Performance of Composite Plate Shear Walls/Concrete Filled (C-PSW/CF) Under Fire Loading: A Numerical Investigation

Abstract

Concrete-Filled Composite Plate Shear Walls (C-PSW/CF), also known as SpeedCore walls, are being increasingly used in commercial buildings due to the benefits of modularization and expedited construction schedules. This paper numerically investigates the behavior of C-PSW/CF subjected to combined gravity and fire loading. 3D non-linear inelastic finite element models of C-PSW/CF were developed and benchmarked to existing experimental data. The benchmarked models were used to understand the thermal and structural behavior of the walls under uniform fire loading, and to evaluate the effect of different parameters on the response of C-PSW/CF to combined gravity and fire loading. The parameters considered in the study were boundary conditions, wall slenderness ratio, wall thickness, axial load ratio, concrete strength, steel plate slenderness, steel reinforcement ratio, and tie bar spacing. Fire loading led to high surface (steel plate) temperatures, the evolution of non-linear thermal gradients through the cross-section, and progressive degradation of the material properties. The walls expanded longitudinally due to the thermal loads. The degradation in material properties resulted in local buckling of the steel plates between the tie bars. Continued fire exposure led to crushing/global instability failure of walls under gravity loads. The time to failure of the walls reduced considerably with a reduction in rotational fixity at the boundary conditions, reduction in wall thickness, and an increase in the wall slenderness. The steel plate slenderness of the walls should be limited to 1.2√Es/Fy to improve the time to failure of the walls. The results from this study will form a basis for the development of recommendations to estimate the fire-resistance rating and the compressive strength of the walls at elevated temperatures.