Experimental and analytical investigation on fire resistance of glulam-concrete composite beams

Abstract

The timber-concrete composite beam characterized by good mechanical behavior, low susceptibility to vibration and high sound insulation has a wide application in high-rise and long-span timber structures. However, the published study on the fire resistance of TCC beam is limited. In this research, one short-term failure test at ambient temperature and five full-scale fire tests were performed on the glulam-concrete composite beams. The influences of the load ratio, presence of timber board and fire-rated gypsum plasterboard on the temperature field and fire resistance were investigated in detail. The test results showed that the fire resistance of the composite beam was decreased with the increase of the load ratio. The composite beam with timber board interlayer outperformed the beam without the interlayer in terms of fire resistance. Moreover, the fire-rated gypsum plasterboard protection on the glulam beam could effectively improve the fire resistance of the composite beam. The finite element models of the composite beams were established to predict the temperature field of composite beams under fire. The average temperature values of concrete slabs under different fire times were obtained from numerical simulations. Considering the influence of high temperature on the glulam beam, concrete slab and shear connectors, the calculation methods of load carrying capacity and bending stiffness of the composite beam under fire were proposed.