Investigation Of Bending Resistance Performance On New-type Prestressed Outer-plated Steel-concrete Composite Beam

The prestressed outer-plated steel-concrete composite beam is a new type of outer-plated steel-concrete composite beam, which developed from the outer-plated steel-concrete composite beam, and possesses with the merits of steel-saving, good stability, large rigidity, increase crack moments at section, enlarge range of spring work, a high load-bearing capacity and plenty of utilizing mechanical performance of composite materials. The study on the prestressed outer-plated steel-concrete composite beam is important significance in both theory and application. Based on the models test numerical computation and theoretical analysis, the resistance to bending of the prestressed outer-plated steel-concrete composite beams are presented. The completion main works and obtained achievements include:Based on the tests of static loads for tree prestressed outer-plated steel-concrete composite simple beams which are 2 meters length, and two prestressed outer-steel-plate-concrete composite continuous beams which are 6 meters length, the resistance of bending of outer-plated steel-concrete composite beams are researched. In test, the strain of cntroled beams section, the crack widths of concrete, the deflections of midspan, the benring capacity of composite beams and the mechanical performances of composite material in all levels load are studied.According to the mechanism of interaction between tendons and structure, the direct inter load method is proposed to calculate prestressed internal load. Based on the theory of the direct inter load method, self-balance of prestressed internal load is proved and the analytic equations of the main internal force in prestressed internal load are given. For the curve profile of tendons, the cubic spline functions are used to describe tendons profile.According to the feature of prestressed outer-plated steel-concrete composite beams, the separate model of finite element is used. In the finite element model, the layered interface elements is proposed and elements matrix are derived to simulate slip mechanical behavior between steel plate and concrete. Based on the comparison between the results of finite element and the tested results, the finite element analysis can show mechanical behavior of composite materials in prestressed outer-plated steel-concrete composite beams under loads, and the data collected from experiments are close to. the results from the numerical simulation.Based on the tested and numerical results and the micro-elements balance of the internal force, the sliping equation of outer-plated steel-concrete composite beams are presented under various loads, and the data collected from experiments and numerical simulation are consistency to the theoretical results;According to tested and numerical results, the methods of compatibility of deformation and the method of trying calculation to slove the equation of bending resistance in various steps of load-bearing are proposed. By the comparison with theoretical, numerical and tested results, the reliability of theoretical analysis abort prestressed outer-plated steel-composite beam are shown.