MECHANICAL BEHAVIOR ANALYSIS OF PRESTRESSED CONCRETE COMPOSITE SLAB

The prestressed concrete composite slab has the beneficial aspects such as thinner thickness, lower quantity of reinforcements, fast erection and high quality due to the using of the prestressed precast concrete bottom slab. Therefore, it has been wildly applied in civil engineering to fully achieve its economic and technical advantages. The prestressed concrete composite slab is composed of prestressed precast concrete bottom slab and superimposed cast-in-situ concrete. Because of the secondary concreting, the mechanical behaviour of the prestressed concrete composite slab is consequently different from the traditional integral casting prestressed slab. The integrity and mechanical property have been obviously dependent on the structural behaviour of the interface between precast and cast-in-situ concrete. There are many technologies or methods that can be used to ensure the integrity performance of the interface, such as natural or artificial rough surface, protruding stirrup and embedded truss reinforcement. With proper treatment on the interface between precast and cast-in-situ concrete, the integrity of composite slab has been believed to be satisfied in current engineering. Actually, it is experimental without necessary analysis work. In this paper, based on a specific project, the comparative analysis was carried out on the composite slab and cast-in-situ slab through FEM. The elastic-plastic material constitutive model had been taken account to in the FEM modal. The mechanism behaviour of the interface was modelled using contact pair elements. The prestressed concrete composite slab model and the integral prestressed slab model were established respectively. The checking calculation of construction progress and ultimate capacity analysis were carried out on the FEM model. The force-deflection curve, failure mode and stress and deformation of the interface had been studied by contrast. The detailed analysis results had shown that with the 4mm deep artificial rough surface applied in this project, the prestressed concrete composite slab had obtained almost the same structural property as the integral prestressed slab.