Seismic Behavior Of Frames Using Double Lipped Cold-formed Steel C-sections

The considerable application of cold-formed thin-walled steel structure in thepractical engineering exists in the circumstance of the sustainable green buildingdevelopment and national housing industrialization. However, the combination sectionof the lipped cold-formed thin-walled C steel improving the bearing capacity ofcomponents is not included in the Technical specification for low-rise cold-formed thin-walled steel buildings (JGJ227-2011). Although the investigations of this cross sectionjoint have been conducted, the frame seismic behavior research is rare.Whereby, the pseudo-static tests of five frame specimens using the lipped cold-formed thin-walled steel C-sections were conducted, and Analyses for the mechanicalproperties and failure patterns of the frames were carried on. The hysteresis curves,skeleton curves, strain process along with the change of horizontal loads curves andplastic hinge orders were presented, and the effects of gusset plate thickness and beam-column line stiffness ratios on the frame hysteretic performance, bearing capacity,stiffness, strength and stiffness degradation, ductility and energy dissipation wereinvestigated. The test frames using ANSYS were calculated under the cycle loads, andhysteretic curves and failure patterns of the calculated specimens were got. Thereliability of finite element calculated specimens for the seismic behavior was verifiedagainst the test frames data.ANSYS was used for the parameter researches including nine calculated specimens.The effects of parameters of C steel thickness, C steel flange width-thickness ratio, thecolumn C steel web depth-thickness ratio and beam C steel web plate depth-thicknessratio on the frame seismic behavior were investigated. The cold-formed thin-walled Csteel, gusset plates, and high strength bolts in various stages stress nephograms werepresented, and the failure patterns and mechanical properties were analyzed. Thehysteretic curves and skeleton curves of specimens were used for the investigation ofthe frame hysteretic performance, bearing strength, stiffness, strength and stiffness degradation, ductility and energy dissipation.The frame has a good seismic behavior via the test and finite element analysis,failure pattern is accordance with the seismic design requirements. Plastic hinge ordersis as following: distal loaded beam end→distal loaded column base→proximalloaded column base→proximal loaded beam end. The bearing capacity and stiffnessdegradation is stable, the displacement ductility coefficient and equivalent viscousdamping ratio are2.47～5.16, and0.16～0.45,respectively. And increasing C steelthickness and decreasing beam-column line stiffness ratio can effectively improve theframe seismic behavior. The proposals that beam-column line stiffness ratios should belarger than0.481,8.8M20friction type high strength bolt is appropriate, and the platethickness should match C steel size can be used for the engineering applications.