Shear failures in concrete structures are very hazardous. These failures can rarely be predicted and often happen explosively. For decades, tests have been done to study this phenomenon, in order to try to understand the shear cracking mechanism in reinforced concrete (RC) beams. Hence, attempts to analytically quantify the mechanism of shear cracking have not been successful to date. However, shear in the current codes are based on empirical procedures.

The initiation of the critical shear cracking is associated with the magnification of actual shear stress produced by a distinct local stress concentration effect arising from the formation of the nearby flexural cracks. This local shear stress concentration is produced by the nature of bond between the concrete and the flexural reinforcements. Thus, it is well established that bond failure at the interface between concrete and flexural reinforcement leads to inclined (“shear”) cracking in RC beams.

The main aim of this dissertation is to investigate the possibility of solving the shear problem by preventing the formation, rather than the extension, of inclined cracking in the critical regions of RC beam elements. Since the causes of such cracking are inextricably linked with the interaction between concrete and the longitudinal steel bars, it is attempted to prevent inclined crack formation by preventing concrete-steel interaction through the use of a PVC pipe to cover over the critical region of simply supported beam specimens.

The specimens tested consist of eight rectangular and square reinforced concrete beams, and all the beams have the same length and longitudinal reinforcement. All beams were simply supported and tested under symmetrical two-point loads at mid span. Six of the eight specimens were subjected to sequential loading comprising axial (N) and transverse (P) components, and the rest to a transverse loading only. For two of the beams, external transverse reinforcement was designed in the shear span.

The results obtained indicate that with the use of a PVC cover to the portion of the flexural bars within the critical regions of the beam elements, shear cracking is prevented in all the beams investigated. All the beam specimens failed because of flexural cracks formed in the mid span. The initiation of this flexural cracking is found to be produced by the nature of bond between the concrete and the portion of the exposed flexural reinforcement. Designing transverse reinforcement for two of the test beams is effective to face the tensile force formed in the interface of cracked and uncracked concrete in the shear span. It is realized that the steel bars in all the beams did not yield and failure happened in concrete only. For further investigation, it is recommended to check the design of longitudinal reinforcements of the beam as it was designed based on full concrete-steel interaction. Thus, this new concept of the bond-prevented flexural failure may lead to savings of the amount of steel bars.