The Effect of Shear Crack Geometry on Aggregate Interlock Action in Reinforced Concrete

Abstract

A shear crack in an RC beam undergoes a load sharing stage where aggregate interlock is dominant along particular segments of the crack path. However, one of the challenges is that this estimation of the aggregate interlock contribution is highly dependent on the shape of the critical shear crack. Therefore, a thorough study is required to determine the characteristics of crack shapes observed in measured experimental crack patterns and subsequently to develop predictive tools. This paper investigates the sensitivity of aggregate interlock action on simplified and higher-order shear crack geometries to assess the best ways of idealising the critical shear crack such that they could be adapted for analytical tools.In addition, a refinement of an existing crack kinematic model is developed for RC beams with low shear reinforcement. As a comparative study, an RC beam which may exhibit different possibilities in terms of the shape of the critical shear crack is considered to calculate the relative aggregate interlock contributions. A polynomial representation of the shear crack is found to be a good approximation for a critical shear crack. It is found that critical shear cracks with a concave downward segment which are located in the middle of a shear span generate larger aggregate interlock contributions than cracks with a concave upward segment or cracks which are located closest to the support.