Experimental Study on Seismic Behavior of Plane and Spatial Concrete Beam-column Joints After Exposure to Fire

Abstract:

The fire behavior of one plane and one spatial beam-column concrete joints was investigated under the fire according to the standard ISO834 temperature time curve, and then four specimens (the two fire-damaged specimens, two comparison specimens under room temperature) were tested under low cycle reciprocating loadings. Thus their post-fire residual seismic performances were studied. Furthermore, the cracks, failure modes, hysteretic loops, envelope curves, load bearing capacity, ductility coefficient, stiffness degradation, and energy dissipation were studied and compared in detail. The experimental results show that shear failure happens only in the joint zone of the fire-damaged plane beam-column joint, and the rest three specimens exhibit bending failure in beam ends. It is also demonstrated that the load bearing capacity, ductility coefficient and energy dissipation of the specimens is reduced, and the deformation is increased, after exposure to fire. However, the contribution of slab and orthogonal beams is weakened due to the damage of concrete after fire, which results in a more significant change in the performance of the space beam-column joint specimens before and after fire exposure.

Key words:fire;spatial joint;concrete;low cycle reciprocating load;seismic behavior