Study On Bearing Capacity Of Prestressed Concrete Hollow Slab Strengthened With Polyurethane Cement Composites

In the long-term operation of a bridge,due to the continuous decline in material properties,coupled with the external environment and the role of car overload,will lead to structural damage,carrying capacity decreased.Many of the bridges of active service can no longer meet the inherent needs of modern transportation,there is a big security risk.Therefore,how to strengthen,strengthen and strengthen the stiffness,strength and stability of the bridge has become the focus of the development of bridge industry in China.In this paper,the mechanical tests of polyurethane cement composites were carried out to determine the mechanical properties of the materials.The bearing capacity of prestressed concrete hollow slab beams strengthened with polyurethane cement composites was simulated by finite element program Midas / FEA,and the effect of bending reinforcement on hollow slab beams was determined.Taking the raft south bridge as the engineering background,the actual reinforcement effect is evaluated and verified that it can be used in the bending reinforcement of the bridge.The main contents include:The optimum mixing ratio of MPC composites was determined,and the relationship between compressive strength,flexural strength and density was summarized,and the adhesion and impermeability of MPC composites were verified.The numerical simulation of Midas / FEA by finite element program shows that the prestressed concrete hollow slab beam is strengthened with MPC composites,and the stress of concrete and the stress of steel strand are strengthened after the reinforcement of hollow slab beam.Significantly reduced,the development of cracks in the cross-section significantly reduced,after reinforcement can effectively inhibit the development of cracks.The results show that the yield and ultimate load of the hollow slab beam are greatly improved by the numerical simulation of the ultimate bearing capacity of the prestressed concrete hollow slab beam strengthened with MPC composite.The reinforcement effect is analyzed by comparing the theoretical and measured values of deflection and strain,and it is proved that the reinforcement of the prestressed concrete hollow slab bridge is feasible by using MPC composites.,And verifies the accuracy and rationality of the finite element program.