A New Connection Type for Use in Intermediate or Special Steel Moment Frames

Moment frames are one way to provide lateral stability to a building structure. For building structures that are located in high seismic regions, specific requirements are presented in applicable building codes pertaining to the moment connections used within these moment frames. The main factor required for these moment connections is their ability to resist cyclic moments at a relatively high drift specified within the applicable building code.This dissertation investigates the potential development of a new moment connection which would be appropriate for use in Intermediate Moment Frames (IMF) and Special Moment Frames (SMF). Two goals were set for this new moment connection. First, the moment connection would contain yielding elements that are easily replaceable after a seismic event while protecting the elements that are not replaceable. This goal is important as most (9 of 10) of the prequalified moment connections available for use in IMF and SMF systems sacrifice the beam during a major seismic event which could lead to the demolition of the structure. Second, the moment connection would not be a proprietary system. This goal is important as many (5 of 10) of the prequalified moment connections are proprietary systems that require payment for use. Also, proprietary systems tend to lead to less understanding by the engineer of record of the building structure as calculations for the moment connection are performed by a third party. The new proposed moment connection will be called the Yielding Threaded Rod, or YTR, moment connection. This connection contains a beam splice located a short distance away from the column to which it is connected. This beam splice has two components. First, a web connection is used to resist the beam shear. This web connection is a standard approved shear connection and is intended to resist shear only. Second, a flange connection is used to resist the beam moment as well as any axial load present in the beam. This flange connection is made with threaded rods connected to the two beam flanges. The threaded rods are sized to resist the forces present in the beam flange while also accommodating the deformations necessary to provide the specified seismic drifts without fracture. Both physical testing and an analytical model of the new proposed moment connection were carried out. Good correlation was found between the physical specimen and analytical model. Both indicated that the connection would be able to resist the required moments past the specified drifts. Therefore, the new proposed YTR moment connection may be a viable additional moment connection available to engineers for use in IMF and SMF systems