Nonlinear Analysis of Moment Frames with Reduced Beam Section Connections after Buckling

Somayeh Ostadi¹ Afshin Moslehitabr²

1) University of Tafresh, Iran, e-mail:
2) University of Tafresh, Iran, e-mail:

Publication : International Conference on Architecture and Civil Engineering - Rome(icaconf.com)
Abstract :
To prevent the premature failure at the beam -column connections in the steel moment resisting frames, various improved details have been proposed, such as circular cut reduced beam section. Weakening the beam compared to reinforcing the connections is proved to be more economical connections, as reducing the cross-sectional properties, the demand in the panel zone and achievement of strong column and weak beam requirements has been minimized. This study proceeds to investigate the buckling in the various forms of sub-frames in different positions in the frames under cyclic load with finite element method. The out-of-plane deformation is due to the web local and lateral modes of buckling followed by the flange local buckling. In this study, T-form connections are compared with cross-form and H-form connections in frames. The H-form connections show weak behaviors especially in case of deeper beams, they show lateral buckling earlier at the reduced section place and become unstable, and lose their resistance earlier in compare to T-form connections which have the same beam and column section. They demonstrate less resistant than the previous result which has been considered base on T-form connections behavior. The results of T-form connections cannot be generalized to all connections of frames. Therefore, it is possible that frames with reduced beam section connections show weak behavior and beams do not have the expected strength and deformation capacity, although by creation of plastic hinges at the reduced beam sections brittle failures are not observed in the panel zone.
Keywords : RBS Connections Steel Moment Resisting Frames and Plastic Design