Calculation and Analysis of Deflection of Steel-Concrete Composite Beam Considering Influence of Long-term Effect

The stress and deflection of the composite section are affected by shear lag effect of the steel-concrete composite beam flange.Based on the interlayer slip, shear deformation, sheer-lag and the long-term behavior of concrete action, then the equilibrium differential equations for calculating the deflection of composite beam under long-term loading were derived based on the energy variational principle. The ANSYS finite element model(FEM) under short-term loading and the MIDAS FEM under long-term loading were established.By combining the MIDAS FEM calculation result about the deflection data of the composite beam under the action of concrete shrinkage and creep with the deflection value of composite beam under short-term action calculated using ANSYS FEM, the total deflection value of steel-concrete composite beam under long-term loading were finally obtained. The results agree well with the theoretical deflection value in this paper.In order to further investigate the influence of shear-lag effect, a simply supported composite beam was introduced to analyze whether to consider the change of deflection of the composite beam with shear lag.Finally, taking the simply supported composite beam as an example, the effect of the effective width coefficient of composite beam fulcrum and the mid-span concrete slab by the wide-span ratio was analyzed and compared with the Chinese code calculation method. The final results show that the effective width coefficient decreases with the increase of the width-span ratio and the effective width at the fulcrum is smaller than that at the mid-span. The error between the calculated value and the code value shall not exceed 5.12%. © 2022, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.