CALCULATION METHOD AND EXPERIMENTAL VERIFICATION OF THE RESIDUAL STRENGTH OF COMPOSITE BEAMS CONSIDERING THE FATIGUE DAMAGE OF MULTI-COMPONENTS

In view of the problem that the residual strength of steel-concrete composite beams after fatigue cannot be calculated in the current codes, a method for calculating the residual strength of composite beams considering multi-component fatigue damage is proposed. Based on the material residual strength theory, the component strength attenuation models of the concrete slab, steel beam and stud connector in a composite beam under fatigue load were introduced. The fatigue stress amplitude of each component under the given fatigue load was then obtained by the stress analysis of the composite beam under fatigue load. The fatigue damage of each component was included in the calculation of the residual strength of steel-concrete composite beams. Considering the change of the shear connection degree of composite beams during fatigue loading, the calculation methods of the residual strength of composite beams under complete and partial shear connections were established and verified through the test of the residual strength of six beams. The results show that the shear connection degree of composite beams decreases gradually under fatigue load, and that the residual strength degradation is obvious and cannot be neglected. The calculation results of the residual strength of composite beams by the method established in this paper are in good agreement with the experimental values. The method has good calculation accuracy and applicability. It complements and improves the existing calculation methods of composite beams.