Seismic Evaluation of the ACI Code Provisions for Lap Splicing of Longitudinal Bars in R/C Rectangular Bridge Columns

Abstract

In this study, the adequacy of the ACI code provisions for detailing of lap-spliced reinforcement in R/C rectangular bridge columns was numerically investigated. Pushover analysis was conducted on a total of 324 R/C rectangular bridge columns with lap-spliced reinforcement, using a modified version of previously developed computer program. The computer modeling is based on moment–curvature analysis of the column section with the inclusion of a bond/slip mechanism and concrete confinement model. In this study, the program was revised to integrate the effectiveness of lateral hoop reinforcement on both concrete confinement and lap-splice clamping. Constant axial load was applied in the analysis. The parameters involved in the study were lap-splice length, volumetric ratio of column hoops, and axial load ratio. The results indicate that the top lateral load–displacement characteristics of the column are enhanced when the lap-splice length at the column base increased. To ensure a minimum displacement ductility of 4.0 for the column, lap splices as short as 30φb (φb = longitudinal bar-diameter) should be avoided at expected plastic hinge locations. The best performance for a wide range of axial load ratios was exhibited by columns having the ACI’s classes A and B tension splices and laterally reinforced with hoops required by the ACI code for seismic design.