Study of the shear performance of inclined screws in glulam-concrete composite beams under standard ISO 834 fire

Abstract

Extensive research has been conducted on the shear behaviour of inclined screws in glulam-concrete composite beams at normal temperatures. However, research on the shear behaviour of inclined screws under fire conditions is limited. In this study, one group of push-out tests at normal temperature and five groups of push-out tests under standard ISO 834 fire were performed. The test results revealed that the failure modes of inclined screws under fire were characterized by compression failure of the timber surrounding the screws and pulling failure of the shear-tension loaded screws. As the fire exposure time increased, the shearing capacity and slip modulus of the inclined screws decreased. Notably, the slip modulus of inclined screws under fire exhibited a more pronounced decrease compared to the shearing capacity. The shear properties of inclined screws under standard ISO 834 fire were enhanced with increasing thickness of the timber side cover of the screws. The comparative results showed that the shearing capacity of inclined screws under standard ISO 834 fire could be accurately predicted based on the analytical model in EN 1995-1-2. In addition, a theoretical method was presented to predict the slip modulus of inclined screws under standard ISO 834 fire.