Design and behavior of enlarged end flange (EEF) steel moment-frame connections

The FEMA-350 indicates that the expected location of the plastic hinge for the frame beams with the Reduced Beam Section (RBS) connections is valid only for beams with gravity loads representing a small portion of the total flexural demand. In order to overcome the limitation of the gravity loads, the Enlarged End Flange (EEF) connection is proposed. In EEF connections, side plates are welded to the beam flanges near the beam ends. This paper presents a hand-calculated design example and the suggested connection details of a beam with the EEF connection. A study of the flexural strength and the interstory drift angular rotations of a total of five EEF beam-to-column connections, with beam sizes ranging from W24 x 94 up to W36 x 182, using the nonlinear static finite element approach is also summarized in this paper. The study concludes that the EEF connection is recommended for use in,an ordinary moment frame system with wide bay widths.