In order to understand rotation behavior of high strength steel endplate connections under fire, this study is compared with existing studies conducted using FEA program. Eurocode 3 presents the three failure modes according to the prediction of bending resistance moment. The parameters of analysis model are temperature, thickness and steel materials of endplate. The rotation stiffness, and bending resistance moment are analyzed according to the parameters. The change of rotation stiffness and

more »

... ending resistance moment are analyzed about the parameters, regression equations are suggested the change of high strength steel endplate connections. Consequently, the regression equations were proposed as the linear and quadratic equation. The moment ratio of high strength steel under fire was more reduced than the carbon steel, and was small effect about the thickness. When the high strength steel under fire was compared with at ambient temperature, the slope of initial rotation stiffness reduced, the increment ratio of moment was slow, and the change of plastic rotation stiffness wasn't effect by the thickness increase.