Analytical approach for bursting cracking analysis of post-tensioned anchorage zone

Abstract

In prestressed concrete structures, improper design and detailing of the anchorage zone frequently cause bursting cracking along the tendon path. Due to the complex stress state in the anchorage zone, it is difficult to estimate the actual cracking load, even in well-controlled experimental tests. Previous studies on anchorage zone cracking are mainly based on numerical simulation. There is still a lack of explicit approaches for practical use. This study aims to provide an analytical approach for predicting the first bursting cracking loads in the post-tensioned anchorage zone. It is found that the stress ratio of compression to tension is significantly higher in the anchorage zone than in the split cylinder. Thus, a strength correction factor is derived to compensate for the tensile-strength reduction due to the effect of biaxial stress state. Besides, a tension chord model is developed to quantify the contribution of bursting reinforcement in enhancing the tensile strength of concrete. After clarifying the effect of biaxial stress state and the contribution of bursting reinforcement, direct equations are proposed for predicting the first bursting cracking loads in the anchorage zone. The analytical approach is compared with existing test data and is applied in the cracking analysis of an actual bridge, indicating that it is accurate and convenient for application.