Effect of Confinement Level and Staggering on Seismic Performance of Lap-Spliced GFRP-Reinforced Concrete Columns

Abstract

In this study, we evaluate the seismic performance of concrete columns reinforced with lap-spliced glass fiber–reinforced polymer (GFRP) bars through simulated earthquake loads. Six 400 × 400 mm columns with an overall height of 1,850 mm were tested. Five columns were reinforced with lap-spliced GFRP bars and one was reinforced with continuous GFRP bars to serve as a reference for comparative purposes. The primary test variables were the transverse reinforcement spacing, tie configuration, and number of bars spliced at the critical section. The experimental investigation was followed by an evaluation of the provisions of related North American design standards on the effect of the confinement and staggering of the lap-splice length. The test results show that the level of confinement and staggering affected the hysteretic response, load-carrying capacity, and bond performance of the column specimens. The influence of the amount of transverse reinforcement on the deformability of the columns was found to be considerable. Staggering, however, did not significantly affect the deformability. A comparison of the results with existing design standards demonstrated that the current provisions in the CAN/CSA S6-19 and ACI 440.11-22 standards for monotonic loading need improvement in order to provide accurate results when considering confinement and staggering in predicting the lap-splice length of GFRP-RC columns under seismic loading.