Resilient Posttensioned Bridge Bent with Buckling Restrained Brace

Abstract

A new method for building seismically resilient bridges is investigated using Accelerated Bridge Construction (ABC) technologies. A hybrid two-column bridge bent with posttensioned precast concrete columns and a diagonal buckling restrained brace (BRB) as an external energy dissipation device was tested under cyclic loads. The design of the initial posttensioning force and selection of BRB tensile yield strength is presented. The connection design at the footing and cap beam of the diagonal BRB considering column-free rocking is described. The experimental performance of the bridge bent subjected to cyclic loads is discussed. The performance of the bridge bent was enhanced in terms of hysteretic energy dissipation until fracture of the BRB steel core at a 5.0% drift ratio. The two unbonded posttensioned (PT) bars of one column yielded shortly after fracture of the BRB steel core. The columns of the hybrid bridge bent underwent rocking and remained undamaged up to a 6.0% drift ratio, at which point the longitudinal mild steel column bars yielded. The gusset assemblies at the cap beam and footing remained elastic throughout the test. The BRB could be replaced after an earthquake, and the proposed system is promising for constructing resilient bridges using ABC technologies in seismic regions.