Understanding and application of shear-compression behaviour of concrete and dowel action of reinforcing bars in concrete beams

Concrete and reinforcing bars in concrete structures are often subjected to complex stress states. In concrete beams, the concrete in the compressive zone resisted both shear and compression stresses, while the dowel action of longitudinal reinforcement in tensile zone resisted shear forces. To investigate the shear-compression behaviour of concrete and the dowel action of reinforcing bars, this study aimed to develop improved theoretical models for evaluating these behaviours and to apply them to predict the shear capacity of concrete beams. To this end, a comprehensive database comprising 442 test datasets from directed shear tests was established. Analysis of the database revealed that the shear strength of concrete increased non-linearly with its compressive strength, initially increasing and then decreasing with increasing lateral stress. Furthermore, the dowel action contribution was found to increase with the product of the ratio and yield strength of transverse reinforcement. Based on stress‑state analysis, new theoretical models were proposed to quantify both the shear-compression behaviour of concrete and the dowel action of transverse reinforcement. Finally, these proposed models were successfully integrated into an analytical framework for evaluating the shear load-bearing capacity of concrete beams, demonstrating improved accuracy through validation against test results.