An Approach for Evaluating the Fire Resistance of CFHSS Columns under Design Fire Scenarios

Abstract

The use of concrete filling offers a practical alternative for achieving the required fire resistance in steel hollow structural section columns. However, the current prescriptive-based approach which evaluates fire resistance based on standard fire exposure does not account for realistic fire scenarios in the design of concrete-filled hollow structural section (CFHSS) columns. This article presents a methodology for evaluating the fire resistance of CFHSS columns under design fire scenarios without the need for costly computational models. The proposed approach is a derivative of the equal area concept, and evaluates the equivalent fire resistance of the column by comparing the time temperature curve of the standard fire exposure with that of the design fire exposure. The method has been validated against the results generated from finite element analysis (coupled heat transfer and strength analysis) on numerous CFHSS columns under a large number of design fires. The applicability of the approach in design situations is illustrated through a numerical example, and it is concluded that the proposed approach offers an attractive alternative for deriving equivalent fire resistance of CFHSS columns exposed to design fire scenarios.

Effect of Transient Creep Strain Model on the Behavior of Concrete Columns Subjected to Heating and Cooling

“…A more realistic representation of the fire will be used that comprises non only a heating phase but also a cooling phase during which the temperature of the fire is decreasing back to ambient temperature. The influence of such realistic fire scenarios in the evaluation of the fire resistance is a key issue in the performance-based approach, as presented for example by Fike et al for concrete-filled hollow structural section columns [11]. Modeling the cooling phase of the fire is important to analyze the risk of collapse of the structure during cooling.…”

Applying the dimensional method for valuation of the strength loss of cement compositions exposed to elevated temperatures

“…The analysis of applied methods [2][3][4][5][6] proves that the existing approaches to evaluation of fire-and thermal stress resistance of stone building materials take into the account only particular properties and therefore are not accurate and complete. The studied analytical methods of manifestation of properties by newly engineered materials on the base of cement compositions exposed to elevated temperatures do not comprise the complex criterion based on integration of thermal-physical, thermal-chemical and physical-mechanical properties obtained by laboratory testing as well as by analytical calculation of evaluation of ultimate limit state point (criteria R, Istructural failure, thermal insulating capacity loss).…”

A performance indicator for structures under natural fire

“…The influence of such realistic fire scenarios on the behavior of structural components is a key issue in the performance-based approach, as shown for example for concrete-filled hollow structural section columns [7] or for single-plate shear connections in which the tensile forces created during the cooling phase can lead to failure [8]. The required duration of stability may be longer than the duration of the heating phase.…”