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Título del libro: Proceedings Of The Asce Pipeline Division Specialty Congress - Pipeline Engineering And Construction
Título del capítulo: Structural model for stress evaluation of prestressed concrete pipes of the Cutzamala system

Autores UNAM:
ROBERTO GOMEZ MARTINEZ; RICARDO VERA GRAZIANO; JOSE ALBERTO ESCOBAR SANCHEZ;
Autores externos:

Idioma:
Inglés
Año de publicación:
2004
Palabras clave:

Concrete pipe; Corrosion; Finite element method; Mathematical models; Steel; Prestress forces; Prestressed concrete pipes; Steel cylinder; Stress concentration


Resumen:

The Cutzamala aqueduct is one of the main works constructed to provide water to more than 6 million residents of Mexico City. The buried aqueduct comprises prestressed concrete pipes of 2.50m (99in) of diameter. The main components of these pipes are a steel cylinder embedded in two concentric rings of concrete; prestressed steel wires wrapped on the exterior concrete liner and an exterior coating of mortar. Failure of two buried prestressed pipes in the aqueduct occurred last year. An afterward inspection showed that some more pipes were showing important levels of corrosion, particularly that related to the prestressed wires. These facts prompted the development of technical studies oriented to evaluate the possible causes of failure, particularly those associated to the loss of prestress, due to corrosion of the prestressed wires. In this paper, the methodology used to predict failures of pipes when subjected to service loads under a progressive loss of prestress forces is described. The analysis used to evaluate the failure process of pipes when the prestressed wires loosestheir strength capabilities is presented, as well as 2D and 3D finite element models of the buried pipe, that were used to simulate different load conditions and distributions of prestress wires. Finally, a criterion for evaluation of failures of prestressed concrete pipes is proposed.


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