American Society of Civil Engineers


Nonlinear Finite-Element Analysis of Posttensioned Concrete Bridge Girders


by Ashraf Ayoub, M.ASCE, (Associate Professor, Univ. of Houston, Houston, TX 77204. E-mail: asayoub@uh.edu)

Journal of Bridge Engineering, Vol. 16, No. 3, May/June 2011, pp. 479-489, (doi:  http://dx.doi.org/10.1061/(ASCE)BE.1943-5592.0000157)

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Document type: Journal Paper
Abstract: Posttensioning is an effective method for the construction of different types of bridge girders such as those used in segmentally erected bridges. Available nonlinear analysis programs for bridge girders under severe loading conditions are computationally expensive though. In addition, they neglect important phenomena such as bond-slip, friction, and anchorage losses. The objective of the proposed work is to develop a new nonlinear finite-element program for analysis of posttensioned bridge girders. The new model overcomes most of the difficulties associated with existing models. The model is based on the computationally efficient mixed formulation and considers bond, friction, and anchorage loss effects. The mixed formulation is characterized by its fast convergence, usually with very few finite elements and its robustness even under severe loading conditions. The posttensioning operation is accurately simulated using a phased-analysis technique, in which each stage of the posttensioning operation is simulated through a complete nonlinear analysis procedure. Correlation studies of the proposed model with experimental results of posttensioned specimens are conducted. These studies confirmed the accuracy and efficiency of the newly developed software program, which represents an advancement over existing commercial software packages for evaluating posttensioned bridge girders, in particular those subjected to severe loading conditions.


ASCE Subject Headings:
Concrete bridges
Girder bridges
Prestressed concrete
Post tensioning
Nonlinear analysis
Bonding
Friction
Anchorages
Finite element method

Author Keywords:
Prestressed concrete
Posttensioning
Finite-element method
Nonlinear analysis
Bond stress
Friction
Anchorages