Hydrocarbon Fire Research Articles

Fire resistance of square reinforced concrete column with one-face gypsum layer insulation under axial loading

This study aims at investigating the fire resistance performance of square-reinforced concrete columns exposed to a standard hydrocarbon fire under a time-range axial loading. The gypsum layer is used as a prime fire protection for aggressive fire-flame. The gypsum boards are commonly employed as finishing material in construction. The ASTM C1529 hydrocarbon fire scenario is adopted in this study for all reinforced concrete samples subjected to axial load simultaneously exposed to direct fire flame of (600 and 900)oC. The experimental investigation is carried out on twelve laboratory-scale concrete samples. The outcome discussed the influence of various gypsum layer thicknesses applied to one face of the column sample under axial loading. The results showed different senses of fire resistance between samples. The gypsum protection layer reduces the effect of fire-exposed concrete specimens. For 1 h duration, 600 °C, and 10 mm and 20 mm gypsum layer thicknesses, the strength load evolution drops by 30.7% and 34.96%, respectively compared to the reference sample. Furthermore, for the 1-h duration, 900 °C, and 10 mm and 20 mm gypsum layer thicknesses, the load evolution drops by 29.6% and 34.58%, respectively compared to the reference model. Also, the strength drops by 15%, 19%, 29.4, and 17.9% for the same testing characterization, but a 2-h fire duration. The results show no spalling or delamination of the concrete substrate. Also, the amount of lateral deflection is improved.

Modelling breakdown of industrial thermal insulation during fire exposure

The aging of many of the installations in the oil and gas industry may increase the likelihood of loss of containment of flammable substances, which could lead to major accidents. Flame temperatures in a typical hydrocarbon fire may reach 1100–1200 °C, which are associated with heat flux levels between 250 and 350 kW/m2. To limit or delay the escalation of an initial fire, passive fire protection (PFP) can be an effective barrier. Additionally, both equipment and piping may require thermal insulation for heat or cold conservation. Previous studies have investigated whether thermal insulation alone may protect the equipment for a required time period, e.g., until adequate depressurization is achieved. The present study entails the development of a numerical model for predicting the heat transport through a multi-layer wall of a distillation column exposed to fire. The outer surface is covered by stainless-steel weather protective cladding, followed by PFP, thermal insulation, and finally an inner column of carbon steel of variable thicknesses. The model for the breakdown of thermal insulation is based on observed dimensional changes and independent measurements of the thermal conductivity of the insulation after heat treatment. The calculated temperature profiles of thermally insulated carbon steel during fire exposure are compared to fire test results for carbon steel with thicknesses of 16, 12, 6 and 3 mm. The model's predictions agree reasonably well with the experiments. The degradation of the thermal insulation at temperatures above 1100 °C limits its applicability as fire protection, especially for low carbon-steel thickness. However, the model predicts that adding a 10-mm layer of more heat-resistant insulation (PFP) inside the fire-exposed cladding may considerably extend the time to breakdown of the thermal insulation.

Impact of partially damaged passive protection on the fire response of bolted steel connections using finite element analysis

This article aims to quantify the impact of a potential failure of passive fire protection on the ultimate response of a top and seat steel connection with double web angles. A numerical, finite element analysis scheme is proposed considering the real, semi-rigid behaviour of the connection, using unilateral contact-friction laws between the interfaces of the beam, the column, and the steel angles. The model has been validated by previous experimental research at ambient temperatures. Scenarios of unprotected connections, undamaged and partially damaged fire protections are numerically tested. A change in the failure mode and a reduction of the strength equal to 28% for standard fire and 35% for hydrocarbon fire arise for the model with the damaged protection. In this case, maximum temperatures locally at the beam reach the ones of the unprotected connection (900 °C), which is more than 800 °C higher than the connection with undamaged protection. Significant temperature increases of more than 288 °C and 406 °C for standard and hydrocarbon fires also arise on the top angle, compared to the model with undamaged fire protection.

The Behavior of Passive Fire Protection Materials Used for Fire Protection of Steel Structures in Standard, Hydrocarbon, and Jet Fire Exposure

Structural steel, when exposed to fire, loses its tensile strength and ability to resist deformation. Both organic and inorganic material-based passive fire protection systems, are being traditionally used to protect steel structures in such scenarios. This study focused on comparing the performance of the same organic and inorganic coatings in standard fire, hydrocarbon fire, and jet fire conditions. Standard, hydrocarbon fire, and jet fire experiments were carried out in full-scale fire resistance furnaces as per ASTM E-119, UL 1709, and ISO 22899-1 respectively. From the results, it was observed that both organic and inorganic materials tend to underperform in jet fire scenarios, when compared with standard and hydrocarbon fire due to the impingement/turbulence effect and the thermo-mechanical effect caused by the velocity of the gas.

Numerical modelling, parametric analysis and design of UHPFRC beams exposed to fire

A non-linear sequentially-coupled thermal–mechanical finite element (FE) paradigm that reasonably tracks the coupled fire-structure response of ultra-high performance fibre reinforced concrete (UHPFRC) beams subjected to the ISO 834 fire is established and presented. A fire resistance parameter study is conducted on UHPFRC beams via the developed FE paradigm, and then flexural based fire-structural assessment is demonstrated, as an avenue to substantiate the viability of numerical performance-based structural fire design. The parameter study considered two variables, notably heating mechanism and load levels. Comparison of results revealed that the fire-structure response was more severe under the hydrocarbon than the ISO 834 heating mechanism and hydrocarbon fire resistance ratings estimation were found to be 30 minutes lower than those determined using the ISO 834 fire. Predicted failure of the beams under the ISO 834 and hydrocarbon fires was observed at load ratios exceeding 0.6 and 0.4, respectively. By reposing on ACI544’s analytical model for UHPFRC beams in flexure, and numerically acquired heat-transfer response, the time-variant reduced nominal moment capacities of UHPFRC beams were computed. Failure predicted via computed residual moment capacities was somewhat consistent with that reckoned by load ratio parameter study.

The thermal assessment of GFRP reinforced concrete bridge decks in fire scenarios

If a concrete structure survives a fire, several questions can arise regarding the safety of the structure and the extent of repair. This paper combines the results of a set of comprehensive material tests on various Glass Fibre Reinforced Polymer (GFRP) reinforcing bars at high temperatures with heat transfer analysis to approximate the extent of the fire-induced damage. The paper discusses the most common fire types in bridges (i.e., hydrocarbon fire and pool fire) occurring at various locations of bridges. A simple guideline for quick assessment of the GFRP reinforced concrete bridge decks is proposed, enabling the bridge authorities and practitioners to make an informed preliminary decision following a fire incident. This paper provides a quick visual inspection method to approximate the level of damage to GFRP reinforcing bars and correlate their mechanical properties to the available information on the post-fire residual properties of GFRP bars. The limitations of this method are presented in section 6. The paper outlines one example to show how to use the method and the information from the paper to determine the reliability and the conditions of GFRP bars at key locations. The findings of this example indicate that GFRP bridge decks can retain sufficient strength although the long-term performance of the bridge must be assessed carefully.

Review of Fire-Related Damage of Steel Offshore Structures

Fixed offshore structures are continuously exposed to risk of hydrocarbon fire or cellulosic fire. Hydrocarbon fire generally causes more detrimental effect than cellulosic fire because the rapid increment of temperature gives little response time for people to evacuate the location or to put off the fire. Metallography tests have demonstrated that steel structures continuously exposed to temperature escalation from fires will lose their mechanical properties such as yield strength, tensile strength, toughness, hardenability and elastic modulus. Thus, to understand the structural response during fire, structural integrity assessment with revised steel mechanical properties is advised to be performed. The outcome of the analysis helps to identify the hotspots of the steel structures due to the fire and allow the investigation team to further perform detailed inspection and proposed structural repair to reinstate the integrity of the steel structures.

Experimental study on the fire performance of prestressed steel parallel wire strands

Bridges are critical components of the transportation system and any damage to these structures can result in important social and economic consequences. The literature concerning design standardization for fire hazard in suspension bridges is limited. High strength prestressed steel cables serve as main load-bearing components for suspension bridges, and exposure to high temperatures may result in their prestress loss, leading to structural failure. This paper experimentally investigates the fire performance of 19-parallel wire strands (PWS cables) with a tensile strength of 1860 MPa used as suspender cables in long-span suspension bridges. PWS cables were prestressed and then subjected to UL1709 hydrocarbon fire and simulated open pool tanker fire scenarios in the gas furnace until failure. The load–deflection plots of PWS cables suggest that the cables at ambient temperature sufficiently withstood 95% of their ultimate load capacity. However, the unprotected PWS cables failed within 3–8 min in the fire tests but still sustained the load at 400 °C, which confirms the conservative estimation of 300 °C critical cable temperature mandated by the Post-tensioning Institute. The stress–strain data of tested steel wires correlated well with recently developed high-strength steel wire material models at elevated temperatures. The wire rupture surfaces indicated a brittle failure at ambient temperature and a ductile failure with visible necking under fire conditions. The ultimate (rupture) strain capacity of steel wires decreased from 5% to almost 1% during fire tests. Further, the post-fire strength of PWS cable was unchanged but the elasticity modulus increased by 19% and the rupture strain decreased by 20%. The experimental findings indicate the necessity of fire protection application on PWS cables to keep cable temperatures below the critical temperature of 400 °C in a fire hazard.

Thermo-Mechanical Modeling of High-Strength Concrete Column Subjected to Moderate Case Heating Scenario in a Fire

This paper presents a numerically developed computer model to simulatethe thermal behavior and evaluate the mechanical performance of a fixedend loaded loaded High Strength Concrete Column (HSCC), subjectedto Moderate Case Heating Scenario (MCHS), in a hydrocarbon fire. Thetemperature distribution within the mid-height cross-sectional area of thecolumn was obtained to determine the thermal and mechanical responsesas a function of temperature. The governing two-dimensional transient heattransfer partial differential equation (PDE), was converted into a set of ordinary algebraic equations, subsequently, integrated numerically by usingthe explicit finite difference method, (FDM). A computer program, VisualBasic for Applications (VBA), was then developed to solve the set of ordinary algebraic equations by implementing the boundary as well as initialconditions. The predictions of the model were validated against experimental data from previous studies. The general behavior of the model as wellas the effect of the key model parameters were investigated at length in thereview. Finally, the reduction in the column’s compression strength and themodulus of elasticity was estimated using correlations from existing literature. And the HSCC failure load under fire conditions was predicted usingthe Rankine formula. The results showed that the model predictions of thetemperature distribution within the concrete column are in good agreementwith the experimental data. Furthermore, the increase in temperature ofthe reinforced concrete column, (RCC), due to fire resulted in a significantreduction in the column compression strength and considerably acceleratesthe column fire failure load.

Failure characteristics of reinforced concrete circular slabs subsequently subjected to fire exposure and static load: An experimental study

AbstractThis study investigated the effect of fire on the ultimate load‐bearing capacity of reinforced concrete (RC) slabs. The structural response of RC circular specimens subjected to static load conditions after exposure to a hydrocarbon fire on one side of the specimen was examined. Two fire exposure times were considered (60 and 120 min) in addition to reference non‐exposed specimens. The static response was evaluated in the damaged specimens in residual conditions after natural cooling from the elevated temperatures. The temperature distribution across the thickness of the slabs and their load–displacement response was measured. The decrease in the stiffness of the slabs due to the thermal exposure was studied by means of direct ultrasonic pulse velocity (UPV) measurements made before and after the fire tests. The decrease in global stiffness was partially accounted for by UPV measurements. The experimental results showed two peaks in the load‐deflection response of the slabs. The first peak was related to an arching mechanism introduced by the specific set‐up used. The second peak, corresponding to the ultimate load, occurred due to tensile membrane action at large deflections. While the former was strongly affected by the fire exposure, with the load being halved after the 120‐min exposure, the latter was not greatly affected by either the presence of fire or the exposure time. Simplified mechanical models were used to explain the behavior of the RC slabs during the tests.

Experimental assessment of explosive spalling in normal weight concrete panels under high intensity thermal exposure

Experiments were conducted to investigate fire-induced explosive spalling in conventionally reinforced normal weight concrete panels that emulate tunnel liners. Nineteen specimens (152.4-mm thick with ∼40 MPa compressive strength and 38.1-mm cover to reinforcement) were subjected to high intensity single-sided thermal loading from a gas-fired radiant panel. Radiant heat flux intensity was calibrated via standoff to achieve 85% or 60% of the ASTM E1529 hydrocarbon fire exposure. Moisture content by mass (MC) and relative humidity were recorded for each specimen prior to testing. Axial load was applied as a percentage of specified ambient compressive strength at three levels: negligibly low (1%), medium (16.7%), and high (33.3%). Fifteen specimens explosively spalled, and the other four showed post-test discoloration with minor cracking after being heated without spalling for at least 30 min. All specimens tested at the higher heat flux intensity with at least medium axial load spalled regardless of MC (from 2.4% to 4.6%). Temperature measurements through the thickness of those specimens indicated that explosive spalling was likely to occur when the concrete surface temperature reached ∼450 °C and generally penetrated to a depth where the concrete temperature was ∼150 °C. Specimens that did not spall typically had very low axial load or MC.

Intumescent alkali silicate and geopolymer coatings against hydrocarbon fires

Intumescent alkali silicate and geopolymer coatings against hydrocarbon fires

Review and discussion on fire behavior of bridge girders

This paper presents an overview on fire behavior of bridge girders mainly including prestressed concrete (PC) bridge girders and steel bridge girders. The typical fire accidents occurred on bridges are illustrated and, the seriousness of posing threats to bridge structures resulted from increasing traffic fires, specially intense hydrocarbon fires generated from petrol-chemicals, is highlighted. The current researches, embracing high-temperature properties of constituent materials, prestress state, measurement in fire tests, numerical methods, structural fire resistance, and so forth, taken on coping with problems existing in fire behavior and structural fire behavior in bridge girders are reviewed and discussed. Further, strategies for enhancing fire resistance of bridge girders followed with failure criterion and mode in types of bridge structures are provided. Future research area along with emerging trends in structural fire behavior of bridge girders is also recommended for mitigating fire hazards occurred on bridge girders. Herein, it can be attained a conclusion from review and discussion that prestressed concrete bridge girders with thin webs, specially T-shaped bridge girder, are prone to unstable under fire exposure conditions. High-strength concrete utilized in prestressed concrete bridge girders is vulnerable to spalling at elevated temperature. Steel-truss bridge girder present a more significant fragility to fire exposure compared than other steel bridge girders. • Fire behavior of bridge girders is reviewed and discussed. • Seriousness of bridge fires is highlighted. • Strategies for enhancing fire resistance of bridge girders are provided. • Fire resistance in types of bridge girders is investigated and presented. • Steel-truss bridge girders are significantly vulnerable to fire damage.

Thermal Characteristics of Fireproof Plaster Compositions in Exposure to Various Regimes of Fire

The problems of the fire safety of oil and gas facilities are particularly relevant due to the increasing complexity of technological processes and production. Experimental studies of steel structures with three different types of plasters are presented to determine the time taken to reach the critical temperature and loss of bearing capacity (R) of the sample, as a result of reaching a rate of deformation growth of more than 10 mm/min and the appearance of the ultimate vertical deformation. The simulation of the heating of steel structures showed a good correlation with the results of the experiment. The consumption of the plaster composition for the steel column was predicted, which allowed a 38% reduction in the consumption of fireproofing. It was found that to obtain the required fire resistance limit, it is necessary to consider the fire regime and apply plaster compositions with a thickness of 30–35 mm, depending on their thermal characteristics. The dependence of thermal conductivity and temperature on density is obtained, showing that the use of plaster compositions with a density of 200 to 600 kg/m3 is optimal to ensure a higher fire resistance limit. It is shown that the values of thermal conductivity of plaster compositions at 1000 °C are higher by 8–10% if the structure is exposed to a hydrocarbon fire regime. It is shown that the values of the heat capacity of plaster compositions at 1000 °C are higher by 10–15% if the structure is exposed to a standard fire regime.

Fire performance of lightweight concrete-filled LSF wall panels

Light Gauge Steel Frame (LSF) wall panels with cold-formed thin-walled steel-Lipped Channel Sections (LCS) and plasterboard linings are increasingly used in the construction industry due to their lightweight and constructability characteristics. However, due to the high thermal conductivity of the LCS, rapid heat transfer is observed in LSF walls, causing negative impacts to the fire performance of the LSF wall elements. Cavity insulation is one of the practical solutions used in the industry to improve the fire performance of LSF walls. Insulation materials such as rockwool, glass fibre, cellulose fibre, ceramic fibre are commonly used as cavity insulation materials in LSF walls. A novel approach in LSF walls is the introduction of lightweight concrete filling as a cavity filler. The effect of lightweight concrete filling on the fire performance of LSF walls was analysed with the numerical investigation in this study. Fire performance of conventional LSF walls with 12.5 mm and 15 mm single and double plasterboard with Autoclaved Aerated Concrete (AAC) with 600 kg/m3 density, Foam Concrete (FC) with 650 kg/m3 density and FC with 1000 kg/m3 density lightweight concrete fillings were compared with LSF walls without cavity insulation and rockwool insulation under standard and hydrocarbon fire conditions. It was observed promising improvement in insulation and load-bearing fire ratings in LSF walls with lightweight concrete filling. Among lightweight concrete materials considered, FC with 1000 kg/m3 density has exhibited the best fire performance. LSF walls performance could be enhanced with lightweight concrete fillings depending on the application with improved fire performance.

Experimental Study of Fire Damage Characteristics in a Petrochemical Plant Facility

As a part of the initial investigation of fire damage diagnosis, fire protection-applied specimens within petrochemical plant facilities were exposed to standard and hydrocarbon fire conditions; then, the heating temperature of the specimens was monitored, and their appearance was checked by visual observation. Although data on the appearance status for discoloration, thickness variations, etc. of fire protection were collated for each set of fire exposure conditions, it was difficult to estimate the heating temperature of the specimens. Therefore, the visual observation method for determining the degree of fire damage needs to be approached somewhat conservatively. Moreover, according to the results of the heating temperature measurements for each specimen, it was confirmed that the paint has a disadvantage in maintaining its fire resistance performance when exposed to a hydrocarbon fire.

The Collapse of World Trade Center 7: Revisited

The catastrophic events of September 11, 2001, stand out as a major motivation for research on improving the understanding of structural behaviour in fire. These events included the first complete collapse of a tall steel framed structure solely due to fire. World Trade Center 7 (WTC7) was a 47-storey office building within the WTC complex that collapsed due to a fire initiated by debris from the collapse of WTC1. In the following years, detailed investigations were carried out by expert teams to pinpoint the cause of the progressive failure of WTC7. Each of the expert teams analysed the fire and structure and made varying conclusions with regards to the mechanisms responsible for initiating and propagating the collapse of the building. This paper revisits the collapse of WTC7 and its investigation, and then explores the hypothesis that a potential hydrocarbon fire may have compromised the large transfer structure within the mechanical space of the building. This is done via two OpenSees finite element models. The first model explores the thermomechanical response of the mechanical floors to a potential diesel fire, and the second investigates the response of the structure to a failure caused by that fire. The outcome of the analyses shows that it is feasible that a mechanical room fire could lead to a failure in the transfer structure, which would then result in the loss of support to at least two columns within the building core. The failure of these columns may unbrace the eastern-most core columns and precipitate in the failure of the structure as observed on 9/11.

A char stratification approach to characterization and quantitative thermal insulation performance of hydrocarbon intumescent coatings

To protect structural steel in the event of a hydrocarbon fire, epoxy-based intumescent coatings, which expand to form a multicellular char layer, are increasingly used. Consequently, to improve formulations and understand the performance of such coatings, it is of great industrial and scientific interest to establish relationships between the char properties and the critical heating times of coated steel plates. In this work, a so-called Stratification Parameter (SP) that combines the relative expansions and insulation efficiencies of individual char layers (termed the sponge-like, the macroporous, and the compact phase, respectively), is introduced to characterize the properties of the multilayered intumescent coating char. An approximate linear relationship was revealed between the SP of the char and the fire-resistance performance (i.e., critical times to 400 and 550°C) of the intumescent coating. Furthermore, owing to the mapped-out exponential relationship between the dynamic viscosity minimum and the char appearance, it was discovered that the SP of the char can be effectively used to point out the required dynamic viscosity change of an intumescent coating to form a given char. Finally, results of thermogravimetric analyses suggest that constraining the coating mass loss during char degradation (to less than 28 wt% for the coatings of the present work) may prevent the formation of the less efficient sponge-like phase. The stratification methodology developed can be used to estimate expected thermal insulation properties of non-uniform hydrocarbon intumescent coating chars.

The analysis of the fire resistance limit of an enclosing wall with a wave-resisting visor as the protection for a group of fuel oil tanks

Introduction. An enclosing wall with a wave-resisting visor may be installed to resist the flow of a liquid spill during a tank collapse in accordance with GOST R 53324-2009. This wall should be continuous along the perimeter; it must be made of incombustible materials and have the fire-resistance limit of not less than E 150. As a rule, varieties of heavy concretes are used to construct these walls. However, the actual fire-resistance limit of a structure depends on both its geometric parameters, thermal characteristics and strength properties of concrete used in the case of the long-term exposure to the hydrocarbon fire regime. The work addresses the assessment of the actual fire resistance limit of an enclosing wall with a wave-resisting visor made of heavy concrete designed as the protection for a group of tanks at fuel oil facilities of a thermal power plant.Calculation methodology and results. The calculation of the actual fire resistance limit of an enclosing wall with a wave-resisting visor, designated for a group of fuel oil tanks was performed. The co-authors used the results of studies on the substantiation of a hydrocarbon fire resulting from a flammable liquid spill and a tank failure, empirical dependences for determining the thermal engineering parameters of heavy concrete, as well as experimental data on a change in the compressive strength of concrete at temperatures up to 1,200 °C. The calculation results show that this wall structure can maintain stability for more than 10 hours. Note that the load-bearing capacity of the wall is more than 11 times greater than the bending moment triggered by the standard load. Indeed, the fire resistance of the wall is not less than RE 600. It exceeds the normative values for these types of walls by a factor of four.Conclusions. A common algorithm can be used to calculate the actual fire-resistance limit of enclosing walls of oil and petroleum product tank storage facilities, set by Construction Regulations 468.1325800.2019. At the same time, the results of the above theoretical and experimental studies are recommended for use as the initial data.

Finite Element Modelling to Predict the Fire Performance of Bio-Inspired 3D-Printed Concrete Wall Panels Exposed to Realistic Fire

Large-scale additive manufacturing (AM), also known as 3D concrete printing, is becoming well-recognized and, therefore, has gained intensive research attention. However, this technology requires appropriate specifications and standard guidelines. Furthermore, the performance of printable concrete in elevated temperature circumstances has not yet been explored extensively. Hence, the authors believe that there is a demand for a set of standardized findings obtained with the support of experiments and numerical modelling of the fire performance of 3D-printed concrete structural elements. In general, fire experiments and simulations focus on ISO 834 standard fire. However, this may not simulate the real fire behaviour of 3D-printed concrete walls. With the aim of bridging this knowledge disparity, this article presents an analysis of the fire performance of 3D-printed concrete walls with biomimetic hollow cross sections exposed to realistic individual fire circumstances. The fire performance of the non-load-bearing 3D-printed concrete wall was identified by developing a suitable numerical heat transfer model. The legitimacy of the developed numerical model was proved by comparing the time–temperature changes with existing results derived from fire experiments on 3D-printed concrete walls. A parametric study of 96 numerical models was consequently performed and included different 3D-printed concrete wall configurations under four fire curves (standard, prolonged, rapid, and hydrocarbon fire). Moreover, 3D-printed concrete walls and mineral wool cavity infilled wall panels showed enhanced fire performance. Moreover, the cellular structures demonstrated superior insulation fire ratings compared to the other configurations.