Bolt Pre-tension Effect on Performance of Bolted Extended End-plate Moment Connections under Cyclic Loading

Abstract

The most important structural part of steel structures is the connections of the building frame. Tests conducted by the American Steel Institute have led to the introduction of prequalified connections, which is a good reference for designing connections in steel structures. In this paper, four bolted stiffened and unstiffened extended end-plate connections have been studied by numerical analysis with ABAQUS software. In this study, to examine the effect of bolt pre-tension rarely studied, a coefficient of pre-tension force, introduced based on the Iranian Steel Structures Design Regulations as well as the US Steel Design Regulations, has been considered. These connections have been modeled cyclically and in a displacement control manner. The cyclic behavior of the connections, dissipated energy, the resisting moment as well as the stress and strain distribution in the connection have been investigated. According to the results, by creating a pre-tension force in the bolts, the resisting moment of the connection would increase. The rate of growth of this resistance in the unstiffened connections was greater than that of the stiffened connections. The maximum increase in resistance was about 27% for the unstiffened connection and about 25% for the stiffened connection. The dissipated energy for the connections also increased with the increment of bolt pre-tension. The energy dissipation incremental rate was enhanced to a maximum of about 31% for the unstiffened connection and up to a maximum of about 24% for the stiffened connection.