Improving damping capabilities in low-rise frames using reinforced rubberized concrete: A comprehensive study

Over the past decade, extensive research has been conducted to investigate the properties and behavior of rubberized concrete as a sustainable green alternative to conventional concrete. This research involves replacing natural aggregates with rubber particles from discarded tires. Generally, these studies have shown an enhancement in ductility, energy dissipation, and the damping ratio of rubberized concrete. However, a significant reduction in mechanical properties, such as compressive and tensile strength, and modulus of elasticity, has been noted compared to standard concrete. Currently, the literature lacks a comprehensive numerical study that could provide structural engineers with a complete understanding of the seismic performance of rubberized concrete frames. Consequently, this study examines three low-rise RC frames subjected to sixty recorded ground motions (near-fault, pulse-like, and far-fault) using nonlinear response-history analysis, comparing rubberized concrete (RBC) with a control concrete (NC-C) and a similar-strength mix (NC-S). Across records, RBC exhibits lower base shear (mean reductions up to 11.6-13.8% versus NC-C and about 3-6% versus NC-S, depending on motion class), higher viscous damping energy (increases of 29-53%), and lower hysteretic energy (reductions of about 10-29%), while interstory drift ratios increase yet remain within ASCE 7 drift limits. Absolute floor accelerations reduce modestly (up to 11.8% in far-fault motions). The results indicate that substituting RBC can enhance damping efficiency and reduce seismic forces relative to both NC-C and NC-S under severe earthquakes at a drift trade-off.