Numerical comparison between the thermo-structural behavior of steel and partially encased steel and concrete composite columns in fire

Abstract

The bare steel structural members have a low fire resistance. However, in steel and concrete composite members, the concrete encasement, besides the contribution to the stiffness of the whole system, reduces the amount of heat that reaches the steel profile, increasing the its fire resistance. The aim of this paper is to conduct a numerical study on the behavior of steel and steel and concrete composite columns in fire, in order to compare their performance based on the variation of parameters such as the stiffness of the surrounding structure, geometric imperfection and load ratio. It has been found that, in general, the intensity of the geometric imperfection and stiffness of the surrounding structure does not affect the fire resistance of steel and composite columns. However, the stiffness of the surrounding structure raised the maximum value of the restraining forces generate throughout the heating. Regarding the load ratio, when increased, the fire resistance and critical temperature decreased.

Thermal numerical analysis of steel and steel and concrete composite columns in a fire situation aimed at the evaluation of the simplified method of ABNT NBR 14323:2013

“…In this context, some studies assess the influence of partially or fully encasing or filling steel columns with concrete under fire situations. The benefits of this material in both the fire resistance and structural behavior can be identified [1,2,11]. When associated with masonry walls, research is even more scarce, thus emphasizing the importance of the present study.…”

“…During the processing of the numerical thermal models for the purposes of calibration and validation, it is worth mentioning that the results obtained were not satisfactory using normative concepts as emissivity. Therefore, based on Simões et al [2], [16], sensitivity analyses for emissivity were developed to obtain more representative values for the same parameter. Table 2 presents the parameters that best represented the experiments in Rocha [7].…”

“…Still in relation to this association, steel reduces the effects of cracking and spalling in concrete. According to Simões et al [2], concrete increases the fire resistance of the purely steel element, because by reducing the average temperature of the set, it can present a resistant capacity for a longer time.…”

Fire behavior of shallow prestressed hollow core slabs from computational modeling

“…It is important to deepen the knowledge about the behavior of hollow core slabs exposed to fire. There are several studies in the literature about reinforced concrete beams and columns exposed to fire [10][11][12][13], as well as steel-concrete composite structures [14][15][16][17]. There are also several studies about the behavior of hollow core slabs exposed to fire, either by tests or computational modeling [18][19][20][21][22][23][24][25][26][27].…”

Experimental and numerical analysis of the thermal and mechanical behaviour of steel and recycled aggregate concrete composite elements exposed to fire

“…This favors the rapid heating of the structural element and an accelerated degradation of its mechanical properties (strength and stiffness). 18 Applying composite structures could be a beneficial solution with regard to this exceptional action, for instance, composite steel and concrete structures, where concrete can be used as partial or total coating of steel profiles, providing contributions regarding the capacity of protection and fire resistance, since it has thermal properties superior to those of steel and whose elements have larger dimensions, which decreases the heat treatment of the steel element. 19 In this regard, the objective of this article was to evaluate the performance of RAC mixtures as a thermal insulator for steel elements.…”