Developments and bending behaviors of GFRP-concrete composite girders at low temperatures

Abstract

This paper reported the experimental and theoretical studies on the low-temperature performance of GFRP box-concrete composite girders (GCCGs) under four-point bending. GFRP box section with three vertical webs was adopted to improve the shear resistance of web. The horizontal shear force at GFRP box-concrete interface (concrete on top of the GFRP box) was resisted by the combined shear connectors with T-bolts and sand coating (TBSC). The effects of low temperatures (T = 20, −30, −60, and −80 ℃) on the mechanical behaviours of composite girders under four-point bending were studied. Test results indicated that the composite girders failed in shear fracture of the GFRP web and compressive fracture of the GFRP box under sagging and hogging moments, respectively. The plane section assumption was not applicable for composite girders under sagging moment because of the shear failure of sand coating. Meanwhile, the low temperatures improved the ultimate resistance (FuT) of GCCGs under four-point bending. Finally, theoretical models with consideration of GFRP box-concrete partial composite action were developed to determine the low-temperature behaviours of GCCGs under four-point bending.