Seismic Performance of High-Strength Steel RC Bridge Columns

This paper presents the results of a testing program developed to assess the performance of circular RC bridge columns constructed with ASTM A706 Grade 80 [550] high-strength steel (HSS) reinforcement. Two pairs of columns were tested (four columns in total). The columns were subjected to lateral cyclic loading to determine the effects of steel reinforcement grade (yield strength) and of moment-shear span ratio on column performance. Each pair consisted of one column constructed with Grade 80 [550] HSS reinforcement and a control column constructed with Grade 60 [420] reinforcement. The first pair had a moment-shear span ratio of six (6), and the second pair had a moment-shear span ratio of three (3). All four columns were designed to have similar nominal bending-moment capacities. Results indicate that the columns constructed with Grade 80 [550] HSS reinforcement achieve similar resistance, similar maximum lateral displacements, and similar curvature ductility values when compared with the control columns constructed with Grade 60 [420] reinforcement. However, columns constructed with Grade 80 [550] reinforcement exhibited lower hysteretic energy dissipation than the control columns. Results also indicate that, independently of the steel grade, as the moment-shear span ratio decreases, the maximum drift ratio decreases, despite an increase in the displacement ductility. (C) 2015 American Society of Civil Engineers.