PUNCHING OF INTERIOR SLAB-COLUMN CONNECTIONS WITH GLASS FIBER-REINFORCED POLYMER REINFORCING BARS

摘要

Concern over the effects of steel corrosion on the durability and safety of structural concrete slabs and bridge decks has prompted the use of fiber- reinforced polymer (FRP) reinforcing bars as an alternative reinforcement for these structural systems. However, punching shear behavior of two-way slabs reinforced with FRP bars has not yet been fully explored while extensive work was done to investigate the flexural behavior of concrete members reinforced with FRP reinforcement. In this study, four two-way interior slab-column specimens reinforced with glass fiber-reinforced polymer (GFRP) bars were tested. The main parameters investigated were the differences in physical and mechanical properties between steel and GFRP bars, the slab flexural reinforcement ratio in the column vicinity, as well as the placement of steel fiber reinforced concrete (SFRC) in the slab near the column faces. The effects of these parameters on the punching shear capacity, stiffness, ductility, strain distribution, and crack control were investigated. In addition, an appropriate method for determining the reinforcement ratio of slabs with a banded distribution was proposed to make predictions of punching shear strength properly reflect the benefit of the slab reinforcement concentration. This paper also presents the comparison of the test results with the punching strength predicted by various code equations and the predictions proposed in the literature specifically for FRP-reinforced slabs.