Comparative Seismic Performance of RC Frame Buildings with URM Infill Walls: A Parametric Study of Material Properties and Modeling Approaches

This study investigates the seismic performance sensitivity of reinforced concrete (RC) frame structures with unreinforced masonry (URM) infill walls, focusing on the influence of material properties and modeling methods. URM infills significantly modify lateral stiffness and strength during seismic events, but their influence is often approximated using simplified models with assumed material values. Using a 3-storey RC frame model in SAP2000, a parametric study was conducted varying the modulus of elasticity (Em) and compressive strength (fm) of the infill masonry. Nonlinear static pushover analyses were used to assess base shear, drift, and hinge formation. Additionally, a conceptual comparison was made between the widely used equivalent strut model and the more detailed continuum finite element model. Results show that small variations in Em and fm lead to substantial changes in seismic response. The findings highlight the importance of accurate material characterization and informed modeling approach selection for seismic design. Recommendations are provided for practical design and future research in performance-based seismic assessment