Study On Seismic Behavior Of Semi-rigid Frames Using Double C Steel With Gusset Plate

Cold-formed thin-walled steel structure, which is characterized by its light weight,energy saving, environmental protection, high efficiency and convenient installation, andsuperiority to the traditional hot-rolled structure, has been widely admired. Investigationson semi-rigid frames using double C steel with gusset plates are few, and most ofsemi-rigid joints are designed according to the rigid joint, which has a significantdifference in the actual engineering. In order to study on the effects of seismic behavior ofsemi-rigid frames with different joint rigidity, multi-storey semi-rigid frames using doubleC steel bolted with gusset plates was conducted through tests and numerical analysis.Two two-layer test frames and seven finite element models with the differentparameters of bolt diameter, plate thickness，bolt spacing and haunched size were designedand conducted under the low cyclic loading. The results show that the buckling occurred atthe beam ends and column bases of all the frames and the frames failed with the overallinstability. The bolt of M16which can not provide the enough bearing capacity of the jointof frame, makes the bolt slippage, while this situation was not occur when using the bolt ofM20. The haunched size has a greatest impact on the stability bearing capacity of frame.The ductility coefficients of all the frames are larger than3, which indicates the frame hasa good ductility. The haunched size and plate thickness have a greatest impact on theductility. The frame energy coefficients ranging from0.31to2.41, which presents a goodenergy dissipation. And plate size has a significant effect on the energy dissipation. Aboveall, the effects of haunched size and plate thickness on the seismic behavior is significant.Six specimens of four-layer full-size frame models were set up by SAP2000for themodal and pushover analysis with different joint rigidity. Natural vibrationperiods, load-displacement curves and ability spectrum curves under the frequentearthquake and rare earthquake were calculated，and the analysis of joint rigidity effects onthe multi-layer frame seismic behavior was conducted. It is noted that the natural vibrationperiod of the frame increases, when the joint rigidity is decreased. With the increasingof the joint rigidity, the bottom shear of structure increases, but the top displacement decreases. The story displacement of frames decreases with the increasingof the joint rigidity.Through studying on the multi-storey semi-rigid frames using double C steel withgusset plates, it is noted that the joint rigidity is one of the main factors affecting theseismic behavior of the frame. The seismic damage behavior of the frame was analyzed,which gives some references and basis for the applications and researches.