Punching shear behavior of concrete slab-column connections reinforced with glass fiber-reinforced polymer (GFRP) bars with different design parameters: Experimental study, finite element simulation, and theoretical model

초록

In this study, experimental and analytical investigations were conducted to evaluate the influence of various design parameters on the punching shear behavior of reinforced concrete (RC) slabcolumn connections reinforced with glass fiber-reinforced polymer (GFRP) bars. An experimental program was conducted on 10 slab-column connection specimens, with the primary variables being the longitudinal reinforcement ratio on the tension side of the slabs, the longitudinal reinforcement layout, the column section dimensions, and the column cross-sectional aspect ratio. The experimental results indicated that increasing the axial stiffness of longitudinal GFRP reinforcement improved the punching shear behavior of GFRP-reinforced slab-column connections in terms of stiffness, punching shear stress capacity, and deflection. Additionally, employing a banded GFRP reinforcement arrangement around the supporting column effectively reduced deflections in slabs under applied loads. The punching shear stress capacity of GFRP-RC slab-column connections is less affected by the aspect ratio of column cross-section, while it exhibited a slight reduction as the ratio of maximum column size to slab's effective depth (c1/d) increased. A finite element (FE) model was developed to simulate the punching shear behavior of GFRP-RC slab-column connections. The simulation results showed that the FE model accurately reproduced the punching shear behavior observed in the experimental tests and provided a reliable explanation for the punching failure mechanism in RC slab-column connections reinforced with either steel or GFRP bars. Finally, a theoretical approach for predicting the punching shear strength of slab-column connections reinforced with GFRP bars is proposed based on punching failure criteria at the critical section, determined by analyzing the interaction between the shear demand and shear capacity curves. The proposed strength model showed good agreement with experimental results from this study and existing studies, with a mean strength ratio of 1.15 and a coefficient of variation of 13 %.

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