Evaluation method of loadcarrying capacity of steelconcretecomposite girders after fire exposure(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2021年2期
- Page:
- 1-11
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Evaluation method of loadcarrying capacity of steelconcretecomposite girders after fire exposure
- Author(s):
- ZHANG Gang; SONG Chaojie; LI Jianzhang; HE Shuanhai; LI Xuyang; TANG Chenhao
- (School of Highway, Changan University, Xian 710064, Shaanxi, China)
- Keywords:
- bridge engineering; residual loadcarrying capacity; finite element analysis; steelconcrete composite continuous girder; safety evaluation method
- PACS:
- -
- DOI:
- -
- Abstract:
- Aiming at the safety problems of steelconcrete composite girders after fire exposure, a safety evaluation method of steelconcrete composite girders after fire exposure was established using fire scenario inversion method and fire temperature estimation method.A threespan steelconcrete composite continuous girder was selected as the research object. Firstly, the fire scenario database was established according to the longitudinal fire position, fire length and spatial fire position inversed from the current situation after fire exposure. Secondly, the fire temperature was inferred based on the appearance characteristics of the steelconcrete composite continuous girder after fire exposure. The loaddisplacement curve of the steelconcrete composite continuous girder after different fire scenarios were analysed using ANSYS finite element software, and the decline curve of ultimate loadcarrying capacity was obtained. Finally,the damage classification standard of loadcarrying capacity was defined by comparing the residual loadcarrying capacity of steelconcrete composite continuous girder with the action effect under dead load and live load. The results show that the larger loadcarrying capacity loss of the steelconcrete composite continuous girder with higher fire temperature and longer fire length. The damage degree of the steelconcrete composite continuous girder is slight after fire exposure in midspan of the middle span, while the middle fulcrum and midspan of the side span after fire exposure have higher damage degree. After fire exposure in midspan of the middle span, the loadcarrying capacity of some cases is grade Ⅱ damage only when the fire temperature reaches 1 000 ℃, and the loadcarrying capacity reaches grade Ⅳ damage when the middle fulcrum and midspan of the side span after fire exposure under same fire temperature. The damage degree of the steelconcrete composite continuous girder is slight after fire exposure on the bridge deck, and fire exposure on the bridge deck and under the bridge have much higher damage degree. After fire exposure on the bridge deck, the loadcarrying capacity damage of some cases reaches grade Ⅱ only when the fire temperature reaches 800 ℃. After fire exposure on the bridge deck and under the bridge, the loadcarrying capacity reaches grade Ⅲ damage when the fire temperature reaches 900℃. The classification and grading safety assessment method established for steelconcrete composite continuous girder after fire exposure is simple and practical. 3 tabs, 10 figs, 27 refs.
Last Update: 2021-04-02