Directional seismic performance of reinforced concrete buildings under near-fault ground motions

Abstract

This study investigates the combined influence of near-fault ground-motion characteristics, directionality effects, and structural system configuration on the seismic performance of reinforced concrete (RC) buildings through nonlinear time-history analyses of a representative RC building from the Antakya building stock affected by the Mw 7.7 Pazarc & imath;k earthquake of 6 February 2023. Particular emphasis is given to the TK-3124 strong-motion record, selected because it contains a pronounced velocity pulse and exhibits high spectral accelerations over a broad period range. The results show that seismic response is governed not only by ground-motion intensity but also by the orientation of loading relative to the structure and the configuration of the lateral load-resisting system. Directionality significantly influences structural response and damage distribution, with its effects becoming more pronounced under pulse-like ground motions. In particular, the velocity pulse component contributes substantially to increased inelastic demands through spectral amplification in the long-period range. The analyses further indicate that the critical structural direction does not necessarily coincide with the direction of maximum pulse intensity but emerges from the interaction between ground-motion characteristics and structural system properties. Structural modifications, including the addition of perimeter beams and shear walls, influence seismic performance by altering stiffness, load-transfer mechanisms, and the spatial distribution of damage within the structural system, although the associated period shortening may increase acceleration demands in certain cases. Overall, the findings emphasize that realistic seismic performance assessment in near-fault regions requires the integrated consideration of directionality effects, pulse-like ground motions and structural system characteristics rather than treating these factors independently.