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Experimental investigation on fireresistant behavior of partial embeddedsteelconcrete composite beams with endrestraints(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:
66-76
Research Field:
桥梁与隧道工程
Publishing date:

Info

Title:
Experimental investigation on fireresistant behavior of partial embeddedsteelconcrete composite beams with endrestraints
Author(s):
ZHANG Dashan1;  WANG Huiqing2;  ZHANG Jianchun1;  WANG Jingqi2
（1. College of Civil Engineering, Huaqiao University, Xiamen 361021, Fujian, China; 2. College ofArchitecture and Civil Engineering, Xiamen Institute of Technology, Xiamen 361021, Fujian, China）
Keywords:
bridge engineering;  fireresistant behavior;  fire test;  steelconcrete composite beam;  endrestraints
PACS:
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DOI:
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Abstract:
In order to investigate the fireresistant behaviour of steelconcrete composite beams, two fullscale fire tests were conducted subjected to ISO 834 standard fire on partial embedded steelconcrete composite beams with endrestraints (PESCBE). The fire environment was simulated by a large structural fire test platform. Temperature field of PESCBE were obtained by embedded thermal couples. The deflections of PESCBE were detected by the transducers laid on the top surface of the concrete slabs. A specialpurpose device was designed and installed to restraint the end rotation of the composite beams and measure the forces during the entire test. Based on the observed experimental phenomenon, measured fireresistant time, vertical deflection, and endrestrained forces, the fireresistant behavior of PESCBEs, which subjected to two different load levels with the ratio of 0.3 and 0.5, were analyzed. The results show that the fireresistant time of the PESCBE with the load ratio of 0.5 is 71 minutes, when the maximum midspan deflection is up to 1/20 of the spanlength finally. The fire test of the PESCBE with the load ratio of 0.3 is terminated unexpectedly at 77 minutes. At that time, its maximum deflection is 147 mm and approximately equal to about 50% of the deflection limits, and so it is supposed that the composite beam has potential capacity to resist the fire attack. According to the variation of the inplane axial forces curves, the catenary action occurred when the PESCBEs are subjected to large deflection, and it plays an active role in improving the fire resistance of the composite beams. The mechanism of catenary action has a relationship with load ratio. Higher load ratio can cause large deflection, and the catenary action can occur earlier accordingly. When the furnace was shut off, the PESCBE had no obvious failure patterns to reduce its loadingcapacity under fire, such as collapse, overall buckling failure of the steel beam, and crushed concrete, etc. However, local buckling is observed at the lower flange of the steel beam adjacent to the support of the composite beams. 14 figs, 23 refs.

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Last Update: 2021-04-02