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Advances in Civil Engineering
Volume 2013, Article ID 580646, 13 pages
Research Article

Bending-Shear Interaction Domains for Externally Prestressed Concrete Girders

1Università di Messina, DICIEAMA, C/da Di Dio, 98166 Messina, Italy
2Università di Palermo, DICAM, Viale delle Scienze, 90128 Palermo, Italy

Received 4 July 2013; Revised 15 September 2013; Accepted 1 October 2013

Academic Editor: Andreas Kappos

Copyright © 2013 Antonino Recupero and Michele Fabio Granata. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In prestressed concrete structures, the evaluation of the safety level is generally carried out by separating the bending moment strength and the shear force capacity. Actually interaction between bending moment (M) and shear force (V) can have significant consequences on evaluations in service life, especially when the ultimate limit state (ULS) is considered. In this paper, the M-V interaction is addressed for prestressed concrete girders, in the cases of both bonded and unbonded prestressing tendons. It can be demonstrated, by drawing the interaction domains (M-V), that a significant reduction of the safety level has to be considered when shear force is evaluated together with bending moment on the ULS of the cross-section, especially for external prestressing in concrete T-shaped or box sections of bridge girders. Interaction domains allow designers to evaluate and optimize reinforcement ratios, geometric properties of the beam, and effects of shear on the ultimate state. An analytical model, based on the stress field theory, is developed and proposed in this paper. A numerical example is developed and interaction domains are given for an example of a box section with variation in reinforcement ratio and tendon slope. A validation of the presented model is given, by comparing experimental data in the literature with results found using the proposed analytical approach.