Stability behavior of Steel-concrete Composite Beams subjected to hogging moment

The behavior of Steel-concrete Composite Beams (SCCB) under the action of hogging moment is not yet fully understood. In this condition, these structural elements may be subjected to local buckling or Lateral Distortional Buckling (LDB). LDB is a mode of stability in which the web must distort in order for the compression flange to displace and twist during buckling. The classic LDB standard procedures start from the determination of the elastic critical moment and subsequently use empirical curves to determine the LDB strength. However, investigations show that there is no consensus in determining the LDB elastic critical moment. In addition, studies indicate that the use of the same empirical curves obtained for the analysis of steel I-beams leads to the conservative results of the LDB strength in SCCB. In this context, this paper investigates the behavior of SCCB under the action of hogging moment through the development of buckling and post-buckling numerical analyses with the ABAQUS software. In the parametric study, the effects of the I-section, the unrestrained length, the reinforcing ratio, the concrete slab height and the slab topology were investigated. The investigations showed divergences between the elastic critical moment and ultimate moment when compared with classic procedures. In addition, the influence of the analyzed parameters is presented. These results can provide a reference for future research and specification reviews.