Seismic Performance of Circular Concrete Bridge Columns Reinforced with ASTM A955 Stainless Steel Rebars

Abstract

This research assesses and compares the seismic performance of four reinforced concrete columns subjected to lateral cyclic loading. Two columns were reinforced with ASTM A955 Grade 75 reinforcement, whereas the other two were reinforced with CSA G30.18 400W reinforcement, each with aspect ratios of 3 and 6. This study aims to lay the foundation for future performance-based seismic design guidelines for reinforced concrete (RC) bridge piers reinforced with stainless steel rebars. This is achieved by delving into various aspects of seismic behavior, including hysteretic response, column ductility, energy dissipation, plastic hinge length, and performance damage states. The ASTM A955 Grade 75 columns showed similar hysteretic behavior to the CSA G30.18 400W columns up to 7.5% drift and ductility level of 4. At failure (20% strength degradation), the stainless steel columns demonstrated comparable drift ratios, albeit a lower overall ductility capacity due to their higher displacement at yield. In terms of energy dissipation, the CSA G30.18 columns showed higher energy dissipation at similar drift levels and at failure compared to the ASTM A955 Grade 75 columns. Evaluation of plastic hinge length prediction models revealed higher discrepancies for columns reinforced with stainless steel reinforcement, and further investigation is warranted. Also, performance damage states, including concrete cracking, cover spalling, stirrup yielding, bar buckling, and bar fracture, showcased material-specific responses and unveiled critical insights about the applicability of code strain limitations and prediction models for ASTM A955 Grade 75 reinforcement. The research emphasizes the need for tailored approaches based on the distinct behavior of stainless steel.