On the Stability of Composite Plate Shear Walls under Fire Loading

Composite plate shear walls (C-PSWs) are being considered for commercial building construction due to their benefits of modularization and schedule contraction. Fire hazard is an important consideration for building design, and the applicability evaluation of the C-PSW system for buildings would be incomplete without consideration of fire loads. The existence of steel plates (analogous to reinforcing bars in traditional reinforced concrete construction) on the surface of the shear walls means that the steel plates will be directly exposed to fire temperatures. Fire loading will result in elevated steel and concrete temperatures and non-linear thermal gradients through the cross-section of the walls. Elevated temperatures result in the degradation of the mechanical properties of steel and concrete. This can result in local buckling of steel plates or global instability of the walls, leading to the collapse of the walls at gravity load magnitudes significantly lower than the ambient compression strength of the walls. The authors have initiated a research project focusing on stability of C-PSWs under fire loading. The existing standard fire tests conducted on scaled C-PSW specimens in S. Korea and China are summarized in the paper. This paper focuses on the development of detailed finite element models to evaluate the stability response of C-PSWs under fire loading. The existing experimental database has been used to benchmark finite element models for the thermal and structural response of the system. The numerical models are conservative in comparison to the experimental results. The surface temperature at failure is a better indicator of the fire resistance of the C-PSWs (in comparison to time to failure). The time to failure can be determined from the surface temperature at failure. The benchmarked analyses will be employed to develop full-scale models of C-PSWs. Parametric studies will be conducted to study the effect of variation in section thickness, steel reinforcement ratio, steel plate slenderness on the local and global stability behavior of C-PSWs subjected to standard fire curves. The authors will also be conducting a series of experimental studies where C-PSW specimens will be subjected to standard fire curves. Results of experimental and numerical studies will be employed to determine the fire resistance of C-PSWs, obtain fire ratings for walls, and provide detailing or design recommendation for performance-based fire design of C-PSWs. These recommendations will enable the engineers to consider fire loading in the design of C-PSWs for building structures.

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