Biaxial Seismic Response of R/C Frames

Abstract

Results of experimental shaking table tests and analytical studies of the biaxial response of a reinforced concrete frame having rectangular columns and inelastic motion induced by earthquake excitation are summarized. The objective of this research program was to evaluate biaxial loading effects on R/C column behavior and implications for aseismic design. Inspection of the response and comparison to a test with uniaxial motion found that biaxial motion seriously affected column and frame behavior. The column capacities (strength, stiffness, deformability, and energy dissipation) were reduced and the response demand was increased compared to those with uniaxial motion. Results indicate that present code‐endorsed methods of analyzing and designing frames independently along their principal axes may result in an unconservative product when biaxial motion occurs.