Full-scale experimental investigation on the seismic performance of PC columns before and after repair of grouting defects

Abstract

This research focused on investigating the influence of insufficient grouting on the seismic performance of precast concrete (PC) columns, connected using grouted sleeves, and validating the feasibility and reliability of the repair method for insufficient grouting. To realize these, five full-scale PC columns were tested under cyclic loads, including one specimen without grouting defects, two specimens with defect ratios of 45% and 60%, respectively, which were determined by previous cyclic test results of grouted sleeve connections (GSCs), and two repaired specimens which had initial defect ratios of 45% and 60%, respectively. The effects of defect ratios and repair actions were analyzed, and the test results indicated the following: 1) The bar slip dominated the failure of two specimens with defect ratios as expected, rather than the flexural failure mode for the specimen without defects. A rocking phenomenon was observed since the occurrence of bar slip, and the pinching phenomenon appeared for the corresponding hysteretic curves. The load-bearing, deformation and energy dissipation capacities were significantly lower than those of the specimens without defects. The increase in the defect ratio decreased the drift ratio associated with the bar-slip phenomenon, but the influence of the defect ratio on the seismic performance after the bar slip was negligible. 2) The bar-slip behavior was effectively prevented after the repair of insufficient grouting. Hence, the repaired specimens exhibited the expected flexural failure mode, and the load-bearing, deformation, and energy dissipation capacities were generally comparable with those of the specimen without defects. Rocking behavior and pinching phenomenon were not observed after repair. The negative influences of insufficient grouting were almost eliminated, thus validating the reliability of the repair method. The research outcome can serve as a reference for quality control of PC structures using GSCs.