Failure analysis of tendon breakout on bottom slab of a pre-stressed concrete box gird bridge during construction

摘要

There were several tendons breakout on bottom slabs happening during construction stage of continuous pre-stressed concrete bridges in recent years in China. The paper studies one case based on numerical simulation that happened on a 47+ 75 +47 m continuous pre-stressed concrete rigidframe bridge. In this paper, both linear elastic and nonlinear inelastic analysis are developed, concrete and reinforcements stress levels before and after pre-stressed tendons stressed are compared, and the path of crack appearance are revealed by calculation. The effects of the incorrect arrangement of reinforcement during construc tion are also analyzed, which is proved not to be the leading reason of the failure. The out comes of the finite element analysis indicate that oversize of the longitudinal prestressed tendons and unreasonable sizes of the bottom slab are the main reasons of the failure. Some advices to avoid similar accident are given for future design.