Experimentation and design rules of loop-reinforced diamond-shaped joints for load-bearing precast concrete walls

The paper aims at characterising the mechanical behaviour of a joint for precast bearing-wall structures made with high-strength steel loops protruding from diamond-shaped recesses left in the precast walls. After a steel bar is inserted into the footprint circle left by juxtaposing loops, high-strength non-shrinking mortar is cast into the recess. An experimental programme has been carried out at the LPMSC laboratory with the collaboration of DLC Consulting in order to investigate the response of the joint under pure shear load, and combined shear and axial loads. The possible failure modes under vertical shear, horizontal shear, and axial load are identified, and corresponding formulations are proposed including multi-axial interaction. The proposed design rules allow to derive interpretations of the test results.