摘要 :
A parametric natural fire model is presented, which is derived on the basis of simulations with heat balance models for realistic natural design fires, taking into account the boundary conditions of typical compartments in residen...
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A parametric natural fire model is presented, which is derived on the basis of simulations with heat balance models for realistic natural design fires, taking into account the boundary conditions of typical compartments in residential and office buildings. These so-called iBMB parametric fire curves are formulated with the help of simplified empirical equations which can easily be used for structural fire design as part of a performance-based natural fire design concept. The iBMB parametric fire curves are checked and validated by comparison with results of different heat balance models and with published fire tests from different fire research laboratories. In addition, a natural fire test in a test room with ordinary office room furnishings has been performed which supports the parametric natural fire model presented here. The application of the iBMB parametric fire curves is demonstrated by means of an example.
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Many studies of the thermal and structural behaviour for large compartments in fire carried out over the past two decades show that fires in such compartments have a great deal of non-uniformity (e.g. Stern-Gottfried et al. [1]), ...
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Many studies of the thermal and structural behaviour for large compartments in fire carried out over the past two decades show that fires in such compartments have a great deal of non-uniformity (e.g. Stern-Gottfried et al. [1]), unlike the homogeneous compartment temperature assumption in the current fire safety engineering practice. Furthermore, some large compartment fires may burn locally and tend to move across entire floor plates over a period of time. This kind of fire scenario is beginning to be idealized as travelling fires in the context of performance-based structural and fire safety engineering.
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A fire test series to study pool fires of ethanol-water mixtures in the small, intermediate and large scale has been performed. Additionally, demonstration tests of piles of PET plastic 0.5-L liquor bottles (39 vol%) in retail sto...
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A fire test series to study pool fires of ethanol-water mixtures in the small, intermediate and large scale has been performed. Additionally, demonstration tests of piles of PET plastic 0.5-L liquor bottles (39 vol%) in retail store arrays were carried out to illustrate their burning behaviour. On the basis of the test results, the burning of pool fires of different alcoholic beverages and the fire load due to alcohol can be evaluated for the purpose of performance-based fire safety design. The fire tests of retail store arrays showed that these fires grow slowly, and their heat release rate maxima are relatively low taking into account the mass of the fire load. The estimated heat release rate maxima of four-layer retail store arrays were ca. 1.5 MW and their growth times were over 600 seconds. Design fires generally used for the fire safety design of shopping centres are typically much more severe than the fire test results of retail store arrays of alcoholic beverages in this study.
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Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Nume...
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Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S/ V_(BO)), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.
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Cross-laminated timber, typical abbreviations CLT or XLAM, is currently one of the most innovative product in building with wood. This solid engineered timber product provides advantages compared to other solid timber slabs as the...
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Cross-laminated timber, typical abbreviations CLT or XLAM, is currently one of the most innovative product in building with wood. This solid engineered timber product provides advantages compared to other solid timber slabs as the dimension stability, i.e. swelling and shrinkage, is controlled by the crosswise laminations. As for other components, the fire resistance has to be verified for this type of product. While fire testing is time consuming and costly, simulations provide flexibility to optimize the product or to develop simplified design models for structural engineers. In this paper, a simulation technique is presented which can be used to determine the fire resistance of CLT. The technique was then used to develop simplified design equations to be used by engineers to predict the behavior of CLT in fire resistance tests and verify its fire resistance. Following existing models, the simplified design model aims for a two-step process whereby in a (i) first step the residual cross section and in (ii) a second step the load bearing capacity of the partly heated residual cross section is determined. The presented simulations consider the effective thermal-mechanical characteristics of wood exposed to standard fire and perform an advanced section analysis using a temperature profile corresponding to the actual protection and the location of the centroid together with the possibility of plasticity on the side of compression. It was shown that simulation results agree well with test results and that they can be used to determine layup specific modification factors used by the reduced properties method or zero-strength layers used by the effective cross section method. It was shown that the use of the zero-strength layers is favorable compared to the modification factors to calculate the resistance of the residual cross section. This is due to the large range of modification factors answering the typical layup of CLT comprising layers with their fiber direction cross the span direction. Subsequently, the methodology was used to determine design equations for initially unprotected and protected three-, five- and seven-layer CLT in bending and buckling. While the zero-strength layer for glulam beams in bending is assumed to be 7 mm (0.3 in), for CLT the corresponding value is in most of the cases between 5 mm and 12 mm but is different for other loading modes such as buckling (wall elements) and depending on the applied protection.
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This article presents a risk-based method for building fire safety design. Because the design fire is the most critical aspect of a building fire safety design, this article uses reliability theory to derive design fires from the ...
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This article presents a risk-based method for building fire safety design. Because the design fire is the most critical aspect of a building fire safety design, this article uses reliability theory to derive design fires from the fire risk acceptance criteria. The fire scenarios are modeled by an event tree, where different fire protection systems are presented as pivotal events. The number of casualties is estimated by the occupant number and the probability that an untenable condition is reached before occupants evacuate to a safe location. Using the probability and consequence of each fire scenario, the expected risk to life is used to integrate the fire risk acceptance criteria into the determination of the target reliability index. A global optimization method is then applied to the reliability index to obtain the design fires for each scenario. A case study was conducted to demonstrate an application of this proposed method.
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Structural fire protection of steel and composite construction in Switzerland. Structural fire protection and the design of steel and composite structures in case of fire has a tradition in Switzerland dating back to the 50s of th...
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Structural fire protection of steel and composite construction in Switzerland. Structural fire protection and the design of steel and composite structures in case of fire has a tradition in Switzerland dating back to the 50s of the last century. The article gives an overview of current regulations regarding the required fire resistance, the handling of passive fire protection measures as well as recent developments in fire design of steel and composite structures.
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Design models are required to assess the behaviour in fire of aluminium structures. These models need to be validated by comparison with test. Up to now tests results are only available for (small scale) individual aluminium compo...
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Design models are required to assess the behaviour in fire of aluminium structures. These models need to be validated by comparison with test. Up to now tests results are only available for (small scale) individual aluminium components. This paper provides the results of tests carried out on aluminium frames. A finite element model in combination with a sophisticated constitutive model are used to simulate the tests. The results of the simulations agree with that of the tests at room and elevated temperatures.
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Charts for insulation design of steel members in fire are usually provided by the manufacturers of the specified fire protection materials. These design charts may not be readily available, particularly for fire protection materia...
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Charts for insulation design of steel members in fire are usually provided by the manufacturers of the specified fire protection materials. These design charts may not be readily available, particularly for fire protection materials which may not have proprietary rights. This paper describes the development of a set of universal charts for the insulation design of steel members in fire for a wide range of fire protection materials of known physical and thermal properties. The main advantage of using these charts for insulation design is that they apply to all types of fire protection material without referring to the manufacturers' design charts. In addition, high density fire protection materials, such as concrete, for steel members have also been included in these universal design charts.
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Various ways exist to represent a design fire curve for tunnels. These can include different fire growth rates or combinations of fire growth rates with constant levels of heat release rate (HRR) coupled to a decay period. This me...
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Various ways exist to represent a design fire curve for tunnels. These can include different fire growth rates or combinations of fire growth rates with constant levels of heat release rate (HRR) coupled to a decay period. This means that the curve has to be represented with different mathematical expressions for different time periods. A more convenient way is to describe the design fire curve with a single mathematical expression. Such a curve has been presented by the author (H. Ingason, Fire development in large tunnel fires, 8th International Symposium on Fire Safety Science, Beijing, China, 18-23 September 2005, pp. 1497-1508), but it does not include a constant HRR period. This paper presents a new, single exponential, design fire curve with a constant maximum HRR. A presentation of available design curves is given as well.
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