Large-Scale Seismic Testing of a Hybrid Sliding-Rocking Posttensioned Segmental Bridge System

Abstract

In this paper, a novel precast concrete segmental bridge system is introduced and experimentally investigated. The system consists of segmental members incorporating hybrid sliding-rocking (HSR) joints and internal unbonded posttensioning (PT). The HSR joints are plane interfaces that are oriented normal to the member axis and do not include shear keys or epoxy adhesives. The HSR joints are designed to exhibit sliding (slip-dominant, SD) or rocking (rocking-dominant, RD) to mitigate the applied seismic loading and reduce damage. The joint response is affected by the PT system, which can include straight or curved tendons. Two types of HSR members are developed and investigated: (1) members with SD joints and straight tendons, intended for substructure columns (HSR-SD columns), and (2) members with RD joints and curved tendons, intended for superstructure girders (HSR-RD girders). The SD joints are shown to offer energy dissipation with low damage through sliding in addition to moderate self-centering. The RD joints, albeit offering low energy dissipation, are shown to provide high self-centering. A series of shake table tests on a large-scale bridge specimen demonstrates the successful integrated response of the HSR-SD substructure and the HSR-RD superstructure for intense horizontal and vertical seismic excitations.