Seismic Response Analysis Of Windmill-shaped Steel Frame Structure Under Different Bracing Conditions

Since the 21 st century,steel frame structures have become one of the main building types in our country.Steel structure buildings are environmentally friendly,recyclable and are highly praised by more and more designers.Seismic response analysis to irregular steel structures is increasingly becoming one of the most well-known studies in our country.In this paper,the seismic response of the irregular windmill structure was analyzed.And software of finite element analysis SAP2000 was used to establish 6 models.Their were model one(original structure),model two(with single inclined rod brace structure),and model three.(Add chevron brace structure).The models were compared in modal analysis,response spectrum analysis and time history analysis,and the seismic effects of different braces on the structure were discussed,and the corresponding conclusions were drawn.The main research contents and methods were shown below:(1)Firstly,according to the modal analysis,the addition of various braces can effectively reduce the natural vibration period and period ratio of the structure,among which Model 4(with X-shaped brace)has the best effect: compared with the original model,the natural vibration period and period ratio of the first mode of Model 4 are reduced by about49.6% and 23.0% respectively.After adding brace,the torsional mode appears in the third mode.It can be seen that adding brace could improve the lateral stiffness of the structure and avoid premature torsion of the structure.Among them,adding X-shaped brace has the best torsion resistance effect on the structure,followed by adding herringbone brace,and finally adding single inclined rod brace.(2)Secondly,in the response spectrum analysis,as the number of floors increases,the deformation continued to increase.After the brace was added,the displacement of each floor was lower than the original structure.Through data comparison and analysis,it could be seen that different braces had different effects on the structure’s lateral resistance.Among them,the maximum displacements and interlayer displacement angles in X and Y directions decreased the most with the addition of X-shaped bracing.The maximum displacements in X and Y directions decreased by 42.8% and 48.8%,respectively.And the maximum interlayer displacement angles decreased by 53.1% and 60.5%,respectively.(3)Thirdly,in the time-history analysis,the dynamic responses of the four models under three seismic waves(El-Centro wave,Taft wave and Lanzhou wave)were analyzed through the data of structural displacement,interlayer displacement Angle,base shear,base bending moment and interlayer shear.The results showed that the inter-storey displacement angles of Model 1 to Model 4 were all less than 0.004,and the peak value of the time history curve of base shear/bending moment was delayed after the addition of brace.In addition,in the actual design of steel structure,the influence of seismic wave and bracing type on the structure should also be considered.Figure: [56];table: [32];reference: [63]...