Experiment and analysis on mechanical behavior at root of large cantilever PC bent cap

Abstract:

Large cantilever prestressed concrete bent caps (hereinafter referred to large cantilever PC bent caps) typically incorporate corbels at the root of the cantilever to ensure the mechanical behavior. However, there is currently a lack of a rational framework for determining the appropriate size of these corbels. In this paper, the shear stress calculation theory of large cantilever PC bent caps with corbels is proposed by equating the corbels to arc segments; a 1∶4 scaled model experiment is carried out to analyze the influence of corbels on the shear stress distribution and stress performance of the cantilever root; The formula for calculating the minimum corbel length ratio under different design parameters of compression edge inclination, cantilever lengths and prestressing level is given according to the bending and shear strength requirements. The findings indicate that the shear stress calculation theory proposed in this study for variable cross-section beams with corbels provides a more accurate representation of the impact of corbels on the longitudinal distribution of shear stress. Additionally, the most critical location for shear stress has shifted from the cantilever root to the changing position of bottom inclination. Furthermore, as the corbel length ratio increases, the stress peaks at the upper and bottom edges of the beams decrease. Therefore, it is essential to control the size of the corbel to ensure the strength of the compression edges. The formula for the minimum corbel length ratio, as presented in this paper, ensures its effective accuracy when applied to large cantilever PC bent caps with varying parameters. This formula demonstrates practicality in construction applications.