WANG Yuzhuo,QIU Hao,XU Tiangui,et al.Change Law of Failure Modes of Reinforced Concrete Beams with Fixed Ends in Fire[J].Journal of Disaster Prevention and Mitigation Engineering,2024,44(01):192-201.
WANG Yuzhuo,QIU Hao,XU Tiangui,et al.Change Law of Failure Modes of Reinforced Concrete Beams with Fixed Ends in Fire[J].Journal of Disaster Prevention and Mitigation Engineering,2024,44(01):192-201. DOI: 10.13409/j.cnki.jdpme.20220829003.
Change Law of Failure Modes of Reinforced Concrete Beams with Fixed Ends in Fire
In order to study the changes in the failure modes of reinforced concrete beams with fixed ends in fire, the temperature field inside a beam was analyzed using finite element analysis software and its distribution at different fire resistance times was determined. The ultimate bearing capacity of the reinforced concrete beam at different fire times was calculated using the simplified calculation formula of bearing capacity. Theoretical analysis was conducted on three sets of beam specimens with fixed ends, taking the upper longitudinal reinforcement area, concrete cover thickness, and concrete strength as transformation factors. The influence of different parameters on the changes of critical point
ξ
in the failure mode of the reinforced concrete beams during fire was discussed. The results show that the larger the reinforcement area of the upper longitudinal reinforcement, the earlier the fire time T of the point
ξ
. The thicker the concrete protective layer and the higher the strength of the concrete, the later the fire time T corresponds to the point
ξ.
To ensure that the beams undergo bending failure within two hours of being exposed to fire, ideas for the fire protection design of beams are provided based on theoretical calculations. The presented method can simplify the analysis of the changes in failure modes of reinforced concrete beams at high temperatures, and provide a reference for the design and calculation of components in fires.
Shi X D , Guo Z H . Experimental studies on fire resistance of reinforced concrete beams with different thickness concrete covers [J]. Industrial Construction , 1996 ( 9 ): 11 - 13,18 . (in Chinese)
Reddy D V , Sobhan K , Liu L X , et al . Size effect on fire resistance of structural concrete [J]. Engineering Structures , 2015 , 99 : 468 - 478 .
Ellingwood B , Lin T D . Flexure and shear behavior of concrete beams during fire [J]. ASCE , Journal of Structural Engineering, 1991 , 117 ( 2 ): 440 - 457 .
Yang Z N , Qi J Q , Duan K D , et al . Experiment study on shear properties of rc beams under high temperature [J]. Industrial Construction , 2020 , 50 ( 10 ): 57 - 62 . (in Chinese)
Khan M S , Prasad J , Abbas H . Shear strength of RC beams subjected to cyclic thermal loading [J]. Construction and Building Materials , 2010 , 24 ( 10 ): 1869 - 1877 .
Lu Z D , Zhu B L , Zhou Y H . Experimental studies on fire response of reinforced concrete simply supported beams [J]. China Civil Engineering Journal , 1993 ( 3 ): 47 - 54 . (in Chinese)
Ding F X , Yao F , Li Z , et al . Fire resistance of simple supported reinforced concrete beams under high temperature [J]. Journal of Northeastern University(Natural Science) , 2015 , 36 ( 10 ): 1476 - 1481 . (in Chinese)
Zhang W Z . Experimental investigation and numerical analysis for RC beams under elevated temperature [J]. Journal of Harbin Institute of Technology , 2009 , 41 ( 2 ): 198 - 201 . (in Chinese)
Liao Y F , Qi Y Q , Ma X Q . Nonlinear finite element analysis of reinforced concrete beams iln fire [J]. Industrial Construction , 2011 , 41 ( 7 ): 31 - 37 . (in Chinese)
Lin X S , Zhang Y X , Nonlinear finite element analyses of steel/FRP-reinforced concrete beams in fire conditions [J]. Composite Structures , 2013 , 97 : 277 - 285 .
Liang X W , Li X W . Analysis of shear capaciy for reinforced concrete beam based on concrete strength criterion [J]. Industrial Construction , 1996 ( 3 ): 8 - 11 . (in Chinese)
Yang J P , Shi X D , Guo Z H . Simplified calculation of ultimate load bearing capacity of reinforced concrete beams under high temperature [J]. Industrial Construction , 2002 , 32 ( 3 ): 26 - 28 . (in Chinese)
Wang Y Z , Fu C G . Calculation of ultimate bearing capacity of prestressed steel reinforced concrete structure under fire [J]. Advanced Materials Research , 2011 , 250-253 : 2857 ‑ 2860 .
Liu D K , Lin M . Calculation of equivalent fire load for RC members subjected to fire [J]. Journal of Harbin Engineering University , 2007 ( 5 ): 519 - 524 . (in Chinese)
Yin A K . Experimental study on shear bearing capacity of reinforced concrete simple supported beams with web bar under fire [D]. Ji'nan : Shandong Jianzhu University , 2018 . (in Chinese)
EN 1994-1-2, The European Standard [S]. Eurocode 4:Design of Composite and Concrete Structure,Partl. 2: Structural Fire Design, 2011 .
Lie T T . Fire resistance of circular steel columns filled with bar-reinforced concrete [J]. Journal of Structural Engineering , 1994 , 120 ( 5 ): 1489 - 1509 .