Slab behaviour in composite beams at web openings

An explanation is provided for the slab behaviour in composite beams at web holes where the concrete slab carries heavy vertical shear. This is based on the truss concept, and requires consideration of shear studs in the hole region as vertical tension members. According to this, a structural action between the concrete slab and shear connectors for carrying or transferring vertical shear to the steel beam was clearly identified.On the basis of the slab behaviour identified, truss idealizations capable of determining the slab shear carrying capacity in a rational manner were developed. Then, the ultimate strength for composite beams at web holes was formulated including the truss idealizations. Another ultimate strength analysis accounting for the slab shear carrying capacity in a simple manner, which was also developed during this research project, is given. This provided the fundamental solution procedure for the plastic analysis used.A series of nine tests was carried out with particular attention being directed to the verification of the proposed truss analogy. The major test parameters included the configurations of the studs in the hole region, the width of the concrete slab and stud detailing near the high moment end of the hole. The ultimate strength predictions were made by the two methods developed, and compared with previous and present test results