Experimental Assessment of Residual Seismic Capacity of Unconfined Slender Reinforced Concrete Walls after Constant Drift Loading Protocols

Abstract

Experimental evaluation of the residual seismic capacity of unconfined slender reinforced concrete (RC) walls is essential for making informed decisions after earthquakes, particularly in seismic-prone regions like Chile. This study addresses the gap in experimental data regarding the impact of constant drift loading cycles on the residual seismic capacity of such walls. The residual seismic capacity of walls is understood as the ability to withstand future seismic demands after prior damage, considering potential changes in stiffness, strength, deformation capacity, and energy dissipation. This capacity is essential for understanding wall behavior during successive or long-duration seismic events. Through a rigorous experimental program, four full-scale wall specimens were subjected to lateral loading cycles under constant axial load to simulate pre-earthquake damage. A comprehensive instrumentation scheme, combined with digital image correlation techniques, was employed to record deformations and loads throughout the entire testing process. Findings illustrate notable stiffness variations attributed to pre-earthquake damage, pinpointing deformation levels reached as the primary cause, rather than the repetitive nature of the loading cycles. Contrarily, the strength, deformation capacity, and energy dissipation capacity attributes of the walls remained unchanged. These results provide valuable insights into the degradation of the shear wall’s strength, deformation capacity, stiffness, and energy dissipation capacity due to cumulative damage. This study also contributes to existing literature with relevant empirical evidence, suggesting reconsideration of FEMA 306 stiffness reduction factors.