Research On Mechanical Properties Of Wet Joint In Steel And Concrete Composite Bridge

In the "13th Five-Year" development plan,the National Development and Reform Commission pointed out that new structure Bridges,especially steel-concrete structure bridges,should be paid attention and promoted.Wet joint is the key structure to ensure the continuity and safety of steel-concrete bridges in the process of longitudinal and transverse stress.At present,there are still many problems in the use of traditional wet joint,for example:the dense reinforcing bars at the wet joint makes the concrete pouring difficult,the narrow space of wet joint makes it difficult to guarantee the welding quality of reinforcing bar,the dehiscence phenomenon is obvious at the interface of new-old concrete,the discontinuity of ordinary reinforcing bars in wet joints affects the force transfer.According to the guidance of the above policy and the problems in the use of wet joints.This essay takes the wet joint of steel and concrete composite girder bridge in a freeway dominant engineering in Shaanxi Province as the engineering background,in view of the above problems in the construction and use of the existing wet joint,a wet joint with better structure is proposed,using software ANSYS to building-up the optimized model of wet joint,compared with the experimental data,the accuracy of wet joint finite element model analysis was verified.And analyze the influence parameters of longitudinal wet joint mechanical properties,and on this basis,further study on transverse wet joint load transfer in the wet joint force when the form.The application of optimized and upgraded wet joints in design and engineering practice is guided.The specific research contents are as follows:(1)Combined with actual engineering examples,this paper combs the common wet joint structures in prefabricated carriageway slab in China,introduces its structure and mechanical theoretical model.In view of the shortcomings of wet joint,and learn from foreign research direction,optimization build upon the original wet joint structure,and analyze the wet joint after optimization in structure and theory calculating method,and the theoretical value of wet joint bearing capacity is compared with the experimental data(2)Verification of finite-element simulation analysis model of wet joint.Referring to domestic and foreign test data,set up the ANSYS model,and contrast the finite element data and test data of ultimate capacity,vertical displacement,damage pattern and load-deflection curves,to test the reliability of finite element method of wet joint mechanical properties analysis.(3)Taking the longitudinal wet joint as an example,through the control variable method to set up the wet joint model,the influence of kernel concrete intensity,reinforcement ratio,reinforcement tension strength and non-contact lap length on the mechanical properties of wet joint.(4)Taking transverse wet joint as an example,in the negative bending moment area,it is subjected to the tension transmitted by the reinforcement reserved in the lane plate.The stress changes of ring reinforcement,through reinforcement and core concrete in wet joint during the whole load-bearing process are analyzed.On this basis,the stress model is simplified and the transmission mechanism is summarized.