Simulation of cantilever construction of cable-stayed bridges taking creep into account
In the design of cable-stayed bridges, the construction analysis is very important since the worst stresses are usually reached during the construction process. In addition, if the bridge is made of concrete, the effects of time dependent phenomena have great importance. Some commercial software are...
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| Formato: | tesis de maestría |
| Fecha de publicación: | 2017 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/117338 |
| Acesso em linha: | https://hdl.handle.net/2117/117338 |
| Access Level: | acceso abierto |
| Palavra-chave: | Cable-stayed bridges -- Design and construction Cable-stayed bridges Cantilever method CIP concrete Creep Dischinger hypothesis Forward analysis Objective service stage Ponts atirantats -- Disseny i construcció Àrees temàtiques de la UPC::Enginyeria civil |
| Resumo: | In the design of cable-stayed bridges, the construction analysis is very important since the worst stresses are usually reached during the construction process. In addition, if the bridge is made of concrete, the effects of time dependent phenomena have great importance. Some commercial software are able to simulate the construction process, but one of their main drawbacks is that they simulate in a backward approach where creep is difficult to analyze. In this thesis two new criteria to define the Objective Service Stage (OSS) are presented which take the constructive process into account. Tensioning operations are very expensive, so the main goal is to define the pretension forces in the stays such that only one pretension operation is necessary in each stay. Furthermore, an algorithm has been developed to simulate the construction process of cable-stayed bridges erected by cantilever method. This algorithm includes the creep effects into the structure. The Dischinger simplification, which is explained in this document, has been improved in order to better take into account the loading time and the age of the concrete in every stage. The creep simulation of the algorithm has been validated with some patch tests. The developed algorithm has been implemented in a full scale FEM model adapted from the Giribaile Dam project developed in 1990. In this study case, the new OSS criteria are implemented. Moreover, the axial forces in the stays, the bending moments, and the displacements are analyzed during the construction process and a comparison is carried out between two cases: with and without taking creep into account. With the first new OSS criterion, the Objective Service Stage is achieved without taking the creep into account. However the creep effects, which are of huge importance in concrete bridges built by cantilever method, require the definition of an OSS which considers time dependent phenomena, which has been defined in this thesis (second criterion). |
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