Strength of Bolted Bamboo Laminate Connections

Transcription

1 Strength of Bolted Bmboo Lminte Connections Shwn PLATT 1 nd Kent A. HARRIES 1, 1 University of Pittsburgh, Civil nd Environmentl Engineering, Pittsburgh, PA USA khrries@pitt.edu Keywords: bmboo, compression, flexure, sher, test methods. Abstrct. This pper presents n experimentl progrm investigting the open-hole tension cpcity nd the effects of stggered open-holes on the cpcity of engineered bmboo strip product. The strip is being developed s n lterntive mens of repiring or retrofitting dmged timber structurl members. The strips displyed relible ptterns of mteril behviour. Net section reduction fctors ccounting for the stress-rising effect of the holes were identified. The impct of stggering the holes ws observed to depend on the spcing between holes. Introduction With n ging infrstructure comes greter need for repirs nd even greter need for pproprite mterils, mens nd methods for those repirs. Additionlly, recent interest hs been redirected from trditionl products to focus of environmentl concerns nd sustinbility. In the cse of timber-frmed building or bridge, replcing dmged timber my be imprcticl, costly or estheticlly unplesing; prticulrly in the cse of historicl preservtion, replcement my be prohibited. With repir being the most cost effective option in mny cses, the question becomes wht kind of repir nd with wht kind of mteril? Trditionlly repirs would often be completed using steel plte bolted nd/or dhered to the dmged timber. Such repir hs some limittions nd potentilly dverse effects on both the fbric nd performnce of the structure. For historicl repir, the use of dhesives my be prohibited s the repir must be ble to be reversed t some time in the future [1]. Secondly, the introduction of mteril with properties tht significntly differ from the prent mteril my result in chnges in the performnce of the system tht could, for instnce, promote or mgnify dmge in other res of the system s result of ltered lod pths. In mny res, fibre reinforced polymer (FRP) composites re t the forefront of repir technology [2]. Bmboo, n old mteril being rediscovered due lrgely to its sustinble credentils, hs been used in construction for millenni nd could be considered nture s originl FRP. Bmboo is composed of vsculr bundles consisting of longitudinl fibers bound together with lignin mtrix. The fibres re the source of bmboo s superior mechnicl properties (including tensile cpcity nd toughness) but lso mke designing with bmboo unlike designing with most conventionl mterils [3]. There hve been mny investigtions into the properties of full-culm bmboo [4, 5, 6]. But the use of the full-culm bmboo in construction is limited nd its use s potentil repir mteril imprcticl, despite its fvourble mechnicl properties. Tking dvntge of superior mechnicl properties, bmboo hs been incorported into pplictions s diverse s flooring nd gluelminted members or glubm [7]; reinforcement for concrete nd msonry [8], nd; reinforcing fibres for mortrs nd polymers [9]. Nonetheless, the FRP-like spect of bmboo mterils (superior, lthough highly nisotropic mechnicl properties) hs not been leverged in mny cses; this hs led to our interest in the repir field. The focus of this study is the ppliction of mnufctured bmboo strips for structurl repir used in mnner similr to modern FRP methods [2]. The ppliction envisioned is the repir of timber structures for which bmboo, it is proposed, offers n estheticlly similr or virtully invisible lterntive. The comprble stiffness of bmboo nd timber results in more nturl interfce mitigting induced stress risers often ssocited with structurl repirs. The tensile strength of bmboo is generlly superior to tht of most species of timber, thereby not only

2 repiring but potentilly strengthening the originl structure without compromising esthetics or the rchitecturl fbric of the structure. With n emphsis on repir of historic or rchitecturlly sensitive structures, bolted externl repirs, rther thn dhesively bonded, re preferred [1]. When compred to isotropic mterils such s steel, bolted connections in n orthotropic mteril such s most FRP mterils nd bmboo, will redistribute stresses mrkedly differently. The nisotropic nd reltively brittle nture of bmboo nd mnufctured bmboo strips render conventionl ssumptions of net section design inpproprite [10]. Furthermore, even dopting guidnce for orthotropic mterils is likely inpproprite since the degree of nisotropy the rtio of longitudinl to trnsverse mteril properties is typiclly much greter for bmboo. Mny studies hve ddressed the engineering properties of full-culm bmboo including some tht hve ddressed the cpcity of bolted connections [4, 5]. Arce-Villlobos [11] found the trnsverse tensile modulus of elsticity to be pproximtely one eighth of tht mesured in the longitudinl direction nd concluded tht the mjority of fittings bsed on some sort of penetrtion normlly used in construction (nils, bolts, pegs) re not suitble for bmboo becuse they crete high tngentil stresses. These previous studies explored the properties of full-culm bmboo; however, there remins need to ddress the properties of new engineered products. There is no previous reserch known tht proposes the use of engineering bmboo s potentil repir mteril. Objective Using limit sttes pproch, it is necessry to ddress ll mnners by which structure or element my fil nd design for these. The focus of the current work is on bolted connections for engineered bmboo-strip repirs of timber members. The limits sttes of the connection include bolt sher; bering/splitting of bmboo; sher-out of bmboo, nd net section filure of bmboo. In the present work steel bolts re considered, in which cse bolt sher is not controlling limit stte. For connections requiring multiple bolts, providing stggered bolt geometry will generlly be more compct nd better engge djcent bolts by reducing the shdowing effect long the direction of the pplied lod. In isotropic mterils, the effect of stggering bolts is to increse the net section tensile cpcity since the filure pth between djcent stggered bolts is longer thn the pth cross the plne net section [12]. Recent studies of the open-hole tension cpcity of highly nisotropic FRP mterils [10] concluded tht the effect of stgger is reduced or negligible in such mterils. The effect of stggered connection geometry is considered in the present study. Experimentl Progrm Direct tension tests of open-hole nd bolted lp-spliced specimens of engineered bmboo strip were conducted. Open-hole tests ssess net section filure criteri while bolted lp-splices ssess bering, splitting nd sher filures of the bmboo strips. All tests were conducted in 600 kn cpcity universl test mchine hving hydrulic grips wider thn the specimen width, ensuring uniform ppliction of stress t the specimen ends. Engineered Bmboo Strip Mteril obtined from Chin ws used in the present study. The strips were fbricted of lminted rdil-cut bmboo nd hve nominl thickness of t = 6.4 mm (Figure 1). Two types of strip were used: nturl (two different btches) nd crmelized. Crmelised strips re nturl strips tht hve been heted in order to crmelise their lignin, thereby drkening the colour of the strip. Specimens pproximtely 89 mm wide nd 406 mm long were cut from the 203 mm wide strips. Longitudinl (L) nd trnsverse (T) mteril properties were obtined from specimens hving no holes s indicted in Tble 1. Secnt modulus of elsticity ws clculted between 0.2Fu nd 0.4Fu in ll cses. As cn be seen, the degree of nisotropy in terms of strength nd modulus (i.e., L/T) is significnt. Little difference ws observed between the nturl nd crmelised bmboo products with the exception of the trnsverse tension strength (FuT) which ws notbly lower thn the longitudinl. This is n indiction tht the crmelistion process dversely ffects the lignin mtrix but not the bmboo fibres.

3 ) 89 mm by 6.4 mm lminted bmboo strips ech b) 20 mm wide rdilly cut strip (nturl) hving five lminted rdilly-cut sections of culm. Nturl (top) nd crmelized (bottom) shown. Figure 1 Engineered bmboo strip mteril. Tble 1 Averge bmboo strip mteril properties. mx. stress, Fu modulus, E test specimens mteril orienttion FuL/FuT MP (COV) MP (COV) L 94.9 (0.11) (0.08) nturl 14.0 Btch 1: open hole (Tble 2) nd T 6.79 (0.11) 874 (0.20) single gge bolted (Tble 3) L 92.5 (0.12) 8746 (0.14) crmelised 22.8 T 4.06 (0.15) 1114 (0.25) Btch 2: multiple gge nd L 91.8 (0.12) 9640 (0.00) nturl 11.7 stggered bolted (Tble 4) nd BP T 7.83 (0.10_ 1403 (0.09) EL/ET Open-Hole Specimens. Thirteen open-hole geometries (OA-ON) were tested s shown in Tble 2 ech consisting of 3 to 5 specimens (smple size, n). Specimens hd from 0 to 3 holes (N) hving dimeter (h) of 12.7 or 25.4 mm with spcing (s) nd gges (g) rnging from 0 to 51 mm. Due to mteril vilbility, not every geometry ws tested with both mterils. A typicl specimen hving mm holes t gge of 25.4 mm is shown in Figure 2. Tble 2 Open-hole specimen geometry. geometry A OB OC OD OE OF OG OH OJ OK OL OM ON N g (mm.) s (mm) ) 89 mm wide open-hole specimen hving mm holes t gge of 25.4 mm b) 89 mm wide bolted lp splice specimen hving mm bolts t spcing, s = 50.8 mm. Figure 2 Direct tension tests.

4 Bolted Lp-splice Specimens consisted of two 89 x 6.4 mm strips bolted together s shown in Figure 3. Two different btches of nturl strips (Tble 1) were used. Spcers were provided t ech grip loction to ensure concentric lod ppliction long the lp splice fying surfce. ASTM A307 Grde A bolts (tensile strength = 414 MP) hving nominl dimeter of 12.7 mm (mesured dimeter of 12.4 mm) were used. The sher cpcity of one bolt exceeds the tension cpcity of the 89 x 6.4 mm bmboo strips; thus bolt sher is not limit stte of concern. Although the sme bolt ws used for ll tests, two hole dimeters (h) were used: 12.7 nd 25.4 mm. The bolts were inserted directly into the 12.7 mm holes while steel sleeves hving 25.4 mm OD nd 12.7 mm ID were used in the 25.4 mm holes s shown in Figure 3. The sleeves were mchined such tht they were 12.7 mm long nd did not protrude beyond the lpped bmboo strips. The sleeves provide lrger bering re ginst the bmboo without the need of providing lrger bolt. Wshers hving 35 mm OD (single gge B-specimens) or 25 mm OD (multiple gge S-specimens) were instlled under both the bolt hed nd nut. All holes were drilled with brd bit in order to minimise dmge to the bmboo fibres in the immedite vicinity of the hole. All bolts were tightened only finger tight so s to not crush the bmboo through its thickness. Figure 3 Bolted lp-splice specimen geometry. Thirteen geometries (BB-BP), shown in Tble 3, included single gge line of from 1 to 6 bolts (N) hving spcing (s) nd edge distnces (Lc) rnging from 51 to 152 mm. All single gge specimen were fbricted with nturl bmboo strips from btch 1 (Tble 1) except BP which ws from btch 2. A typicl specimen hving mm bolts t spcing of 50.8 mm is shown in Figure 2b. Similr to the open-hole geometries considered, nine geometries (SB-SK), shown in Tble 4, of bolted lp-splice hving from 1 to 3 bolts (N) hve gges (g) of 25.4 or 38.1 mm nd spcing (s) rnging from 25.4 to 76.2 mm were considered. The edge distnce (Lc) for ll S-geometry specimens ws constnt t 102 mm. All S-geometry specimens were fbricted with nturl bmboo strips from btch 2 (Tble 1).

5 Tble 3 Single gge bolted lp-splice specimen geometry. geometry A BB BC BD BE BF BG BH BJ BK BL BM BN BP N s (mm) L C (mm) Tble 4 Multiple gge nd stggered bolted lp-splice specimen geometry. geometry A SB SC SD SE SF SG SH SJ SK N g (mm.) s (mm) L C (mm) Open Hole Test Results Specimens tested hving only single row of bolts (i.e. s = 0) demonstrted some reduction in open-hole tensile cpcity (Tn) beyond the clculted effect of net section re (An = Ag Nht) s described by the fctor k in Eq. 1. This is n indiction of the stress-concentrting effect of the holes. Tn = kful(ag Nht) (1) In which FuL is the nominl (no-hole) longitudinl tensile cpcity given in Tble 1, Ag is the gross sections re nd Nht is the re represented by N holes of dimeter h through the strip thickness t. As shown in Tble 5, for the nturl bmboo mteril, the observed open-hole strength reduction ws ner unity for 12.7 mm dimeter holes nd k 0.8 for 25 mm holes. The vlue of k 0.9 for 12.7 mm holes in the crmelized mteril. These vlues of k re greter thn comprble vlues observed in GFRP mterils [10] s should be expected due to the greter degree of nisotropy in the bmboo.

6 Tble 5 Averge open-hole strength of bmboo strip hving single row of holes. nturl mteril crmelised mteril h g mx. strength mx. strength geometry N stress, Fu reduction, k filure stress, Fu reduction, k filure mm mm MP mode mode F (COV) u/f MP u, N=0 F (COV) u/f u, N=0 A (0.11) (0.12) - OB (0.10) 0.90 I (0.13) 0.87 I-b OC (0.05) 1.05 I (0.06) 0.92 I-c OD (0.05) 0.95 I-b 77.8 (0.17) 0.94 I-b OJ (0.07) 1.03 I-c 84.1 (0.22) 0.91 I-d OB (0.17) 0.78 I OD (0.10) 0.83 I-b normlised by geometry A Filure modes observed for open-hole specimens re shown in Figure 4. These were combintion of sher (I-) nd splitting (I-b) for one nd two holes. When third hole is introduced, the net re is reduced to the point where net section rupture (I-c) is observed. For the crmelised mteril hving notbly lower trnsverse strength multiple longitudinl sher plnes formed (I-d). I-: sher rupture emnting from hole I-b: longitudinl splitting I-c: net section frcture I-d: longitudinl splitting of stggered hole rrngements (note initilly continuous horizontl lines) Figure 4 Filure modes observed in open-hole tests. Effect of Stgger. Tble 6 shows results from cses in which stggered hole lines were tested. Only 12.7 mm dimeter holes were considered nd, due to limited mteril vilbility, only crmelized mterils were tested (Tble 1). For the cse of stggered connection, the stress, Fu, is clculted bsed on plne net section ccounting for ll holes cross the section (i.e., An = Ag Nht) regrdless of stgger spcing (s). Longitudinl splitting filures (I-b nd I-d) dominted the stggered open-hole behviour. Tble 6 Averge open-hole cpcity nd observed effect of hole stgger (crmelised mteril). geometry N g s c-to-c mx. stress, Fu effect of stgger Filure mm mm mm MP (COV) F u/f u, s=0 type OC (0.06) - I-b OD (0.17) - I-b OE (0.10) 1.10 I-b OF (0.05) 1.10 I-b OG (0.12) 1.12 I-b OH (0.04) 0.95 I-b OJ (0.22) - I-c OK (0.06) 0.84 b I-d OL (0.13) 0.97 I-d OM (0.07) 1.00 b I-d ON (0.05) 1.20 I-d normlised by geometry OC, OD or OJ hving sme vlue of g b normlized by geometry OJ hving g = 25

7 While the results of this pilot study re not conclusive, providing stgger is observed to increse the open-hole cpcity mrginlly provided dequte spcing between the holes is provided. Providing digonl center-to-center distnce (c-to-c, in Tble 6) of more thn 51 mm (4 hole dimeters) resulted in n increse in net section strength. Below 51 mm, interction between stress concentrtions developed t the holes is believed to occur resulting in reduction in net section cpcity. Further study is required to verify nd quntify this effect. Bolted Lp-splice Test Results Figure 5 identifies nd provides exmples of the rnge of filure modes observed in the bolted lp-splice tests. In some cses, the chnge of filure mode with vrying prmeters helps to identify the limit sttes of the connection s is discussed in the following sections. Type II: longitudinl splitting of bolted connection (three exmples shown) Type III: net section rupture of bolted connection Type IV: Sher-out filure of bolted connection (three exmples shown) Type V: block sher of bolted connection (three exmples shown) Type VI: bmboo crushing ( plowing ) Figure 5 Filure modes observed in bolted tests. Type VII: pull-through

8 Tble 7 summrises the cpcities of the single gge bolted connections described in Tble 3 while Tble 8 summrises the cpcities of the multiple gge nd stggered bolt connection tests described in Tble 4. Significntly, no bolted tests pproched the cpcity of the bmboo strips (reported s geometry A in ech tble. Net section rupture (filure mode III) ws only observed in few cses nd typiclly only in cses where multiple bolts incresed the cpcity of the connection. geometry geometry Tble 7 Averge strength of single gge bolted connections. N h s Lc mx. lod, Pu multiple of single bolt cpcity filure modes mm mm mm kn (COV) P u/p b u, s=0 A (0.11) - - BB (0.07) - IV BC (0.06) 1.13 II, IV BD (0.05) 1.25 II, VI BE (0.15) 1.55 II BF (0.01) 1.72 IV BG (0.03) 2.28 IV BH (0.07) 2.04 IV BJ (0.10) 2.62 III BK (0.05) 3.05 IV BL (0.10) 3.44 IV BM (0.05) 4.36 IV, III BP (0.03) 3.86 IV BN (0.22) 4.18 III BB (0.24) - IV BC (0.12) 1.40 II, VII BE (0.05) 2.07 IV normlized by geometry BB (N = 1) hving sme vlue of L c nd h Tble 8 Averge strength of multiple gge nd stggered bolted connections. N h g s c-to-c mx. lod, Pu multiple of single bolt cpcity mm mm mm mm kn (COV) P u/p u, N=1 effect of stgger filure modes A (0.12) - - SB (0.06) - - IV SC (0.07) IV, V SD (0.01) II, IV, V SE (0.02) III SF (0.17) V SG (0.06) II, IV, V SH (0.06) IV, V SJ (0.10) II SK (0.05) II normlized by geometry SB hving N = 1 b normlised by geometry SE hving s = 0 Multiple Bolts, N. For isotropic ductile mterils such s steel, the cpcity of bolted connection is the sum of the cpcities (regrdless of limit stte) of the individul bolts. Essentilly, ll bolts in connection re ssumed to resist connection forces eqully. This is not the cse for nisotropic nd/or non-ductile mterils such the bmboo strips tested in this study. As shown in

9 multiple of single bolt cpcity Tbles 7 nd 8, there is reduction ssocited with the cpcity of multiple bolt connections. As shown in Figure 6, for N 5 bolts, the cpcity of the bolted connection, Pu, is well represented by: Pu = 0.85NPu1 (2) In which Pu1 is the cpcity of single bolt (geometry BB, BC or SB) regrdless of other connection prmeters BB, BC & SB SC & SD BF BE BK BJ single row; s = 0 single gge line; s = L c = 50.8 mm single gge line; s = L c = 102 mm number of bolts in connection, N Figure 6 Reltive cpcities of connections hving multiple bolts. Leding Edge Distnce, Lc. By compring the trnsition of filure modes s Lc is incresed from 50.8 mm (BB) to 102 mm (BC) nd finlly to 152 mm (BD) n understnding n pproximtion of the of the bolt limit sttes my be mde s shown in Tble 9. The longitudinl sher cpcity of the strips resisting the Type IV sher out filure flls between 6 10 MP. The bering cpcity corresponding to Type I filure is essentilly equl to the longitudinl cpcity of the mteril reported in Tble 1. The bering ssocited with Type II splitting filure is lso very close to, lthough lower thn this vlue bsed on the hierrchy of filures observed. Tble 9 Summry of the effect of leding edge distnce nd ssocited single bolt filure modes. stress resulting from Pu geometry Lc Pu sher out (IV) bering force (VI) filure mode P u/(2l ct) P u/ht mm kn MP MP BB IV BC II, IV BD II, VI Longitudinl Bolt Spcing, s. Bolts ligned in the sme longitudinl gge shdow ech other. The leding bolt crries more lod, shdowing the triling bolts. For this reson minimum bolt spcing is conventionlly prescribed [e.g., 12]. In compring the results of ll specimens hving N = 2 bolts, it is seen tht BE, hving s = 50.8 mm, hs lower cpcity thn the other specimens hving s 102 mm. This is n indiction tht the spcing, s, required to ensure tht the cpcity of ll bolts long gge line re engged is pproximtely 102 mm, or 8 bolt dimeters, since the cpcity does not pper to increse for s > 102 mm. SE BL BM BN BP

10 Tble 10 Cpcities of specimens hving N = 2. BE BF BG BH SC SD s 50.8 mm 102 mm 102 mm 152 mm - - Pu 10.7 kn 13.5 kn 15.8 kn 14.1 kn 14.1 kn 13.8 kn Bolt Dimeter. Only three geometries were tested with 12.7 mm bolts nd 25.4 mm bolt sleeves. There ws no significnt difference in the cpcities or filure modes of single bolts connections (BB nd BC) lthough single BC specimen exhibited Type VII pull-through filure which my hve resulted from the bolt not being sufficiently tightened. For two bolts in single gge line (geometry BE), the lrger bolt sleeve resulted in trnsition from splitting (Type II) to sher out (Type IV) filure nd mrginlly greter cpcity. The wider bering re is believed to hve reduced the concentrted stress tht initites the splitting (II) filure lthough more study of this effect is necessry. Effect of Stgger. Similr to the open-hole tests, lthough more pronounced, the effect of stggering the bolts ws to increse the cpcity of the connection reltive to single row of bolts (see Tble 8). For geometries in which the stggered holes re reltively close, complex block sher (Type V) filure ws observed. This filure is combintion of longitudinl splitting nd sher or tension rupture (See Figure 4). In stggered connection, longitudinl splitting filure will initite n unblnced force cross section due to the loss of bolt symmetry; this leds to the subsequent sher or tension rupture portion of the filure. Conclusions This experimentl progrm investigted the limit sttes ssocited with bolted connections of n engineered bmboo strip product. Open-hole tests ssessed net section filure criteri while bolted lp-splices ssessed bering, splitting nd sher filures of the bmboo strips. Bolted connection limits sttes were observed to dominte behviour over tht of open-hole net section cpcity. Two btches of the bmboo strip mteril obtined from the sme source were used in this study. Some vrition of mteril properties ws seen between these nd significnt loss of lignindominted trnsverse properties ws observed for crmelised version of the mteril. As result, it is recommended tht only the nturl form of the strips be used in structurl pplictions. Open-hole tests of the strips displyed relible ptterns of mteril behviour. Net section reduction fctors ccounting for the stress-rising effect of the holes were identified to be function of hole dimeter nd mteril nisotropy. While no net section reduction ws observed for 12.7 mm holes in n 89 mm wide specimen, reduction fctor of 0.8 ws observed for 25.4 mm holes in the sme mteril. A reduction of 0.9 ws observed for 12.7 mm holes in crmelised mteril in which the trnsverse mteril properties re reduced (Tble 1). The impct of stggering the holes ws observed to depend on the spcing between holes. Additionl study is necessry to quntify these effects since the effect of introducing the hole is detrimentl (Tble 6), while the effect of stggering the holes my counterct this effect (Tble 6). Continued study using digitl imge correltion is plnned nd should help to ddress the pprent interction observed. Bolted lp-splice tests identified number of limit sttes nd provided initil guidnce for designing bolted connections of the engineering bmboo strip mteril considered. In no cse ws the bolted connection tested ble to rech the net section rupture cpcity of the bmboo strip indicting tht this limit stte is unlikely to be criticl in the envisioned connections. Connections hving multiple bolts exhibited mrginlly reduced proportionl cpcity. For connections with fewer thn five bolts, only bout 85% of the sum of the single bolt cpcities could be chieved. A leding edge distnce, Lc, of 152 mm, corresponding to 12 bolt dimeters, is necessry to develop the bering cpcity of the bolted connection ginst the bmboo. Additionlly, the longitudinl sher-out cpcity of the strip ws determined to fll between 6 nd 10 MP, requiring Lc > 102 mm (8 bolt dimeters) to mitigte this filure. For vlues of Lc between 8 nd 12 bolt dimeters, splitting filure ws observed. Similrly, for bolts in the sme gge line, longitudinl

11 spcing, s exceeding 102 mm (8 bolt dimeters) is required to ensure tht the cpcity of the djcent bolts is obtined. The results of this pilot study indicte tht engineered bmboo strip mteril my represent vible lterntive for tensile-driven repirs of timber structures. The strips themselves exhibited mteril properties similr to those of timber while the bolted connections demonstrte predictble limits sttes behviour. Acknowledgements Testing ws conducted in the University of Pittsburgh s Wtkins-Hggrt Structurl Engineering Lbortory (WHSEL). Mterils were provided by Dr. Qingfeng Xu of the Shnghi Reserch Institute of Building Sciences. Funding ws provided by WHSEL, the University of Pittsburgh Swnson School Of Engineering, nd the Office of the Provost. References [1] United Sttes Deprtment of the Interior, The Secretry of the interior s Stndrds for the Tretment of Historic Properties with Guidelines for Preserving, Rehbilitting, Restoring nd Reconstructing Historic Buildings, Ntionl Prk Service, Wshington, DC.188 pp, [2] Americn Concrete Institute (ACI), ACI 440.2R-08 Guide for the Design nd Construction of Externlly Bonded FRP Systems for Strengthening of Concrete Structures, Americn Concrete Institute, Frmington Hills, MI, USA, [3] Hrries, K.A., Shrm, B. nd Richrd, M.J., Structurl Use of Full Culm Bmboo: The Pth to Stndrdiztion, Interntionl Journl of Architecture, Engineering nd Construction. 1(2) (2012) [4] Jnssen, J., Bmboo in building structures. PhD Thesis, Eindhoven University, Eindhoven, The Netherlnds, [5] Shrm, B., Seismic Performnce of Bmboo Structures. PhD Thesis, University of Pittsburgh, [6] Richrd, M.J., Assessing the Performnce of Bmboo Structurl Components. PhD Thesis, University of Pittsburgh, [7] Xio, Y., Shn, B., Chen, G., Zhou, Q., nd She L.Y., Development of new type of Glulm Glubm. Modern Bmboo Structures, Xio, Y., Inoue, M., nd Pudel S.K., eds., London, UK, (2008). [8] Ghvmi, K., Bmboo s reinforcement in structurl concrete elements. Cement nd Concrete Composites, 27 (2005) [9] Li, F., Liu, Y.F., Gou, M., Zhng, R. nd Du, J., Reserch on Strengthening Mechnism of Bmboo Fiber Concrete under Splitting Tensile Lod, Advnced Mterils Reserch, (2011) [10] Cunninghm, D., Hrries, K.A. nd Bell, A.J., Open-Hole Tension Cpcity of Pultruded GFRP Hving Stggered Hole Arrngement, Engineering Structures, 95 (2015) [11] Arce-Villlobos, O., Fundmentls of the design of bmboo structures. PhD Thesis, Eindhoven University, Eindhoven, The Netherlnds, [12] AISC, Specifiction for Structurl Steel Buildings. ANSI/AISC Americn Institute for Steel Construction, Chicgo, IL, 2010