High strength steel; Endplate connection; moment capacity; connection rotation

A beam-to-column connection has a significant role in the behavior of steel structure under the effect of verity loads. Rigid connection in steel moment frame has a special role in the behavior of these structures. Moreover, the fire resistance of these connections can be important. Among these parameters, steel material used in the connection is important and its investigation seems necessary. In this article, the behavior of 9 steel moment end-plate connections under the effect of various degrees of temperatures was studied using finite element methods through ABAQUS software. The connections have been designed, modeled and analyzed using three types of steel materials. The models verified by the use of an experimental model through elastic and plastic amplitudes up to collapse and during numerical results, the effect of large deformation in the nonlinear region has also been considered. The results of this study show that using of the stiffeners improves connection capacity and performance. The results of this study show that declined slope of moment capacity of connection with stiffener coming in all temperatures and is almost smooth and constant. However, it observed that the declined slope of moment capacity of connection with and without stiffener which designed with low strength steel was less than other connections during 800 to 900 degree which shows better performance of this connection.