Quasi-Static Cyclic Testing of Hybrid Posttensioned Bridge Column Supported on a Monopile Foundation

Abstract

In this research, a low-damage posttensioned rocking solution referred to as dissipative controlled rocking (DCR) connection is proposed for bridge columns supported on monopile foundations. The DCR connection is a low-damage system that replaces the plastic hinge mechanism in a column and aims to minimize and potentially eliminate the repair time and costs after an earthquake. A DCR bridge system combines unbonded posttensioning and replaceable dissipaters to provide self-centering and energy absorption capabilities, respectively. Current research on DCR column systems has focused on the performance of bridge bents founded on a fixed foundation, neglecting soil damping effects. In this research, a one-third scaled bent supported on a monopile with passive soil resistance was tested under quasi-static cyclic loading to validate the lateral seismic response of a DCR bridge bent with the contribution of the soil–foundation–structure interaction. When developing the details for the DCR connection, particular emphasis was made on utilizing conventional construction materials and forms for a low-damage bent that yields a similar construction cost to a monolithic joint. Nevertheless, the proposed DCR connection can be easily and quickly repaired or replaced after a significant seismic event. The performance of the bent was compared against a benchmark structure with an emulative connection type that resembles a monolithic cast-in-place joint. Results from testing suggest a greater performance of the low-damage DCR column. The dynamic response of the DCR column built on a flexible foundation differed from that of a fixed-base structure, which is primarily due to the energy dissipation capability of the flexibly supported structure. Flexibility in the soil foundation increased the structural period of the structure and reduced the seismic response of the DCR column. Damage to the DCR bent was limited to concrete crushing at the rocking interface, which proved to be easily repairable. In contrast, the bent with an emulative connection developed plastic hinging at the bottom of the column, which was nonrepairable.