Headed Bar Connections Between Precast Concrete Panels Loaded in Bending: Fid-Bau Portal

Headed Bar Connections Between Precast Concrete Panels Loaded in Bending

Vella, Jean Paul / Vollum, Robert / Jackson, Andrew

Abstract As part of a wider study into headed bar connections, this research concerns tests on precast concrete specimens connected by means of a joint developed and patented by Laing O’Rourke, known as the “E6 joint”. The joint consists of lapped headed bars that, along with additional vertical shear studs and transverse bars used as confining reinforcement, allow a narrow joint width of only 200 mm to be used. The first part of this research included testing of small scale joint specimens subjected to direct tension, while the specimens presented here are tested in flexure. Variables tested include; the concrete strength in the joint, vertical misalignment of the precast panels, and absence of shear studs. Results show that tests in bending achieve a higher ultimate capacity than calculated from strengths of corresponding direct tension tests, whilst showing similar failure mechanisms. The experimental results are used to validate a three dimensional non-linear finite element model (NLFEM) of the joint. A strut-and-tie model (STM) used to determine the E6 joint design strength has been found previously to give safe predictions for specimens in tension whilst not fully capturing the observed joint behaviour. The STM gives even more conservative results for specimens in bending. The results presented in this paper will be used in future research to further optimise the joint design and reduce the degree of conservatism associated with the design model.