Resumen de Analisis de estructuras de hormigon armado expuestas al fuego
When a structure of reinforced concrete is exposed to a fire, a set of physics-chemical phenomena both in the concrete and in the steel, are produced. These effects can compromise the stability of the structure. Among the most important processes is the spalling phenomenon. There are two possible explanations to the spalling: Spalling due to pore pressure build up (hydraulic spalling) or an excessive increase of compressive stress produced by restrained thermal expansion. To take into account the hydraulic spalling in the analysis is necessary to consider a model with the hygral component of the concrete.
In this Thesis a hygro-thermo-mechanical model is presented. This model allows representing the general behaviour of the reinforced concrete exposed to high temperatures and especially to simulate the spalling phenomenon.
A consistent thermodynamic frame is proposed in a first step. Then, the state variables of the model are derived, and they are used to the government equations development. Once the government equations of the problem are established, the numerical aspects for the problem resolution are described. For the spatial integration of the problem the Finite Elements Method is used and the Finite Differences Method is applied for the temporary integration. A block iterative scheme for the coupling dealing is proposed.
This methodology is included in a numerical tool specially developed for this work.
For the validation of the proposed model a couple of examples are present. In these examples the numerically and experimental obtained results are compared.
Finally, a set of application examples are presented. These examples show the capability of the proposed model to represent the general behaviour of a reinforced concrete structure exposed to the fire and especially the spalling phenomenon.
