Hybrid RC Building Structures with Corrugated Steel Shear Panels

Transcription

1 Creting nd Renewing Urbn Structures 1 Hybrid RC Building Structures with Corrugted Steel Sher Pnels Susumu KONO Associte Professor Dept. of Architecture Kyoto University Kyoto, JAPAN kono@rchi.kyoto-u.c.jp Susumu Kono, born 1963, received his Ph. D. from the Univ. of Illinois. Yukko ICHIOKA Ph. D. Cndidte Dept. of Architecture Kyoto University Kyoto, JAPAN rc.ichiok@rchi.kyoto-u.c.jp Yukko Ichiok, born 198, received her MA degree from Kyoto University. Yoshihiro OHTA Structurl Engineer Tkenk Reserch & Development Institute, Tkenk Corp., Jpn oht.yoshihiro@tkenk.co.jp Yoshihiro Oht, born 196, received his MA degree from Kyoto University. Fumio WATANABE Professor Emeritus Dept. of Architecture Kyoto University Kyoto, JAPAN kono@rchi.kyoto-u.c.jp Fumio Wtnbe, born 1944, received his Ph. D. from Kyoto University. Summry This reserch ims to estblish n economicl seismic response controlling system of RC frmes using corrugted steel sher pnels (CSSP), which ws originlly proposed for building structures by Mo nd Perng in. The hybrid system with CSSP hs lrge ductility nd possibly decreses to construction cost by lrge mount. The dvntge of using CSSP in described from the design view point. Then, the experimentl work on two specimens is introduced to show the excellence of CSSP in resisting the seismic force. A stud-type nchorge ws employed in two hlf-scle specimens to fix CSSP to the surrounding RC frme. The degrdtion of lterl lod crrying cpcity fter the pek lod ws smll compred to reinforced concrete sher wlls (RCW) due to stble mnner of yielding nd buckling of CSSP. The finl filure mode of the hybrid system ws the tering of CSSP nd the formtion of collpse mechnism of the surrounding reinforced concrete frme. Keywords: Corrugted steel sher pnel (CSSP); dmge control; sher wll; stud nchorge. 1. Introduction It is common prctice to use reinforced concrete sher wlls (RCW) in reinforced concrete structures to mintin high lterl lod crrying cpcity nd stiffness. However, high lterl stiffness with brittle ultimte filure mode of RCW often increses the required lterl lod crrying cpcity. In order to improve the ductility of reinforced concrete sher wlls, some efforts hve been mde such s using low yield strength reinforcement nd introducing slits but the ductility enhncement ws not very prominent. Use of steel sher wlls in order to increse ductility hs some decdes of reserch history. In 1973, Tkhshi et l. [1] studied the chrcteristics of loddeflection reltions of flt steel sher pnels obtined experimentlly nd reported the effects of

2 2 17TH CONGRESS OF IABSE, CHICAGO, 8 configurtion, width-thickness rtio, stiffeners stiffness, etc. on the lod-deflection reltions. Studies on steel sher wlls hve been continuing since then [2][3]. However, flt steel sher pnels need stiffeners to prevent plte buckling, leding to the increse of self-weight nd cost. In order to solve these problems, corrugted steel sher pnels (CSSP) hve been used in bridge structures since lte 198s. They weigh less nd decese prestressing loss due to their negligible xil stiffness compred to flt steel sher pnels reinforced with stiffeners. In, Mo nd Perng [4] reported use of corrugted steel sher pnels s min lterl lod crrying component for building structures. They reported tht CSSP re effective to dely buckling of sher pnels. However, bolt nchorge fstening CSSP to the surrounding RC frme ws not very effective nd lrge slip took plce t the interfce resulting in pinched hysteresis loops with smll energy dissiption. Their test results provided interesting informtion on the potentil cpbility of CSSP but CSSP hs not been used in prctice s min lterl lod crrying component. This pper proposes the use of CSSP s sher wlls insted of RCW by introducing the experimentl work on RC portl frmes with CPPS. The stud-type nchorge of CSSP used in bridge girders ws employed to fully utilize the sher cpcity nd stiffness of CSSP. CSSP hs lrger buckling strength thn the flt sher pnel due to its configurtion, with negligible flexurl nd xil stiffness. CSSP dissiptes much greter energy fter the pek lod compred to RCW. If CSSP is employed s min lterl lod crrying component in building structures, it is possible to ssign verticl lod to columns nd sher lod to corrugted steel sher pnels, resulting in cler design philosophy. In ddition, the ductility fter sher yielding or even fter buckling is excellent nd it is possible to decrese the required lterl lod crrying cpcity. 2. Use of corrugted steel sher pnels in design CSSP hs mny dvntges over RCW if it is used s min lterl lod crrying component in building structures s summrized in Tble 1. When n RC frme with CSSP is subjected to lterl force, sher deformtion domintes. Hence, CSSP deforms in sher nd the whole pnel evenly dissipte energy fter yielding. Energy is dissipted even fter the buckling of the pnel. CSSP does not exhibit ny noticeble dmge until the buckling, which tkes plce t reltively lrge deformtion. Uniform deformtion of CSSP cuses uniform stress distribution to the surrounding RC frme nd dmge does not loclize in the RC frme either. Since the sher stiffness nd Tble 1: Comprison between corrugted steel sher wlls nd reinforced concrete sher wlls CSSP (Corrugted steel sher pnels) RCW (Reinforced concrete structurl wlls) Deformtion Uniform sher deformtion is lwys dominnt Deformtion loclizes if flexure mode is dominnt. Weight Light Hevy Crcking None Possible Energy dissiption Lrge Low

3 Creting nd Renewing Urbn Structures 3 strength of CSSP is bout ten times higher thn tht of RCW nd the density is bout eight times lrger, CSSP tends to weigh less thn RCW if two components hve equivlent sher stiffness nd strength. One of the most ttrctive dvntge of CSSP is its lrge energy dissiption cpbility fter yielding. The energy dissiption cpbility does not degrde very much even fter buckling. Lrge ductility of CSSP produces nother dvntge in design s schemticlly shown. In Figure 1, the required sher cpcity, Qu, is divided by the elstic design sher force, Qe, for the ordinte. When RCW is incorported in RC frmes, required sher cpcity becomes high becuse of the brittle filure mode of RCW. However, CSSP is incorported in RC frmes, the required sher cpcity cn be drsticlly decresed due to its ductility. In the figure, Qu/Qe is required to exceed.4 for RC frme with RCW but.3 for RC frme with CSSP. The reduced requirement on Qu for RC frme with CSSP decreses the design force on ll structurl members, leding to lrge cost sving. Following chpters show experimentl works to demonstrte the dt supporting interesting fetures of CSSP explined in this chpter..4.4 R C frm e w ith RC sherw ll.3.3 R C frm e w ith sher pnel Q u/q e.2.2 RC sherw ll Sher pnel.1.1 R C frm e Drift (%) Figure 1. Required sher cpcity - drift ngle reltion

4 4 17TH CONGRESS OF IABSE, CHICAGO, 8 3. Experiment 3.1 Setup Specimens were mde of reinforced concrete portl frme with different nchorge configurtions of corrugted steel sher pnels. Dimensions of four RC frmes re identicl s shown in Figure 2 nd test vribles re shown in Tble 2. Two sher pnels hd flnge t the four side nd two verticl stiffeners s shown in Figure 3. Thickness of flnge nd stiffeners were 4.mm. Mechnicl properties of mterils re listed in Tble () Specimen dimensions Be m width = Cov er =2 Longitudinl rebr 8- D13 (SD34) Sher rebr 3- D6@ ( KSPD8) Cov er =2 1 Longitudinl rebr 4- D16 (SD34) Sher rebr 2- D6@ ( KSPD8) (b) reinforcement of columns (c) reinforcement of bem (d) Dimensions of the corrugted steel sher pnel used in the experiment. (e) Specimen A Figure 2. Dimensions nd reinforcement rrngement of specimens (Unit:mm) t= 4. 12@ t= 4. 12@ 1 t= 4. t= 1 St iffner t = 4. Line 1 St iffner t = 4. Line C () A (Double studs) (b) B (Stggered studs) Figure 3. Dimensions of sher pnels (Unit:mm. Ech stud hd 9mm-dimeter bolt with hed) Tble 2: Test vribles Anchorge of the A rrngem ent of studs corrugted sher Specimen pnelto the surrounding frm e Horizontljoints V erticljoints (N o.of studs) (N o.of studs) A φ9 double@ 1 (26) φ9 double@ 1 (12) studs B φ9 stggered@ 1 (13) φ9 stggered@ 1 (6) * φ 9 double@67. ws used t the end region.

5 Creting nd Renewing Urbn Structures Tble 3: Mechnicl properties of mterils () Concrete (b) Steel Compressive strength (M P ) Tensile strength (M P ) Young's modulus (G P ) Concrete M ortr Type Yield strength (M P ) Tensile strength (M P ) Young's modulus (G P ) D D D C orrugted pnel Flnge plte Stud The number of studs of Specimen A ws determined bsed on the following eqution. ( p p ) ( q q ) (1) where p is the design tension force, q is the design sher force, p is the tensile strength when the stud experiences tension only, q is the sher strength when the stud experiences sher force only. The tensile strength, p, is the minimum vlue of 1) tensile strength due to cone filure of surrounding concrete, 2) tensile strength due to tensile yielding of the stud, nd 3) tensile strength due to bering filure of concrete. The sher strength, q, is the minimum vlue of 1) sher strength due to bering filure of concrete, nd 2) sher strength due to sher yielding of the stud. The design tensile force, p, nd the design sher force, q, were obtined from elstic FEM nlysis. When the sher pnel reched the yield strength, the mximum norml stress ws 31. N/mm 2 nd the verge sher stress ws 16 N/mm 2 t the upper edge of the sher pnel, which were substituted in p nd q. Using of double studs of φ 9 t 1 mm spcing, the left side of Eq. (1) becme.99 nd the eqution ws just stisfied. This determined the number of studs t the upper horizontl joint of Specimen A. The other interfces were similrly computed. The mximum number of studs in four interfces ws tken fter ll. The number of studs ws simply hlved in Specimen B. kn hydrulic jck Loding frme 1kN hydrulic jck Lod cell Lod cell Lod cell 1kN hydrulic jck North South Rection floor Figure 4. Loding system

6 6 17TH CONGRESS OF IABSE, CHICAGO, 8 Figure 4 shows the loding system. Constnt xil lod of 36 kn (Axil lod level.1) ws introduced to ech column. Equl mgnitude of lterl lod ws pplied to the both ends of the bem by two 1 kn hydrulic jcks. Two cycles of lterl lod ws pplied t ±1 kn nd ±2 kn. Then two cycles of preselected drift ws enforced t ±.1%,±.2%,±.4%,±.6%, ±.8%,±1.%,±2.%,±4.%. 3.2 Test results Lterl lod drift reltions Figure shows the lterl lod drift reltions up to R=4.%. Both specimens showed similrly ft hysteresis loops up to the pek lod t which buckling took plce. Even fter the buckling, the degrdtion of lod crrying cpcity ws not drstic s RC sher wlls filing in sher nd resonble mount of energy ws dissipted. Specimen B experienced lrge degrdtion of lod crrying cpcity. Horizontl Lod (kn ) () A experim ent nlysis Drift (% ) Horizontl Lod (kn ) experim ent nlysis Drift (%) (b) B Figure. Lterl lod - drift ngle reltions nd results of pushover nlysis Tble 4: Test results Mximum lterllod cpcity Specimen Yielding lterllod Initil Positive direction Negtive direction stiffness Ry (%) Qy (kn ) R (%) Qmx (kn ) R (%) Qmx (kn ) (1 kn /rd) A B The yielding lterl lod, the mximum lterl lod crrying cpcity nd the initil stiffness re summrized in Tble 4. The mximum lterl lod cpcity, Q mx, cused by buckling of the sher pnel in positive nd negtive directions re lrge for Specimen A thn Specimen B nd reflects the number of studs. However, the yielding lterl lod, Q y, ws similr for two specimens lthough Q y of Specimen B is slightly higher. Drift ngles t yielding, R y, of Specimen A ws smller. This reflects the number of studs but the initil stiffness does not necessrily reflect the number of studs. Drift ngles t the mximum cpcity were similr for two specimens. Specimens A nd B did not show ny brittle filure until R=1%. It cn be seen tht behvior of the hybrid system is gretly ffected by the mount of studs nd resulting constrint.

7 Creting nd Renewing Urbn Structures Lterl lod crried by sher pnel Lterl lod crried by the sher pnel is plotted in Figure 6. The sher force crried by sher pnel ws computed from three Rosett strin gges on Line C in Figure 3 ssuming the plne stress condition nd elstic-perfectly plstic yield condition with von Mises yield criteri. Sher force of the sher pnel incresed rpidly for Specimen A but with slower rte for Specimen B. As the number of studs incresed, the sher pnel becme stiffer nd the buckling initited erlier. The sher pnel crried 6% to 7% of the lterl lod from the very beginning of the loding till buckling took plce t R=1.%. The computed contribution ws expected to be 64% t the ultimte condition by considering the story sher force t the formtion of collpse mechnism of the surrounding RC frme nd the sher force of the sher pnel t yielding Lterl lod crried by sher pnel Equivlent viscous dmping rtio, H eq, is shown in Figure 7. H eq of specimens incresed rpidly from R=.4% t which the sher pnel yielded, nd lrge mount of energy ws dissipted even fter the buckling. Specimen A hd lrger H eq thn Specimen B until yielding. Even fter R=1.%, lrge mount of energy ws dissipted in both specimens.

8 8 17TH CONGRESS OF IABSE, CHICAGO, 8 Sher force of sher pnel (kn ) specim en A specim en B A nlysis (A ) D rift (% ) Figure 6. Lterl lod crried bycssp 4 Equivlent dm ping fctor heq (% ) Specim en A Specim en B D rift (% ) Figure 7. Equivlent viscous dmping rtio

9 Creting nd Renewing Urbn Structures Numericl Simultion of lod drift reltions using simple frme model Behvior of Specimen A ws simulted using frme nlysis progrm. The nlyticl model is shown in Figure 8(). Two columns nd bem were modeled s single bem-column element with nonliner rottionl spring t both ends. Since the sher pnel hd sher stiffness without neither xil nor flexurl stiffness, it ws replced with nonliner spring with n equivlent stiffness in the horizontl direction to the sher stiffness of CSSP. Figure 8(b) shows the simultion of Specimen A up to R=2%. It lso shows tht the hysteresis loops were well simulted until R=1.% t which buckling took plce. After buckling, experimentl loops becme pinched but the nlysis does not show this degrdtion. Figure 8(c) seprtely shows the contribution of the sher pnel nd the surrounding RC frme in the nlysis.

10 1 17TH CONGRESS OF IABSE, CHICAGO, Q/ 2 N Nonliner spring representing sher pnel Nonliner Rottionl spring 1 N Sher force (kn) A nlysis Experim ent Pushover D rift (%) S her force (kn ) Totl R C frm e Sher pnel D rift (%) () frme model (b) Cyclic nd pushover Anlysis (c) Contribution of the RC frme nd sher pnel Figure 8. Sher force - drift ngle reltions for Specimen A 4. Conclusions A study ws conducted on how to use corrugted steel sher pnels (CSSP) s min lterl lod crrying component in building structures. The experiment on two RC frmes reinforced with CSSP is introduced to demonstrte the dvntge of CSSP. The revised hybrid system with corrugted steel sher pnels excellently behved s seismic controlling system with lrge sher stiffness nd sher cpcity. In ddition, the system showed some increse in sher force fter yielding until buckling. The behvior fter buckling ws ductile nd degrdtion in lterl lod crrying cpcity ws bout 2% even t R=%. The behvior ws stble if the number of studs stisfied the Jpnese design guidelines (Specimen A). However, even specimens with hlf number of studs (Specimen B) showed the similr behvior lthough the stiffness nd lterl lod crrying cpcity ws lower. Lterl lod crrying cpcity t the pek ws greter nd the post-pek degrdtion in lterl lod crrying cpcity ws less for specimens with the lrger number of studs. CSSP dissipted lrge mount of energy fter yielding nd the dissiption continued even fter buckling of sher pnel.. Acknowledgements A prt of this reserch ws finncilly supported by Jpnese Ministry of Lnd, Infrstructure nd Trnsport (PI, F. Wtnbe), Jpn Science nd Technology Agency in Reserch for Promoting Technologicl Seeds (PI, S. Kono), nd Structurl Engineering Reserch Center, Tokyo Institute of Technology (PI, Prof Shizuo Hyshi). The uthors cknowledge Mr. Y. Kshiwi nd Mr. K. Chos, former students t Kyoto University, for conducting experiments. 6. References [1] Tkhshi, Y., Tked, T., Tkemoto, Y. nd Tkgi, M., Experimentl Study on Thin Steel sher Wlls Prticulr Steel Brcings under Alterntive Horizontl Lod, Preliminry Report of IABSE Symposium, Lisbon, [2] Gccese, V., Elgly, M. nd Chen, R., Experimentl Study on Thin Steel-Plte Sher Wlls under Cyclic Lod, Journl of Structurl Engineering, ASCE, Vol. 119(2), pp. 88-6, [3] Driver, R G., Kulk, G. L., Kennedy, L. nd Elwi, A., Cyclic Test of Four-Story Steel Plte Sher Wll, Journl of Structurl Engineering, ASCE, Vol. 124(2), pp , [4] Mo, Y. L. nd Perng, S. F., Hybrid RC Frme-Steel Wll Systems, Composite nd Hybrid Systems, ACI, SP-196, pp ,.