Full-range nonlinear analysis of post-tensioned anchorage zones based on modified strut-and-tie model

Abstract

The strut-and-tie model (STM) has been adopted as a preferred methodology for the design of the post tensioned concentric anchorage zones. However, the STM is just a design model at ultimate limit state developed based on the elastic stress trajectory without the consideration of stress redistribution after cracking, which can not be used to predict the serviceability behavior of anchorage zones. To address this issue, this paper is devoted to developing a modified strut-and-tie model (MSTM) to predict the behavior of concentric anchorage zones throughout loading process. The compatibility condition was introduced into MSTM based on the principle of stationary complementary energy at each load step. According to MSTM, the elastic and inelastic behavior of concentric anchorage zones, including load-strain response, load-deformation response and crack width, can be estimated from loading to failure. Moreover, simplified formulas have been proposed to calculate the first cracking load, ultimate load and the maximum crack width. Finally, the proposed MSTM was validated by the testing results.