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1 – 10 of over 1000
Article
Publication date: 22 April 2022

Mhd Anwar Orabi, Jin Qiu, Liming Jiang and Asif Usmani

Reinforced concrete slabs in fire have been heavily studied over the last three decades. However, most experimental and numerical work focuses on long-duration uniform exposure to…

Abstract

Purpose

Reinforced concrete slabs in fire have been heavily studied over the last three decades. However, most experimental and numerical work focuses on long-duration uniform exposure to standard fire. Considerably less effort has been put into investigating the response to localised fires that result in planarly non-uniform temperature distribution in the exposed elements.

Design/methodology/approach

In this paper, the OpenSees for Fire framework for modelling slabs under non-uniform fire exposure is presented, verified against numerical predictions by Abaqus and then validated against experimental tests. The thermal wrapper developed within OpenSees for Fire is then utilised to apply localised fire exposure to the validated slab models using the parameters of an experimentally observed localised fire. The effect of the smoke layer is also considered in this model and shown to significantly contribute to the thermal and thus thermo-mechanical response of slabs. Finally, the effect of localised fire heat release rate (HRR) and boundary conditions are studied.

Findings

The analysis showed that boundary conditions are very important for the response of slabs subject to localised fire, and expansive strains may be accommodated as deflections without severely damaging the slab by considering the lateral restraint.

Originality/value

This work demonstrates the capabilities of OpenSees for Fire in modelling structural behaviours subjected to non-uniform fire conditions and investigates the damage pattens of flat slabs exposed to localised fires. It is an advancing step towards understanding structural responses to realistic fires.

Details

Journal of Structural Fire Engineering, vol. 14 no. 1
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 27 December 2011

Chao Zhang and Guo-Qiang Li

The popular CFD code FDS is adopted to predict the thermal behaviors of steel columns exposed to localized fires. Two real localized fire tests (one surrounded fire test that the…

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Abstract

The popular CFD code FDS is adopted to predict the thermal behaviors of steel columns exposed to localized fires. Two real localized fire tests (one surrounded fire test that the column is inside the fire source and one adjacent fire test that the column is adjacent to the fire source) are modeled in FDS. The effects of input parameters such as grid size and number of solid angles on the accuracy of the numerical results have been investigated. Experimental results concerning heat fluxes and temperatures are compared with the numerical results. Good agreements between the predicted and measured results are found in surrounded fire case, whilst acceptable predictions are given in adjacent fire case.

Details

Journal of Structural Fire Engineering, vol. 2 no. 4
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 6 September 2021

Kristian Dahl Hertz, Lars Schiøtt Sørensen and Luisa Giuliani

This study aims to analyze and discuss the key design assumptions needed for design of car parks in steel, to highlight the impact that the increased fire loads introduced by…

Abstract

Purpose

This study aims to analyze and discuss the key design assumptions needed for design of car parks in steel, to highlight the impact that the increased fire loads introduced by modern cars and changes in the fire dynamics have on the design, such as fire spread leading to non-localized fires.

Design/methodology/approach

In particular, a reliable fire load density to be used for structural design of car park structures is assessed, based on investigations of the fire loads of modern cars. Based on knowledge of fire load and fire performance of cars, the consequences on the fire safety design of steel structures are presented.

Findings

Design recommendation about fire load density and fire protection of common steel profiles are given. Finally, the proposed design is compared with a design practice that has been applied in many instances for car parks constructed with unprotected steel, and recommendations for a reliable design process are provided.

Originality/value

Numerous car park buildings have recently been designed of steel structures without passive or active fire protection. The key assumptions that makes possible such design are local fire scenarios, outdated values of the car fire load and utilization of the ultimate steel strength. This paper identifies the shortcomings of such key assumptions, indicating the need for revisiting the methods and possibly even checking the analyses carried out for some already-built car parks.

Details

Journal of Structural Fire Engineering, vol. 13 no. 1
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 12 December 2023

T.M. Jeyashree and P.R. Kannan Rajkumar

This study focused on identifying critical factors governing the fire response of prestressed hollow-core slabs. The hollow-core slabs used as flooring units can be subjected to…

Abstract

Purpose

This study focused on identifying critical factors governing the fire response of prestressed hollow-core slabs. The hollow-core slabs used as flooring units can be subjected to elevated temperatures during a fire. The fire response of prestressed hollow-core slabs is required to develop slabs with greater fire endurance. The present study aims to determine the extent to which the hollow-core slab can sustain load during a fire without undergoing progressive collapse under extreme fire and heating scenarios.

Design/methodology/approach

A finite element model was generated to predict the fire response of prestressed hollow core slabs under elevated temperatures. The accuracy of the model was predicted by examining thermal and structural responses through coupled temperature displacement analysis. A sensitivity analysis was performed to study the effects of concrete properties on prediction of system response. A parametric study was conducted by varying the thickness of the slab, fire and heating scenarios.

Findings

Thermal conductivity and specific heat of concrete were determined as sensitive parameters. The thickness of the slab was identified as a critical factor at a higher load level. Asymmetric heating of the slab resulted in higher fire resistance compared with symmetric heating.

Originality/value

This is the first study focused on studying the effect of modeling uncertainties on the system response by sensitivity analysis under elevated temperatures. The developed model with a parametric study helps in identifying critical factors for design purposes.

Details

Journal of Structural Fire Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2040-2317

Keywords

Open Access
Article
Publication date: 2 December 2021

Roberto Felicetti

This study aims to develop an assessment strategy for fire damaged infrastructures based on the implementation of quick diagnostic techniques and consistent interpretation…

Abstract

Purpose

This study aims to develop an assessment strategy for fire damaged infrastructures based on the implementation of quick diagnostic techniques and consistent interpretation procedures, so to determine the residual safety margin and any need for repair works.

Design/methodology/approach

In this perspective, several tailored non-destructive test (NDT) methods have been developed in the past two decades, providing immediate results, with no need for time-consuming laboratory analyses. Moreover, matching their indications with the calculated effects of a tentative fire scenario allows harmonizing distinct pieces of evidence in the coherent physical framework of fire dynamics and heat transfer.

Findings

This approach was followed in the investigations on a concrete overpass in Verona (Italy) after a coach violently impacted one supporting pillar and caught fire in 2017. Technical specifications of the vehicle made it possible to bound the acceptable ranges for fire load and maximum rate of heat release, while surveillance video footage indicated the duration of the burning stage. Some established NDT methods (evaluation of discolouration, de-hydroxylation and rebar hardness) were implemented, together with advanced ultrasonic tests based on pulse refraction and pulse-echo tomography.

Originality/value

The results clearly showed the extension of the most damaged area at the intrados of the box girders and validated the maximum heating depth, as predicted by numerical analysis of the heat transient ensuing from the localized fire model.

Details

Journal of Structural Fire Engineering, vol. 13 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 22 June 2017

Jean-Marc Franssen and Thomas Gernay

This paper aims to describe the theoretical background and main hypotheses at the basis of SAFIR®, a nonlinear finite element software for modeling structures in fire. The paper…

2185

Abstract

Purpose

This paper aims to describe the theoretical background and main hypotheses at the basis of SAFIR®, a nonlinear finite element software for modeling structures in fire. The paper also explains how to use the software at its full extent. The discussed numerical modeling principles can be applied with other similar software.

Design/methodology/approach

Following a general overview of the organization of the software, the thermal analysis part is explained, with the basic equations and the different possibilities to apply thermal boundary conditions (compartment fire, localized fire, etc.). Next, the mechanical analysis part is detailed, including the time integration procedures and the different types of finite elements: beam, truss, shell, spring and solid. Finally, the material laws are described. The software capabilities and limitations are discussed throughout the paper.

Findings

By accommodating multiple types of finite elements and materials, by allowing the user to consider virtually any section type and to input the fire attack in multiple forms, the software SAFIR® is a comprehensive tool for investigating the behavior of structures in the fire situation. Meanwhile, being developed exclusively for its well-defined field of application, it remains relatively easy to use.

Originality value

The paper will improve the knowledge of readers (researchers, designers and authorities) about numerical modeling used in structural fire engineering in general and the capabilities of a particular software largely used in the fire engineering community.

Details

Journal of Structural Fire Engineering, vol. 8 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 17 June 2015

Tom Molkens

Since FDS simulations of real fire scenarios are time-consuming, parametric studies are to be avoided, and it is worth investigating whether an alternative analytical model can…

Abstract

Since FDS simulations of real fire scenarios are time-consuming, parametric studies are to be avoided, and it is worth investigating whether an alternative analytical model can predict the structural impact of the fire load with the same accuracy. This experimental study is designed to reflect the conditions of a tall building with a rather high steel structure level (starting at 11m) and low fire level (car fire at 1.5m). For this featured project, the difference is investigated between several car fires and the localised fire scenarios from annex C of EN 1991-1-2 (Heskestad model).

Details

Journal of Structural Fire Engineering, vol. 6 no. 3
Type: Research Article
ISSN: 2040-2317

Article
Publication date: 22 June 2017

Jean-Christophe Mindeguia, Guillaume Cueff, Virginie Dréan and Gildas Auguin

The fire resistance of wooden structures is commonly based on the calculation or measurement of the char layer. Designers usually estimate the char layer at the surface of a…

Abstract

Purpose

The fire resistance of wooden structures is commonly based on the calculation or measurement of the char layer. Designers usually estimate the char layer at the surface of a structural element by using analytical models. Some of these charring models can be found in regulations, as Eurocode 5. These analytical models, quite simple to use, are only reliable for the standard fire curve. In that case, the design of the structure is qualified as “prescriptive-based design” and can lead to oversizing the structure. Optimization of a structure can be achieved by using a “Performance-based design”, where realistic fire scenarios are taken into account by means of more or less complex models [parametric fires, two-zones models, computational fluid dynamics (CFD)]. For these so-called “natural fires”, no model for charring is available. The purpose of this paper is to present a novel methodology for applying a performance-based design to a simple timber structure.

Design/methodology/approach

This paper presents the development of a numerical model aiming to simulate the thermal transfer and charring in wood, under any type of thermal exposure, including non-standard fire curves. After presenting the physical background, the model is calibrated and compared to existing experimental studies on wood samples exposed to different fire curves. The model is then used as a tool for assessing the fire resistance of a common wooden structure exposed to standard and non-standard fire curves.

Findings

The results show that the fire resistance is obviously dependent on the choice of the thermal exposure. The reliability of the model is also discussed and the importance of taking into account particular reactions in wood during heating is underlined.

Originality/value

One aim of this paper is to show the opportunity to apply a performance-based approach when designing a wooden structure. It shows that more knowledge of the material behaviour under non-standard fires is still needed, especially during the decay phase.

Details

Journal of Structural Fire Engineering, vol. 9 no. 1
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 21 August 2013

Filippo Gentili, Luisa Giuliani and Franco Bontempi

This paper focuses on the modelling of fire in case of various distributions of combustible materials in a large compartment.Large compartments often represent a challenge for…

Abstract

This paper focuses on the modelling of fire in case of various distributions of combustible materials in a large compartment.

Large compartments often represent a challenge for structural fire safety, because of lack of prescriptive rules to follow and difficulties of taking into account the effect of non uniform distribution of the combustible materials and fire propagation.

These aspects are discussed in this paper with reference to an industrial steel building, taken as case study. Fires triggered by the burning of wooden pallets stored in the premises have been investigated with respect to different stacking configurations of the pallets with the avail of a CFD code. The results in term of temperatures of the hot gasses and of the steel elements composing the structural system are compared with simplified analytical model of localized and post-flashover fires, with the aim of highlighting limitation and potentiality of different modelling approaches.

Details

Journal of Structural Fire Engineering, vol. 4 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

Open Access
Article
Publication date: 25 September 2019

Venkatesh Kodur, Puneet Kumar and Muhammad Masood Rafi

The current fire protection measures in buildings do not account for all contemporary fire hazard issues, which has made fire safety a growing concern. Therefore, this paper aims…

87663

Abstract

Purpose

The current fire protection measures in buildings do not account for all contemporary fire hazard issues, which has made fire safety a growing concern. Therefore, this paper aims to present a critical review of current fire protection measures and their applicability to address current challenges relating to fire hazards in buildings.

Design/methodology/approach

To overcome fire hazards in buildings, impact of fire hazards is also reviewed to set the context for fire protection measures. Based on the review, an integrated framework for mitigation of fire hazards is proposed. The proposed framework involves enhancement of fire safety in four key areas: fire protection features in buildings, regulation and enforcement, consumer awareness and technology and resources advancement. Detailed strategies on improving fire safety in buildings in these four key areas are presented, and future research and training needs are identified.

Findings

Current fire protection measures lead to an unquantified level of fire safety in buildings, provide minimal strategies to mitigate fire hazard and do not account for contemporary fire hazard issues. Implementing key measures that include reliable fire protection systems, proper regulation and enforcement of building code provisions, enhancement of public awareness and proper use of technology and resources is key to mitigating fire hazard in buildings. Major research and training required to improve fire safety in buildings include developing cost-effective fire suppression systems and rational fire design approaches, characterizing new materials and developing performance-based codes.

Practical implications

The proposed framework encompasses both prevention and management of fire hazard. To demonstrate the applicability of this framework in improving fire safety in buildings, major limitations of current fire protection measures are identified, and detailed strategies are provided to address these limitations using proposed fire safety framework.

Social implications

Fire represents a severe hazard in both developing and developed countries and poses significant threat to life, structure, property and environment. The proposed framework has social implications as it addresses some of the current challenges relating to fire hazard in buildings and will enhance overall fire safety.

Originality/value

The novelty of proposed framework lies in encompassing both prevention and management of fire hazard. This is unlike current fire safety improvement strategies, which focus only on improving fire protection features in buildings (i.e. managing impact of fire hazard) using performance-based codes. To demonstrate the applicability of this framework in improving fire safety in buildings, major limitations of current fire protection measures are identified and detailed strategies are provided to address these limitations using proposed fire safety framework. Special emphasis is given to cost-effectiveness of proposed strategies, and research and training needs for further enhancing building fire safety are identified.

Details

PSU Research Review, vol. 4 no. 1
Type: Research Article
ISSN: 2399-1747

Keywords

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