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SUMMARYSteel elements behave differently in fire case when isolated or embedded in building walls. The walls on one hand have a favorable effect protecting the elements from the excessive heating resulting from the fire and on the other hand they have a detrimental effect due to the thermal gradients originated in the elements cross-section. The simplified calculation methods proposed in EN 1993-1-2 for fire design do not take into account the case of steel elements embedded in walls, stipulating only a formulation for the assessment of the resistance for uniform temperature distribution. This paper presents a proposal of 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 partially embedded 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 to the wall surface provide greater thermal gradients in the cross-sections.

The growing demand for knowledge about the effect of fire on structures has stimulated research worldwide. This article presents experimental results of short, composite columns made of steel and concrete when submitted to high temperatures in furnaces, with and without axial compression loading, as well as a numerical analysis of the temperature distribution in these columns. The columns were modeled as concrete-filled tubes with three thicknesses and two diameters considered. In addition, standard fire temperature-time curves were obtained experimentally for use in the numerical calculations.

Resumen En el trabajo se aborda el estudio de los factores que inciden en la resistencia, en situación de incendio, de las conexiones tipo perno en estructuras compuestas hormigón-acero con tipología de viga y losa maciza. Se realiza el diseño del experimento, la modelación térmica de los especímenes del ensayo push-out y el análisis de significación de diferentes parámetros en las relaciones de temperatura en secciones compuestas con vigas sin revestimiento y con revestimiento contra incendio. Por último, se proponen las temperaturas a considerar en el hormigón y el conector, expresadas como porcientos de la temperatura en el ala del perfil, para determinar los factores de reducción de la resistencia de la conexión en situación de incendio. Los resultados demuestran que los porcientos propuestos por EN 1994-1-2 (2005) para determinar la temperatura en el hormigón y el conector a partir de la temperatura en el ala no son válidos para todas las situaciones de diseño dentro del alcance del código.

No abstract