Papers (estruturas em incêndio) #incêndio

Foram pesquisados alguns dos mais importantes países da América Latina e as informações sobre sua legislação são apresentadas no artigo

The Brazilian standards of structures in fire prescribe minimum dimensions for the ribbed slabs to ensure fire resistance. However, a new composite ribbed slab is not covered by any of the Brazilian standards in fire. The objective of this work is to present unpublished results from numerical and thermal analyses for this type of slab. Ribbed slabs filled with cell concrete blocks, ceramic bricks and EPS supported by cimentitious board were studied. The constructive element is considerate as thermal insulation if it has the capacity to prevent the occurrence, on the face non exposed to fire, temperature increments greater than 140 °C on the average or greater than 180 ºC at any point. The support function was determined limiting the temperature of the beams and slabs rebars to 500 ºC. The analyses were carried out with the ATERM and Super Tempcalc, software for two-dimensional thermal analysis by means of the finite element method. As a result, tables will be presented that link the fire resistance required time to slab dimensions and position of rebar. Prior to use in designing these results must be confirmed by experimental analysis, which is already being provided.

An essential component of a composite beam is the shear connection between the steel section and the concrete slab. Contrasting to the great quantity of push-out tests carried out at room temperature, a reduced number of push-out tests at elevated temperatures has been reported. Comparisons of temperature development in two different types of specimens are made between existing test results and numerical simulations using the finite element package SuperTempcalc. Values for the thermal properties of materials, the heat transfer coefficient and emissivity recommended in EN 1991-1-2 and EN 1994-1-2 were taken as essential references. The sensitivity of the calibrated model to variation in connector diameter and height is assessed, taking into account the defined scope of the formulations of the above mentioned codes. Also, different alternatives on the level at which should be considered the concrete temperatures are evaluated. The parametric numerical studies demonstrate that the connector height, the concrete compressive strength and the level in which the concrete temperature is considered, have a great influence on the resistance, specifically when concrete failure prevails against stud failure.

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.