Shake Table Studies and Analysis of a Precast Two-Column Bent with Advanced Materials and Pocket Connections

Shake table experiments and analyses of a large-scale precast two-column bent with advanced materials in plastic hinge zones were conducted to develop bridge bents for use in accelerated bridge construction (ABC) in moderate and high seismic zones. Ultrahigh performance concrete (UHPC) and engineered cementitious composite (ECC) were used in column plastic hinge zones to reduce earthquake damage. Precast square columns were connected to a precast footing and a cap beam using pocket (also known as socket) connections. The primary objectives of this investigation were to evaluate the seismic response of the precast bent and the pocket connections and to assess the effectiveness of UHPC and ECC in reducing damage in the plastic hinge zones. The bent was subjected to successive motions simulating scaled versions of the 1994 Northridge-Sylmar earthquake until failure. The experimental results showed that the pocket connections performed well, and the structural integrity was maintained up to a drift ratio of 9.6% and displacement ductility of 12. UHPC and ECC effectively reduced the column plastic hinge damage, although the extent and location of damage for the two materials were different. Another finding of the study was that a relatively simple computational model of the bent in OpenSees led to close correlation between the measured and calculated responses.