Seismic Strengthening of Bond-Critical Regions in Wall-Type Bridge Piers Using Active Confinement

Abstract

Active confinement by means of pretensioned steel anchor rods is used for bond strengthening of lap-spliced reinforcement and for improving the seismic performance of wall-type bridge piers. Representative as-built and strengthened pier specimens with lap-spliced reinforcement within the critical hinging region were tested under large drift reversals. The test parameters included ratio of pier longitudinal reinforcement, diameter of the spliced bars, and configuration of the pretensioned steel rods. The strengthened piers developed enhanced bond resistance and low bond degradation of the spliced bars, increases in the lateral load and drift capacities, and much less pinching in the lateral load–drift response when compared with the as-built specimens. In this study, a design approach is developed for engineers to evaluate the active lateral pressure required for adequate bond strengthening and for designing the strengthening system. A design example is provided to illustrate the use of the proposed approach.