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Structural Engineering and Mechanics   Volume 62, Number 6, June25 2017, pages 663-674
DOI: https://doi.org/10.12989/sem.2017.62.6.663
 
Evaluating fire resistance of prestressed concrete bridge girders
Gang Zhang, Venkatesh Kodur, Wei Hou and Shuanhai He

 
Abstract     [Buy Article]
    This paper presents an approach for evaluating performance of prestressed concrete (PC) bridge girders exposed to fire. A finite element based numerical model for tracing the response of fire exposed T girders is developed in ANSYS. The analysis is carried out in three stages, namely, fire temperature calculation, cross sectional temperature evaluation, and then strength, deformation and effective prestress analysis on girders exposed to elevated temperatures. The applicability of the computer program in tracing the response of PC bridge girders from the initial preloading stage to failure stage, due to combined effects of fire and structure loading, is demonstrated through a case study, and validated by test data of a scaled PC box girder under ISO834 fire condition. Results from the case study show that fire severity has a significant influence on the fire resistance of PC T girders and hydrocarbon fire is most dangerous for the girder. The prestress loss caused by elevated temperature is about 10% under hydrocarbon fire till the girder failure, which can lead to the increase in deflection of the PC girder. The rate of deflection failure criterion is suggested to determine the failure of PC T girder under fire.
 
Key Words
    bridge fires; fire resistance; PC girders; FEM analysis; failure criterion; fire scenario
 
Address
Gang Zhang, Wei Hou and Shuanhai He: School of Highway, Chang´an University, Xi´an, Shaanxi 710064, China

Venkatesh Kodur: Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48864, USA
 

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