Nonlinear Dynamic Analysis Of Hybrid Frames

Abstract

This study proposes a hybrid frame system consisting of rigid and semi-rigid connections subjected to a dynamic loading. Two building geometries are chosen to represent low-rise and high-rise buildings. Multiple locations for placement of semi-rigid connections are proposed, and the hybrid systems with the most efficient energy dissipation are identified. During this analysis, five earthquake records are used to provide a spectrum of frequencies. Five practical semi-rigid connection types and one connection with analytical parameters are also modeled into the selected hybrid combinations by applying zero-length springs at the ends of beams, in which their nonlinear constitutive relation is defined by bilinear moment-rotation curves. Incremental transient dynamic analysis including P-Δ effects is conducted. The results of the research indicated that the proposed placement of partially restrained connections significantly decreases moment and shear force demands on structural members in the studied tall building during high-frequency earthquakes. In contrast, earthquakes with low frequency acceleration records adversely affect the deflections and member forces in the selected hybrid buildings compared to their rigid equivalents.