Damage analysis of steel-concrete composite beams under static loads

This paper presents a study of the static behavior of steel-concrete composite beams with different types of damage. Since the behavior of a composite beam under load is governed by the shear connection, it is important to investigate the overall structural response due to different levels of damage in the interface and composite layers. A finite element (FE) model of a steel-concrete composite beam is developed based on two Euler-Bernoulli beams as the composite layers coupled with a deformable shear connection. Three different damage indices are defined for the concrete slab, the steel girder, and the distributed shear connection and then embedded into the stiffness matrix of the composite beam. This model is validated by comparing its load-displacement behavior with an equivalent FE model developed using the commercial FE software ABAQUS. The impact that the loading location has on the results is then investigated. A convergence study is also carried out in terms of the displacements and strains to determine the number of composite beam FEs. The maximum displacements and strains of composite beams with different types and levels of damage are then investigated. The numerical analysis showed that after an initial reduction when the number of FEs increase, the changes in displacement and strain at each location are very small. Moreover, the bonding slip has almost no effect on the measurements, and the changes in maximum displacement and strain from undamaged to maximum damage are almost the same.