Experimental and numerical investigation on seismic behaviours of beam-column joints of precast prestressed concrete frame under given corrosion levels

Corrosion as a major threat to civil infrastructures has been extensively investigated for decades. For precast concrete structures, corrosion medium are easier to penetrate into structural joints where precast components are connected or post-casting is applied. The corrosion process and structural deterioration, however, highly depend on structural configuration and construction procedure. Taking the frame structure comprised of precast prestressed concrete components (SCOPE) for example, this paper presents an experimental study on the seismic behaviors of corroded beam-column joints of the SCOPE system. Five specimens with different levels of corrosion were tested under cyclic loading, and crack propagation, hysteretic loops, envelope curves, bearing capacity, ductility and energy dissipation were compared and analyzed. It is observed that the cracking in concrete and the cross-sectional loss of corroded bars had a more obvious influence on the yielding load but had a relatively smaller influence on the ultimate load. The asymmetrical structural configuration of the beam-column joint resulted in non-uniform corrosion of the reinforcing steel bars in the top and bottom of the beams; accordingly, the post-peak behaviors of the specimens in positive and negative loading were different. The difference was found to be more significant with the increase of the corrosion ratio. A numerical method is proposed for simulating the behaviors of corroded beam-column joints through the constitutive models for concrete and steel reinforcements, and agreement is observed between simulated and experimental results.