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Fire resistance of steelconcrete composite continuous bridge girder(PDF)

长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]

Issue:
2019年06期
Page:
89-98
Research Field:
桥梁与隧道工程
Publishing date:

Info

Title:
Fire resistance of steelconcrete composite continuous bridge girder
Author(s):
SONG Chaojie;  ZHANG Gang;  QIN Zhiyuan;  HE Shuanhai;  CHENG Huacai;  HUANG Qiao;  YAO Weifa
(1. School of Highway, Changan University, Xian 710064, Shaanxi, China; 2. Anhui Highway Test and Research Center Co. Ltd., Hefei 230601, Anhui, China; 3. School of Transportation, Southeast University, Nanjing 210096, Jiangsu, China)
Keywords:
bridge engineering;  steelconcrete composite continuous bridge girder;  FEM;  fire;  fire resistance
PACS:
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DOI:
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Abstract:
Aimed at the serious threat to steel bridge caused by tanker fire, a fourspan doubleribbed steelconcrete composite continuous bridge girder (4×35 m) was selected as research object. According to characteristics of tanker fire, the closest HC temperaturetime curve was selected, and four fire modes of tanker fire were restored according to the actual fire characteristics. The finite element model was established using thermodynamic coupling calculation method and validated by experimental results. Firstly, the temperature field of steelconcrete composite bridge girder under tanker fire was analyzed. Then, the calculation method of flexural capacity of doubleribbed steelconcrete composite bridge girder was proposed, and degradation of flexural capacity in positive moment region under tanker fire was calculated based on the results of temperature field. In addition, the deflection progression of steelconcrete composite bridge girder under different fire scenarios was analyzed, and fire resistance of steelconcrete composite bridge girder was obtained, using flexural capacity and deflection failure criterion. Finally, the failure modes of the steelconcrete composite bridge girder under different fire scenarios were studied. The results show that the temperature rise of steel is much larger than that of concrete. The steelconcrete composite bridge girder presents an obvious temperature gradient along the girder depth and its maximum value is 1 020 °C. The thermal bowing caused by temperature gradient is the main reason for deflection of steelconcrete composite bridge girder at the initial stage of fire. Flexural capacity decreases slowly at the initial stage of fire, after entering high temperature stage, flexural capacity decreases rapidly. Finally, at about 30 min, failure of the steelconcrete composite bridge girder occurs, when flexural capacity drops below the bending moment resulting from applied load. The general trend of deflection progression can be grouped into three stages, fire exposure length of side span has great influence on deflection progression of the composite girder, and the faster deflection increases with the larger fire exposure length. Using deflection criterion to judge failure of composite bridge girder is unsafe compared with flexural capacity criterion, and deflection criterion is revised based on flexural capacity criterion. Side span exposed to tanker fire presents fully collapse and midspan presents large deflection of concrete slab and swell of steel girder. 3 tabs, 11 figs, 32 refs.

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Last Update: 2019-12-19