Test Study Of External Prestressed Composite Steel-Concrete Beams Structure

This contents in the paper is relied on the project of "test study of external prestressed composite steel-concrete beams structure" funded by traffic office and project of "theory and test study of cohesionless partial prestressed steel-concrete composite beams" funded by science and technology office. In the paper, the stress, displacement and failure state of external prestressed composite beams are studied under vertical concentrated loads. Simple formula of bearing capacity at ultimate state is also presented. In the paper, numerical simulate analysis is also done. It includes six chapters. Part three and part four are important and part four is the hardcore of the paper.Chapter 1 is mainly talk about the study background, study significance, study content and study method. Prestressed steel-concrete composite beam bridge is a new type structure developed from the conventional composite structure. The material elastic scope is enlarged by externally prestressing force to steel, thus the high tensile material performance is substantially brought into play. Test study and theory analysis indicate that it is a kind of structure with the merits of safety, high efficiency, economic and conveniently construction, especially adapting to large span, heavy load bridge structure. Comparing with conventional steel beam, it can economize investment for about 20%. In china, a lot of existing railway steel bridges, highway steel bridges and composite bridges are all need to be reinforced or maintained, it is proved the most simple, efficiency and applicable method by exerting cohesionless prestressing force to reinforce these steel bridges, this is the underlying field of the technology.Eight prestressed steel-concrete composite simply supported beams and two steel -concrete composite simply supported beams have been constructed for static load tests. It costs for about two years for the model tests. In chapter two, the design of test beam, the constitutive relation of the material, the use of the test equipment and the test scheme are presented in detail. Loading equipment is the servo systemcontrolled by computer (WAW-1000) so that it can keep the load at any time with the error little than O.lKn. The vertical deflection is measured by displacement gauge with the dynamic and static data collection system of DH3817, the precision is 0.01mm. the strain of testing point is measured by static strain analysis system of DH3816. Strain rosette for steel beam with 3 mm distance is glued by 502 gluewater, Strain rosette for concrete with 10 mm distance is glued by 502 gluewater after nibdown and smeared the 801 gluewater concreting for about 24 hours.Chapter 3 is mainly talk about the stress change of prestressed tendons and the shearing strain's difference between steel and concrete, the shearing force lag phenomena at flange concrete slab and section strain change laws by test, some valuable conclusions are presented as follows:(l) the external prestressed steel concrete composite structure is still satisfied the plain section presume while the loading is still small, but at the plastic stage, it dose not satisfied the plain section presume.(2)the concrete compression flange has the phenomena of shearing lag for positive and negative are all existed and the coefficient is greater than 1.2.(3)shearing slip between the interface of steel-concrete is evident at the shearing region, it has the maximal value at the location of vertical concentrated loading that have bigger effect to combination effect, especially to the curvature and the stress, while should be considered fully. (4) after exerting the presressing force, the capacity and rigidity of composite beam are all improved while the plastic of member have no change, so the prestressed steel-concrete composite beam have the bigger span capacity and have the wider used prospect than the steel-concrete structure.Chapter 4 is the hardcore of the paper. The numerical simulated model is presented. The test process of PSCT-4 beam is simulated. By comparing the test results with the simulated results, it indicates that the fem model results are well fit with the test results, so the model can be used to calculate and analysis the shearing slag, shearing slip, deflection under monotony loading effectual, which can obtain...