Seismic Performance of Post-heated Reinforced Concrete Frame Joints

Abstract

An experimental study was carried out to investigate the seismic performance of post-heated reinforced concrete frame joints. Three full-scale joints that are part of reinforced concrete frames, and exposed to fire, were tested under a combined axial loading and cyclic lateral displacement history, to simulate earthquake loading. The joints were tested in two groups, namely in the unheated and post-heated states. In terms of seismic performance, test results indicate that the frame joints did not sustain much damage with 60 min fire exposure time, since the concrete did not lose much of its mechanical properties and steel rebars recovered much of temperature induced strength loss. Hence the energy dissipation capacity in joints of the frame that exposed to 60 min of fire remained mostly in fact. However, the damage to joints was more serious in frame with 90 min fire exposure time, due to loss of mechanical properties in concrete and steel rebars, leading to lower seismic performance of joints after fire exposure. All three fire exposed joints failed in shear failure mode under seismic loading