A comparison between CFD and thermal-structural analysis of structural steel members subjected to fire

Purpose Standard fire resistance curves such as ASTM E119 have been used for so long in structural fire practice. The issue with use of these curves that they do not represent real fire scenarios. As a result, the alternatives have been to either conduct experiments or find other tools to represent a real fire scenario. Therefore, the purpose of this paper is to understand the temperature effects resulted from a designed fire on steel beams and whether the standard fire curves represent a designed fire scenario. Design/methodology/approach Computational fluid dynamics (CFD) models were developed to simulate a designed fire scenario and to understand the structural responses on the beams under elevated temperatures. Consequently, the results obtained from the CFD models were compared with the results of three-dimensional (3D) non-linear finite element (FE) models developed by other researchers. The developed FE models were executed using a standard fire curve (ASTM E119). A parametric study including two case studies was conducted. Findings Results obtained from performing this study showed the importance of considering fire parameters such as fuel type and flame height during the thermal analysis compared to the standard fire curves, and this might lead to a non-conservative design as compared to the designed fire scenario. The studied cases showed that the steel beams experienced more degradation in their fire resistance at higher load levels under designed fires. Additionally, the models used the standard fire curves underestimated the temperatures at the early stages. Originality/value This paper shows results obtained by performing a comparison study of models used ASTM E119 curve and a designed fire scenario. The value of this study is to show the variability of using different fire scenarios; thus, more studies are required to see how temperature history curves can be used to represent real fire scenarios.

Performance of Segmental Post-Τensioned Concrete Beams Exposed to High Fire Temperature

The present study illustrates observations, record accurate description and discussion about the behavior of twelve tested, simply supported, precast, prestressed, segmental, concrete beams with different segment numbers exposed to high fire temperatures of 300°C, 500°C, and 700°C. The test program included thermal tests by using a furnace manufactured for this purpose to expose to high burning temperature (fire flame) nine beams which were loaded with sustaining dead load throughout the burning process. The beams were divided into three groups depending on the precast segments number. All had an identical total length of 3150mm but each had different segment number (9, 7, and 5 segments), in other words, different segment lengths. To simulate genuine fire disasters, the nine beams were exposed to high-temperature flames for one hour along with the control specimens. The selected temperatures were 300°C (572°F), 500°C (932°F), and 700°C (1292°F) as recommended by the standard fire curve (ASTM–E119). The specimens were cooled gradually at ambient laboratory conditions. The performance of the prestressed segmental concrete beams through the burning process was described with regard to the beams camber, spalling, and occurred deterioration.

Comparison of fire resistance of damaged fireproofed steel beams under hydrocarbon pool fire and ASTM E119 fire exposure

Purpose The purpose of this paper is to investigate different types of fire on structural steel members with damaged fireproofing. Two types of fire scenarios are considered, ASTM E119 fire and Hydrocarbon fire. In industrial facilities such as oil refineries, certain units maybe subjected to hydrocarbon fire, and its effect might be different than standard fire. The purpose of this study is to compare both types of fire scenarios on steel beams with damaged fireproofing and determine the fire rating of the damaged beams under each fire scenario. Design/methodology/approach The study is performed using computational methods, thermal-stress finite element analysis that is validated with experimental results. The results of practical beam sizes and typical applied loads in such structures have been plotted and compared with steel beams with non-damaged fireproofing. Findings The results show significant difference in the beam fire resistance between the two fire scenarios and show the fire resistance for beam under each case. The study provides percentage reduction in fire resistance under each case for the most commonly used cases in practice under different load conditions. Originality/value Extensive literature search has been performed by the authors, and few studies were found relevant to the topic. The question this study answers comes up regularly in practice. There are no standards to codes that address this issue.

Alkaline Aluminosilicate Binder-Based Adhesives with Increased Fire Resistance for Structural Timber Elements

The paper presents data on the use of the alkaline aluminosilicate binder-based adhesive of the system Na2O•Al2O3•(4-6)SiO2•(17-20)H2O for gluing and fire protection of structural timber elements. The results of the study of thermoresistant phases in the reaction products of the alkaline aluminosilicates are reported and discussed. The results allowed to show that at SiO2/Al2O3 between 5 and 6 the zeolite-like phases of heulandite types, which, under action of temperatures, are able to form a porous aluminosilicate artificial stone with low thermal conductivity (λ=0.09 Wt/m•К, DSTU B V.2.7-105-2000 (GOST 7076-99)) are formed in the reaction products. The use of the developed aluminosilicate adhesives allow for to classify the structural timber elements as hardly burnable and hardly flammable materials (GOST 12.1.044-1989, EN 13823 + A1: 2014-12, ASTM E119-07). They have the following characteristics: water resistance D3 (EN 204:2001), resistance in splitting up 7.8 MPa (GOST 16483.5-1973), adhesion in normal pull-off test up to 2.6 MPa (GOST 32299-2013 (ISO 4624:2002)).

Evaluation of Standard and Real Fire Exposures to Predict the Temperature Response of a Railcar Floor Assembly

Current standards such as NFPA 130 [1] require railcar floor assemblies to achieve a fire resistance rating according to ASTM E119 [2] by exposing the assemblies to a prescribed 30 minute time-temperature curve using a furnace. Though the ASTM E119 is a standard test procedure, it does not represent a real fire scenario which can have temporal and spatial varying exposure. This work developed a computational framework to evaluate and compare standard fire exposures such as ASTM E119 to real fire exposures to determine the difference in the temperature rise of a railcar floor assembly. The dimensions of the assembly used in this work consisted of the entire width of the railcar ∼3.0 m (10 ft) and a length of 3.7 m (12 ft) as described in NFPA 130. The real fire exposures simulated in this work have been identified in a review [3] of incidents involving fire exposures to railcars in the US and internationally over the past 50 years. The fire exposures consisted of a continuously fed diesel fuel spill, a localized trash fire, and a gasoline spill simulated from a collision of the railcar with an automobile. These realistic fire exposures were applied to a floor assembly model in Fire Dynamics Simulator (FDS) [4] which also included the undercarriage equipment to better capture the fire dynamics. The thermal exposure at the underside of railcar assembly was extracted using the heat transfer coefficient and the adiabatic surface temperature provided by FDS. These spatial-temporal exposures were coupled with a detailed railcar floor assembly finite element (FE) model in ABAQUS [5] to analyze the thermal behavior of the assembly. The thermal model in ABAQUS provided the evolution of temperature in different components of floor assembly consisting of a structural frame, insulation, and a composite floor. The standard scenarios were simulated for two hours instead of the typical 30 minutes to identify the appropriate exposure duration which can better represent a real fire scenario.

Effect of High Temperature Additives in Fire Resistant Materials

The effect of high temperature additives in intumescent systems was examined in a laboratory environment. A matrix of ceramic fibers/minerals was incorporated into two intumescent systems. The material performance was determined using a series of small-scale propane-fired furnace tests based on the ASTM E119 time-temperature curve for fire tests of building construction and materials. Several formulations were identified using a 15-minute screening fire test before testing for a longer time period.