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Behaviour of Endplate Joints Subjected to Elevated Temperature after Cyclic Loads
Zhen Guo,Xuecheng Zhang,Xingzhi Jia 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11
This paper presents the performance of an end-plate joint at elevated temperature after cyclic loads. Prime interest of the end-plate joints, subjected to elevated temperature, lies on the effect of three kinds of external conditions: monotonic loads, cyclic loads and local damages. Parametric studies have been systematically conducted using simplified models. The Behaviour of endplate joints subjected to high temperature is examined under two levels of damage caused to the structure, i.e., deformation damage and fracture damage under earthquake. Numerical results indicate that dead loads on beam and material properties of endplate joints are still playing a significant role in fire resistance. Under only deformation damage, the dominance of joints’ resistance to fire is still primarily the property of the material itself. Once experiencing fracture damage, for instance endplates fracture and bolts breakage, the behaviour of joints will degrade severely in post-earthquake fire. The results of this study demonstrate that the deformation damages has limited effect on the endplate joint at elevated temperature after an earthquake. The achieved results can be adopted during the design stage in order to minimize the probability of collapse in the fire.
Fire Resistances of Restrained Steel Beams Subjected to Fire Loads
Zhen Guo,Rui Gao,Xuecheng Zhang,Xingzhi Jia 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8
Conventional fire loads and fire resistances of a steel beam still lack an adequate correlation. This paper has established therelationship between the responses of restrained steel beams and fire actions by using a new definition of fire resistances and a newexpression of fire loads. By using reduction factors of elastic modulus and yield strengths, has presented three critical equations topredict the limit state of a restrained steel beam in a fire. Based on these equations and the heat transfer formula, the paper provided anew definition of fire resistances. By using the heat release rate and effective rate coefficient of thermal absorption, a new expressionof fire loads has been argued. Compared with tests, the proposed approach in this paper is in good agreement with the measuredvalues in tests. The results show that the new fire resistances could be able to reflect the facts of heat transfers and duration time. Incontrast to conventional fire loads, the new fire loads are more efficient to indicate a fire load.