Numerical Model for the Analysis of Unbonded Prestressed Members

Abstract

A numerical model for the study of prestressed members with bonded and unbonded tendons has been implemented, considering the hybrid type finite element formulation for planar frames. With such an approach, accurate curvature distributions are obtained, allowing a good computational performance and an adequate unbonded tendon stresses evaluation. The computer program also includes geometric nonlinearity, composite construction, and time-dependent effects. Linear Maxwell chain models are used for both concrete and prestressed steel time-dependent behavior. This paper presents a general description of the numerical model proposed, including the structural idealization approach, a hybrid type finite element formulation review, the material constitutive models, and the main numerical procedures. A brief review of the behavior of unbonded prestressed members is also presented. Numerical and experimental results are compared, showing the good performance of the model for the analysis of unbonded prestressed elements. Unbonded tendon stresses and cracking pattern results are included, showing the capability of the numerical model. The model is proposed as an efficient analytical tool for further research on unbonded prestressed members.