ABSTRACT
The design procedure for steel moment resisting frame (MRF) beam-to-column connections, as recommended by FEMA 350 [FEMA 350, 2000], calculates the maximum probable moment expected on the connections from the capacity of the beam. The beam overstrength capacity is calculated considering the upper bound of the uncertainty in the material yield strength (Ry), and the strain-hardening expected. AISC [AISC, 1994] specifies design procedure for 3 types of moment resisting frames, namely, SMF, IMF and OMF, depending on the level of inelastic rotation expected at the beam-column joints. However, while implementing the effect of strain-hardening for the different types of frames, designers have difficulties in translating the code prescribed rotation requirements into appropriate forces for the design of connections. This paper presents a refined procedure for the capacity design of beam-to-column connections, which overcomes this difficulty. The design procedure proposed in this study calculates the maximum probable beam moment considering the overstrength factors as described by FEMA 350. In addition, the proposed procedure also takes into account the level of inelastic rotation expected at the beam-column joint. A cover-plated and ribbed configuration is proposed for beam-to-column connection. Step-wise procedure for the design of this cover plated and ribbed connection is also proposed. The proposed beam-to-column connection configuration and design procedure is compared with the AISC and FEMA recommended connection configurations and the associated design procedures currently in use.
