Unbalanced Moment Transfer in GFRP-RC Slab–Column Connections

Abstract

When reinforced concrete (RC) slabs are supported directly on columns, a combination of shear forces and unbalanced bending moments is transferred between the slab and the columns at slab–column connections. The unbalanced moment transferred between a slab and a column can be significantly increased by the application of horizontal loads, such as wind and seismic loads. According to current design codes and standards for steel–RC structures in North America, a portion of the unbalanced moment is assumed to be transferred by the eccentricity of shear, while the remaining portion is assumed to be transferred by flexure. Previous research shows that the slab width that contributes to transferring the flexure portion is bounded by lines located at a distance of 1.5 times the slab thickness on each side of the column. This study investigates whether the same slab width can be used to transfer the unbalanced moments in slab–column connections reinforced with glass fiber–reinforced polymer (GFRP) reinforcement. A similar approach to that used for steel–RC connections is followed to analyze data from 27 GFRP-RC connections without shear reinforcement reported in the literature. Furthermore, a previously validated finite-element model is used to investigate the strain distribution in the longitudinal slab reinforcement along the transverse direction of the slab. The results show that a smaller slab width bounded by lines located at a distance of 0.5 times the slab thickness on each side of the column is recommended for GFRP-RC slabs.