Influence of the Longitudinal Shear Transfer on the Vertical Shear Capacity in CSTC Beams

Abstract

AbstractUnlike typical composite beams using downstand steel profiles, Composite steel truss in concrete (CSTC) beams consist of steel trusses welded to a steel plate and embedded in concrete. In this case, the longitudinal shear transfer relies on the mechanical interlock between the surrounding concrete and the embedded diagonals which carry simultaneously most of the vertical shear force. The current work aims to assess to what extent the longitudinal shear transfer affects the capacity of these diagonals, such that the current approach for determining the vertical shear resistance is suitable. Hence, a simplified 3D finite element (FE) model was firstly developed and several simulations were carried out. The results were post‐processed in consideration of the slip distribution and load conditions which may occur along the actual beam. Finally, a more advanced FE model was created to evaluate and compare the vertical shear resistance of a 6m CSTC beam with the corresponding value according to the current design method. Whilst the former methodology (simplified model) shows that a 15% yielding resistance reduction of the diagonal is sufficient to ensure the safety of the current design approach, the latter (advanced beam model) shows that no reduction is required.