Experimental study on seismic behavior of prefabricated reinforced concrete beams with large-diameter reinforcements

Abstract

This paper proposes a new beam type, i.e., a prefabricated reinforced concrete beam with large-diameter reinforcements and floor slabs, and studies its seismic performance to solve the problems that too many reinforcement joints and too dense sleeve gaps in the splicing joint of prefabricated concrete components affect the speed and quality of joint construction. Taking the large reinforcement diameter and the setting of additional connecting reinforcements as study parameters, this paper performs the low-cycle reciprocating test on four full-scale specimens so as to measure their hysteretic curves, skeleton curves, and failure modes. This work also clarifies the failure mechanism of prefabricated reinforced concrete composite beams considering the effect of floor slabs. Further, a finite element model is established utilizing ABAQUS software and verified, and the material constitutive relationship suitable for simulating the hysteretic performance of such components is proposed. The results demonstrate that under low-cycle reciprocating loading, the prefabricated concrete beams with fixed ends experiences the beam-end bending failure, the positive stiffness of the member degrades obviously when its failure, and the concrete in the compression area of the lower flange of the beam collapses. It is feasible to use a grouting sleeve to connect large-diameter reinforcements in prefabricated reinforced concrete beams. Increasing the diameter of the longitudinal reinforcement can significantly improve the cracking load, yield load, and ultimate bearing capacity of the composite beams with floor slabs. The hysteretic curves of the composite beams with the large-diameter high-strength reinforcements are full, and the setting of additional reinforcements negligibly impacts the hysteretic behavior of the composite beams. The proposed concrete damage plasticity model and Fang’s hysteretic constitutive model of steel bars can effectively simulate the hysteretic behavior of prefabricated reinforced concrete beams with large-diameter reinforcements. Although the cracking load of beam with large-diameter reinforcements is reduced by about 10 %, it has little effect on the seismic performance. The number of reinforced joints is reduced by about 50 %, which significantly improves the field assembly efficiency and pouring quality of prefabricated concrete components. It is suitable for application and promotion in prefabricated concrete structures.