Analytical study on the cracking transition of concrete shear key

The objective of this paper is to study analytically the transition phenomenon between a large single curvilinear crack and diagnoal multiple cracks observed during the shear-off failure sequence of concrete shear key joints. Based on the principle of the conservation of strain energy, well-known elastic solutions are applied to analyze the principal strain distribution along the shear key base after a large single curvilinear crack propagation. The analytical prediction is compared with the principal strain distribution obtained by the smeared crack FEM analysis. The analytical model is found in relatively good agreement with FEM analysis, indicating that the nonlinear strain localization at the cracking transition could be quantified in a simple manner to a certain extent. In addition, it is analytically clarified that the cracking transition is induced by the change of the boundary condition.