Mechanical behavior of glulam-concrete composite beam with notched connections under ISO 834 standard fire

Abstract

Most research has focused on the fire performance of glulam-concrete composite (GCC) beams with screw connections. However, research on the mechanical behavior of GCC beams with notched connections under fire is limited. In this research, four groups of push-out experiments were conducted to explore the influence of fire exposure time on the shear behavior, load-slip performance, and failure mechanism of notched connection under ISO 834 standard fire. In addition, the bending test was carried out on the GCC beam with notched connections under ISO 834 standard fire. The experiment results demonstrated that the shearing capacity and slip modulus of the notched connection decreased as the fire exposure time increased. The main reason was that the temperatures of the glulam and concrete at the notch gradually increased, which reduced the material properties of the glulam and concrete. Notably, the slip modulus of the notched connection under fire exhibited a more pronounced decrease than the shearing capacity. The bending stiffness and load-carrying capacity of the GCC beam with notched connections were reduced with increased fire exposure time. The calculation methods were proposed to predict the shearing capacity and slip modulus of the notched connection under ISO 834 standard fire. The theoretical model for the mechanical behavior of GCC beam under ISO 834 standard fire was presented, considering the influences of high temperatures on the glulam member, concrete flange, and notched connection.