Studying the seismic performance during the construction of the steel bending frame according to different scenarios in the implementation of the bolt of the BUEEP connection

In the process of implementing steel structures with bolted connections, the bolts are temporarily tight by the workers and so-called tightened, in this article, called the initial stage. After performing the connections of several different parts in the form of primary fastening, in the following stages of construction, the bolts of connection are pre-tensioned so that the minimum pre-tensioning force of the regulations is created in them. Therefore, in the process of the construction of steel structures with pre-qualified connections of the steel moment end plate frame, the effects of the construction sequence are important, because during the construction, due to the different construction situations of the project implementation conditions, delays In the secondary fastening of the connections, the lack of completion of the lateral restraint system of the structure and on the other hand the possibility of earthquakes with different magnitudes can lead to local or general damage to the structure and ultimately lead to the imposition of exorbitant costs on the project. In this research, the acceleration records proposed by FEMA-P695 (ATC-63) were used with the nature far field, and then the vulnerability of the BUEEP connection was investigated using the fragility curves. Without implementing the secondary fastener in the structure, the connections have a semi-rigid behavior and the discussion of damping and reducing the seismic demand caused by it is more noticeable. This trend was more visible at lower accelerations. In general, in slight and medium performance levels, the effect of not using the secondary fastener is greater due to the slack of the connections and the need for lower drifts to reach this level of performance.