Modelo constitutivo del comportamiento de hormigones de alta resistencia a elevadas temperaturas

Abstract

When concrete is subjected to high temperatures, it  experiences a series of chemical reactions that cause  transformations in its microstructure and moisture content,  which produce appreciable changes in the physical-mechanical  properties of the material. In this paper a proposal of  constitutive and state equations are presented, that have  allowed to physically model the effect of the chemical  transformations on high strength concrete and to describe  the transitory evolution of the physical-mechanical properties  with the increase of temperatures. In addition, a sensitivity  analysis of the proposed model has been carried out which  evaluates the responsiveness to the variation of different  input parameters such as heating speed, intrinsic permeability,  saturation and hydration initial degree and polypropylene fiber  content. The results of the sensitivity analysis have shown that  the assumptions and proposed equations allow to model the  phenomenon with sufficient precision for its application for  practical purposes.