Assessment of internal forces for intermediate anchorage zone of post-tensioned concrete structure

•We investigated the stress distribution in the intermediate anchorage zone of post-tensioned concrete structure.•We explained the stress transfer mechanism in the intermediate anchorage zone during load application.•We presented the calculation equation of the internal forces based on the concept of strut-and-tie model.•We compared the result of the proposed method and traditional method.

The purpose of this study is to present a simple way to predict the internal forces in the intermediate anchorage zone of post-tensioned concrete structures. Guyon presented the concept of a symmetrical prism and gave a simple equation to denote the relationship between internal forces and an eccentric load at the end anchorage zone. A series of finite element analyses were conducted to obtain the internal stresses for the intermediate anchorage under different eccentric prestressing loads. By use of Guyon’s concept and by integrating stresses, a series of simple equations to assess the internal forces within the intermediate anchorage zone is obtained. The equations were validated through comparing the predicted internal forces using the proposed equations with the values of the internal forces within the ties of the model presented by the International Federation for Prestressing (FIP).