Low Seismic Damage Columns for Accelerated Bridge Construction

Abstract

This report describes the design, construction, and shaking table response and computation simulation of a Low Seismic-Damage Bridge Bent built using Accelerated Bridge Construction methods. The proposed bent combines precast post-tensioned columns with precast foundation and bent cap to simplify off- and on-site construction burdens and minimize earthquake-induced damage and associated repair costs. Each column consists of reinforced concrete cast inside a cylindrical steel shell, which acts as the formwork, and the confining and shear reinforcement. The column steel shell is engineered to facilitate the formation of a rocking interface for concentrating the deformation demands in the columns, thereby reducing earthquake-induced damage. The precast foundation and bent cap have corrugated-metal-duct lined sockets, where the columns will be placed and grouted on-site to form the column–beam joints. Large inelastic deformation demands in the structure are concentrated at the column–beam interfaces, which are designed to accommodate these demands with minimal structural damage. Longitudinal post-tensioned high-strength steel threaded bars, designed to respond elastically, ensure re-centering behavior. Internal mild steel reinforcing bars, debonded from the concrete at the interfaces, provide energy dissipation and impact mitigation.