In The Existing Concrete Beams Forever Prestressed Test Study

Existing prestressing force of in-service concrete beams is one of the most important indexes reflecting the actual structural condition. Therefore, the exact prediction of the existing prestressing force becomes crucial.In this paper, through the indoor model test of two rectangular beams and combined with the dynamic and static theories, regression relationships between the effective dynamic stiffness and prestressing force, between the static stiffness and prestressing force, and between the strain on concrete and steel and prestressing force are built respectively. Furthermore, according to the relationships and the research of the corresponding stress releasing method, the prestressing force can be predicted. Finally, dynamic stiffness prediction method, static stiffness prediction method and stress releasing prediction method are put forward, and at the same time the prediction procedure and its application analysis of the three methods are introduced in actual projects.The research of the prediction method in this paper can promote the research on the structural evaluation of in-service prestressed concrete bridges, and it provides some reference to the quick evaluation method of bridges.