Structural Fire Resistance Research Articles

A comparative analysis of the requirements of Russia and the United States to the fire resistance of building structures of oil refineries and petrochemical plants

Introduction. Currently, national standards and codes of practice contain deterministic values of the fire resistance of building structures of facilities of the Russian fuel and energy complex (FEC), while a probabilistic approach to determining their fire resistance is not specified in the Russian regulatory documents. The methodology of the probabilistic approach to the fire resistance of structures is detailed in API 2218 “Fireproofing Practices in Petroleum and Petrochemical Processing Plants”, developed by the American Petroleum Institute.Methods. A comparative analysis of the Russian regulatory documents on fire safety and API 2218 in terms of the established concepts of fireproofing and requirements for the fire resistance limits of building structures of oil and gas industry facilities, is carried out.Results. It was established that the Russian Federation has no regulatory documents establishing methods based on the probabilistic approach, including determination of the required fire resistance limits and points of application of fire-resistant coatings at facilities of the fuel and energy complex by analogy with international standard API 2218.Conclusion. Based on the analysis, it was concluded that approaches to the philosophy of the fire resistance of structures of buildings and structures of the fuel and energy complex in the documents under consideration are fundamentally different. In order to improve the Russian regulatory and technical framework, governing fire safety and fire resistance, it is proposed to consider the requirements of foreign documents that take into account proven international engineering and technical practices, in particular, the use of a probabilistic approach taking into account hydrocarbon fires.

Research on the Charring Rate of Cross Laminated Timber Structural

<p>本研究透過蒐集歐洲、北美、日本等地有關直交集成板CLT之構造防火法規與規範，以直交集成板CLT之構造耐火試驗及防火特性進行探討研究，並針對木構造建築物設計及施工技術規範〔1〕提出有關直交集成板CLT構造增修建議。預計進行2組CLT樓板及2組CLT牆板之耐火實驗，探討做為驗證所需。實驗試體使用5層15cm日本扁柏CLT(符合JAS規定)〔2〕及5層12cm日本扁柏加柳杉(符合JAS規定)〔2〕分別進行樓板與牆各1小時及2小時之耐火實驗。CLT實驗試體經耐火試驗後，進行炭化層之刮除以確認炭化深度及炭化速率。 CLT實驗試體加熱面經清除炭化層後所殘留之結構斷面，以每100mm距離量測其縱向及橫向炭化深度值，將量測之炭化深度及炭化速率結果，以日本木材炭化率預估模式〔3〕，藉由公式之計算與實際實驗後所得到之炭化深度交叉比對分析，利用實驗數據與預估模式之相關係數討論公式預估之準確性，提出炭化深度防火規定建議值，以作為木構造結構設計之依據。</p> <p> </p><p>This research is collecting about the fire regulations and codes for the construction of Cross Laminated Timber of CLT in Europe, North America, Japan, and discussion and research on the structural fire resistance test and fire characteristic execute of the Cross Laminated Timber CLT, and according to the reference manual for fire design and construction of wooden structures, suggestions on the addition and repair of the CLT structure of the Cross Laminated Timber are proposed. It is expected to execute the fire resistance test of 2 sets of CLT floor and 2 sets of CLT wall to discuss for verification. The test specimens used 5 layers of 15cm Japanese cypress CLT (in compliance with JAS regulations) and 5 layers of 12cm Japanese cypress and Cryptomeria (in compliance with JAS regulations) to execute fire resistance tests for the floor and wall for 1 hour and 2 hours. After the CLT test specimen to the fire resistance test, the charring layer is scraped to confirm the charring depth and the charring rate. After the charring layer has been clearing for structural section of the CLT specimens heating surface, and the longitudinal and transverse charring depth values are measured every 10cm. The charring depth and charring measurement rate results are by the Japanese wood charring rate prediction model, it is calculated by the formula and cross-compared analyzed with the charring depth obtained after the practical experiment. Use the correlation coefficients of test data and estimation models to discuss the accuracy of the predictions, and serve as a reference for the design of wooden structures for future reference revisions.</p> <p> </p>

Fire Resistance, Thermal and Anti-Ageing Properties of Transparent Fire-Retardant Coatings Modified with Different Molecular Weights of Polyethylene Glycol Borate.

Four kinds of polyethylene glycol borate (PEG-BA) with different molecular weights were grafted into cyclic phosphate ester (PEA) to obtain flexible phosphate esters (PPBs), and then applied in amino resin to obtain a series of transparent intumescent fire-retardant coatings. The comprehensive properties of the transparent coatings containing different molecular weights of PEG-BA were investigated by various analytical instruments. The transparency and mechanical analyses indicate that the presence of PEG-BA slightly decreases the optical transparency of the coatings but improves the flexibility and adhesion classification of the coatings. The results from fire protection and cone calorimeter tests show that low molecular weight of PEG-BA exerts a positive flame-retarded effect in the coatings, while high molecular weight of PEG800-BA behaves against flame-retarded effect. Thermogravimetric and char residue analyses show that the incorporation of low molecular weight of PEG-BA clearly increases the thermal stability and residual weight of the coatings and generates a more compact and stable intumescent char on the surface of the coatings, thus resulting in superior synergistic flame-retarded effect. In particular, MPPB1 coating containing PEG200-BA exerts the best flame-retarded effect and highest residual weight of 36.3% at 700 °C, which has 57.6% reduction in flame spread rate and 23.9% reduction in total heat release compared to those of MPPB0 without PEG-BA. Accelerated ageing test shows that low molecular weight of PEG-BA promotes to enhance the durability of structural stability and fire resistance of the coatings, while PEG800-BA with high molecular weight weakens the ageing resistance. In summary, the fire-resistant and anti-ageing efficiencies of PEG-BA in the coatings depend on its molecular weight, which present the order of PEG200-BA > PEG400-BA > PEG600-BA > PEG800-BA.

Study on Fire Resistance of Floor Structures in High-speed Train

According to the standard EN 45545, fire resistant tests of floor structures in high-speed train were carried out. Two typical floor structures which were placed in the passenger train were tested. Integrity and insulation are main performance criteria to evaluate fire resistance of floor structures. The furnace temperature is in accordance with the requirements in the standard ISO 834. The surface temperature and deflection were recorded with time. Glass wool and aluminium corrugated sandwich structure in two structures were burned through. The experiments were terminated at 30 minutes and 31 minutes respectively for the two structures. A large amount of smoke and the sound of cracking of the exposed surface of the test piece were produced, although the unexposed surface of test pieces did not reach the failure condition.

Sequentially coupled structural modelling of LSF floor-ceiling systems

Fire resistance levels provide a standardised measurement of building elements' fire resistance under structural, integrity and insulation criteria, and are usually obtained from standard full-scale fire tests. However, these tests consume excessive time and money and thus the use of validated advanced numerical models is preferred. This paper presents the details of a sequentially coupled structural modelling study of LSF floor-ceilings made of Lipped Channel beam (LCB) and rivet fastened Rectangular Hollow Flange Channel beam (RHFCB) section joists used in eight different floor-ceiling configurations, and its results. Ambient temperature structural finite element (FE) models of LCB and RHFCB joists were developed first and validated using experimental results. Full scale fire test results of LCB floor system were then used to validate a structural FE model developed and analysed using a sequentially coupled approach utilising the time-temperature profiles from the same fire test. Finally, using the validated sequentially coupled structural FE models, the effects of a range of influential parameters such as joist types and floor-ceiling configurations were investigated. The results of structural fire resistance/failure times versus load ratio showed that the new RHFCB joists gave only minor improvements, however, they provided superior load bearing capacities. Fire resistance improved significantly when more gypsum plasterboard layers were used. The use of thin steel sheathing also improved the failure times, and is recommended as the fire exposed layer due its ability prevent plasterboard fall-off. Finally, suitable critical mid-web temperatures are proposed for predicting the structural fire resistance times of LSF floor-ceiling systems.

Experimental analysis of cross-laminated timber rib panels at normal temperature and in fire

The results of an experimental programme on the structural behaviour, fire behaviour, and fire resistance of CLT rib panels are presented. The floor system consists of cross-laminated timber (CLT) plates rigidly bonded to glued-laminated timber ribs by means of screw-press gluing.The experimental programme comprised ultimate-load tests at normal temperature as reference tests and full-scale fire resistance tests on four cross-sections. In addition to the reference tests, shear tests of the glue line between CLT plate and glued-laminated timber rib were performed for analysis of the cross-sections’ composite action.The results of the reference tests show good agreement with results based on the simplified method according to EN 1995-1-1 [1] and its final draft of CLT design [2]. The importance of the glue line’s quality was confirmed. The fire resistance tests show results on the safe side compared to predictions of the fire behaviour according to EN 1995-1-2 [3] and its actual draft [4]. However, the fire resistance was underestimated due to conservative assumptions about the composite cross-section’s structural behaviour.The experimental programme addressed the fire behaviour and fire resistance of CLT rib panels currently not covered in standards. The project’s overall aim is the development of design rules in fire for EN 1995-1-2.

Multi‐scale bolt connection model for thermomechanical simulations

AbstractA multi‐scale simulation approach is proposed to predict the fire resistance of structures comprising connections by bolts, as a supplement to an existing two‐way coupled CFD‐FEM method. In the existing model, fire is modelled by CFD, and its effects on the overall structure are found via thermodynamic and thermomechanical models. In this paper, detailed thermomechanical models are presented to predict the behaviour of a bolt connection, in order to find the equivalent linear elastic stiffness for the bolt connection that is modelled as a spring in the overall structure. Each load step, the stiffness of the spring is determined by the detailed model, which for a certain temperature, boundary conditions, and load type, predicts the connection behaviour, including geometric and material non‐linearity and failure. It will be shown that the detailed model simulates existing experiments for elevated temperatures well, and is able to predict all possible failure modes as listed in the Eurocode for ambient temperatures. It is then demonstrated that the model can also be used for all these failure modes for elevated temperatures. In the near future, a strategy will be developed to include the detailed models in the overall structure, within the two‐way coupled CFD‐FEM method.

Experimental Research of Piece-Mold Casting: Gilt-Bronze Pensive Bodhisattva

We have tried the experimental research of lost-wax casting to reconstruct Gilt-Bronze Pensive Bodhisattva; preliminary and reconstruction experiment based on ancient texts. Main object to reconstruct is Korean National Treasure No.83, Gilt-Bronze Pensive Bodhisattva (Maitreya), then we measure alloy ratio and casting method based on the scientific analysis. Other impurities were removed from the base metal components(copper : tin : lead) and their ratio was set to 95.5 : 6.5 : 3 where the ratios for tin and lead were increased by 2.5% each. The piece-mold casting method was used, and piece-mold casting experiments were carried out twice in this study but supplementary research on piece-mold casting was necessary. The microstructure was confirmed to be typical cast microstructure and the component analysis result was similar to that of the prior study. Analysis of the chemical composition is confirmed to copper, tin, lead, and zinc, and the chemical composition of the matrix was 87.8%Cu-7.5%Sn-2.7%Pb-2.1%Zn, and similar to previous experimental research. Also resulted in the detection of small impurity in Zn. Analysis of the mould revealed that the mould was fabricated by adding quartz and organic matter for structural stability, fire resistance, and air permeability. We expect that our research will contribute to provide base data for advanced researches in future.

Fire performance of modular wall panels: Numerical analysis

The Modular Building System (MBS) is increasingly popular and promoted due to the inherent advantages over conventional construction. Fire performance of a building has become a crucial design consideration because of the recent detrimental fire accidents. However, for modular buildings, there has been less previous evidence of research on the fire performance. Investigations become necessary since double skin wall and floor modular panel systems are involved in MBS in contrast to conventional buildings. Therefore, this work investigates the fire performance of Light-gauge Steel Framed (LSF) modular wall panels with different configurations through numerical analyses. Heat transfer numerical models were developed and validated against the full-scale fire test results comparing the time–temperature response. The validated numerical models were subsequently extended to analyse the fire performance of conventional and modular LSF wall panels. This includes 16 modular wall configurations with single and double fire resistance plasterboard linings and three different insulations, namely rock wool, glass fibre and mineral wool. The structural fire resistance time was determined using the established Load Ratio (LR) vs critical Hot-Flange (HF) temperature correlation. The results demonstrated that there is no noticeable difference in the structural fire resistance time between the modular and the corresponding mapped conventional LSF wall configurations. However, modular wall panels experience enhanced insulation fire resistance up to 170% for single-lined plasterboards and up to 80% for double-lined plasterboard configurations. The analysis also yields that there is no significant influence of the choice of insulation material between rock-wool, glass-fibre and mineral-wool on structural fire resistance.

Numerical study of LSF walls made of cold-formed steel hollow section studs in fire

Cold-formed steel square and rectangular hollow section (SHS/RHS) studs are often used to replace the conventional lipped channel section studs in light gauge steel frame (LSF) wall systems to meet the required high load demand. To ensure adequate structural fire resistance of SHS/RHS stud walls, four full-scale fire tests were previously completed under standard fire conditions. However, the full-scale fire tests are expensive and time-consuming, while the complex fire performance cannot be adequately explained through test observations and results alone. Hence, a numerical study was undertaken by developing simplified and sheathed stud finite element (FE) models of tested walls. This paper provides the details of the developed models of LSF walls made of SHS/RHS studs at both ambient and elevated temperatures and a comparison with experimental results. The validated models were used to highlight the advantage of using SHS/RHS studs in cavity insulated stud walls and further understand the factors that may affect the fire resistance of LSF walls, such as steel grade and stud depth. In addition to the simplified stud model, advanced modelling techniques were used to explore the effects of sheathing and localised plasterboard fall-off on the wall behaviour in fire. Overall, this paper presents a numerical study of SHS/RHS stud walls and the simplified stud model developed in this paper can be used to predict the fire performance of other SHS/RHS stud walls with similar wall configurations.

Banana Fiber-Reinforced Epoxy Composites: Mechanical Properties and Fire Retardancy

Currently, the growing field of technology has paved the way for using environmental friendly resources; in particular, plant origin holds ecological concern and renewable aspects. Currently, natural fiber composites have widening attention, thanks to their eco-friendly properties. In the present work, the composite material is reinforced with natural fibers from the bark of banana trees (banana fibers), a material available in Vietnam. Banana fibers are extracted from banana peels, pretreated with NaOH 5%, and then cut to an average length of 30 mm. Banana fiber is reinforced for epoxy resin Epikote 240 with mass percents: 10 wt.%, 15 wt.%, 20 wt.%, and 25 wt.%. The results were evaluated through structural morphology (SEM), mechanical properties, fire resistance, and thermal properties. Experimental results show that the tensile, compressive, and impact strengths of biosynthetic materials up to 20% by weight have increased compared to epoxy neat. Flame retardant and thermal properties are kept stable; 20 wt.% banana fiber gives a limiting oxygen index of 20.8% and satisfactory thermal stability.

Enhancing the Fire Resistance of Concrete Structures by Applying Fire-Retardant Temperature-Resistant Metal Coatings

The issues relating to an increase in the fire-resistance of concrete structures by applying (heat dissipating) fire-retardant and fire resistant metal coatings onto them was considered. The experimental investigation data obtained for the heating rate of the brick coated with the aluminum layer as heat dissipating coating were given. The investigation was carried out through the comparison of a time-dependent change in the temperature of the material coated with the aluminum layer with the temperature of uncoated material. The obtained research results proved a decrease in the heating rate of the coated brick exposed to the thermal irradiation.

Post-earthquake fire resistance of tall steel concentrically braced frames

The fire which occurs after an earthquake causes great problems for buildings situated in moderate to high seismic regions. In this article in order to have an understanding regarding the impacts of post-earthquake fire on the structures, implementing the finite element method, the behaviour of tall steel concentrically braced frames when subjected to this type of loading was investigated. The simulation under seismic loading was done using the nonlinear time history analysis. Assuming the post-earthquake situation of the structure as the initial condition, the mechanical-thermal analysis was applied using the temperature-time diagram on the exposed elements. The analysis results showed that regardless of the earthquake record and fire scenarios for the tall steel concentrically braced frames, the fire resistance duration was short and the impacts of the previous earthquake on the structure fire resistance were not considerable.

Probabilistic risk assessment of the effects of fire service intervention on structural fire resistance design of unsprinklered buildings

This paper presents a probabilistic analysis method to explicitly include the influences of fire service intervention (FSI) in structural reliability analysis of unsprinklered buildings exposed to fire. The method considers different scenarios of fire behaviour following FSI, based on probabilistic analysis of the current UK fire data to estimate different components of intervention time, size of the fire on arrival of the fire service and extent of damage of the fire at the end of intervention. These statistical data are then used to generate random fire temperature-time curves to calculate the probability of structural failure of intumescent coating protected steel members using the Monte Carlo Simulation method. To aid deterministic design, a simplified method is developed to derive fire load modification factors (δn,FSI) to account for the effects of FSI so that when the fire load modification factor is applied, the deterministic design method gives the same probability of structural failure as that from explicit probabilistic calculation. An extensive parametric study covering a wide range of practical design factors has been carried out and an Analysis of Variance (ANOVA) is performed on the results to examine whether any design factor has significant effect on the fire load modification factor. The results show that fire growth rate and compartment floor area are the most influential. The effects of fire load, steel critical temperature and fire protection thickness have moderate effects. Based on the results of this study, it is suggested that the design fire load should not be reduced if the fire floor area does not exceed 250 m2, or the fire growth rate is ultrafast. If the fire growth rate is fast, the design fire load should not be reduced for fire floor areas less than 1000 m2. For other situations, a fire load modification factor of δn,FSI = 0.78, as in the current Eurocode, may be applied.

Study on thermo-mechanical coupling method of ship cabin with ceiling vent under fire condition

Objectives The performance analysis of ship cabin steel structures in fire situations is fundamental to structural fire resistance design. Compared with research conducted under traditional standard fire conditions, research based on the real fire temperature field can more accurately analyze the mechanical response behavior of cabin structures. Aiming at an open cabin (i.e. engine room) structure, a fire-heat-structure coupling method combining FDS and ANSYS is developed. Methods First, the FDS simulation is utilized to obtain the temperature information of the inside ship wall exposed to the fire, which is then used as the boundary condition transferred to the structural finite element analysis software ANSYS. Transient thermal analysis concerning the temperature field of the cabin structure is then conducted, and the thermal-structural coupling analysis of the ship cabin structure carried out in a real fire scenario. Results The results of the case study using the proposed method demonstrate that the stress distribution is not uniform due to the uneven temperature distribution. The maximum stress is concentrated at the edge of the cabin, with a value of 19 MPa. The structure does not reach the failure limit after being exposed to fire. Conclusions Compared with the traditional standard fire curve method, the proposed method has two advantages for addressing structural response: the non-uniform elevated temperature of the structure and real fire temperature rise. More attention should be paid to the change in structural internal force caused by non-uniform temperature rise in an open ship cabin.

Effect of temperature on mechanical properties of ultra‐high performance concrete

SummaryHigh temperature mechanical property data are needed for evaluating fire resistance of structural members. Being a relatively new construction material, there is a lack of temperature‐dependent mechanical property data on ultra‐high performance concrete (UHPC). To address this knowledge gap, this paper presents results from an experimental study on the effect of temperature on mechanical properties of UHPC. Specimens made of two UHPC mixes: one with only steel fibers (UHPC‐S) and the other with hybrid fibers, that is, both steel and polypropylene (UHPC‐H), were tested under different heating conditions in 20 to 750°C temperature range. Compressive strength, tensile strength, stress‐strain response, and elastic modulus of UHPC were evaluated at various temperatures. Results generated from these property tests on UHPC were compared with property relations specified in design codes for conventional normal strength concrete (NSC) and high strength concrete (HSC). The comparisons show that UHPC experiences faster degradation in compressive strength and elastic modulus as compared to conventional concrete. However, UHPC exhibits slower degradation in tensile strength and ductility at elevated temperatures due to the presence of steel fibers. Data generated from these property tests were utilized to propose relations for expressing the mechanical properties of UHPC as a function of temperature and these relations can be used as input to numerical models for evaluating fire resistance of structures made of UHPC.

Fire Performance of Self-Tapping Screws in Tall Mass-Timber Buildings

Building elements are required to provide sufficient fire resistance based on requirements set forth in the National Building Code of Canada (NBCC). Annex B of the Canadian standard for wood engineering design (CSA O86-19) provides a design methodology to calculate the structural fire-resistance of large cross-section timber elements. However, it lacks at providing design provisions for connections. The objectives of this study are to understand the fire performance of modern mass timber fasteners such as self-tapping screws, namely to evaluate their thermo-mechanical behavior and to predict their structural fire-resistance for standard fire exposure up to two hours, as would be required for tall buildings in Canada. The results present the great fire performance of using self-tapping screws under a long time exposure on connections in mass timber construction. The smaller heated area of the exposed surface has limited thermal conduction along the fastener’s shanks and maintained their temperature profiles relatively low for two hours of exposure. Based on the heat-affected area, the study presents new design principles to determine the residual length of penetration that would provide adequate load-capacity of the fastener under fire conditions. It also allows determining safe fire-resistance values for unprotected fasteners in mass timber construction exposed up to two hours of standard fire exposure.

Modeling the biomass allocation of tree resprout in a fire-prone savanna

Young savanna trees can quickly grow back from belowground storage structures after topkill. This capacity is a tolerance trait that confers persistence at the plant individual level, enabling them to survive diverse disturbance regimes.We simulated the growth of a single resprouting stem (without and with fire) of a deciduous tree species that allocates its photo-assimilates during the vegetation season to reserves, belowground and aboveground parts (leaves and stem). As savannas grow under highly seasonal climates, the model considers that trees are leafless during the dry season and following growth is only possible thanks to reserves. Stem architecture constrains the leaf biomass to be proportional to stem length rather than biomass. We compared the success of different allocation strategies, with and without fire and according to the seasonality. To do so, the height of the resprouting stem after 50 yrs and the time to reach 2 m were modeled for three species of a humid savanna.The viable and faster growth strategies are those for which allocation to belowground parts is <40%. There is very little sensitivity to allocation to reserves since successful growth is observed for allocation to reserves between 0.5% and 85% of photo-assimilates. In the literature and in our results, there is little impact of fire on the stem height or the time needed to escape the fire trap. Our model suggests that (1) allocation to leaves is determinant as leaves are the primary source of assimilates that can then be turned into fire-resistant structures (reserves and roots) and (2) fire only weakly slows down the plant growth compared to dry season..

Structural fire design of SHS, RHS and CHS high strength steel columns

Despite substantial progress in recent years to improve the design guidance for high strength steel (HSS) structural elements, this has mainly been for ambient conditions with their fire response still in need of further research. Accordingly, this paper reports on an investigation into the structural performance of unprotected HSS hollow section columns in fire. Finite element models of columns made from square, circular and rectangular hollow sections are developed and are validated against test data at ambient and elevated temperature. The validated models are employed to perform parametric studies to assess the influence of a range of variables such as the grades of HSS, levels of temperature exposure and cross-sectional geometry. The structural fire design resistance method for a column given in the Eurocode is assessed based on the FE results. Consequently, new buckling curves are proposed, which provide a more accurate prediction of the real capacity and reliability analysis is also performed on the new proposed design formulations.

Spalling Mechanism: Key for Structural Fire Resistance of Tunnels

The need to consider tunnel safety, especially with respect to fire, has been highlighted in the past by various severe tunnel fires that have occurred throughout Europe. This article provides a general overview of the current rules and regulations governing the fire resistance design of tunnel structures. Subsequently, the engineering perspective is presented, focusing on the assessment of fire severity and the resulting thermal loading on the tunnel structure, which may result in spalling of concrete. Thereafter, a scientific perspective is provided, reflecting recent advances made in numerical calculations with respect to the spalling mechanism. From the numerical results and comparison with observations from full-scale tests, it is concluded that thermal restraint is dominant for spalling. Spalling is triggered by the buckling of concrete layers loaded with strains imposed by temperature, which is a new perspective for future scientific research and innovative engineering solutions.