Search results
1 – 10 of over 3000Kamila Cabová, Filip Zeman, Lukáš Blesák, Martin Benýšek and František Wald
This paper aims to present a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. Temperatures calculated inside the timber…
Abstract
Purpose
This paper aims to present a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. Temperatures calculated inside the timber beam are compared to measured values from the fire test.
Design/methodology/approach
The paper presents a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. The presented part lies in a virtual furnace which simulates temperature environment around tested elements in the furnace. Comparison of results show good agreement in the case when burning of timber is included in the numerical model.
Findings
The virtual furnace presented in this paper allows to calculate temperature environment around three timber beams. After validation of the fire dynamics simulator (FDS) model, the temperature conditions are passed to the FE model which solves heat transfer to the tested element. Temperatures inside the timber beam which are solved in software Atena Science are compared to measured temperatures from the fire test. The comparison of temperatures in three control points shows good accuracy of the calculation in the point closer to the heated edge. An inaccuracy is shown in points located deeper in the beam cross-section – below the char layer.
Research limitations/implications
In conclusion, the virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. However, passing the temperature field from the FDS model into FE model may decrease the level of accuracy. The solution lies in a coupled CFD-FE model. A weakly coupled model including fluid dynamics, heat transfer and mechanical behaviour is under development at Faculty of Civil Engineering, Czech Technical University in Prague. The fluid dynamics part which is presented in this paper is solved by FDS and the thermo-mechanical part is computed by object-oriented finite element model (OOFEM). The interconnection of both software is made owing to MuPIF python library.
Practical implications
The virtual furnace takes advantage of great possibilities of computational fluid dynamics code FDS. The model is based on an accurate representation of a real fire furnace of fire laboratory PAVUS a.s. located in the Czech Republic. It includes geometry of the real furnace, material properties of the furnace linings, burners, ventilation conditions and tested elements. Gas temperature calculated in the virtual furnace is validated to temperatures measured during a fire test.
Social implications
The virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions.
Originality/value
The virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. However, passing the temperature field from the FDS model into FE model may decrease the level of accuracy. The solution lies in a coupled CFD-FE model. A weakly coupled model including fluid dynamics, heat transfer and mechanical behaviour is under development at Faculty of Civil Engineering, Czech Technical University in Prague. The fluid dynamics part which is presented in this paper is solved by FDS and the thermo-mechanical part is computed by OOFEM. The interconnection of both software is made thanks to MuPIF python library.
Details
Keywords
Batuhan Der, Sylvie Raszková, František Wald, Gisèle Bihina, Christian Gaigl, Vasile Rus and Mikko Malaska
This study aims to propose a new design value, based on experimental and numerical studies, for surface emissivity of zinc hot-dip galvanized members exposed to fire.
Abstract
Purpose
This study aims to propose a new design value, based on experimental and numerical studies, for surface emissivity of zinc hot-dip galvanized members exposed to fire.
Design/methodology/approach
The paper sums up experiments, used specimens and also shows results. Four experiments were performed in a horizontal furnace and one test in a fire compartment of the experimental building. Several tests were carried out for determination of the surface emissivity of galvanized steel structures in fire. The experimental and numerical studies were used for preparation of new generation of the structural steel fire standard Eurocode EN 1993-1-2:2025.
Findings
Hot-dip galvanizing is one of the most widely used processes for corrosion protection of steel products. The new design value for surface emissivity of zinc hot-dip galvanized members exposed to fire is determined using experimental results as 0.35. The value is proposed for next generation of EN 1993-1-2:2025. If hot-dip galvanization additionally can contribute beneficially to the fire resistance of unprotected steel members, it would be a huge economic advantage.
Originality/value
Experimental studies in the past years have indicated the influence of hot-dip galvanizing on the heating of steel members. This study suggests 50% reduction of the surface emissivity of a carbon steel member. This amendment will be incorporated in future versions of Eurocodes 3 and 4 and has already been implemented in some fire design tools for steel members in order to consider the beneficial contribution of hot-dip galvanized for fire-resistance requirements of less than 60 min.
Details
Keywords
András Jakab, Viktor Hlavicka, Ágoston Restás and Eva Lubloy
During the building designing, it is very important to deal with the fire resistance of the structures. The designed materials for escape routes should be selected to ensure the…
Abstract
Purpose
During the building designing, it is very important to deal with the fire resistance of the structures. The designed materials for escape routes should be selected to ensure the usability of the structures until the time of escape. Planning affects the glass structures similarly, so these can also be partition walls and load bearing structures, although the latter is less applied on escape routes. The heat protection of the glasses can be improved with heat-protective foils, while fire protection is provided by gel intumescent material.
Design/methodology/approach
To research the topic of fire resistance, laboratory experiments were carried out on small-scaled glass elements with thermal protection foil at Budapest University of Technology and Economics at the Department of Construction Materials and Technologies.
Findings
Fire protection of small model specimens was tested with blowtorch fire and furnace heat load. During the experiments, six foils were tested. Single pane glass, double layered and triple glazed specimens were tested with blowtorch fire.
Originality/value
Fire protection of small model specimens was tested with blowtorch fire and furnace heat load. During the experiments, six foils were tested. Single pane glass, double layered and triple glazed specimens were tested with blowtorch fire. In case of heat-protected glazing, the foils on the “protected” side of the single pane glass do not have a fire protection effect based on blowtorch fire test. For double glassed specimens, the P35 foil has a perceptible effect, even for the requirements of the flame breakthrough (E, integrity), when the foil is placed on the inner side (position 3) of the second glass layer. The stratification of each triple glazed specimens was effective against blowtorch fire load (3 M, S4&P35), so (EI, integrity and isolation) it can meet the requirements of flame breakthrough and thermal insulation.
Details
Keywords
Seyed Vahid Khonsari, Shahin Nejati, Mohammadreza Rahdan and Mahdi Ahmadi
The paper aims to report a fire test conducted on a three-dimensional frame in order to investigate the behaviour of bare steel flush end-plate connections with relatively low…
Abstract
Purpose
The paper aims to report a fire test conducted on a three-dimensional frame in order to investigate the behaviour of bare steel flush end-plate connections with relatively low thickness at elevated temperatures.
Design/methodology/approach
A half-scale model was fabricated and exposed to modified (scaled) ISO 834 heating curve using a semi-open furnace. The maximum temperature inside the furnace reached 1,026 °C.
Findings
The rotations of connections are reported and compared with those of a previous study on an exactly the same model with thick end-plates. Various modes of failure such as local buckling of the beams flanges and lateral-torsional buckling of beams were observed during the test. Finally, the structure collapsed after 29 min of heating due to the fracture of weld between one of the beams and one of its attached end-plates whilst the other beam had undergone a maximum deflection of 35 cm (≈ 1/6 span length). Other observed failure modes included bolt fracture, bolt thread stripping and large inelastic deformation of the end-plates.
Originality/value
Although the adoption of thin end-plates increased the rotational capacity of the connections, it did not improve the robustness of the structure under fire conditions.
Details
Keywords
C. Kahanji, F. Ali and A. Nadjai
The purpose of the study was to investigate the spalling phenomenon in ultra-high performance fibre reinforced concrete (UHPFRC) beams on exposure to a standard fire curve (ISO…
Abstract
Purpose
The purpose of the study was to investigate the spalling phenomenon in ultra-high performance fibre reinforced concrete (UHPFRC) beams on exposure to a standard fire curve (ISO 834) under a sustained load.
Design/methodology/approach
The variables in this study were steel fibre dosage, polypropylene (PP) fibres and loading levels. The research investigated seven beams – three of which contained steel fibres with 2 vol.%, another three had steel fibres with 4 vol.% dosage and the seventh beam had a combination of steel fibres (2 vol.%) and PP fibres (4 kg/m3). The beams were tested for 1 h under three loading levels (20, 40 and 60 per cent) based on the ambient temperature ultimate flexural strength of the beam.
Findings
Spalling was affected by the loading levels; it exacerbated under the load level of 40 per cent, whereas under the 60 per cent load level, significantly less spalling was recorded. Under similar loading conditions, the beams containing steel fibres with a dosage of 4 vol.% spalled less than the beams with fibre contents of 2 vol.%. This was attributed to the additional tensile strength provided by the excess steel fibres. The presence of PP fibres eliminated spalling completely.
Originality/value
There is insufficient research into the performance of UHPFRC beams at elevated temperature, as most studies have largely focussed on columns, slabs and smaller elements such as cubes and cylinders. This study provides invaluable information and insights of the influence of parameters such as steel fibre dosage, PP fibres, loading levels on the spalling behaviour and fire endurance of UHPFRC beams.
Details
Keywords
Saeed Bakhtiyari, Arsalan Kalali, Leila Taghi Akbari and Farhang Farahbod
This paper aims to evaluate fire resistance of carbon fiber-reinforced polymer (CFRP)-strengthened concrete slabs in two forms of unprotected and protected against fire.
Abstract
Purpose
This paper aims to evaluate fire resistance of carbon fiber-reinforced polymer (CFRP)-strengthened concrete slabs in two forms of unprotected and protected against fire.
Design/methodology/approach
To achieve the objective, an unstrengthened and two CFRP-strengthened concrete slabs were first subjected to increasing gravity loading until failure. Subsequently, the unstrengthened concrete slab was placed on a furnace and was subjected to a constant service gravity load and then, the temperature of the furnace was increased according to a standard temperature–time curve until the failure of the slab occurred. This slab was strengthened by CFRP with two different amounts and then, in two cases of unprotected and protected against fire, was tested in accordance with the aforementioned method.
Findings
The gravity test results revealed that CFRP strips bonded to concrete slabs increased the load-bearing capacity considerably. So, this method can be suitable for flexural strengthening of concrete slabs. The fire test results showed that because of more load-bearing capacity and subsequently increase in service gravity load, the strengthened concrete slab failed in a short time due to the lack of CFRP resistance against fire. By contrast, the protected specimens resisted the fire in a considerable time. In addition, it was revealed that details of fire protective coating had an important effect on fire resistance duration.
Originality/value
It is notable that in the literature, there is a lack of data on the fire endurance of fiber-reinforced polymer-strengthened concrete slabs alone without any fire protection system. Furthermore, the applicability and effectiveness of a new kind of spray mineral fire protective coatings was evaluated.
Details
Keywords
Hendrig Marx and Richard Walls
The Southern African Institute of Steel Construction has developed a novel cellular beam structure (CBS) for multi-storey buildings that is entirely devoid of concrete. Channel…
Abstract
Purpose
The Southern African Institute of Steel Construction has developed a novel cellular beam structure (CBS) for multi-storey buildings that is entirely devoid of concrete. Channel sections between the cellular beams support a complex sandwich flooring system, which contains a fire-resistant ceiling board, metal sheeting, an interior fibre-cement board and an access-flooring system. As for all structures, the CBS requires a fire rating. This paper aims to investigate the thermal behaviour of the CBS using numerical modelling and experimental fire testing, as it has a unique setup.
Design/methodology/approach
Experimental fire tests on the flooring system were conducted to validate finite element models, which were developed in ABAQUS. These models were then extended to include floor beams and the structural steelwork.
Findings
Good correlations were found between the experimental and numerical results, with temperature variations typically in the range of 0-5%, although with localised differences of up to 20%. This allowed larger finite element models, representing the sandwich floor system of the CBS, to be developed and analysed. A 1-hour rating can be obtained by the system in terms of insulation and integrity requirements.
Practical implications
The CBS allows for more economical steel structures, due to the rapid construction of its modular panels. A suitable fire resistance will ensure the safety of the occupants and prevent major structural damage. Steelwork and flooring temperatures are determined which has allowed for global structural analyses to be carried out.
Originality/value
The originality of this study lies in thermal analysis and testing of a new cellular beam flooring system, through determining behaviour in fire, along with beam temperatures.
Details
Keywords
M.A. Denney and J.C. Martindale
WITH the development of supersonic aircraft there is an increasing requirement for structural materials operating at elevated temperatures. To ensure optimum utilization of…
Abstract
WITH the development of supersonic aircraft there is an increasing requirement for structural materials operating at elevated temperatures. To ensure optimum utilization of reinforced plastics it is essential to provide the designer with accurate data on performance at these temperatures.
Prabhakar Sathujoda, Paul Arnell and Andrew Deans
As fire doors are passive fire protection parts, the doors have to be certified through standard fire tests. It is usual practice to perform the standard fire testing on the…
Abstract
Purpose
As fire doors are passive fire protection parts, the doors have to be certified through standard fire tests. It is usual practice to perform the standard fire testing on the components which require the fire certification. However, some gas turbine enclosure doors are too large to test at the test facility and hence the fire resistance test is practically not possible. The purpose of this paper is to develop a reliable finite element model, validate the model using the specimen door test results and extend the method to actual gas turbine enclosure doors to support the fire certification.
Design/methodology/approach
First, the standard fire testing on enclosure door test specimen was carried out. Second, the finite element analysis model was built and tuned to match the standard fire test deflections, and finally, the same modelling technique was extended to model the actual gas turbine enclosure door to verify the results for fire certification process.
Findings
Gap analysis, a method of post processing is suggested for result analysis. It was found suitable to verify the gap openings which are required for A0 rated fire certification according to fire test procedure code and also to check the mechanical integrity of the enclosure door frame assembly.
Originality/value
The method presented in this work could be used as support information along with the test specimen results for A0 class fire rating certification of the doors according to International Maritime Organization Resolution MSC.307 (88) Annexure 1: Part 3.
Details
Keywords
Mohamed A. Khalifa, Mohamed A. Aziz, Mohamed Hamza, Saber Abdo and Osama A. Gaheen
Fire door should withstand a high temperature without deforming. In the current paper, the challenges of improving the behaviour of the conventional fire door were described using…
Abstract
Purpose
Fire door should withstand a high temperature without deforming. In the current paper, the challenges of improving the behaviour of the conventional fire door were described using various internal stiffeners in pair swinging-type fire door.
Design/methodology/approach
The temperature distribution on the outside door surface was measured with distributed eight thermocouples. Subsequently the internal side was cooled with pressurized water hose jet stream of 4 bar. The transient simulation for the thermal and structure analysis was conducted using finite element modelling (FEM) with ANSYS 19. The selected cross sections during numerical simulation were double S, double C and hat omega stiffeners applied to 2.2 m and 3 m door length.
Findings
During the FEM analysis, the maximum deformations were 7.2028, 5.4299, 5.023 cm for double S, double C and hat omega stiffeners for 2.2 m door length and 6.57, 4.26, 2.1094 cm for double S, double C and hat omega stiffeners for 3 m door length. Finally, hat omega gives more than three times reduction in the deformation of door compared to double S stiffeners which provided a reference data to the manufacturers.
Research limitations/implications
The research limitation included the limited number of fire door tests due to the high cost of single test, and the research implication was to achieve an optimal study in fire door design.
Practical implications
Achieving the optimum design for the internal door stiffeners where the hat omega stiffener gives minimum door deformation compared to the other stiffeners was considered the practical implication. The work included two experimental fire door tests according to the standard fire test (ANSI/UL 10C – Positive Pressure of Fire Tests of Door Assemblies) for a door of 2.2 m length with double S stiffeners and a door of 3 m length with hat omega stiffeners, which achieved minimum deformation.
Originality/value
The behavior and mechanical response of door leaf were improved through using internal hat omega stiffeners under fire testing. This study was achieved using FEM in ANSYS 19 for six cases of different lengths and stiffeners for fire doors. The simulation model showed a very close agreement with the experimental results with an error of 0.651% for double S and 1.888% for hat omega.
Details