Legolizing infrastructure

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1 Legolizing infrastructure Quick building with prefabricated building blocks - a pleasure for the economy ir. M.A. (Maurice) van Heesch 1 and ing. J. (Johan) de Groot 1 Wagemaker, P.O. Box 412, 5240 AK Rosmalen, the Netherlands; phone: ; mah@wagemaker.nl 2 Wagemaker, P.O. Box 412, 5240 AK Rosmalen, the Netherlands; phone: ; jdg@wagemaker.nl ABSTRACT Nordrhein-Westfalen in Germany feels the urge to renovate large amounts of bridges and viaducts. In the Netherlands loads on bridges are constraint. Surveys in Europe and North America have shown that most existing bridges already exhibit significant degrees of degradation. Some Dutch solutions for the upgrading and the renewal of infrastructural structures dramatically enhance the economic and environmental performance because they are cheaper and reduce the disturbance of ongoing and ever busier traffic. Under the topic Innovative building concepts the method Quick building with prefabricated building blocks is presented to inform an international audience about these government approved methods of building concrete infrastructure. This paper consists of three topics. First, a description of the problems occurring in current concrete infrastructural structures is given. You can think of damages, old age and desired upgrades to allow more traffic and heavier loads. Secondly, the speed of building can be increased enormously by using precast parts. This means very little nuisance and only few disadvantages for the economy. But one of the conditions to create a successful shorter construction time is a more thorough preparation. Therefore, some insights in the advantages and points of interest in engineering, preparation and building with prefabricated parts in infrastructure are given. In this paper, parametric design and standardization of building blocks are considered more specifically. First experiences are shown for a precast girder, precast chamber elements and a transitional structure. In conclusion, the paper demonstrates a possible solution and obvious advantages for the renewal of a viaduct in/over a motorway by using prefabricated building blocks, either a modular system. Keywords: prefabrication, time efficiency 1. INTRODUCTION In the Netherlands, we are having a busy traffic road network for a long time now. This is why a couple of decades ago, the application of precast girders became very popular. Nowadays we must deal with a new issue. Are the bridges and viaducts, built by our parents and grandparents strong enough for us and our children? A new replacement of our civil structures seems to be leading. To minimize the nuisance for the traffic, the application of precast building blocks can be developed into a complete modular system. In this respect, discipline and repetition may be key factors. It can be a chance in busy traffic areas abroad, who also must deal with replacements of existing bridges fib Maastricht-paper Legolizing page 1

2. PROBLEMS ARISING IN TODAY S CONCRETE INFRASTRUCTURE? In the Netherlands, construction business was booming during the 1930s and 1960s.

The first main issue that leads to problems is the following. The traffic load increased drastically, both in intensity and weight.

Are there still additional safety margins present in the existing structures, or is the load-bearing capacity insufficient what causes a safety concern?

2 2. PROBLEMS ARISING IN TODAY S CONCRETE INFRASTRUCTURE? In the Netherlands, construction business was booming during the 1930s and 1960s. Hence, a substantial amount of structures built in that time nowadays exhibit aging. In certain cases, degradation effects due to aging seem inevitable. The first main issue that leads to problems is the following. The traffic load increased drastically, both in intensity and weight. This functional load change has impact on the infrastructural objects. Are there still additional safety margins present in the existing structures, or is the load-bearing capacity insufficient what causes a safety concern? Another factor that can lead to problems may be the state of maintenance. Is sufficient and frequent maintenance conducted? Different choices in maintenance can be made in history, mostly cost based or risk based for a certain amount of time. A third stumbling point can be the quality of concrete. Implementation methods of concrete are very diverse and can be affected by many factors, for example temperature. When the quality of concrete is insufficient, there is a risk that the design life span is not achieved. Possible solutions range from either a passive attitude to complete replacement of the structure. Intermediate solution strategies may be adoption of strengthening measures, or measures to increase durability. Figure 1 indicates the adoptable management strategies graphically. This paper will focus on replacement of a structure. replacing renewal monitoring Figure 1: Graphical representation of adoptable management strategies 2017-fib Maastricht-paper Legolizing page 2

3 3. REPLACEMENT OF AN EXISTING STRUCTURE 3.1. GENERAL Nowadays, new project plans for upcoming infrastructure involves many stakeholders. All these stakeholders introduce specific requirements the new structure should fulfil. Furthermore, an environment demanding minimal disruption is present NUISANCE In the past, building usually was performed in the open field. Nuisance for the environment was of minimal proportions. A few months increase in intended construction time was considered irrelevant. The focus was put on reducing construction costs. Nowadays, building is increasingly being performed within an existing (urban) environment. This is often the case with replacement. This leads to more nuisance for traffic with the worst-case scenario: (temporary) road closures. There are several measures to effectively use the term nuisance. Rijkswaterstaat (Dutch Government) uses a 7 step program (Werkwijzer Minder Hinder): 1. Smart plan 2. Smart construction 3. Mobility management 4. Traffic management 5. Communication 6. Audience-oriented implementation 7. Regional cooperation Legolizing infrastructure can be assigned to smart construction. With a modular system flexibility is created on several fronts. In any case, this is reflected in both construction speed and design speed. 4. SMART DESIGN BY USING PRECAST CONCRETE Traditionally, concrete is a material that is applied in situ. The construction parts are manufactured on the construction site. For the concrete parts, a formwork and sometimes an additional temporarily support structure needs to be built. Then reinforcement/prestressing steel will be placed. Finally, this part is ready for pouring concrete. After the concrete has attained its final strength, the process of demoulding needs to take place. This construction process is labour-intensive, which can result in a relatively long construction time. In the Netherlands, prefabricated concrete for infrastructural structures has won popularity since the 1980s. A quick construction method became important in a densely-populated country. The open field situation slowly became a utopia. With the prefabrication of concrete, especially precast girders, concrete as a material gained an additional advantage: decreased construction time. In the Netherlands, precast girders are commonplace and the next step will be a complete modular building system. This means not only precasting piles and girders, but also precasting abutments (Figure 2) and pillars (Figure 3). Eventually, complete structures can be assembled with solely using precast elements (Figure 4) and (Figure 5) fib Maastricht-paper Legolizing page 3

Figure 2: Precast abutment (Source: Gebr.

4: Precast substructure (Source: Haitsma) Figure 5: Complete

Online manual Prefab beton Ab-Fab) Since the structure is built

The connection details should be designed in a sophisticated

4 Figure 2: Precast abutment (Source: Gebr. De Koning) Figure 3: Precast pillars (Source: Strukton) Figure 4: Precast substructure (Source: Haitsma) Figure 5: Complete structure assembled with solely precast elements (Source: Online manual Prefab beton Ab-Fab) Since the structure is built in modules, there are interfaces between the elements. The connection details should be designed in a sophisticated manner. This leads to the need of a thorough preparation fib Maastricht-paper Legolizing page 4

5. PREPARATION OF PRECAST CONCRETE ELEMENTS - THE KEY TO SUCCESS The key factor for the success of applying precast elements is a thorough preparation. Several factors are playing an important role.

5 5. PREPARATION OF PRECAST CONCRETE ELEMENTS - THE KEY TO SUCCESS The key factor for the success of applying precast elements is a thorough preparation. Several factors are playing an important role. Design should be performed in terms of efficiency, speed and repetition. Further, the implementation and logistics in and around the concrete factory are important factors DESIGN The design phase will increase its refinement in time. Usually, the process starts with trade off matrices, resulting in a preliminary design of the preferred variant. In the next design phase the dimensions will be determined. Finally, a detailed design for implementation is ready so the realisation can start. In the framework of parametric design, variables need to be defined such as geometrical parameters, size of openings and reinforcement configurations. In this respect, a balance between the amount of variables and efficiency needs to be found. Interaction between designer and supplier is essential to satisfy all requirements and needs. A standard model of for instance a precast girder may be the result, where calculations and associated drawings may be automated by running a simple script. Integral design for modular systems is essential. BIM models, which nowadays are more and more common, can be a useful tool. With this tool, different parties and specialists can provide input at the right time. In this way, the feasibility of the solution throughout the design process can be secured continually. For example, traditionally a supplier of precast concrete is contracted by the contractor at the end of the engineering phase. Since this specific knowledge enters at the end of the design stage, this may result in modifications in the design at an undesirable moment in time (other disciplines are affected as well) MANUFACTURING PRECAST ELEMENTS Preparation to pour the concrete product After finishing the design, the production of precast elements can start. This starts with the preparation of the concrete part that needs to be poured. A formwork or a standard mould needs to be set up (Figure 6). The reinforcement, pretensioning steel, recesses and other utilities are positioned in the formwork under conditioned circumstances. Quality is guaranteed as this aspect typically is embedded in the suppliers production procedures. Figure 6: Standard mould box-girder (Source: Hendriks Precon) 2017-fib Maastricht-paper Legolizing page 5

5.2.2. Pouring concrete When preparation is ready, the concrete can be poured. In the composition of the concrete the mixture can be optimized in terms of, for example, product quality or costs.

Demoulding formwork of the element In the end, when the concrete has attained a minimal strength, the concrete object can be demoulded.

6 Pouring concrete When preparation is ready, the concrete can be poured. In the composition of the concrete the mixture can be optimized in terms of, for example, product quality or costs. Of course, the contract requirements must be respected and the choices must be considered in the detailing of the design Demoulding formwork of the element In the end, when the concrete has attained a minimal strength, the concrete object can be demoulded. The element can be moved to the storage area, ready for transport Chances in manufacturing Use of a central BIM (model) allows direct controlling of factory machinery, for instance to prepare cutting lists. Also reinforcement bending schemes may be exchanged with the reinforcement supplier to automate preparation of reinforcements. Finally, the use of robots will be a serious opportunity in the next future TRANSPORT When the precast concrete elements are ready, they must be transported to the construction site. In general, it is possible to transport by axle (Figure 7) or by ship (Figure 8). Important variables are the dimensions of the element and their weight. Can the construction site be reached with regular transport or are there a lot of obstacles? Examples of problems that may rise are physical impossibilities (clearance gauge) or other bridges which can resist a maximal weight smaller than the applied vehicle weight (axle loads). Maybe a license for transportation is necessary. Logistics must also be thoroughly prepared to get the precast product on the construction site on the right time. Figure 7: Transportation by axle (Source: Spanbeton) Figure 8: Transport by ship (Source: Sarens) 5.4. THE PLACEMENT OF PREFABRICATED ELEMENTS A well-structured construction planning is necessary. When parts are to be placed, lifting plans must be available. These plans must be considered thoroughly at an early stage of the preparation. For example: What type of and how many cranes are needed for a lifting operation? Is there enough free space on the construction site for these cranes to manoeuvre? After the placement of prefabricated objects, the elements must be connected in accordance to the design. With respect to the connections a variety of solutions is possible fib Maastricht-paper Legolizing page 6

6. EXAMPLES OF PARAMETRIC MODELS FOR PRECAST ELEMENTS This section shows some examples of parametric designs developed at the company of Wagemaker. 6.1.

7 6. EXAMPLES OF PARAMETRIC MODELS FOR PRECAST ELEMENTS This section shows some examples of parametric designs developed at the company of Wagemaker OQ GIRDER Introduction This new developed bridge girder has been semi-automated by Wagemaker for a precast concrete supplier in the Netherlands. This girder type is efficient in material usage, it has a fast production time and does not need post-stressing after placement. A highly effective concept in infrastructural projects with a tight time schedule. Figure 9 shows this type of girder during placement. Figure 9: Lifting of a OQ girder Process In the early stage of engineering there has been consultation with all the involved team members about standardizing the concept. By making agreements about the way of producing these elements, a list of requirements is created which the girder model should satisfy. Also the variables became clear. Every detail has been discussed. The structural analyzer, the modeler, the craftsmen and the rebar supplier all agreed on those matters. When all the members of the engineering team and production team made decisions about how to prefabricate this new girder type, Wagemaker created so called sub-scripts. All these scripts together create every possible OQ-girder within the concept agreements. Every sub-script is controlled by a parameter set. All the scripts together form the OQ girder with all its specifications for production (this also means cast-in units, rebar, pre-stressing, polystyrene). All the logical behavior of the concept is automatically calculated and modelled after the variables have been set for the project fib Maastricht-paper Legolizing page 7

$6.1.3. Experiences In the end tools are created to model a OQ-girder in a fraction of the time spend before these tools were made.$ it went in production.

8 Experiences In the end tools are created to model a OQ-girder in a fraction of the time spend before these tools were made. Not only less hours of engineering was needed, also the quality of the product became better because many processes were now automated and the product could be checked in 3D before it went in production. The created model is 100% BIM and contains all the meta data to make exports like (semiautomatic) drawings, 3D IFC models, shopping lists, volumes, bending schedules and more. The manufacturer can choose how to turn this data into production. Figure 10 illustrates examples of the models. Figure 10: Impression of Tekla-model for four different beams 2017-fib Maastricht-paper Legolizing page 8

6.2. TRANSITIONAL STRUCTURE 6.2.1. Introduction In the Netherlands we often need transitional structures behind the abutments of bridges to cope with future soil deformations.

9 6.2. TRANSITIONAL STRUCTURE Introduction In the Netherlands we often need transitional structures behind the abutments of bridges to cope with future soil deformations. These concrete plates can vary in geometry but always follow national guidelines for calculating and constructing these objects. They consume relatively more engineering time as other elements that are part of the complete (infrastructural) structure. This is why a parametric script was created to instantly create a model of these object by just determining one line in space (x,y,z) and filling in a list of parameters that determine the length, inclination angle and other parameters. All the construction data is generated automatically. The bending schemes can be exported for any machine, the model can match the integral BIM and, if desired, the construction drawings can be exported automatically. Figure 11 shows a model of a transitional structure. Figure 11: Model of a transitional structure Process When an IFC model of the total structure is imported in the modelling software (at Wagemaker this is 3D BIM), the location where the plates need to be modelled is determined. The module then automatically divides the transitional structure into elements according to the national guideline. After this step every object instantly gains detailed information (e.g. reinforcement, annotations etc.). The model is then finished, and the script also creates views to be implemented on drawing Experiences At the time the supplier of the reinforcement cages is known, we can automate the engineering for the rebar bending facility (digital data or construction drawings) and make an effective division of the elements for the contractor. There is many interest for this tool because every bridge or tunnel in the Netherlands contains these objects and they always need to be engineered. We can now offer a custommade delivery package of production data for only a fraction of the traditional price. This gives a big boost to the production efficiency fib Maastricht-paper Legolizing page 9

6.3. CHAMBER ELEMENTS 6.3.1. Introduction How far can we go with this modern technology in (civil) engineering?

This was possible by programming a script that combined parametric subscripts and let them work together to make a huge diversity in concrete products. Let us be clear: over 3.600.000.

For a precast supplier in the United Kingdom we created this one-button solution for the engineering of precast large size chambers.

10 6.3. CHAMBER ELEMENTS Introduction How far can we go with this modern technology in (civil) engineering? We are proud to announce that in 2016 we created a full automated design process with no manual engineering involved. This was possible by programming a script that combined parametric subscripts and let them work together to make a huge diversity in concrete products. Let us be clear: over possible configurations are possible (please feel free to pronounce that number)! For a precast supplier in the United Kingdom we created this one-button solution for the engineering of precast large size chambers. The calculation, structural analysis, the modelling and the output, like construction drawings, rebar schemes and amount lists are automatically generated. Figure 12 illustrates a small amount of possible chamber elements. Figure 12: Multiple chamber elements Process Only one source of input is filled in by a salesman or a customer. This can be in any form. Think about a list in excel, a website or an app on your telephone. This data (list of parameters) is the input for the automated calculation of the large sized chambers. This calculation is automatically exported into a certificate document that proofs all the rebar and concrete satisfy the national standards. Figure 13 shows two models. Figure 13: Model of a chamber structure 2017-fib Maastricht-paper Legolizing page 10

11 The result of the calculation is also split up in specific data sets. All these data sets feed dynamic components in the modeling software. Because all the dynamic components are fed with the data sets coming from one calculation, in the end everything works together as one object. Every component has its own behavior. This behavior is determined in an intensive process we developed through the years by our own experience. Please feel free to ask us more about this Experiences We see great potential in this process for future engineering issues in precast production worldwide. There is many interest for our engineering method in the precast industry. Every participant of the building team benefits from it and the quality of the product is much higher than with traditional engineered objects. For now the department Virtual design at Wagemaker continues with the most interesting objects to automate, but for the future we see many potential worldwide for this way of working. 7. CONCLUSION For the replacement of bridges and viaducts in the existing infrastructure contractors can choose for a quick construction period. This choice is mostly based on minimal nuisance for the traffic and often it is economically justified. By the use of modular systems of prefabricated concrete elements, concrete is a competitive construction material. This way of building, like all variants in construction, has some process related conditions to take into account. For example, a thorough preparation and attention for transportation and handling is required. Typically, in cases where traffic burden (e.g. temporarily roadblocks) should be limited to an absolute minimum the additional costs for transportation and handling in order to reduce construction time may be justified. There are plenty of other opportunities and innovations in precast concrete possible: Because of the fact that under conditioned circumstances elements can be manufactured, material innovations can be used optimal; Robotizing may result in more efficient production of individual elements; In terms of sustainability and the environment, precast concrete can be a competitive material. Mainly because of its recyclability; National standards and regulations should provide a framework with a certain degree of freedom for innovation and application of modular systems, although it is recognized that the structural safety should be guaranteed at all times. It is recommended to treat structural safety and innovative concepts in a responsible way without being conservative. At this moment noticeable differences among countries exist. Adopting parametric design as a new design concept for prefabricated elements is very efficient, and provides lots of opportunities in terms of efficiency, amongst others. It also reduces errors in design. Using a BIM environment will lead to more effective manufacturing processes, and also reduces the amount of errors. In short, legolizing infrastructure with precast concrete building blocks in a busy existing infrastructure We are already doing it! REFERENCES Rijkswaterstaat RWS (Dutch Ministry of Infrastructure and the Environment). Werkwijzer Minder Hinder, Deel A, de hoofdlijn. (2009) fib Maastricht-paper Legolizing page 11

RAPID CONSTRUCTION-INOVATIVE APPROCH OF PREFABRICATED CONSTRUCTION

RAPID CONSTRUCTION-INOVATIVE APPROCH OF PREFABRICATED CONSTRUCTION Krushil K. Ponkiya 1, Dhyey K. Shah 2, Rushabh A. Shah 3 PG. Student, SNPIT & RC, Umrakh, Gujarat, India 1 PG. Student SNPIT & RC, Umrakh,