This paper is the second part of a two-part paper presenting the cyclic tests of four two-story narrow steel plate shear walls (SPSWs). The first paper introduces the analytical studies and the specimen designs. This paper describes the test results. Some design implications including the capacity design for the first story column and the width-to-thickness ratio check for the beam web are discussed based on key observations from the tests. Test results confirm that the simplified strip model can accurately predict the inelastic responses of the specimens. Test results also confirm that the proposed capacity design method is effective in ensuring the plastic hinge formation at the bottom end of the first story column for SPSW with or without restrainers. Test results also show that the horizontal restrainers are effective in reducing the member forces in the boundary beam and column elements. Comparing the test results of the typical SPSW with those of the restrained SPSW (R-SPSW) specimens, it is found that the R-SPSW possesses an improved cyclic performance and reduced material weight. Analytical results predict the compressed column moments at the onset of the column plastic hinge formation well. The analytical hysteretic energy distribution in the first story column agrees very well with the observed inelastic actions developed in the four specimens. The detailed frame response analyses and the test results confirm that the assumptions made in developing the proposed column capacity design method are reasonable.KEY WORDS: steel plate shear wall (SPSW); restrained steel plate shear wall (R-SPSW); capacity design; narrow steel plate shear wall Figure 1. Details of the specimens.beam-to-column joint for both the middle and the top beams. Thus, the unbraced length of the columns was equal to the story height. A reference column was erected to measure the lateral displacement of the specimens at various elevations ( Figure 2). Positive values of force or displacement indicated pushing or movement toward the east direction. The cyclic displacements were imposed according to the loading history shown in Figure 3, starting from small roof drift and increasing up to 5% radian. The north actuator was displacement controlled while the south one was force-slaved.
SUMMARYThis study consists of two parts. In this two-part research, four two-story narrow steel plate shear walls (SPSWs) were cyclically tested at the Taiwan National Center for Research on Earthquake Engineering in 2007. This paper, Part 1, proposes a capacity design method for the first-story boundary column of the SPSW to ensure that the plastic hinges form at the column bottom ends when the SPSW develops the plastic mechanism. The design method was developed based on the superposition method considering the frame sway action and the panel force effects of the SPSW. Restrained steel plate shear wall (R-SPSW) studied herein adopts pairs of the horizontal restrainers sandwiching over both sides of the infill panels and connected to the boundary columns. Analytical studies on four SPSW example designs using nonlinear finite element (FE) models and the simplified strip models confirm that the restrainers could also effectively reduce the column force demands and allow the infill panel to stretch more uniformly. In addition, the FE analytical studies verify the effectiveness of the proposed column capacity design method and the seismic design recommendations for the restrainer. This paper introduces the designs of the four narrow SPSW specimens, presenting the selections of the boundary beams and columns, the designs of the beam-to-column connections and the construction details of the restrainers. The experimental results, key observations and the design implications are reported in the companion paper.
SUMMARY Coupled steel plate shear wall (C‐SPSW) consists of two or more steel plate shear walls interconnected by coupling beams at the floor levels. In this study, a six‐story C‐SPSW prototype building was designed. A 40% scale C‐SPSW specimen, which is representative of the bottom two‐and‐half‐story substructure of the prototype, was cyclically tested using Multi‐Axial Testing System at the National Center for Research on Earthquake Engineering in 2009. In addition to a constant vertical force representing the gravity load effects, cyclic increasing displacements and the corresponding overturning moments transmitted from the upper stories were computed online and simultaneously applied on the substructural specimen. This paper firstly introduces the designs of the prototype C‐SPSW and the test specimen. Then, the test results and the numerical simulation are discussed in detail. Test results confirm the effectiveness of the proposed column capacity design method, which aims at limiting the plastic hinge formation within the bottom quarter height of the bottom column. Test and analytical results suggest that the coupling beam rotational demands can be estimated as the design story drifts when the formation of desirable plastic mechanism of the C‐SPSW is expected. Copyright © 2011 John Wiley & Sons, Ltd.
Summary This paper proposes a novel implementation of buckling‐restrained braces (BRB) in new reinforced concrete (RC) frame construction. Seismic design and analysis methods for using a proposed steel cast‐in anchor bracket (CAB) to transfer normal and shear forces between the BRB and RC members are investigated. A full‐scale two‐story RC frame with BRBs (BRB‐RCF) is tested using hybrid and cyclic loading test procedures. The BRBs were arranged in a zigzag configuration and designed to resist 70% of the story shear. The gusset design incorporates the BRB axial and RCF actions, while the beam and column members comply with ACI 318‐14 seismic design provisions. Test results confirm that the BRBs enhanced the RCF stiffness, strength, and ductility. The hysteresis energy dissipation ratios in the four hybrid tests range from 60% to 94% in the two stories, indicating that BRBs can effectively dissipate seismic input energy. When the inter‐story drift ratio for both stories reached 3.5% in the cyclic loading test, the overall lateral force versus deformation response was still very stable. No failure of the proposed steel CABs and RC discontinuity regions was observed. This study demonstrates that the proposed design and construction methods for the CABs are effective and practical for real applications. Copyright © 2016 John Wiley & Sons, Ltd.
Summary A ductile Vierendeel frame can be constructed by incorporating steel panel dampers (SPDs) into a moment‐resisting frame (MRF). Thus, the stiffness, strength, and ductility of the lateral force–resisting system can be enhanced. The proposed 3‐segment SPD possesses a center inelastic core (IC) and top and bottom elastic joints. This paper discusses the mechanical properties, capacity design method, and buckling‐delaying stiffeners for the SPDs through the use of cyclic loading tests on 2 specimens. Tests confirm that SPDs' cyclic force vs deformation relationships can be accurately predicted using either the Abaqus or PISA3D model analyses. The paper also presents the capacity design method for boundary beams connected to the SPDs of a typical SPD‐MRF. The seismic performance of an example 6‐story SPD‐MRF is evaluated using nonlinear response history analysis procedures and 240 ground accelerations at 3 hazard levels. Results indicate that under 80 maximum considered earthquake ground accelerations, the mean‐plus‐one standard deviation of the shear deformation of the ICs in the SPDs is 0.055 rad, substantially less than the 0.11 rad deformational capacity observed from the SPD specimens. The experimental cumulative plastic deformation of the proposed SPD is 242 times the yield deformation and is capable of sustaining a maximum considered earthquake at least 8 times before failure. This paper introduces the method of using one equivalent beam‐column element for effective modeling of the 3‐segment SPD. The effects of the IC's relative height and stiffness on the overall SPD's elastic and postelastic stiffness, elastic deformation limits, and inelastic deformational demands are discussed.
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