Precast Bent System for High Seismic Regions: Laboratory Tests of Column-to-Drilled Shaft Socket Connections

2013PDFTech ReportFHWA-HIF-13-038DTFH61-09-G-00005Precast concreteEarthquake resistant designColumnsBridge constructionUnited StatesUnited States. Federal Highway AdministrationTran, Hung VietStanton, John F.Eberhard, Marc O.United States. Federal Highway AdministrationBergerABAM, Inc.Federal Highway AdministrationThis report provides detailed information from the laboratory investigation of two precast column-to-drilled shaft large-scale tests, including descriptions of the specimen design, testing, data reduction, and conclusions regarding the use of the connection with the precast bent system. The tests provide data regarding the performance of the precast column-to-drilled shaft connection. The results indicate that the connection, when used with a precast column, is sufficiently strong to resist plastic hinging in the column above the drilled shaft splice zone. The column reinforcing bars were anchored with headed bar ends to facilitate column strength development. The behavior is emulative of cast-in-place performance. The specimens tested were based on the minimum practical difference in diameters of the shaft relative to the column. When adequate confinement in the reinforcing cage of the shaft is included in the splice zone, the column can form a plastic hinging mechanism above the shaft without incurring damage in the shaft splice zone. If sufficient confinement is not included, then the resulting behavior is undesirable because the splice zone strength rapidly deteriorates. Recommendations for transverse reinforcement are provided to ensure desirable performance, and these result in more reinforcement in the upper portion of the splice zone than in the lower portion.85