Study On Stiffness Of Steel-concrete Composite Beams

Steel - concrete composite structure as a new structure developed on the basis ofthe steel structure and reinforced concrete structure, makes full use of steel andconcrete materials respective advantages, technical significant economic and socialbenefits, and has been used in many high-rise buildings and large-span bridges. Whilesteel-concrete composite beams are the important horizontal load-bearing components,the performance of its popularization and application of research is of greatsignificance.In general, the change of the stiffness of steel - concrete composite beam can bedivided into three stages: flexible Stage, plastic stage and the stage of degradation,composite beams under service load are in the general state of flexibility, stiffnessdetermine a direct impact on the deflection calculated accurately. Interface and therelative slip of the normal use of composite beams under the influence of deformationcan not be ignored, especially Shear Connectors for flexible, it has been confirmed byexperiments. This thesis is based on the inadequacy of existing norms and amendsthrough analytical method relative slip differential equations, and when simplysupported composite beams are under three typical load the function of stiffness alongthe beam is made up by binomial coefficients. Then additional deformation of simplysupported composite beams can be determined, the results agree well with the resultsof experiments. Similarly this paper analyses stiffness of continuous composite beamsbecause of no working of the concrete of the negative wing plates, which can be acombination of that continuous beam interface slip can be calculated in the elasticstate, resulting in the deformation-formula and proving the results are somewhat safe.Besides the composite beams of the frame work similarly to the continuous compositebeam, and the incremental energy variational principle is used to get stiffness matrixof the composite beam element. At last, stiffness of cross-section of composite beamin rehearsal load calculation formula is simplified, the curves compared well with theexperimental curves, and can forecast composite beams the working process.