Clifton, Butterworth, and Zaki 2003
In this paper, two joints (FBJ and SHJ) have been developed and tested to determine their respective behaviors during a seismic event. FBJs are simple to fabricate and erect, and are intended for low levels of design ductility demand. SHJs are also simple to fabricate, but are more complex to erect. They are intended for higher levels of design ductility demand. Both joints can undergo rotation during a severe earthquake while suffering minimal structural damage. Research results show that both of these joints remain effectively rigid up to the design level ultimate limit state earthquake forces because they have been designed and detailed to withstand the expected inelastic rotation associated with the design loads.
System Concept
The authors tested structures composed of steel frames with FBJ or SHJ connections. Fuses were placed at the connections of the steel frames. The FBJ involves connecting the beam to the column through plates to the top and bottom flanges of the beam, and a plate to the beam web. The SHJ involves pinning the beam relative to the column at the beam top flange level via top flange bolts and a top flange plate. These bolted connections can be replaced. Due to the mechanism of the connections, a dynamic self-centering characteristic is provided.
Experimental Study, Results and Discussion
Large and small scale experimental tests were undertaken to assess and improve the behavior of the joints at hand. Large-scale experimental tests helped determine adequate bolt size and layout. Small scale tests were performed to determine bolt size, ratios of design shear capacity of bolt group to plate axial strength, the effect of repeated loading on bolts and plates, and the effect of loading rate. Both these semi-rigid joints offer considerable advantages over traditional rigid jointed MRSFs and have the potential to set the future direction for MRSF seismic-resisting system application.
Analytical Study
Numerical integration time-history (NITH) analyses were undertaken to determine the demands on the system. The computer program RUAUMOKO was used for these analyses. Rotation dem
Reference
Clifton, G. C., Butterworth, J., and Zaki, R. J. (2003). “Two New Semi Rigid Joints for Moment Resisting Steel Frames,” Proceedings of the 7th Pacific Structural Steel Conference, Long Beach, CA, March 24-27.