Crack analysis of concrete beams based on pseudo-discrete crack model

摘要

Crack widths are important considerations in both serviceability and durability design of concrete structures and should be evaluated to ensure compliance with design limits. However, existing empirical formulas for maximum crack width prediction are discrepant with each other, and they cannot reveal key information such as crack number and crack spacing. To obtain such information, finite element analysis has to be adopted. However, conventional finite element analysis has its limits in carrying out crack analysis. Particularly, the common smeared crack models, which do not realistically reflect bond-slip of reinforcing bars, would not give correct crack widths. In contrast, the discrete crack models are difficult to apply because of the need to adaptively generate discrete crack elements according to the cracks formed during the loading process. In this paper, a pseudo-discrete crack model is developed for finite element implementation. The conventional smeared crack model is transformed and reformulated, and a novel crack queuing algorithm is introduced for crack analysis. The method has been applied to analyse concrete beams in the literature. It is demonstrated that the computational results of crack number, spacing and widths agree closely with the measured results.