SHEAR TESTS OF REINFORCED CONCRETE BEAMS WITH THE INFLUENCE OF INITIAL SHEAR CRACKS

Abstract

Cracks in reinforced concrete (RC) structures can be detrimental if they grow beyond the limits, so it is important to include their influences in the structural health monitoring method. For example, the impact of shear cracks on the structural performance of RC beams remains unknown. To fully understand the impact of cracks, judging by crack patterns alone is insufficient. This study focuses on the initial shear cracks and investigates whether shear cracks in different locations reduce the load-bearing capacity of beams at different levels. Four sets of beams that exhibited different types of initial shear cracks were cast, including (i) reference beams with no cracks, (ii) beams with inclined cracks in the bending span, (iii) beams with shear cracks in the shear span, and (iv) beams with pre-defined notches in the shear span. The initial cracks were carefully documented, and all the specimens were tested in four-point bending tests. The test results of beams with initial cracks or notches were compared with reference beams. The comparison indicated that the initial cracks in the bending span had limited influence on the load-bearing capacity, while the cracks in the shear span significantly reduced the ultimate load of the beams. Also, the cracks in the shear span were likely to further propagate to become the dominant cracks.