Analysis On Effective Width Of Concrete Slab In Steel-concrete Composite Truss Beams

Steel-concrete composite truss is a new type of structure developed on the basis of common composite beam, it is composited by concrete slab and steel truss which are connected through the shear connector work together. Because the structure fully plays the compressive property of concrete and tensile property of steel, it has significant technical and economic benefits while meeting the structural function and force. It has been widely used in high-rise, ultra-high buildings and Bridges, etc.The effective width of concrete slab is a very important parameter which directly influences deformation and carrying of the composite truss, when we study its computation theories. Many scholars have done a lot of research on the effective width of ordinary composite beams but less of the steel-concrete composite truss, and the corresponding analysis and calculation is not mature, and Chinese current specification doesn't give the calculation methods of composite truss's effective width. Then to the common composite beam steel-concrete composite truss, as a new type of structure, has many incomparable advantages, such as big bending stiffness, little use of steel, small structure height and convenient pipeline layout, and has a very broad application space and development prospects. Meanwhile, in the actual design of engineering, it also is a problem to be solved whether the ways of common composite beam's effective width are used in composite truss.In view of the situation above, the thesis systematically studies the effective width of composite truss based on finite element analysis software. Based on simulation results, the paper analyses the influence of function forms, width-span ratio, the thickness of concrete wing, the connection degree of shear connectors, depth-span ratio and the position along composite truss to the effective width, and finds the general rule of change with load. Based on the analysis of influence parameters, this paper puts forward the calculation formula of composite truss's effective width under the uniformly distributed load in elastic limit state. Finally it proposes the simplified model of composite truss under the complete action of shear connection, and deduces every generation rods' calculation formula of cross-sectional area which can be used as the design reference in practical engineering.