NONLINEAR SEISMIC RESPONSE OF RC BRACED FRAMES USING A DAMAGE PLASTICITY MICROPLANE MODEL

This study investigates the nonlinear seismic performance of reinforced concrete (RC) frames strengthened with different bracing systems, using a damage plasticity microplane model implemented in ANSYS.Unlike previous studies that primarily focused on steel bracing or simplified frame models, this work provides a direct comparison between RC and steel braces in both concentric and eccentric configurations.A single-bay RC frame was analyzed under pushover loading using 3D solid and beam elements, capturing cracking, plastic hinge formation, stress redistribution, and ductility development.Results show that all bracing systems enhance lateral strength and energy dissipation compared to the unbraced frame.Concentric RC bracing achieved the highest strength increase, while eccentric RC bracing offered superior ductility and post-yield deformation due to effective shear link action.Steel bracing provided more uniform stress distribution and practical detailing advantages, making it highly suitable for retrofitting applications.The findings highlight that RC bracing systems, although less studied, can outperform steel in ductility-critical designs, while steel bracing remains a practical choice for seismic rehabilitation.This dual-material comparative framework contributes new insights for