Hysteretic Response of Steel-Clad, Wood-Framed Shear Walls Under Reverse-Cyclic Loading
Mai, Khoi Duc
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Steel-Clad, Wood-Framed (SCWF) shear walls are used as the main lateral load resisting system in post-frame buildings under wind and earthquake lateral loadings. However, seismic design coefficients have not been developed for the design of SCWF shear walls as a main lateral force resisting system for seismic forces. Research is needed to help designers of post-frame construction with accurately determining the behavior of SCWF shear walls subjected to lateral loads. To address these needs, finite element analysis (FEA) models of SCWF shear walls under monotonic and cyclic loading as well as the reversed cyclic SCWF shear wall tests were developed. With validated FEA predictions, and experimental data on behavior of SCWF shear walls, design information can be developed for post-frame buildings in seismic and high wind regions. FEA models were developed and validated to predict shear strength and effective shear modulus of SCWF shear walls under monotonic loading. Moreover, the hysteretic behavior of SCWF shear walls was predicted using hysteretic behavior of sheathing-to-framing connector elements. Analyses were performed to assess the shear strength, stiffness, ductility, equivalent energy elastic plastic (EEEP), and hysteretic parameters of tested SCWF shear wall specimens. Experimental tests also provided the seismic design coefficients of SCWF shear walls, which are currently lacking in the building codes. The dynamic implicit FEA models predicted well the shear strength and effective shear stiffness of SCWF shear walls under monotonic loading. The dynamic implicit FEA also overcame the deficiencies of the static implicit approach with regard to bucking, nonlinear geometry behavior of steel cladding. In addition, experimental test results showed that SCWF shear walls had high ductility, especially for unstitched shear wall configurations. Based on the research herein, shear walls with high ductility can be considered equivalent to light-framed wood shear walls with regard to behavior under seismic loading. Moreover, the hysteretic behavior of SCWF shear walls under cyclic loading was predicted well, especially for unstitched shear wall configurations. Good agreement was also obtained with regard to shear strength backbone curve, except for heavily stitched shear walls. Therefore, the FEA models can be used to determine the equivalency between SCWF shear walls and light-framed wood shear walls.