Seismic design coefficients and factors for coupled composite plate shear walls/concrete filled (CC-PSW/CF)

Abstract

ASCE7–16 (2016) [4] defines three seismic performance factors to approximately predict the inelastic response of a seismic resisting system. These factors are the response modification factor, R; deflection amplification factor, Cd; and the system over-strength factor, Ωo. The research presented here was conducted, using FEMA P695 methodology, to determine the value of the above factors for a special seismic-force resisting system defined as Coupled Composite Plate Shear Walls-Concrete Filled (CC-PSW/CF). The ASCE 7–16 (2016) [4] and AISC 341–16 (2016) seismic provisions provide specific requirements for the use of planar composite steel plate shear walls in seismic regions. However, the ASCE-7–16 standard does not differentiate between coupled and non-coupled walls. Coupled walls can benefit from the added energy dissipation provided by their coupling beams and are accordingly expected to exhibit better seismic hysteretic behavior than uncoupled walls. Therefore, coupled walls systems should arguably have a higher response modification factor value. In this paper, the FEMA P695 approach taken for determining the seismic parameters of CC-PSW/CF is presented. To enhance confidence in the results, the Incremental Dynamic Analyses needed as part of the P695 procedure were conducted in parallel using two different non-linear hysteretic models. Complementary studies were also conducted to investigate the sensitivity of results to assumptions related to damping and yielding models. Results show that values R = 8, Cd = 5.5, and Ωo = 2.5 would be appropriate for CC-PSW/CF.