Characterization of the Splitting Behavior of Steel-concrete Composite Beams with Shear Stud Connection: Fid-Bau Portal

Characterization of the Splitting Behavior of Steel-concrete Composite Beams with Shear Stud Connection

Lowe, Daniel / Das, Raj / Clifton, Charles

Steel-concrete composite beams combine the high tensile strength of steel with the high compressive strength of concrete to create a stronger stiffer composite member. For the beam to act compositely, internal longitudinal actions must be transferred from the steel to the concrete through shear stud connectors. Once the stud-concrete interface starts to fracture or crush, the load carrying capacity of the beam is compromised. Shear connector capacity has been determined experimentally; however these tests do not generate a detailed understanding of the force transfer mechanisms between stud and concrete. This paper aims to characterise the behaviour of the composite beam when it fails by fracture of the concrete along the line of the studs, known as splitting failure. Experiments have been conducted on 5 steel-concrete composite beams, with shear stud connections, to investigate in detail the splitting behaviour at the stud-concrete interface. All beams were internal primary beams designed to fail by splitting. Testing was carried out on a specially developed push off rig (A. Gillies et al., 2006), with four specimens being loaded monotonically until failure and the fifth one loaded cyclically and then failed monotonically according to EuroCode 4 (1994) recommendations. Crack initiation and propagation in both the vertical and longitudinal direction were measured, as well as local and global strains. Results show very small changes in rib width as load is increased, giving indication of when micro and macro cracking occurred. It was shown in the cyclic test that concrete splitting and crack growth propagations occurs at very low applied loads. From these measurements it can be concluded that the zone of transverse deformation around the stud is very localized. The stress field in the concrete around the base of the stud is non-uniform, with a high build-up of compression on one side of the stud and a small amount of tension on the other side.