Dynamic analysis of tall reinforced concrete walls designed with minimum vertical reinforcement

Abstract

Analysis of tall walls subjected to the earthquake ground motions highlights the amplified dynamic moment response at the mid-height due to the higher mode effect. The amplified moment demand may result in unexpected reinforcement yielding extending to the upper portion outside of plastic hinge region, impacting termination rules for vertical reinforcement. The aim of this research was to investigate the dynamic response of tall reinforced concrete walls designed with minimum vertical reinforcement contents. A series of parametric analyses were conducted to investigate the higher modes effect on tall walls designed with light reinforcement contents, including the ground motion types and impact of cracking moment exceeding yielding moment strength. An extreme case with higher concrete tensile strength, lower reinforcement contents at the upper stories, and lower axial load ratio was conducted to investigate the impact of potential cracking and reinforcement yielding outside of the plastic hinge region. Comparison of the dynamic and pushover analyses indicated that the minimum required termination height of additional vertical reinforcement in the plastic hinge region maybe insufficient to prevent yielding extending beyond the prescribed plastic hinge region. The results of dynamic analysis will be presented along with recommendations for revisions to current design provisions for minimum vertical reinforcement and termination rules.