<p>Several recent incidents have demonstrated vulnerability of bridges to fire hazard. Fire-induced damage or collapse of bridges can disrupt the functioning of infrastructure networks, leading to significant costs to public including business interruption from route closures as well as potential casualties. While application of fire protection in a selective manner might be necessary to achieve a resilient bridge design for bridges, an across the board fire-rating approach similar to what is used in building design practice is unrealistic and uneconomical. A performance-based approach can provide a better hazard assessment for each individual bridge, thus leading to a cost-effective fire protection scheme.</p><p>Although the benefits of a performance-based approach are well-known, attempts in practice face an efficiency challenge to go through the steps of hazard analysis and identification of realistic scenarios, fire simulation and determination of design variables while keeping the process repeatable. This paper presents an innovative computational approach that allows the engineer to evaluate a bridge for several possible fire scenarios in a generalized scheme to determine if there exists a scenario that can potentially threaten the integrity of the structure. If such a case is identified, advanced detailed computational methods can be used for a more accurate evaluation. An example study is conducted on fire retrofit of a highway interchange with interconnected bridges to showcase this approach. Various fire scenarios caused by tanker truck accidents are initially analysed using simple computational tools that account for direct radiative heat transfer and lumped mass heat conduction while the bridge is subjected to realistic temperature curves. Necessity of advanced Finite Element analysis is determined based on the results of initial evaluation.</p>
<p>Performance-based fire engineering (PBFE) is an efficient alternative to the conventional prescriptive design of fire protection. The method allows engineers to develop more cost-effective and resilient designs, whose performance is verified by simulating the response of the structure under various fire scenarios. Tall and supertall buildings can particularly benefit from a performance-based approach to fire protection, as the traditional prescriptive approach does not consider fire hazards and risks more specific to tall buildings.</p><p>This paper demonstrates the potential benefits of PBFE for tall buildings through the example of a generic 50-story mixed-use building whose structure combines steel and concrete. Computational fluid dynamics (CFD) analyses are performed with the Fire Dynamic Simulator (FDS) software to simulate the initiation and development of several fire scenarios in typical office and mechanical floors. For each scenario, heat transfer and structural response analyses are then performed on a finite element model of the structure. The scope and complexity of the structural analysis varies from individual members to a large segment of the entire structural system depending on the fire scenario. Particular care is given to the analysis of the steel trusses of a transfer level, as failure or excessive deformation of these trusses could severely damage multiple floors of the building. This demonstrates the flexibility of PBFE and its ability to focus on the fire risk posed by the specific configuration of each building structure.</p>
<p>Analysis of the structural performance under realistic fire scenarios makes Performance Based Fire Engineering (PBFE) particularly suited to design fire protection of tall buildings. In this paper, the impact of using the PBFE method is studied using a standard tall building as an example. The parametric temperature- time curves recommended in Eurocode 1 are used to define the fire loads. The thermal and mechanical response of the building to the imposed fire loading is subsequently analyzed by means of a finite element model of the mixed-use tower. Particular care is devoted to analyzing the performance of a steel truss at a transfer level, to study potential global effects of a local fire, effects that are not studied or understood within the prescriptive design framework.</p>
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