Structural capacity of a composite slim-floor beam with hollow steel tube shear connectors

A slim-floor composite beam's structural performance relies on the composite action provided by shear connectors. However, the information on the performance of composite slim-floor beam with HSTs connectors in flexural in term of moment capacity, shear interaction and ductility still needs to be clarified. Thus, six specimens of the composite beams with square and rectangular HSTs with two different beam sections, I and inverted T, were tested. The main failure was found to be concrete crushing in the area of the connectors. HST connectors prevented the concrete slab from uplifting, particularly in the specimens without a top flange. Subsequently, this increased moment capacity to 230% and 152% for inverted T and I-beam sections, respectively. Furthermore, ductility behavior was also improved and met EC4 requirements. The degree of shear interaction was increased from 0.4 up to 0.9 compared to the beam without HST. The predicted results from the suggested procedure to estimate moment capacity agreed well with the experimental results, with a maximum difference of 7% in the I-section specimen. In contrast, the predicted value for the inverted T specimen overestimates about 26%. Overall, the beam with the HST shear connector significantly improved the flexural performance of the composite slim floor beam.