Shear Strength Analysis of Reinforced Concrete Beams with the Influence of Initial Shear Cracks

Abstract

Cracks in reinforced concrete (RC) structures may result in a reduced loadbearing capacity, and thus understanding the effects of cracks is an important part of a comprehensive structural health monitoring strategy. It is known that the impact of cracks cannot be quantified solely based on the crack patterns. In particular, shear cracks form as a result of a more complex stress state and their influence on the structural performance of RC beams is yet to be studied in detail. This research focuses on the shear cracks and aims to correlate their location to the load-bearing capacity of beams. In an experimental program, initial shear cracks were first generated by loading at varying positions and then the beams were loaded to failure. Four types of beams were tested; these were beams with: (i) no cracks, (ii) inclined cracks in the bending span, (iii) shear cracks in the shear span, and (iv) a pre-defined notch in the shear span. Furthermore, FE analyses were carried out to model the structural behavior of the beams using two different methodologies. The results indicate that compared with reference beams, the initial cracks in the bending span decreased the structural stiffness of RC beams but have limited impacts on the ultimate capacity. However, the cracks in the shear span not only decreased the stiffness, but also significantly reduced the load-carrying capacity of the beams. The observed behaviors were also reasonably well captured in FE analyses.