Research On Seismic Behavior Of Steel Frames With Reduced Beam Sections

During the 1994 Northridge earthquake and 1995 Kobe earthquake, the typical beam-column moment connection (bolted-web-welded-flange) in steel moment-resisting frame suffered unexpected brittle failures. After 1994 Northridge earthquake and 1995 Kobe earthquake many studies on the behavior of beam-column connections used in steel moment resisting frame and their effect on seismic behavior of steel frames have been carried out. This paper presents a contrastive analysis between the behavior of single normal steel beam-column connection and that of single dog-bone connection. Furthermore, a comparison between the seismic behaviors of steel frames with these two different kinds of connections is also given.Based on elaso-plastic Finite Element Analysis, this paper presents a contrastive analysis of energy dissipation between normal steel beam-column connections and dog-bone connections. It is found that the design of dog-bone connections can transfer the yielding joint from flange welds to parent metal zone, which possesses better plasticity and avoid yielding joints in weak welds. This design also enables beam flanges to dissipate earthquake energy and protects weak welds. Under cyclic loads, the energy-dissipating capacity of dog-bone connections is better than normal connections.A contrastive analysis of energy dissipation between steel frames with normal steel beam-column connections and dog-bone connections is also given. It is found that dog-bone connections can enhance the plastic energy-dissipating capacity of steel frames. And they can reduce the shear force in the bottom layer and the kinetic energy which is dissipated by steel frames as well. Furthermore, they will not increase the relative displacement of top layer in steel frames obviously.Static elaso-plastic analyzes of steel frames with normal steel beam-column connections and dog-bone connections are carried out respectively. Based on the results, it is obtained that steel frames with dog-bone connections can make it eaier for yielding joints to be formed in beams instead of columns than steel frames with normal connections. Therefore steel frames with dog-bone connections can meet the design requirement Strong Column Weak Beams and improve seismic behaviors of structures greatly. It is economical and reasonable to employ dog-bone beam-column connections in the bottom layers in steel frames.meets the design requirement Strong Column and Weak Beams. For steel frames with dog-bone connections, yielding zone occurs first in reduced-beam section in steel beams, which improves seismic behavior of structures.