Reducing Beam Section by Corrugated Webs for Developing a Connection of Specially Moment Resisting Frame

After 1994 Northridge earthquake, extensive studies were conducted to improve performance of SMRFs. Two types of Modifications for SMRF connections are presented to reduce the demand of plastic hinge moments on the beam to column connections. These modifications are strengthening and weakening methods. A common weakening method is the prequalified RBS moment connections as described in FEMA350-353. In RBS moment connections, cutting beam flanges cause local and consequent global instabilities and resulting in premature failures. In this paper a new method for weakening of beam sections is presented and it seems to have particular advantages. This method is replacing of beam web by corrugated plates in a limited zone adjacent to the column face. Due to the accordion effect of the corrugated web, moment contribution of the beam web to total plastic hinge moment becomes negligible and the ultimate expected plastic hinge moment of the beam section can be calculated based on the flange only. As corrugated plates can be designed to have adequate shear capacity, the plastic hinge shear resistance can be provided without any problem. The most application of this connection can be in steel plated girders and column-tree construction. Decoupling of flexural and shear stresses in flanges and webs would remove stress concentration and decrease ductility demand on beam to column connections under cyclic loading. These specifications enhance the low cyclic fatigue life of this moment frame connection. For investigating the seismic performance of this new type of RBS moment connection, a series of parametric 3D-finite element analyses have been executed. The analyses results have shown that the corrugated web will improve the plastic hinge stability and accommodate large deformation capacity at the plastic hinge location. The parametric studies on beam depth show that effectiveness of this connection is in deep beams.