Analysis of unstiffened and stiffened octagonal bolt extended end plate moment connection under thermal conditions: A critical review

The Bolted Extended End-Plate (BEEP) moment-resisting connection is prequalified for use in Special and Intermediate Moment Frames. It offers several advantages over other types of connections, including eliminating field welding and facilitating fast field erection of building frames. One of the key features of this connection is by placing a stiffener plate between the end plate and the beam flanges, the extended portion of the end plate is strengthened. This lessens prying action and more evenly distributes flange forces throughout the bolt group. In recent years, researchers have studied the seismic performance and analysis of octagonal bolt arrangements, beam column connections, and reduced beam sections both experimentally and analytically. They have found that the octagonal bolt arrangement promotes more uniform distributions of forces across the bolt group and provides better strength and post-yield stiffness. Compared to other connections, the octagonal bolt arrangement results in a maximum of 10% difference in peak tensile strains between the inner and outer columns of bolts. Additionally, researchers have found that within a certain range of flange thicknesses, as thickness increases, both the stiffness and strength of the connection increase. Reduced beam section connections are also more ductile and can dissipate energy more effectively than other connections. By eliminating continuity plates, the BEEP connection can reduce material and labor costs, providing an economic benefit to steel moment frame construction. In summary, the BEEP connection offers several advantages over other types of connections, including eliminating field welding, facilitating fast field erection, and reducing costs. Ongoing research continues to explore ways to optimize the design of this connection to improve its seismic performance and reduce costs further.