download: 832-6585-3-PB.pdf .Ultimate limit state curves of short reinforced concrete columns in fire situation are going to be presented in this paper. The authors created a code developed in Matlab. It makes a discretization of the cross sections of the columns and calculates the equilibrium integrals of them. The curves were plotted with the code considering the 500 °C isotherm method.Leia Mais
O aço e demais materiais estruturais têm sua capacidade resistente reduzida com o aumento de temperatura em situação de incêndio. No caso dos perfis de aço sob campo uniforme de temperaturas, define-se temperatura crítica àquela que os conduz ao colapso. Neste artigo, considera-se que o colapso ocorre quando os valores de cálculo dos esforços solicitantes se igualarem os esforços resistentes, ambos em situação de incêndio. Para este trabalho foi desenvolvida uma ferramenta gráfica, que permite determinar de forma expedita a temperatura crítica de pilares e vigas com base no método simplificado da norma brasileira e empregando o programa AcoInc desenvolvido pelos autores. Ferramenta similar não foi encontrada na literatura pesquisada. Seu uso simplifica sobremaneira o método de dimensionamento normatizado.
download: 836-5677-3-PB.pdf .Obtaining internal load capacity, in reinforced concrete sections, at ambient temperature, under biaxial bending, is one of the most common tasks done by structural engineers, but not so common when the member is in fire situation. The intention of this paper is to show that is possible to correlate the ultimate limit state (ULS), in fire situation, with ULS at ambient temperature, for square cross sections under fire from all faces. To reach the purpose and give support to the numerical analysis of this article, a computer program, in Delphi language, called COL FIRE, is being developed by the authors.Leia Mais
download: 866-5795-3-PBenglish.pdf .In many situations, the Brazilian Legislation does not require verification of roof structures in a fire, since its failure will not endanger the stability of the structure. In fire, the steel roof of an industrial building deforms by heating in geometry similar to a catenary, resulting in horizontal forces in the upper extremities of the columns. Thus, even roofs that do not constitute a frame with the columns may lead them to collapse, therefore, should be protected against fire. Due to the small dimensions of the structural elements of the roof, fire coating is uneconomical. So there is a problem in the design practice. This paper presents a procedure based on British literature, which considers the horizontal load on the columns. This horizontal load must be supported by the columns and the foundations. The aim of this paper is to detail this procedure, adapt it to Brazilian standards and apply it to a case study.Leia Mais
Steel elements behave differently in fire case when isolated or embedded in building walls. The wallson one hand have a favorable effect protecting the elements from the excessive heating resulting fromthe fire and on the other hand they have a detrimental effect due to the thermal gradients originated inthe elements cross-section. The simplified calculation methods proposed in EN 1993-1-2 for fire designdo not take into account the case of steel elements embedded in walls, stipulating only a formulationfor the assessment of the resistance for uniform temperature distribution. This paper presents a proposalof a new simplified calculation method to evaluate the temperature of steel columns embedded in walls.The method is based on numerical simulations and fire resistance tests. Steel columns totally or partiallyembedded in walls, with the web perpendicular or parallel to the wall surface, were tested.In the study it was also observed that thicker walls or H steel columns with the web perpendicular tothe wall surface provide greater thermal gradients in the cross-sections.