MULTIDISCIPLINARY CENTER FOR EARTHQUAKE ENGINEERING RESEARCH

Full Scale Steel Plate Shear Wall: MCEER/NCREE Phase II Tests

Bing Qu, Michel BruneauDepartment of Civil, Structural, and Environmental Engineering, University at Buffalo

ABSTRACTSteel plate shear walls (SPSW), which are allowed to buckle in shear and form a diagonal tension field, have been used as the primary lateral force resisting systems in buildings for decades. There have been extensive monotonic, cyclic and shaking table tests on SPSW in the United States, Canada, Japan, Taiwan and United Kingdom and seismic design requirements now exist for this system. However, little experimental information exists on the behavior of intermediate beams in SPSW as well as the performance of such beams having reduced beam sections and composite behavior. The work presented here is an experimental investigation of SPSW system with emphasis on seismic adequacy of intermediate beams.

In order to investigate the related issues, the cooperative full scale experimental research on SPSW MCEER/NCREE project was developed . This poster descries some parts of Phase II researches of this project. In phase II, a full scale two-story one-bay steel plate shear wall specimen was obtained by replacing the web plates of the steel shear wall specimen of Phase I. The new specimen used A36 steel infill plates and reduced beam sections at the beam-ends like the specimen of Phase I, which would be normal practice in North America. Tests ofthe specimen were done under pseudo-dynamic and cyclic conditions.

BACKGROUNDAlthough, there has been extensive analytical and experimental research, the behavior of intermediate beams in SPSW as well as the performance of such beams having reducedbeam sections and composite behavior have not been thoroughly studied.

Research on SPSW has produced useful models for design and analysis of such kind of lateral load resisting system. Some of these have ended up in the newest version of the Canadian Institute of Steel Construction Specifications (CSA, 2003) and AISC Seismic Provision for Steel Structural Buildings (2005). Berman and Bruneau (2003), Vian and Bruneau (2005) and Lopez Garcia and Bruneau (2005) have respectively proposed a simple plastic analysis method to estimate the lateral load bearing capacity, an analytical model for the SPSW with perforated or cutout corner panel and top/bottom anchor beams design methods.

OBJECTIVESThe objectives of this research are:• To investigate whether it is possible to replace the steel panel in SPSW after a severe

earthquake.• To observe how the repaired SPSW would behave in a second earthquake after the

replacement of steel plate panel in light of the residual capacity of frame of the steel plate shear walls.

• To study how the intermediate beam would behave as part of this system.• To investigate the residual lateral load bearing capacity of the specimen after a severe

earthquake.• To access the hysteretic properties of this specimen.

METHODSThe experiments were conducted in the NCREE laboratory. The specimen was tested under pseudo-dynamic load to an earthquake having a 2% in 50 years probability of occurrence (Chi_Chi_CTU082EW-2/50 PGA=0.67g) and subsequently cyclic load to failure. Figure 1, Figure 2 and Figure 3 show some information related to the test set up.

Fig. 1 Test Setup Fig. 2 In Plane Actuators Fig. 3 Out Plane Actuators

The thicknesses of the infill panel were 3.2 mm at first story and 2.3 mm at the second story. The specimen was connected to the strong floor of NCREE using fixed ends at column bases.

RESULTSFigure 4 and 5 show the hysteretic base shear-drift loops at the first story and the second story under pseudo-dynamic load. Figure 6 and 7 show the hysteretic base shear-drift loops at the first story and the second story under the subsequent cyclic load. The specimen behaved well under the simulated earthquakes and reached an ultimate story drift of 2.5%. Cyclic test was imposed up to drift of 5% at which point failure occurred in the load transfer mechanism, i.e. through the concrete slab at top level of the specimen. Some severe plate damage and intermediate beam damage also occurred at drifts between 2.5% and 5%. Examples of fractures at intermediate beam-column connection and concrete slab are shown in Figure 8and Figure 9.

Fig. 4 1F Hysteresis in Pseudo-dynamic Test Fig. 5 2F Hysteresis in Pseudo-dynamic Test

Fig. 6 1F Hysteresis in Cyclic Test Fig. 7 2F Hysteresis in Cyclic Test

Fig. 7 Intermediate-beam-column Connection 5% Drift Fig. 8 Slab at Top Level 5% Drift

CONCLUSIONSIt was shown that the specimen obtained by replacing the web plates of the steel shear wall specimen of Phase I achieved satisfactory ductility and energy dissipation in the pseudo-dynamic test and succeeding cyclic test. RBS detailing in top/bottom anchor beam behaved well during the whole drift history. RBS detailing in intermediate beam performed well at low drifts (0%-2.5%) and fractures at the intermediate beam-column connections developed at high drifts (2.5%-5%).

ACKNOWLEDGEMENTSProgram area: 2 Task number: 9.2.2Principal investigator and/or faculty advisor: Dr. Michel BruneauAcknowledgements: This work was supported in whole by the Earthquake Engineering Research Centers Program of the National Science Foundation under Award Number ECC-9701471 to the Multidisciplinary Center for Earthquake Engineering Research.

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