Vulnerability of bridges to fire

Engineering Structures, 2000

This paper presents an overview of fire hazard in bridges. A detailed review of actual fire incidents, case studies related to fire hazards, and post-fire assessment and repair strategies in bridges is presented and summarized. In doing so, this review points to the importance of fire hazard in bridges, aids practicing engineers with practical tools for developing strategies for repairing

2016

Abstract. The new steel bridge “Hans-Wilsdorf ” in Geneva is an exceptional steel structure that will drive general traffic through a main transportation axis. As the investment cost of the project is important, a structural fire analysis has been performed to study the sensitivity of the structure to a high temperature exposure, such as a truck in fire on the deck. This analysis will allow deciding whether a severe fire could be an unacceptable economical risk for the bridge. 1

Journal of Constructional Steel Research, 2012

The response of bridges subject to fire is an under researched topic despite the number of bridge failures caused by fire. Since available data shows that steel girder bridges are especially vulnerable to fire, this papers delves into their fire response by analyzing with a 3D numerical model the response of a typical bridge of 12.20 m. span length. A parametric study is performed considering: (1) two possibilities for the axial restraint of the bridge deck, (2) four types of structural steel for the girders (carbon steel and stainless steel grades 1.4301, 1.4401, and 1.4462), (3) three different constitutive models for carbon steel, (4) four live loads, and (5) two alternative fire loads (the hydrocarbon fire defined by Eurocode 1 and a fire corresponding to a real fire event). Results show that restraint to deck expansion coming from an adjacent span or abutment should be considered in the numerical model. In addition, times to collapse are very small when the bridge girders are built with carbon steel (between 8.5 and 18 minutes) but they can almost double if stainless steel is used for the girders. Therefore, stainless steel is a material to consider for steel girder bridges in a high fire risk situation, especially if the bridge is located in a corrosive environment and its aesthetics deserves special attention. The methodology developed in this paper and the results obtained are useful for researchers and practitioners interested in developing and applying a performance-based approach for the design of bridges against fire.

IABSE Congress Report, 2012

In order to protect a bridge against the fire attack mainly due to the turning over accident of a tank lorry vehicle, a Fire Protection Panel has been developed by the authors, because it can see some serious damaged examples of viaduct and bridge by fire accident in USA, Germany, Japan and so on in a last decade. Some of those bridges had fall down by fire attack and self-weight of bridge. The developed standard external dimension of the fire protection panel has 500mm wide, 2000mm long and 80mm thickness. The panel consists of a steel frame, meshed bars and fire protecting materials of Ceramic Fiber Blanket and Autoclaved Lightweight aerated Concrete plate. The fire test of this panel was carried out to confirm the fire resisting performance by using the Hydrocarbon curve given by Eurocode. This paper shows the applicability of the Fire Protection Panel based on the test results and its construction details.

Transportation Research Record, 2010

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

Engineering Structures, 2019

Although structural robustness under different fire scenarios has been widely studied in numerous engineering projects, performance-based method still needs to be further defined for better design of bridge structures under fire accidents. This paper presents a practical framework for the performance-based design of bridge structures under vehicle-induced fires. Fire scenarios, structural-thermal analysis method, fire-resistance levels, and a risk analysis-based maintenance cost evaluation process are all defined in detail. The applicability and rationality of this design process are illustrated through a typical case study. The results of the case study demonstrate that the initial properties of the bridge structure can satisfy the defined fire-resistance levels properly, while additional measures for decreasing the burning time are still needed to limit the fire maintenance cost in an acceptable level. The proposed performance-based design process can be widely used in engineering practice.

Steel Construction, 2017

Fire safety in bridge design is not as developed as fire safety in building design, even though a bridge failure can cause significant economic damage impacting on an area. This paper addresses an unanswered question with regard to fire safety, i.e. the capability to identify the governing failure mode of a bridge subjected to severe fire loading and ranking the regions of greatest fire exposure risk. Hence, this proposed methodology is also expected to support forensic work identifying the failure mode where a bridge has failed due to a severe fire, as will be shown using the 9-Mile Road Overpass collapse as an example. In an effort to mitigate fire damage, the fire protection panel (FFP) is introduced, which is part of a sacrificial structure shielding the bridge superstructure from exposure to fire from underneath.

2015

RESPONSE OF FIRE EXPOSED STEEL BRIDGE GIRDERS By Esam Mohammed Aziz Fire is one of the most severe environmental hazards to which civil structures may be subjected during their lifetime. In recent decades, due to rapid development of urban ground-transportation systems, as well as increasing transportation of hazardous materials, bridge fires have become a growing concern. Steel structural members which are widely used in bridges exhibit lower fire resistance as compared to concrete members due to rapid degradation of strength and stiffness properties at elevated temperature. Therefore, behavior of steel girders under fire conditions is of critical concern from fire safety point of view. Unlike structural members in buildings, no specific fire resistance provisions (active or passive) are required for bridges as per specifications in AASHTO and other standards. Currently, there is no approach to evaluate fire resistance or residual capacity of steel girders after fire exposure. Also...

Engineering Structures, 2014

Bridge fires are a major concern because of the consequences that these kind of events have and because they are a real threat. However, bridge fire response is under researched and not covered in the codes. This paper studies the capabilities of numerical models to predict the fire response of a bridge and provides modeling guidelines useful for improving bridge design. To reach this goal, a numerical analysis of the fire of the I-65 overpass in Birmingham, Alabama, USA in 2002 is carried out. The analyses are based on computational fluid dynamics (CFD) for creating the fire model, and finite element (FE) software for obtaining the thermomechanical response of the bridge. The models are validated with parametric studies that consider heat release rate of the spilled fuel, discretization of the fire temperature in the transition from CFD to FE modeling, and boundary conditions. The validated model is used in a study to evaluate the influence of fire scenario (CFD versus standard fires), and live load. Results show that numerical models are able to simulate the response of the bridge and can be used as a basis for a performance-based approach for the design of bridges under fire. Additionally, it is found that applying the Eurocode standard and hydrocarbon fires along the full length of the bridge does not adequately represent a real bridge fire response for medium-long span bridges such as this case study. The study also shows that live loads essentially do not influence the response of the bridge.

Journal of Bridge Engineering, 2013

In current practice, no special measures are applied for enhancing structural fire safety of steel bridge girders. Further, there is very limited information and research data in the literature on the fire resistance of structural members in bridges. In this paper, the fire response of a steel bridge girder under different conditions is evaluated using the FEM computer program ANSYS. In the analysis, the critical factors that influence fire resistance, namely, fire scenario, fire insulation, and composite action arising from steel-concrete interaction, are accounted for. Results from numerical studies show that the composite action arising from steel-girder-concrete-slab interaction significantly enhances the structural performance (and fire resistance) of a steel bridge girder under fire conditions. Other significant factors that influence fire resistance of steel bridge girders are fire insulation and type of fire scenario.