Effect of Creep on Shear Tab Connections under Fire Temperatures

Abstract

The effect of creep on the strength capacities, ductility, and failure modes of shear-bolted lap joints at elevated temperatures is investigated. Thirteen bolted lap joints (representing shear tab connections) are tested under different loading rates: fast rate (10 mm/min) and slow rates (1 mm/min and 0.3 mm/min) for temperatures ranging from 450°C to 700°C. The temperature- and the time-dependent behavior of the lap joints are examined. The results show a change in failure mode from tear-out failure when using fast loading rate to net section fracture when using slow loading rates at temperatures 450°C and 500°C. The results show that the failure mode of the bolted lap joints changed from plate failure to bolt shear failure at temperatures larger than 500°C. The slow loading rate tests resulted in a reduction in the bolt shear capacities when compared to the fast rate tests. Moreover, finite element models are developed to understand the change in failure mode of the connections from tear-out failure to net section fracture and to bolt shear failure. This study is considered as a step towards developing design guidelines for shear tab connections at elevated temperatures while considering the effect of creep.