Seismic-resistant bridge columns with ultrahigh-performance concrete segments

Abstract

The flexural capacity of a well-designed RC column deteriorates under extreme ground motion as a result of crushing of the core concrete and buckling of the longitudinal bars in the plastic hinge regions. Thus, it is important to minimize damage at the plastic hinge region to develop high-performance bridge columns. A column that uses ultrahigh-performance concrete (UHPC) segments at the plastic hinge region is proposed to address this issue. Three reduced-scale columns were constructed and tested at the Tokyo Institute of Technology in Japan. Two of the columns with different plastic hinge details were investigated using bilateral cyclic loading. The first column had a reinforced concrete core encased in an UHPC jacket. The second column had an UHPC hollow-core plastic hinge combined with posttensioning. Both columns were designed to have approximately the same nominal strength. They were tested under orbital bilateral cyclic loading customized to impose flexural deformations and investigate the possibility of twisting of the columns. The column that had a solid concrete core was able to carry the applied axial load to a drift of 6%. The posttensioned column was able to carry the applied axial load to a drift of 3.5%. The third column was tested to investigate the seismic performance of the first column, which had a concrete core, under hybrid simulation. The proposed UHPC column exhibited good performance for a seismic-resistant column. Energy dissipation and hysteresis damping were also calculated. Two analytical approaches were used to estimate the columns' capacities.