The curves have full envelopes with considerable post peak response. The reference deformation was selected to be.17 in for specimens assembled with nails and having the load applied perpendicular to the grain of the wood member. The reasons for the selection are the following: The load-slip curves did not show significant sensitivity to the different reference deformation values used. Both values yielded curves with full envelopes and reasonable post-peak response. A lower bound was desirable in order to obtain reasonable curves for the different specimen configurations. Testing will be conducted on many specimens with weaker configurations than those tested during this preliminary study, which are representative of the baseline configuration. For the weaker specimens, a higher value for the reference deformation could cause the specimens to fail prematurely, lacking therefore any post-peak response. Such an occurrence would make it very difficult, if not impossible, to determine the parameters necessary for modeling those specimens. Several parallel-to-grain specimens were also tested using a monotonic loading protocol. The results are summarized in Table 14. A set of seven specimens assembled with the nail driven in the center of the smaller cross-sectional dimension of the wood member was tested. Unlike the perpendicular-to-grain specimens, no specimen with an offset nail was tested. Because the load was applied parallel-to-grain, there would not have been any difference in response between a specimen with offset nail and one with the nail driven in the center of the wood member (see Figure 3). The value for as determined from these parallel-to-grain tests was.23 in. This value is similar to the value obtained from the perpendicular-to-grain tests conducted on specimens with nails driven in the center of the wood member. Cyclic tests were also conducted for the parallel-to-grain condition. All specimens were assembled with the nail in the center of the wood member and tested using the simplified basic loading protocol. A group of six specimens were tested with the reference deformation equal to.17 in, and a group of four specimens were tested with the reference deformation equal to.2 in. Simplicity was the main reason for using the same values for the reference deformation as used to test perpendicular-to-grain specimens. The load-slip curves of the six first specimens are shown in Figure 33 and for the last four specimens in Figure 34. Consideration was given only to the positive load-and-slip portion of the curves, because this portion of the curve contains the limiting information needed for modeling purposes. All specimens, with exception of specimen No 4 of the first group, failed because the nail tore through the sheathing 18 Nail, Wood Screw, and Staple Fastener Connections

35 panel edge. Nail withdrawal was observed for specimen No. 4 of the first group. The load-slip curves of all specimens exhibit the desired behavior for modeling purposes. The curves have full envelopes with considerable post-peak response. The reference deformation was selected also to be.17 in for specimens assembled with nails and having the load applied parallel to the grain of the wood member. The reasons are (a) that some of the parallel-to-grain specimens were expected to be weaker than those tested in this preliminary study, and (b) simplicity. Reference Deformation for Wood Screws The procedure to establish a reference deformation for the specimens assembled with nails was followed for specimens assembled with wood screws. The main difference is that only specimens perpendicular-to-grain and with wood screws inserted in the center of the wood member were tested (see Figure 29). Four specimens were tested using a monotonic loading protocol; the results are summarized in Table 15. The value for as determined from these tests was.12 in. Cyclic tests were also conducted. The specimens were assembled with the wood screw in the center of the wood member and tested using the simplified basic loading protocol. A group of three specimens were tested with that reference deformation value. Two other specimens were tested with the reference deformation equal to.17 in. The load-slip curves of the three first specimens are shown in Figure 35 and for the other two specimens in Figure 36. Consideration was given only to the positive load-and-slip portion of the curves, because this portion of the curve contains the limiting information needed for modeling purposes. All specimens experienced fatigue failure of the wood screw. The sudden drop in load after the peak load is evidence of this behavior. Although there is a sudden decrease in load after the peak load, the load-slip curves of all specimens still exhibited some post-peak response and therefore the desired behavior for modeling purposes. Thus, the reference deformation was selected to be.12 in for specimens assembled with wood screws. This reference deformation will be used regardless of the loading direction. Introduction 19

36 Reference Deformation for Staples The procedure previously used to establish a reference deformation for the specimens assembled with nails and wood screws was also followed for specimens assembled with staples. Only specimens with staples inserted in the center of the wood member were considered (see Figure 29). Staples are thought to be similar to nails. In fact, loads for staples can be reasonably taken to be equal to twice the value for a nail with a shank diameter equal to that of one leg of the staple, provided that the crown width is adequate and that the penetration of both legs of the staple into the wood member is approximately two-thirds of the length (1994, 1995b). Thus, very few staple specimens were considered in this preliminary study. Two specimens were tested using a monotonic loading protocol; the results are summarized in Table 16. These specimens were loaded perpendicular-to-grain. The value for as determined from these tests was.3 in, a value significantly larger than the one obtained from tests conducted on specimens with nails. The staple did not tear through the edge of the sheathing panel, as was the case with the specimens assembled with nails. Furthermore, as slip increased the peak load remained essentially constant as the staple slowly withdrew from the wood member. Slip was notably large before the load dropped, for the first time, below 8 percent of the peak load. Consequently, the reference deformation was therefore significantly large and even unrealistic. Cyclic tests were conducted using a more realistic value for the reference deformation. Two values were studied:.17 in and.2 in. The specimens were assembled with the staple in the center of the wood member and tested using the simplified basic loading protocol. Two specimens were tested with the load applied perpendicular-to-grain: one with a reference deformation equal to.17 in and another with a reference deformation equal to.2 in. A third specimen was tested with the load applied parallel-to-grain and with a reference deformation equal to.17 in. The load-slip curves for those specimens are shown in Figures 37, 38, and 39, respectively. Consideration was given only to the positive load and positive slip portion of the curves, because this portion of the curve contains the limiting information needed for modeling purposes. All three specimens experienced fatigue failure of the staple. The sudden drop in load after the peak load is evidence of this behavior. It is expected that most of the specimens assembled with staples will fail in a similar matter. Although there is a sudden decrease in load because of the failure mode of the staple specimens, some post-peak response is still evident, and the parameters necessary for modeling can be extracted. The reference deformation was therefore selected to be.2 in for specimens assembled with staples. This value was deemed to be appropriate and will be used regardless of the loading direction. 2 Nail, Wood Screw, and Staple Fastener Connections

37 Loading Rate The frequency selected for testing all coupons was.5 Hz. The testing protocol does not have any specific recommendation on loading rate; however, reference is made to ISO, which recommends a displacement rate between.1 and 1 mm/sec. The loading frequency used was converted to loading rate using a simple conversion factor. Figures 4(a), 4(b), and 4(c) show the loading rate for the entire loading history for the three reference deformations used in this testing program, respectively:.12 in for the wood screws,.17 in for the nails, and.2 in for the staples. Because the loading frequency was constant throughout the entire loading history, the loading rate varied throughout the loading history. Introduction 21

38 Preliminary Studies Several preliminary investigations were conducted prior to testing the complete set of specimens. These investigations involved the following variables: The recommended loading histories that may represent the seismic demands imposed on the connection due to ordinary ground motion. The friction between the specimen and the testing fixture. Loading History This study involved testing several specimens using the basic and the simplified basic loading histories. The simplified basic loading history is a potentially simplified alternative to the basic loading history. Both loading histories are defined by variations in deformation amplitudes, using the reference deformation as the absolute measure of deformation amplitude. The basic loading protocol consists of initiation cycles, primary cycles, and trailing cycles. All cycles have identical positive and negative amplitudes. Initiation cycles are executed at the beginning of the loading history. A primary cycle is a cycle that is larger than all of the preceding cycles and is followed by smaller cycles, which are called trailing cycles. All trailing cycles have amplitudes equal to 75 percent of the amplitude of the preceding primary cycle. The simplified basic loading history is similar to the basic loading history except that the trailing cycles of the basic loading history are replaced by cycles of amplitude equal to that of the preceding primary cycle. Thus, in the simplified basic loading history, cycles of equal amplitude are being executed at each step. Seven specimens were tested using the basic loading history; six specimens were tested using the simplified basic loading history. Both loading histories used a reference deformation equal to.17 in. All specimens were assembled perpendicular-to-grain with the nail driven in the center of the smaller cross-section dimension of the wood member (see Figure 29). The load-slip curves for the specimens tested using the basic loading protocol are shown in Figure 41; the load-slip curves for the specimens tested using the simplified basic loading protocol are shown in Figure 42. Consideration was given only to the positive load and positive slip portion of the curves, because this portion of the curve contains the limiting information needed for modeling purposes. All specimens failed because the nail tore through the sheathing panel edge. Both loading histories were developed with an emphasis on performance evaluation. Emphasis was placed on a conservative but realist simulation of cycles that contribute significantly to damage at the 1/5 hazard level, as well as on adequate simulation of potentially damaging cycles at hazards levels associated with higher performance levels. Both considerations make the basic loading history more complicated because they require the distinction between primary and trailing cycles as well as the execution of a large number of relatively small cycles. In contrast, the simplified basic loading history makes no distinction between primary and trailing cycles. This simplification facilitates the execution of the test as well as the interpretation of the 22 Nail, Wood Screw, and Staple Fastener Connections

39 results; however, it may overestimate the extent of damage, particularly for large amplitude cycles. A qualitative comparison between the load-slip curves of the specimens tested illustrates the intent of the loading history. The specimens tested using the basic loading history have on average a slightly greater load-slip curve envelope and are able to sustain slightly more deformation. In contrast, the specimens tested using the simplified basic loading history have on average load-slip curves that exhibit slightly earlier failure and slightly less capacity. Nevertheless, there is no significant difference between the responses of the specimens tested using the two loading protocols. Similar results were found from a quantitative comparison between the load-slip curves of the specimens tested. The results, shown in Tables 17 and 18, are compared on an average basis. The initial stiffness and maximum load for the simplified basic loading history connection type were 9 and 17 percent lower, respectively, than that of the basic loading history connection type. The slip at maximum load had also decreased by 18 percent from the basic loading history connection type to the simplified basic loading history connection type. In addition, the simplified basic loading history connection type absorbed 6 percent less total energy than the basic loading history connection type. These results confirm the qualitative comparison that was preformed and also show that there is no significant difference between the two loading protocols. The simplified basic loading protocol is particularly useful for the development of analytical models. The extraction of the database parameters from load-slip curves obtained from simplified basic loading history tests will be significantly simpler without compromising the results. Thus, the simplified basic loading protocol was selected for this research initiative. Friction This study was conducted to determine the magnitude of the friction within the testing setup. As shown in Figure 43, two main sources of friction exist within the testing system: the sheathing panel rubbing against the rollers of the testing apparatus, and the rollers rubbing against the rest of the testing apparatus. The following precedure was used to quantify the overall friction within the setup: A test was conducted without any specimen but with the testing apparatus mounted on the INSTRON testing machine (Condition No. 1). Figure 44(a) shows the test setup for this condition. The data recorded represents the signal noise of the testing machine. A test was conducted with a piece of sheathing panel clamped on the top part of the testing apparatus and pressed as tightly as possible against the rollers of the testing apparatus (Condition No. 2). Figure 44(b) shows the test setup for this condition. This condition represents a worst-case scenario because in an actual test setup, the sliding backside of the testing apparatus will not be pressed against the sheathing panel. Although the sliding of the backside of the apparatus is a manual procedure, the operator must be careful not to cram the backside against the sheathing panel. Furthermore, the Introduction 23

40 sliding backside is fitted with a frictionless rolling system that should allow the sheathing panel to move freely. The results of this test give the friction between the sheathing panel and the testing apparatus, combined with the friction between the frictionless rollers and the rest of the testing apparatus. The final test was conducted with a full specimen (Condition No. 3). Figure 44(c) shows the test setup for this condition, which represents actual testing conditions. To obtain the correct force applied to a specimen, the force measured during the sheathing panel test must be subtracted from the force measured during the final test. Several tests were conducted using Conditions No. 1 through No. 3. The measured load-slip curves for Conditions No. 1 are shown in Figure 45(a). These results indicate that the signal noise in the load cell is approximately 1. lb. This value corresponds to approximately 1 percent of the load cell range. The measured load-slip curves for Condition No. 2 are shown in Figure 45(b). These results show that the combined friction between the sheathing panel and the rollers and between the rollers and the rest of the testing apparatus is less than 1.5 lb. In fact, it is difficult to distinguish between the friction within the testing setup and the signal noise of the load cell. Figure 42 shows the measured load-slip curve for condition No. 3. As shown in these curves, measured load values for actual tests are in the neighborhood of 2 lb. The signal noise, as well as the load value corresponding to the friction within the system, accounts for about 1 percent of the measured load in an actual set up. Thus the friction within the system can be neglected, for all practical purposes. 24 Nail, Wood Screw, and Staple Fastener Connections

41 Simple Analysis The objective of this research initiative doesn t include analysis of the data. A comprehensive analysis of the data is being conducted as a separate research program. A study of the response of connection types No. 3 and No. 47 (see Table 1) is included in this report as an example of the analysis being conducted. Figure 46 and Figure 47 show the load-slip curves for all specimens of connection types No. 3 and No. 47, respectively. Connection type No. 3 was assembled with 3/8 in OSB, Douglas-Fir Larch green wood member, flush-driven 8d cooler nails, and 3/8 in edge distance. Connection type No. 47 was assembled with the same materials, except that 8d common nails were used. Both sets were tested after the wood member reached a dry condition. Loading was applied perpendicular to the grain of the wood member. Tables 19 and 2 summarize the material properties and the results for each specimen within both sets. Results are given in terms of initial stiffness, maximum load, and slip at maximum load. Results are compared on an average basis. The initial stiffness and maximum load for connection type No. 47 are approximately 23 and 6 percent greater, respectively, than those for connection type No. 3. The slip at maximum load, however, is 17 percent greater for connection type No. 3 than that of connection type No. 47. Thus, on average, connection type No. 47 is stiffer, has greater strength capacity, but has slightly less slip capacity. These results are very typical in the sense that an increase in initial stiffness and strength capacity are usually followed by a decrease in slip capacity. Figure 48 shows the average values for initial stiffness, maximum load, and slip at maximum load for both connection types. Also plotted are the standard deviations, which are significantly high. In fact, there is an overlap of almost plus or minus one standard deviation for the averages. For example, the average initial stiffness minus one standard deviation for connection type No. 47 is approximately the same value as the average initial stiffness for connection type No. 3. Similarly, the average initial stiffness plus one standard deviation for connection type No. 3 is approximately the same value as the average initial stiffness for connection type No. 47. These results, therefore, show that connector type No. 47 is stiffer and has greater strength capacity but has less slip capacity than connector type No. 3. Introduction 25

42 Data Reduction and Viewer The objective of this testing program was to establish a parameter database for sheathing-towood connections tested in lateral bearing under fully reversed cyclic loading. The parameters are necessary for modeling purposes. The parameter database will eventually be integrated into the 3-Dimensional Seismic Analysis Software for Woodframe Construction developed in Task Analysis Software. As discussed in this report, several sheathing-to-wood connections were tested. The test results were summarized as load-slip curves. For each connection type, a group of ten specimens was tested. The database comprised a set of ten parameters for each connection type. Two of the parameters were maintained constant; the rest were extracted from the load-slip curve of each specimen and averaged for the ten specimens of each group. The parameters are defined below and shown graphically in Figure K o Initial stiffness 2. δ u Slip corresponding to maximum load F u 3. r 1 Secondary stiffness divided by K o 4. F 1 The load corresponding to the y intercept of the line with slope r 1 K o 5. r 2 Degradation stiffness divided by K o 6. r 3 Unloading stiffness divided by K o 7. r 4 Pinching stiffness divided by K o 8. F I The load corresponding to the y intercept of the line with slope r 4 K o 9. α Stiffness degradation factor 1. β Strength degradation factor. The first five parameters, K o, δ u, r 1, F 1, and r 2, establish the envelope response of a connector subjected to monotonic loading. The representation of the envelope response by these parameters captures crushing of the wood member and sheathing panel and the yielding of the connector. The other five parameters, r 3, r 4, F I, α, and β, define the hysteretic part of the connector response to general cyclic loading. The parameters were extracted from the positive quadrant (where positive load and positive slip are plotted) of the load-slip curve. As a specimen is cyclically loaded, depending on the direction of the loading, the connector will either tear through the edge of the sheathing panel or bear against the sheathing panel, which would cause the connector to withdraw from the wood member. There is, therefore, a noticeable difference between the positive quadrant and the negative quadrant (where negative load and negative slip are plotted) of a load-slip curve. Plotted in the positive quadrant is the tearing data, while plotted in the negative quadrant is the bearing data. Because the tearing data usually cause the failure of the specimen; those data appear to represent more realistically what a sheathing-to-wood connection will actually experience. A simple program was written to extract the parameters from the load-slip curves. A significant number of curves were generated from the testing program. Thus it became necessary to 26 Nail, Wood Screw, and Staple Fastener Connections

43 automate the extraction procedure. The program simply reads a data file and extracts the parameters. The extraction procedure is outlined below: Two cable extension transducers were used to measure the slip of the connector. The average of the two measurements is calculated, and the initial slip is subtracted from the measured slip. The data are separated into primary and secondary loops. Primary loops are those generated from the first loading to a given applied displacement level. Secondary loops are generated from all the subsequent cycles to that same applied displacement level. The maximum load, F u, and its corresponding slip, δ u, are extracted. The initial stiffness, K o, is determined by using the ascending branch of the first primary loop of the data. Figure 5 shows the part of a typical load-slip curve used to determine the initial stiffness. The data used in determining the initial stiffness are bracketed between two percentage values of the maximum load. For example, if the maximum load is 2 lb, the lower bound is 1 percent, and the upper bound is 4 percent, the data between 2 and 8 lb would then be used to determine the initial stiffness for the curve. A lower bound was necessary to avoid data in the range of the signal noise while the upper bound was necessary to avoid the nonlinear part of the curve. Once the data were bracketed, the initial stiffness was determined using a least squares fit to the data. The parameter r 1 and the load corresponding to the y intercept of the line with slope r 1 K o, F 1 are also determined by using the ascending branch of the primary loop of the data. Figure 51 shows the part of a typical load-slip curve used to determine both parameters. The data to be used in determining a secondary stiffness are bracketed between the maximum load and a percentage value of that load. For example, if the maximum load is 2 lb and the lower bound is 6 percent, the data between 12 and 2 lb would be used to determine the secondary stiffness for the load-slip curve. Once the data were bracketed, a least squares fit was used to fit a line through the data. The parameter r 1 is then determined by dividing the slope of the line by K o. The parameter F 1 corresponds to the y intercept of that line. The parameter r 2 is determined using a similar procedure to that used to determine the parameter r 1, except that the data used are the descending branch of the envelope curve (after the maximum load has been reached). The primary loops of the data are also used to determine r 2. Figure 52 shows the part of a typical load-slip curve used to determine parameter r 2. The data to be used in determining the descending stiffness of the envelope curve are bracketed between the maximum load and a percentage value of that load. Descending stiffness was the stiffness of the envelope curve past the maximum load. For example, if the maximum load is 2 lb and the lower bound is 6 percent, the data between 2 and 12 lb would be used to determine the descending stiffness for the loadslip curve. Once the data were bracketed, a least squares fit was used to fit a line through the data. The parameter r 2 is then determined by dividing the slope of the line by K o. The parameter r 3 is determined using a similar procedure to that used to determine parameters r 1 and r 2. The primary and secondary loops are used to determine r 3. Figure 53 shows the part of a typical load-slip curve used to determine parameter r 3. The data to be used in determining the unloading stiffness are bracketed along the load axis and along Introduction 27

44 the slip axis. Along the load axis the data are bracketed between the maximum load and a percentage value of that load. Along the slip axis the data are bracketed between a certain number of cycles prior to reaching the maximum load and a certain number of cycles after the maximum load is reached. For example, if the maximum load is 2 lb and the lower bound is 5 percent, the data would be bracketed along the load axis between 1 and 2 lb. By considering four cycles before and one cycle after the maximum load is reached, the data would be bracketed along the slip axis between those cycles. For each cycle bracketed, a least-squares fit was used to fit a line through the data. The total number of lines will depend on the number of cycles considered. An average line was then determined. The parameter r 3 was then determined by dividing the slope of the average line by K o. The parameter r 4 and the load corresponding to the y intercept of the line with slope r 4 K o, F I are determined by using the pinched part of the load-slip curve. Figure 54 shows the part of a typical load-slip curve used to determine both parameters. Significant pinching is generally noticeable on a few cycles prior to the reaching of the maximum load and continues a few cycles prior to failure of the specimen. The data to determine the pinching stiffness are bracketed along both axes. Along the load axis the data are bracketed by choosing the number of cycles prior to the reaching of the maximum load. Along the slip axis, the data are bracketed by selecting a percentage value of the slip corresponding to the maximum load. The percentage value corresponds to an upper bound to limit the selection to the linear part of the pinching. The percentage value is used in both slip directions. For example, if the slip corresponding to the maximum load is.2 in and the upper bound is 2 percent, the data would be bracketed along the slip axis between.4 and +.4 in. By considering two cycles before and two cycles after the maximum load is reached, the data would be bracketed along the load axis between those cycles. For each cycle bracketed, there will be a set of data for positive load and a set of data for negative load. A least-squares fit is then used to fit a line through the data. The total number of lines will depend on the number of cycles considered. An average line is then determined. The parameter r 4 is then determined by dividing the slope of the average line by K o. The parameter F I corresponds to the y intercept of the average line. Stiffness and Strength Degradation Parameters The stiffness degradation parameter influences the stiffness of secondary loops, while the strength degradation parameter influences the maximum load secondary loops reach. A simple study was conducted to determine the sensitivity of the overall response of a sheathingto-wood connection to these two parameters. The measured load-slip curve was compared to the load-slip curve generated using the extracted parameters. The study was conducted by setting all parameters constant, except α or β. Then, either α or β was also maintained constant while the other parameter was varied by small increments. Figure 55 shows the result of one of the case studies. For the case shown, β was set equal to 1.1, and α varied from.4 to.8 in.1 increments. The various curves in Figure 55 show that the load-slip response of a specimen is not sensitive to small changes in α. In fact, the study shows that the load-slip response is not sensitive to changes in the values of α and β. Reasonable values for α and β were around.6 and 1.1, respectively. 28 Nail, Wood Screw, and Staple Fastener Connections

45 In this research, the stiffness degradation parameter, α, was set equal to.6, and the strength degradation parameter, β, was set equal to 1.1. Load-Slip Curves A typical load-slip curve for each fastener type was generated using the parameters from their specific load-slip curve. The measured and calculated curves for the typical perpendicular-tograin specimens fastened with a nail, wood screw, and staple are shown in figures 56, 57, and 58, respectively. There is very good agreement between the positive quadrant data of the actual and calculated curves. The agreement is not so good in the negative quadrant because the data shown for the computed curve were generated using the parameters extracted from the actual positive quadrant data. The load-slip curve generated using the parameters will, therefore, always be symmetric. A set of ten parameters was extracted for each type of sheathing-to-wood connection. In order to establish a curve for each connection type, the parameters for the ten tests conducted per group were averaged. Figure 59 shows the measured load-slip curve and the load-slip curve generated using the averaged parameters for that specific connection for a typical sheathing-to-wood connection assembled with a nail perpendicular to the grain of the wood member. As seen in Figure 59 the agreement between the measured curve and the average generated load-slip curve is not very good. The reason is simply because the average curve cannot represent accurately an individual measured curve. Data Viewer A data viewer was designed to present the ten parameters from each type of sheathing-to-wood connection tested in this research initiative. Also included is the set of parameters for each individual specimen. The data viewer also provided a way to easily link the parameters, the actual data, and a picture of each specimen. The picture shows the specimen after testing. The mode of failure of each specimen is also presented. Another feature of the data viewer is a comparison of the theoretical strength values with the actual values observed from testing. The theoretical values were obtained by using the NDS yield mode calculations for a monotonically pulled connection. These values should indicate the maximum load that the connection can be expected to resist and the initial yield mode of the connection. The initial yield mode was not easily observed in the cyclic testing, but overall calculated strength values correlated well with the measured values. The data viewer was designed and constructed in a spreadsheet. A copy of the data viewer will be made available from CUREE on a CD-ROM. Introduction 29

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47 References American Society of Testing and Materials (ASTM) Standard Test Methods for Mechanical Fasteners in Wood, ASTM D , Annual Book of Standard, ASTM, Philadelphia, P.A. American Society of Testing and Materials (ASTM) Standard Test Methods for Direct Moisture Content of Wood and Wood-Base Materials, ASTM D , Annual Book of Standard, ASTM, Philadelphia, P.A. American Society of Testing and Materials (ASTM) Standard Test Methods for Specific Gravity of Wood and Wood-Base Materials, ASTM D , Annual Book of Standard, ASTM, Philadelphia, P.A. American Institute of Timber Construction (AITC) Timber Construction Manual, 4th ed., AITC, Englewood, CO. American Society of Testing and Materials (ASTM). 1995a. Standard Test Method for Determining Bending Yield Moment of Nails, ASTM F , Annual Book of Standard, ASTM, Philadelphia, P.A. Faherty, Keith F., and Williamson, Thomas G. (eds.). 1995b. Wood Engineering and Construction Handbook, 2nd ed., McGraw-Hill, New Your, NY. American Society of Testing and Materials (ASTM). 1996a. Standard Test Methods for Evaluating Properties of Wood-Base Fiber and Particle Panel Materials, ASTM D137 96a, Annual Book of Standard, ASTM, Philadelphia, P.A. American Society of Testing and Materials (ASTM). 1996b. Standard Test Methods for Mechanical Properties of Lumber and Wood-Base Materials, ASTM D , Annual Book of Standard, ASTM, Philadelphia, P.A. International Conference of Building Officials (ICBO). 1996c. Acceptance Criteria for Test Method to Determine Bending Yield Moment of Nails, AC95. ICBO, Whittier, CA. International Conference of Building Officials (ICBO). 1996d. Acceptance Criteria for Wood Screws, AC12. ICBO, Whittier, CA. American Forest and Paper Association (AF&PA). 1997a. National Design Specification for Wood Construction and Supplement ed., AF&PA, Washington, DC. National Evaluation Service Committee. 1997b. Power-Driven Staples and Nails for Use in All Types of Building Construction, Report No. NER-272, Council of American Building Officials (Available from ISANTA, Chicago, IL). Rabe, Justin A. and Fonseca, Fernando S. 2. The effect of Over-Driven Nails Heads on Single Shear Connections with Oriented Strand Board Sheathing, Technical Report No. CES--4, Brigham Young University, Department of Civil and Environmental Engineering, Provo, UT. Introduction 31

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49 Tables Tables 33

50 Table 1: Test Matrix Test Test Sheathing Wood Moisture Fastener Edge Overdriven Loading No. Variable Name Member Condition Type Distance Depth Direction Samples 1 Control 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 2 Control 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 3 Task /8 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 4 Task /8 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 5 Task /16 OSB mfg 1 DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 6 Task /16 OSB mfg 1 DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 7 Task /32 OSB T&G DF-L Wet / Dry 1d Framing Nail 3/8" Perp 1 8 Task /32 OSB T&G DF-L Wet / Dry 1d Framing Nail 3/8" Para 1 9 OSB Density 3/8 OSB mfg 1 DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 1 OSB Density 3/8 OSB mfg 1 DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 11 OSB Density 19/32 OSB mfg 1 DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 12 OSB Density 19/32 OSB mfg 1 DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 13 OSB Density 3/8 OSB mfg 2 DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 14 OSB Density 3/8 OSB mfg 2 DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 15 OSB Density 19/32 OSB mfg 2 DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 16 OSB Density 19/32 OSB mfg 2 DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 34 Nail, Wood Screw, and Staple Fastener Connections

51 Table 1 (Cont.): Test Matrix Test Test Sheathing Wood Moisture Fastener Edge Overdriven Loading No. Variable Name Member Condition Type Distance Depth Direction Samples 17 Panel 15/32 PLY std DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 18 Panel 15/32 PLY std DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 19 Panel 2 Layers 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 2 Panel 2 Layers 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 21 Panel 2 Layers 19/32 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Perp 1 22 Panel 2 Layers 19/32 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" Para 1 23 Wood Member 7/16 OSB std PT HF Wet / Dry 8d Cooler Nail 3/8" Perp 1 24 Wood Member 7/16 OSB std PT HF Wet / Dry 8d Cooler Nail 3/8" Para 1 25 Moisture Condition 7/16 OSB std DF-L Dry / Dry 8d Cooler Nail 3/8" Perp 1 26 Moisture Condition 7/16 OSB std DF-L Dry / Dry 8d Cooler Nail 3/8" Para 1 27 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" -1/16 Perp 1 28 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" -1/16 Para 1 29 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" +1/16 Perp 1 3 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" +1/16 Para 1 31 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" +1/8 Perp 1 32 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" +1/8 Para 1 Tables 35

52 Table 1 (Cont.): Test Matrix Test Test Sheathing Wood Moisture Fastener Edge Overdriven Loading No. Variable Name Member Condition Type Distance Depth Direction Samples 33 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" +3/16 Perp 1 34 Nail Overdrive 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/8" +3/16 Para 1 35 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail L1 3/8" Perp 1 36 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail L1 3/8" Para 1 37 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail L2 3/8" Perp 1 38 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail L2 3/8" Para 1 39 Fastener Common 7/16 OSB std DF-L Wet / Dry 8d Common Nail 3/8" Perp 1 4 Fastener Common 7/16 OSB std DF-L Wet / Dry 8d Common Nail 3/8" Para 1 41 Fastener Common 7/16 OSB std DF-L Wet / Dry 1d Common Nail 3/8" Perp 1 42 Fastener Common 7/16 OSB std DF-L Wet / Dry 1d Common Nail 3/8" Para 1 43 Fastener Common 19/32 OSB std DF-L Wet / Dry 8d Common Nail 3/8" Perp 1 44 Fastener Common 19/32 OSB std DF-L Wet / Dry 8d Common Nail 3/8" Para 1 45 Fastener Common 19/32 OSB std DF-L Wet / Dry 1d Common Nail 3/8" Perp 1 46 Fastener Common 19/32 OSB std DF-L Wet / Dry 1d Common Nail 3/8" Para 1 47 Fastener Common 3/8 OSB std DF-L Wet / Dry 8d Common Nail 3/8" Perp 1 48 Fastener Common 3/8 OSB std DF-L Wet / Dry 8d Common Nail 3/8" Para 1 36 Nail, Wood Screw, and Staple Fastener Connections

53 Table 1 (Cont.): Test Matrix Test Test Sheathing Wood Moisture Fastener Edge Overdriven Loading No. Variable Name Member Condition Type Distance Depth Direction Samples 51 Fastener Size 7/16 OSB std DF-L Wet / Dry 1d Framing Nail 3/8" Perp 1 52 Fastener Size 7/16 OSB std DF-L Wet / Dry 1d Framing Nail 3/8" Para 1 53 Fastener Size 19/32 OSB std DF-L Wet / Dry 1d Framing Nail 3/8" Perp 1 54 Fastener Size 19/32 OSB std DF-L Wet / Dry 1d Framing Nail 3/8" Para 1 55 Fastener Staple 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" Perp 1 56 Fastener Staple 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" Para 1 57 Fastener Staple 15/32 OSB std DF-L Wet / Dry 16ga. Staple 3/8" Perp 1 58 Fastener Staple 15/32 OSB std DF-L Wet / Dry 16ga. Staple 3/8" Para 1 63 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" -1/16 Perp 1 64 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" -1/16 Para 1 65 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" +1/16 Perp 1 66 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" +1/16 Para 1 67 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" +1/8 Perp 1 68 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" +1/8 Para 1 69 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" +3/16 Perp 1 7 Staple Overdrive 7/16 OSB std DF-L Wet / Dry 16ga. Staple 3/8" +3/16 Para 1 Tables 37

54 Table 1 (Cont.): Test Matrix Test Test Sheathing Wood Moisture Fastener Edge Overdriven Loading No. Variable Name Member Condition Type Distance Depth Direction Samples 81 Fastener Screw 7/16 OSB std DF-L Wet / Dry #8 Rolled-Hardened L1 3/8" Perp 1 82 Fastener Screw 7/16 OSB std DF-L Wet / Dry #8 Rolled-Hardened L1 3/8" Para 1 83 Fastener Screw 7/16 OSB std DF-L Wet / Dry #1 Rolled Hardened 3/8" Perp 1 84 Fastener Screw 7/16 OSB std DF-L Wet / Dry #1 Rolled Hardened 3/8" Para 1 85 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 1/4" Perp 1 86 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 1/4' Para 1 87 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/16" Perp 1 88 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 3/16" Para 1 89 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 1/8" Perp 1 9 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 1/8" Para 1 91 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Common Nail L1 3/8" Perp 1 92 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Common Nail L1 3/8" Para 1 93 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Common Nail L2 3/8" Perp 1 94 Limited Penetration 7/16 OSB std DF-L Wet / Dry 8d Common Nail L2 3/8" Para 1 95 Fastener Screw 7/16 OSB std DF-L Wet / Dry #8 Rolled-Hardened L2 3/8" Perp 1 96 Fastener Screw 7/16 OSB std DF-L Wet / Dry #8 Rolled-Hardened L2 3/8" Para 1 38 Nail, Wood Screw, and Staple Fastener Connections

55 Table 1 (Cont.): Test Matrix Test Test Sheathing Wood Moisture Fastener Edge Overdriven Loading No. Variable Name Member Condition Type Distance Depth Direction Samples 97 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail + 2" Perp 1 98 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail + 2" Para 1 99 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 2" Perp 1 1 Edge Distance 7/16 OSB std DF-L Wet / Dry 8d Cooler Nail 2" Para d short Normal 7/16 OSB std DF-L Wet / Dry 1d Common Short 3/8" Perp d short Normal 7/16 OSB std DF-L Wet / Dry 1d Common Short 3/8" Para d short Flat 7/16 OSB std DF-L Wet / Dry 1d Common Short 3/8" Perp d short Flat 7/16 OSB std DF-L Wet / Dry 1d Common Short 3/8" Para 1 Tables 39

56 Table 2: Sheathing Panel Manufacturers Sheathing Name Thickness (in) Type 1 Manufacturer 3/8 OSB 3/8 OSB 7/16 OSB 7/16 OSB Ainsworth Louisiana Pacific Slocan Group Ainsworth Slocan Group 15/32 OSB 15/32 OSB Louisiana Pacific 19/32 OSB 19/32 OSB Boise Cascade Louisiana Pacific Tolko Industries Weyerhaeuser 15/32 PLY 15/32 Plywood Unknown 1 OSB stands for Oriented Strand Board 4 Nail, Wood Screw, and Staple Fastener Connections

57 Table 3: Density of the Oriented Strand Board Sheathing Panels Sheathing Sample Initial Final Moisture Volume Density Name Number Weight (g) Weight (g) Content (in 3 ) sp gr 1 (pcf) 3/8 OSB std % % % Average 3.3% /8 OSB mfg % % % Average 4.4% /8 OSB mfg % % % Average 2.9% /16 OSB std % % % Average 3.3% /16 OSB mfg % % % Average 3.9% /32 OSB std % % % Average 5.1% sp gr stands for specific gravity Tables 41

58 Table 3 (Cont.): Density of the Oriented Strand Board Sheathing Panels Panel Sample Initial Final Moisture Volume Density Type Number Weight (g) Weight (g) Content (in 3 ) sp gr 1 (pcf) 19/32 OSB std 19/32 OSB mfg 1 19/32 OSB mfg 2 19/32 OSB T & G 15/32 PLY std % % % Average 4.% % % % Average 4.3% % % % Average 3.7% % % % Average 3.7% % % % Average 5.4% sp gr stands for specific gravity 42 Nail, Wood Screw, and Staple Fastener Connections

59 Table 4: Lumber Moisture Content at Assembly Board Moisture Board Moisture Number Date Content Comments Number Date Content Comments 1 28-Jun- 44.% Oct- 29.3% 2 2-Jun- 26.3% Oct- 37.8% 3 2-Jun- 26.2% Oct- 49.1% 4 2-Jun- 31.5% 29 3-Oct- 26.8% 5 23-Jun- 37.5% 3 3-Oct- 26.8% 6 2-Jun- 36.6% 31 3-Oct- 22.5% 7 2-Jun- 29.2% 32 3-Oct- 24.% 8 2-Jun- 3.4% 33 3-Oct- 26.7% 9 2-Jun- 28.4% 34 3-Oct- 24.2% 1 31-Jul- 27.5% 35 3-Oct- 34.5% Not Used 36 3-Oct- 18.7% Too Dry Jul- 38.% 37 3-Oct- 18.8% Too Dry Jul- 32.7% Nov- 28.9% Jul- 28.8% Nov- 27.8% 15 1-Aug- 27.% 4 15-Nov- 44.8% 16 1-Aug- 24.4% Nov- 27.7% 17 1-Aug- 29.9% Nov- 44.2% 18 1-Aug- 4.1% Nov- 47.3% 19 1-Aug- 26.8% Not Used 2 1-Aug- 27.% Nov- 27.3% 21 1-Aug- 26.6% Nov- 27.6% 22 2-Oct- 27.2% Nov- 35.9% 23 2-Oct- 25.4% Nov- 8.% Dry Sample 24 2-Oct- 28.% Nov- 29.8% Oct- 28.3% 5 18-Nov- 31.4% Tables 43

60 Table 4 (Cont.): Lumber Moisture Content at Assembly Board Moisture Board Moisture Number Date Content Comments Number Date Content Comments Nov- 32.3% Not Used Nov- 28.2% 67 9-Dec- 26.8% Nov- 26.% Not Used Nov- 26.7% Not Used Nov- 28.2% 7 8-May % Nov- 29.4% 71 8-May % 57 9-Dec- 25.5% May % 58 9-Dec- 49.9% 59 9-Dec- 24.7% 6 9-Dec- 3.7% 61 9-Dec- 42.9% 62 9-Dec- 48.1% 63 9-Dec- 39.5% 64 9-Dec- 29.3% 65 9-Dec- 26.6% 44 Nail, Wood Screw, and Staple Fastener Connections

61 Table 5: Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content 1-1 < 6.% % % % 1-2 < 6.% % % % 1-3 < 6.% % % % % % % % 1-5 < 6.% % % % 1-6 < 6.% % % % % % % % 1-8 < 6.% % % % % % % % % % % % % % % % 2-2 < 6.% % % % % 4-8 < 6.% % % 2-4 < 6.% % % % 2-5 < 6.% % % % 2-6 < 6.% 5-1 < 6.% % % 2-7 < 6.% % % % % % % % 2-9 < 6.% % % % % % 7-1 < 6.% % % 5-6 < 6.% % % % % % % 3-3 < 6.% 5-8 < 6.% % % % % % % % % % % Tables 45

62 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % 17-2 < 6.% 19-7 na % % % % % % % % % % % % % % % 2-1 < 6.% % % % 2-2 < 6.% % % 17-8 < 6.% 2-3 < 6.% % % % 2-4 < 6.% % % % % % % % % % % % % % % % % % % % % % % % 2-1 < 6.% 46 Nail, Wood Screw, and Staple Fastener Connections

63 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % % % % % % % % % % 24-1 < 6.% % 29-1 < 6.% % 24-2 < 6.% % 29-2 < 6.% % 24-3 < 6.% % 29-3 < 6.% % 24-4 < 6.% % 29-4 < 6.% % 24-5 < 6.% % 29-5 na % 24-6 < 6.% % % 22-2 < 6.% 24-7 < 6.% % 29-7 < 6.% 22-3 < 6.% % % 29-8 < 6.% % 24-9 < 6.% 27-4 < 6.% 29-9 < 6.% 22-5 < 6.% 24-1 < 6.% % 29-1 < 6.% % % % 3-1 < 6.% % % % 3-2 < 6.% % % % 3-3 < 6.% % % % 3-4 < 6.% % % % % % % % % % % % 3-7 < 6.% % % % 3-8 < 6.% % % % 3-9 < 6.% % % % 3-1 < 6.% Tables 47

64 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % 31-4 < 6.% % % % % % % % 31-6 < 6.% % % % 31-7 < 6.% 34-2 < 6.% % % % % % % % 34-4 < 6.% % % % % % % % % % % % % % % % 34-8 < 6.% % % % % 37-4 na % 32-5 < 6.% 34-1 < 6.% % % % 35-1 < 6.% % % % % % % 32-8 < 6.% % % % 32-9 < 6.% % % % % % % % % % % % % % % % % % % % % % % % % % % % 48 Nail, Wood Screw, and Staple Fastener Connections

65 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % % 43-9 na % % % % % % % % % % % % % % % % % 51-3 < 6.% % % % % % % % 51-5 na % % % % % % % % % % % % % % % % % % % % % % % % % % % 52-2 < 6.% % % % 52-3 < 6.% % % 47-9 < 6.% 52-4 < 6.% % % % % % % % % % % % 52-7 < 6.% % 45-8 na % 52-8 < 6.% % % % 52-9 < 6.% % 45-1 < 6.% % 52-1 < 6.% Tables 49

66 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % 55-6 < 6.% % % % % % % % % % % % % % % % % % % % % % % 53-7 < 6.% % % % % % % 65-3 < 6.% % % % % % % % 65-5 < 6.% 54-1 < 6.% % % % % % 63-2 < 6.% % 54-3 < 6.% % 63-3 < 6.% % % % 63-4 < 6.% % % % % 65-1 < 6.% % % 63-6 < 6.% % 54-7 < 6.% % 63-7 < 6.% % % 57-3 < 6.% 63-8 < 6.% % % % 63-9 < 6.% % % % 63-1 < 6.% % % % % % % 57-7 < 6.% % % % % % % % % % % % % % % 5 Nail, Wood Screw, and Staple Fastener Connections

67 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content 67-1 < 6.% % % % 67-2 < 6.% % % % % % % % 67-4 < 6.% % % % 67-5 < 6.% % % % 67-6 < 6.% % % % 67-7 < 6.% % % % % % % % % % % % % % % % % % % % % % % % % % 83-3 < 6.% % % % % % 68-5 < 6.% 7-1 < 6.% % % 68-6 < 6.% % 83-6 < 6.% 86-1 < 6.% 68-7 < 6.% 81-2 < 6.% % 86-2 < 6.% % % % % 68-9 < 6.% % 83-9 < 6.% 86-4 < 6.% % 81-5 < 6.% % 86-5 < 6.% % 81-6 na % 86-6 < 6.% 69-2 < 6.% % % % % 81-8 < 6.% % % % % % % % % % % Tables 51

68 Table 5 (Cont.): Lumber Moisture Content at Testing Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % 87-2 < 6.% % 92-2 na % 87-3 < 6.% % % % % % % % % % % % % % % % % % % % % % 92-8 < 6.% % 87-9 < 6.% % % % 87-1 < 6.% % % % 88-1 < 6.% % % % 88-2 < 6.% % % % 88-3 < 6.% % 93-3 < 6.% % % % % % % 9-1 < 6.% % 95-1 < 6.% 88-6 < 6.% % % % % % % % % 91-3 < 6.% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % 52 Nail, Wood Screw, and Staple Fastener Connections

69 Table 6: Results of the Study Validating the Moisture Meter Sample Sample Moisture Method B Percent Type Number Meter Oven-Drying Difference W1 26.5% 17.2% 54% W2 27.3% 19.5% 4% Wet W3 27.9% 21.% 33% W4 33.% 25.6% 29% W5 25.2% 19.5% 29% W6 27.% 2.2% 34% Average 27.8% 2.5% 36% Dry D1 8.2% 6.1% 33% D2 8.3% 6.3% 32% D3 8.1% 6.1% 33% Average 8.2% 6.2% 33% Tables 53

70 Table 7: Lumber Moisture Content at Assembly (Corrected) Board Moisture Board Moisture Number Date Content Comments Number Date Content Comments 1 28-Jun- 32.4% Oct- 21.5% 2 2-Jun- 19.3% Oct- 27.8% 3 2-Jun- 19.3% Oct- 36.1% 4 2-Jun- 23.2% 29 3-Oct- 19.7% 5 23-Jun- 27.6% 3 3-Oct- 19.7% 6 2-Jun- 26.9% 31 3-Oct- 16.5% 7 2-Jun- 21.5% 32 3-Oct- 17.6% 8 2-Jun- 22.4% 33 3-Oct- 19.6% 9 2-Jun- 2.9% 34 3-Oct- 17.8% 1 31-Jul- 2.2% 35 3-Oct- 25.4% Not Used 36 3-Oct- 13.8% Too Dry Jul- 27.9% 37 3-Oct- 13.8% Too Dry Jul- 24.% Nov- 21.3% Jul- 21.2% Nov- 2.4% 15 1-Aug- 19.9% 4 15-Nov- 32.9% 16 1-Aug- 17.9% Nov- 2.4% 17 1-Aug- 22.% Nov- 32.5% 18 1-Aug- 29.5% Nov- 34.8% 19 1-Aug- 19.7% Not Used 2 1-Aug- 19.9% Nov- 2.1% 21 1-Aug- 19.6% Nov- 2.3% 22 2-Oct- 2.% Nov- 26.4% 23 2-Oct- 18.7% Nov- 5.9% Dry Sample 24 2-Oct- 2.6% Nov- 21.9% Oct- 2.8% 5 18-Nov- 23.1% 54 Nail, Wood Screw, and Staple Fastener Connections

71 Table 7 (Cont.): Lumber Moisture Content at Assembly (Corrected) Board Moisture Board Moisture Number Date Content Comments Number Date Content Comments Nov- 23.8% Not Used Nov- 2.7% 67 9-Dec- 19.7% Nov- 19.1% Not Used Nov- 19.6% Not Used Nov- 2.7% 7 8-May % Nov- 21.6% 71 8-May-1 19.% 57 9-Dec- 18.8% May % 58 9-Dec- 36.7% 59 9-Dec- 18.2% 6 9-Dec- 22.6% 61 9-Dec- 31.5% 62 9-Dec- 35.4% 63 9-Dec- 29.% 64 9-Dec- 21.5% 65 9-Dec- 19.6% Tables 55

72 Table 8: Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content 1-1 < 4.5% % % % 1-2 < 4.5% % % % 1-3 < 4.5% % % % % % % % 1-5 < 4.5% % % % 1-6 < 4.5% % % % % % % % 1-8 < 4.5% % % % % % % % % % % % % % % % 2-2 < 4.5% % % % % 4-8 < 4.5% % % 2-4 < 4.5% % % % 2-5 < 4.5% % % % 2-6 < 4.5% 5-1 < 4.5% % % 2-7 < 4.5% % % % % % % % 2-9 < 4.5% % % % % % 7-1 < 4.5% % % 5-6 < 4.5% % % % % % % 3-3 < 4.5% 5-8 < 4.5% % % % % % % % % % % 56 Nail, Wood Screw, and Staple Fastener Connections

73 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % 17-2 < 4.5% 19-7 na % % % % % % % % % % % % % % % 2-1 < 4.5% % % % 2-2 < 4.5% % % 17-8 < 4.5% 2-3 < 4.5% % % % 2-4 < 4.5% % % % % % % % % % % % % % % % % % % % % % % % 2-1 < 4.5% Tables 57

74 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % % % % % % % % % % 24-1 < 4.5% % 29-1 < 4.5% % 24-2 < 4.5% % 29-2 < 4.5% % 24-3 < 4.5% % 29-3 < 4.5% % 24-4 < 4.5% % 29-4 < 4.5% % 24-5 < 4.5% % 29-5 na % 24-6 < 4.5% % % 22-2 < 4.5% 24-7 < 4.5% % 29-7 < 4.5% 22-3 < 4.5% % % 29-8 < 4.5% % 24-9 < 4.5% 27-4 < 4.5% 29-9 < 4.5% 22-5 < 4.5% 24-1 < 4.5% % 29-1 < 4.5% % % % 3-1 < 4.5% % % % 3-2 < 4.5% % % % 3-3 < 4.5% % % % 3-4 < 4.5% % % % % % % % % % % % 3-7 < 4.5% % % % 3-8 < 4.5% % % % 3-9 < 4.5% % % % 3-1 < 4.5% 58 Nail, Wood Screw, and Staple Fastener Connections

75 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % 31-4 < 4.5% % % % % % % % 31-6 < 4.5% % % % 31-7 < 4.5% 34-2 < 4.5% % % % % % % % 34-4 < 4.5% % % % % % % % % % % % % % % % 34-8 < 4.5% % % % % 37-4 na % 32-5 < 4.5% 34-1 < 4.5% % % % 35-1 < 4.5% % % % % % % 32-8 < 4.5% % % % 32-9 < 4.5% % % % % % % % % % % % % % % % % % % % % % % % % % % % Tables 59

76 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % % % % % % % % % % 43-9 na % % % % % % % % % % % % % % % % % 51-3 < 4.5% % % % % % % % 51-5 na % % % % % % % % % % % % % % % % % % % % % % % % % % % 52-2 < 4.5% % % % 52-3 < 4.5% % % 47-9 < 4.5% 52-4 < 4.5% % % % % % % % % % % % 52-7 < 4.5% % 45-8 na % 52-8 < 4.5% % % % 52-9 < 4.5% % 45-1 < 4.5% % 52-1 < 4.5% 6 Nail, Wood Screw, and Staple Fastener Connections

77 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % 55-6 < 6.% % % % % % % % % % % % % % % % % % % % % % % 53-7 < 4.5% % % % % % % 65-3 < 4.5% % % % % % % % 65-5 < 4.5% 54-1 < 4.5% % % % % % 63-2 < 4.5% % 54-3 < 4.5% % 63-3 < 4.5% % % % 63-4 < 4.5% % % % % 65-1 < 4.5% % % 63-6 < 4.5% % 54-7 < 4.5% % 63-7 < 4.5% % % 57-3 < 4.5% 63-8 < 4.5% % % % 63-9 < 4.5% % % % 63-1 < 4.5% % % % % % % 57-7 < 4.5% % % % % % % % % % % % % % % Tables 61

78 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content 67-1 < 6.% % % % 67-2 < 6.% % % % % % % % 67-4 < 4.5% % % % 67-5 < 4.5% % % % 67-6 < 4.5% % % % 67-7 < 4.5% % % % % % % % % % % % % % % % % % % % % % % % % % 83-3 < 4.5% % % % % % 68-5 < 4.5% 7-1 < 4.5% % % 68-6 < 4.5% % 83-6 < 4.5% 86-1 < 4.5% 68-7 < 4.5% 81-2 < 4.5% % 86-2 < 4.5% % % % % 68-9 < 4.5% % 83-9 < 4.5% 86-4 < 4.5% % 81-5 < 4.5% % 86-5 < 4.5% % 81-6 na % 86-6 < 4.5% 69-2 < 4.5% % % % % 81-8 < 4.5% % % % % % % % % % % 62 Nail, Wood Screw, and Staple Fastener Connections

79 Table 8 (Cont.): Lumber Moisture Content at Testing (Corrected) Sample Moisture Sample Moisture Sample Moisture Sample Moisture Number Content Number Content Number Content Number Content % % % % 87-2 < 4.5% % 92-2 na % 87-3 < 4.5% % % % % % % % % % % % % % % % % % % % % % 92-8 < 4.5% % 87-9 < 4.5% % % % 87-1 < 4.5% % % % 88-1 < 4.5% % % % 88-2 < 4.5% % % % 88-3 < 4.5% % 93-3 < 4.5% % % % % % % 9-1 < 4.5% % 95-1 < 4.5% 88-6 < 4.5% % % % % % % % % 91-3 < 4.5% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % Tables 63

80 Table 9: Dimensions of the Fasteners Fastener Type Fastener Name Fastener Size Length (in) Diameter (in) Crown (in) Nail Wood Screw 8d Cooler 2 3/ d Cooler L1 1 11/ d Cooler L d Common 2 1/ d Common L1 1 13/ d Common L d Framing d Common d Common Short 2 1/ #8 Rolled-Hardened L #8 Rolled-Hardened L #1 Rolled-Hardened Staple 16 Gage 1 3/4.63 1/2 64 Nail, Wood Screw, and Staple Fastener Connections

81 Table 1: Nail Bending Yield Strength Sample Number Nail Bending Yield Strength (psi) 8d Cooler 8d Common 1d Framing 1d Common 1 116,328 18,52 122,284 17, ,961 13, ,15 16, ,341 95, , , ,25 95, , , ,961 11, ,935 17, ,37 12, ,15 19, ,645 1, ,769 18, ,37 14, , , ,25 11, ,15 1, ,177 13, ,46 11, ,341 15, ,593 99, ,465 18, ,46 11, ,189 15,81 116,769 11, ,797 13, ,737 14, ,721 98,43 125,46 114,92 Average 16,7 12, ,849 17,936 Tables 65

82 Table 11: Wood Screw Bending Yield Strength Sample Number Wood Screw Bending Yield Strength (psi) #8 Rolled L1 #8 Rolled L2 #1 Rolled 1 18,61 81,932 93, , ,168 17, ,122 14,363 16, ,37 91,847 18, , ,96 16, , ,752 95, ,718 9,669 14,7 8 99,99 84,534 1, ,72 113,333 92, ,966 91,847 18, ,179 91,149 1, , ,647 95, ,637 12,241 92, ,977 86,657 92, ,21 11,33 15,11 Average 98,157 12,475 1,6 66 Nail, Wood Screw, and Staple Fastener Connections

83 Table 12: Reference Deformations Fastener Loading Reference Type Direction Deformation, (in) Nail Wood Screw Staple Perpendicular Parallel Perpendicular Parallel Perpendicular Parallel Tables 67

84 Table 13: Monotonic Loading Results for Perpendicular Loaded Specimens Assembled with Nails Sample Maximum 8% Max Number Load (lb) Load (lb) m (in) (in) Comments x4 Fracture Clamp Opened During Test Lifting of Front Edge of 2x Lifting of Front Edge of 2x Average a) First Set Sample Maximum 8% Max Number Load (lb) Load (lb) m (in) (in) Comments Average b) Second Set 68 Nail, Wood Screw, and Staple Fastener Connections

85 Table 14: Monotonic Loading Results for Parallel Loaded Specimens Assembled with Nails Sample Maximum 8% Max Number Load (lb) Load (lb) m (in) (in) Comments Average Tables 69

86 Table 15: Monotonic Loading Results for Perpendicular Loaded Specimens Assembled with Screws Sample Maximum 8% Max Number Load (lb) Load (lb) m (in) (in) Comments Average Nail, Wood Screw, and Staple Fastener Connections

87 Table 16: Monotonic Loading Results for Perpendicular Loaded Specimens Assembled with Staples Sample Maximum 8% Max Number Load (lb) Load (lb) m (in) (in) Comments Average Tables 71

88 Table 17: Property Summary for the Basic Loading History Connection Type Sample Initial Maximum Slip at Total Absorbed Number Stiffness (lb/in) Load (lb) Max Load (in) Energy (lb-in) CTR B CTR B CTR B CTR B CTR B CTR B CTR B Average Std Dev Nail, Wood Screw, and Staple Fastener Connections

89 Table 18: Property Summary for the Simplified Basic Loading History Connection Type Sample Initial Maximum Slip at Total Absorbed Number Stiffness (lb/in) Load (lb) Max Load (in) Energy (lb-in) CTR S CTR S CTR S CTR S CTR S CTR S Average Std Dev Tables 73

90 Table 19: Variable and Property Summary for Connection Type No. 3 Sheathing Type Sheathing Manufacturer Sheathing Density Wood Member Loading Direction Fastener Edge Distance Overdriven Depth Fastener Type Bending Yield Strength 3/8 in OSB Slocan Group 38.5 pcf Douglass Fir - Larch Perpendicular 3/8 in None 8d Cooler Nail (2 3/8 in x.113 in) 16 ksi a) Variables Sample Initial Maximum Slip at Max Wood Moisture at Number Stiffness (lb/in) Load (lb) Load (in) Assembly Testing % 7.1% % 7.2% % < 6.% % 6.6% % 6.4% % 6.8% % 6.7% % 7.4% % 8.% % 6.5% Average % 7.% Std Dev %.51% b) Properties 74 Nail, Wood Screw, and Staple Fastener Connections

91 Table 19 (Cont.): Variable and Property Summary for Connection Type No. 3 Sample Failure Yield Design Maximum Number Mode Mode Load (lb) Load (lb) 1 Withdrawal Mode IIIs Tear Out - Withdrawal Mode IIIs Withdrawal Mode IIIs Withdrawal Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs Withdrawal Mode IIIs Tear Out Mode IIIs Tear Out - Withdrawal Mode IIIs Withdrawal Mode IIIs c) Failure Information Tables 75

92 Table 2: Variable and Property Summary for Connection Type No. 47 Sheathing Type Sheathing Manufacturer Sheathing Density Wood Member Loading Direction Fastener Edge Distance Overdriven Depth Fastener Type Bending Yield Strength 3/8 in OSB Slocan Group 38.5 pcf Douglass Fir - Larch Perpendicular 3/8 in None 8d Common Nail (2 in x.131 in) 13 ksi a) Variables Sample Initial Maximum Slip at Max Wood Moisture at Number Stiffness (lb/in) Load (lb) Load (in) Assembly Testing % 6.2% % 7.9% % 7.% % 6.5% % 6.6% % 7.1% % 7.7% % 6.6% % < 6.% % 6.3% Average % 6.9% Std Dev %.6% b) Properties 76 Nail, Wood Screw, and Staple Fastener Connections

93 Table 2 (Cont.): Variable and Property Summary for Connection Type No. 47 Sample Mode Yield Design Maximum Number of Failure Mode Load (lb) Load (lb) 1 Tear Out Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs Withdrawal Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs Tear Out Mode IIIs c) Failure Information Tables 77

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95 FIGURES Figures 79

96 Figure 1: Typical Specimens Applied Load Applied Load Sheathing Panel Sheathing Panel Fastener Wood Member Wood Member Perpendicular Specimen Parallel Specimen 8 Nail, Wood Screw, and Staple Fastener Connections

97 Figure 2: Schematic Representation of the Specimens Applied Load Sheathing Panel Fastener Wood Member Applied Load Sheathing Panel Wood Member Fastener Figures 81

98 Figure 3: Type and Thickness of Sheathing Panels 3/8 OSB 7/16 OSB 15/32 OSB 19/32 OSB 15/32 PLY 82 Nail, Wood Screw, and Staple Fastener Connections

99 Figure 4: Wood Member Douglas Fir-Larch Pressure Treated Hem-Fir Figures 83

100 Figure 5: Fasteners 8d Cooler Nail (2 3/8 x.113 ) 8d Cooler Nail L1 (1 11/16 x.113 ) 8d Cooler Nail L2 (2 x.113 ) 8d Common Nail (2 1/2 x.131 ) #8 Rolled Hardened Screw L1 (2 x.164 ) #8 Rolled Hardened Screw L2 (3 x.164 ) #1 Rolled Hardened Screw (3 x.19 ) 16 gage Staple (1 3/4, 1/2 ) 8d Common Nail L1 (1 13/16 x.131 ) 8d Common Nail L2 (2 x.131 ) 1d Framing Nail (3 x.131 ) 1d Common Nail (3 x.148 ) 1d Common Short Nail (2 1/8 x.148 ) 84 Nail, Wood Screw, and Staple Fastener Connections

101 Figure 6: Fastener Edge Distance 3/8 Figures 85

102 Figure 7: Fastener Driven Depths Underdriven Flush-Driven Overdriven Wood Member Sheathing Panel 86 Nail, Wood Screw, and Staple Fastener Connections

103 Figure 8: Stamps on Sheathing Panels 3/8 OSB std 7/16 OSB std 15/32 OSB std 19/32 OSB std Figures 87

104 Figure 9: Moisture Box 88 Nail, Wood Screw, and Staple Fastener Connections

105 Figure 1: Moisture Meter Figures 89

106 Figure 11: Specimens Drying 9 Nail, Wood Screw, and Staple Fastener Connections

107 Moisture Content 5% 45% 4% 35% 3% 25% 2% 15% 1% 5% % Figure 12: Time Required for Specimens to Achieve a Dry Condition Time (days) Avg 14th Day 12% MC Figures 91

108 Figure 13: Testing Apparatus for Determining Bending Yield Strength of Fasteners 92 Nail, Wood Screw, and Staple Fastener Connections

109 Figure 14: Bending Yield Strength Test in Progress Figures 93

110 Load (lb) Load (N) Figure 15: Typical Load-Slip Response of a Fastener to the Bending Yield Strength Test Slip (mm) Slip (in) 94 Nail, Wood Screw, and Staple Fastener Connections

111 Figure 16: Locations Along a Screw Where the Bending Yield Strength Can Be Determined Mid-Length Location Transition Zone Figures 95

112 Figure 17: Specimen Assembly Apparatus 96 Nail, Wood Screw, and Staple Fastener Connections

113 Figure 18: Punches for Nails Figures 97

114 Figure 19: Punches for Staples 98 Nail, Wood Screw, and Staple Fastener Connections

115 Figure 2: Testing Apparatus Figures 99

116 Figure 21: Testing Apparatus Parts a) Clamps to Secure Wood Member 1 Nail, Wood Screw, and Staple Fastener Connections

117 Figure 21 (Cont.): Testing Apparatus Parts b) Sliding Backside Away from Specimen c) Sliding Backside in Final Position d) Top Clamp Figures 11

118 Figure 22: Frictionless Rolling System 12 Nail, Wood Screw, and Staple Fastener Connections

119 Figure 23: Testing Apparatus Load Cell Figures 13

120 Figure 24: Testing Apparatus String Pots 14 Nail, Wood Screw, and Staple Fastener Connections

121 Figure 25: Overall Testing Setup Figures 15

122 Percent of Delta Figure 26: Simplified Basic Loading History 4% 3% 2% 1% % -1% -2% -3% -4% Cycles 16 Nail, Wood Screw, and Staple Fastener Connections

123 Load (lb) Load (N) 25 Figure 27: Typical Monotonic Load-Slip Response of a Specimen Slip (mm) F max.8 F max Slip (in) m Figures 17

124 Figure 28: Typical Perpendicular Specimen with an Offset Fastener Sheathing Panel Fastener Wood Member 18 Nail, Wood Screw, and Staple Fastener Connections

125 Figure 29: Typical Perpendicular Specimen with a Center Fastener Sheathing Panel Fastener Wood Member Figures 19

126 Figure 3: Typical Parallel Specimen with a Center Fastener Fastener Sheathing Panel Wood Member Fastener 11 Nail, Wood Screw, and Staple Fastener Connections

127 Load (lb) Load (N) Load (lb) Load (N) Figure 31: Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in a) Offset Specimen No. 1 - Nail Slip (mm) Slip (in) Slip (mm) b) Offset Specimen No. 2 Nail Slip (in) Figures 111

128 Load (lb) Load (N) Load (lb) Load (N) Figure 31 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in c) Offset Specimen No. 3 - Nail Slip (mm) Slip (in) Slip (mm) d) Offset Specimen No. 4 - Nail Slip (in) 112 Nail, Wood Screw, and Staple Fastener Connections

129 Load (lb) Load (N) Load (lb) Load (N) Figure 31 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in e) Offset Specimen No. 5 - Nail Slip (mm) Slip (in) Slip (mm) f) Offset Specimen No. 6 - Nail Slip (in) Figures 113

130 Load (lb) Load (N) Load (lb) Load (N) Figure 32: Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.2 in a) Specimen No. 1 - Nail Slip (mm) Slip (in) Slip (mm) b) Specimen No. 2 - Nail Slip (in) 114 Nail, Wood Screw, and Staple Fastener Connections

131 Load (lb) Load (N) Figure 32 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.2 in Slip (mm) c) Specimen No. 3 - Nail Slip (in) Figures 115

132 Load (lb) Load (N) Load (lb) Load (N) Figure 33: Load-Slip Response to the Simplified Basic Loading History, Parallel, Δ =.17 in a) Specimen No. 1 - Nail Slip (mm) Slip (in) Slip (mm) b) Specimen No. 2 - Nail Slip (in) 116 Nail, Wood Screw, and Staple Fastener Connections

133 Load (lb) Load (N) Load (lb) Load (N) Figure 33 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Parallel, Δ =.17 in c) Specimen No. 3 - Nail Slip (mm) Slip (in) Slip (mm) d) Specimen No. 4 - Nail Slip (in) Figures 117

134 Load (lb) Load (N) Load (lb) Load (N) Figure 33 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Parallel, Δ =.17 in e) Specimen No. 5 - Nail Slip (mm) Slip (in) Slip (mm) f) Specimen No. 6 - Nail Slip (in) 118 Nail, Wood Screw, and Staple Fastener Connections

135 Load (lb) Load (N) Load (lb) Load (N) Figure 34: Load-Slip Response to the Simplified Basic Loading History, Parallel, Δ =.2 in a) Specimen No. 1 - Nail Slip (mm) Slip (in) Slip (mm) b) Specimen No. 2 - Nail Slip (in) Figures 119

136 Load (lb) Load (N) Load (lb) Load (N) Figure 34 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Parallel, Δ =.2 in c) Specimen No. 3 - Nail Slip (mm) Slip (in) Slip (mm) d) Specimen No. 4 - Nail Slip (in) 12 Nail, Wood Screw, and Staple Fastener Connections

137 Load (lb) Load (N) Load (lb) Load (N) Figure 35: Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.12 in Slip (mm) a) Specimen No. 1 - Screw Slip (in) Slip (mm) b) Specimen No. 2 - Screw Slip (in) Figures 121

138 Load (lb) Load (N) Figure 35 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.12 in Slip (mm) c) Specimen No. 3 - Screw Slip (in) 122 Nail, Wood Screw, and Staple Fastener Connections

139 Load (lb) Load (N) Load (lb) Load (N) Figure 36: Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in Slip (mm) a) Specimen No. 1 - Screw Slip (in) Slip (mm) b) Specimen No. 2 - Screw Slip (in) Figures 123

140 Load (lb) Load (N) Figure 37: Load-Slip Response to the Simplified Basic Loading History, Specimen with Staple, Perpendicular, Δ =.17 in Slip (mm) Slip (in) Nail, Wood Screw, and Staple Fastener Connections

141 Load (lb) Load (N) Figure 38: Load-Slip Response to the Simplified Basic Loading History, Specimen with Staple, Perpendicular, Δ =.2 in Slip (mm) Slip (in) Figures 125

142 Load (lb) Load (N) Figure 39: Load-Slip Response to the Simplified Basic Loading History, Specimen with Staple, Parallel, Δ =.17 in Slip (mm) Slip (in) Nail, Wood Screw, and Staple Fastener Connections

143 Rate (mm/sec) Rate (mm/sec) Figure 4: Loading Rate Corresponding to Loading Frequency a) For Δ =.12 in 4 Displacement Level b) For Δ =.17 in Displacement Level Figures 127

144 Rate (mm/sec) c) For Δ =.2 in Figure 4 (Cont.): Loading Rate Corresponding to Loading Frequency Displacement Level Nail, Wood Screw, and Staple Fastener Connections

145 Load (lb) Load (N) Load (lb) Load (N) Figure 41: Load-Slip Response to the Basic Loading History, Perpendicular, Δ =.17 in a) Specimen No. 1 - Nail Slip (mm) Slip (in) Slip (mm) b) Specimen No. 2 - Nail Slip (in) Figures 129

146 Load (lb) Load (N) Load (lb) Load (N) Figure 41 (Cont.): Load-Slip Response to the Basic Loading History, Perpendicular, Δ =.17 in c) Specimen No. 3 - Nail Slip (mm) Slip (in) Slip (mm) d) Specimen No. 4 - Nail Slip (in) 13 Nail, Wood Screw, and Staple Fastener Connections

147 Load (lb) Load (N) Load (lb) Load (N) Figure 41 (Cont.): Load-Slip Response to the Basic Loading History, Perpendicular, Δ =.17 in e) Specimen No. 5 - Nail Slip (mm) Slip (in) Slip (mm) f) Specimen No. 6 - Nail Slip (in) Figures 131

148 Load (lb) Load (N) Figure 41 (Cont.): Load-Slip Response to the Basic Loading History, Perpendicular, Δ =.17 in Slip (mm) g) Specimen No. 7 - Nail Slip (in) 132 Nail, Wood Screw, and Staple Fastener Connections

149 Load (lb) Load (N) Load (lb) Load (N) Figure 42: Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in a) Specimen No. 1 - Nail Slip (mm) Slip (in) Slip (mm) b) Specimen No. 2 - Nail Slip (in) Figures 133

150 Load (lb) Load (N) Load (lb) Load (N) Figure 42 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in c) Specimen No. 3 - Nail Slip (mm) Slip (in) Slip (mm) d) Specimen No. 4 - Nail Slip (in) 134 Nail, Wood Screw, and Staple Fastener Connections

151 Load (lb) Load (N) Load (lb) Load (N) Figure 42 (Cont.): Load-Slip Response to the Simplified Basic Loading History, Perpendicular, Δ =.17 in e) Specimen No. 5 - Nail Slip (mm) Slip (in) Slip (mm) f) Specimen No. 6 - Nail Slip (in) Figures 135

152 Figure 43: Rolling System and Sources of Friction Rollers Rubbing 136 Nail, Wood Screw, and Staple Fastener Connections

153 Figure 44: Testing Apparatus Setup for Friction Study a) No Specimen b) With Sheathing Panel Only Figures 137