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Performance failure of steelconcrete composite continuousbox girder exposed to tanker fire(PDF)

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

Issue:
2018年06期
Page:
98-108
Research Field:
桥梁与隧道工程
Publishing date:

Info

Title:
Performance failure of steelconcrete composite continuousbox girder exposed to tanker fire
Author(s):
QIN Zhiyuan;  ZHANG Gang;  WANG Gaofeng;  HUANG Qiao;  YAO Weifa;  LI Yuan
（1. School of Highway, Changan University, Xian 710064, Shaanxi, China; 2. School of Transporation,Southeast University, Nanjing 210096, Jiangsu, China）
Keywords:
bridge engineering;  steelconcrete composite continuous box girder;  FEM;  thermomechanical coupling;  temperature field;  ultimate load;  failure mechanism
PACS:
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DOI:
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Abstract:
To investigate the performance failure of steelconcrete composite continuous box girders when exposed to tanker fire, ANSYS finite element model of a twospan steelconcrete continuous composite box girder bridge was built using the thermostructural coupling analysis method. For a scenario that assumed the box girder was exposed to tanker fire, the model simulated the temperature at important points on the test section and the vertical temperature gradient of the box girder. In addition, the distribution of the temperature field of the girder was analyzed, and the load displacement of the test section and attenuation of the ultimate bearing capacity of the girder were obtained. Furthermore, the failure process of the box girder was analyzed under two different fire scenario The result shows that, when the fire occurs beneath the bridge, the entire steel girder heats up quickly, the base plate attains the highest temperature because its proximity to the fire, followed by the web plate, and then the flange plate. The temperature of the concrete changes minimally. When the fire occurs above the bridge, the concrete attains a higher temperature than that of the case where the fire occurs beneath the bridge, and the temperature of steel girder is lower. The cross section of the box girder indicates a large vertical temperature gradient. The reduction in the ultimate bearing capacity of the bridge is more substantial when the fire occurs beneath the bridge than when it occurs above the bridge. In addition, after the fire burns for 25 min, the ultimate bearing capacity decreases by more than 95% at the middle fulcrum, by about 68% at midspan, and by about 64% at the side fulcrum. Furthermore, buckling failure occurs at the middle fulcrum, bending failure occurs at midspan and at the side fulcrum. When the fire occurs above the bridge, the ultimate bearing capacity at midspan reduces by only 29% due to thermal insulation by the concrete and less heat impact on the steel girder. In addition, a plastic hinge occurs at midspan.

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Last Update: 2018-12-18