The Influence of Bolt Dimensions, End Plate and Beam Flange Thickness on the Moment Capacity of Prequalified Seismic-Resistant Steel Beam-Column Connections According to SNI 7972:2020

Abstract

The 1994 Northridge earthquake that struck Los Angeles, California, revealed structural failures in steel beam-column connections of building frames that occurred prior to the formation of plastic hinges in the beams. To prevent similar failures in the future, ANSI/AISC 358-16/358s1-16[2] introduced prequalified steel connections, which were later adopted into the Indonesian steel structure standard, SNI 7972:2020[1]. This study aims to investigate the influence of bolt diameter, end-plate thickness, and beam flange thickness on the moment capacity of prequalified and modified 4ES-type steel beam-column connections. The analyzed models consist of standard and modified 4ES-type connections based on SNI 7972:2020, using IWF beam profiles of 300x150, 350x175, and 400x200. Bolt diameter and end-plate thickness were varied to achieve connection moment capacities exceeding the beam's plastic moment capacity and satisfying the required plastic hinge rotation. The moment capacity and ultimate plastic hinge rotation were calculated in accordance with the provisions of SNI 7972:2020[1]. The results of this study indicate differences in moment capacity and rotation due to variations in steel yield strength (Fy) in both standard and modified 4ES-type connections. A relationship was established between the minimum end-plate thickness (Tp), bolt diameter (Db), and beam flange thickness that enables the connection to exceed the plastic moment of the beam and meet the required plastic hinge rotation for special moment frames. These findings are useful for developing steel frame designs that satisfy the criteria for seismic-resistant special moment connections. Additionally, the use of high-strength steel (Fy = 413 MPa) is investigated to meet the requirements of high moment capacity and plastic hinge rotation exceeding 0.04 radians in high-rise earthquake-resistant buildings.