Behavior of Steel-Plate Composite Wall Piers under Biaxial Loading

Abstract

Steel-plate composite (SC) structures may be subjected to combination of in-plane and out-of-plane forces for extreme loading combinations (e.g., seismic and accident thermal). This paper presents the results from behavioral and experimental investigations conducted to evaluate the interaction of in-plane and out-of-plane forces on SC wall piers (without boundary elements). Experimental results indicate that the effect of out-of-plane forces on the in-plane behavior of SC wall piers depends on the location and magnitude of the out-of-plane loading. Wall piers subjected to out-of-plane shear equal to their nominal shear strength (per US codes) develop flexural yielding and failure due to interaction between the in-plane and out-of-plane moments. Shear failure does not occur in these wall piers. Wall piers subjected to out-of-plane shear forces significantly greater than the nominal shear strength (per US codes) are forced into a shear failure mode by the interaction of in-plane shear and out-of-plane shear. An interaction equation for in-plane and out-of-plane moments is developed to characterize the flexure-controlled behavior of wall piers. This interaction equation can be used to design and to evaluate the behavior of SC wall piers subjected to combination of in-plane and out-of-plane moments.