Research On Seismic Performance Of The Steel Mechanical Parking Garage(SMPG)

The steel mechanical parking garage(SMPG)is of great significance for solving the problem of parking in modern cities.However,SMPG is a kind of unconventional frame structure without floor slabs,which has no corresponding design specification at present.In order to compile the corresponding technical guides and better guide the design of SMPG,it is necessary to conduct in-depth research on the mechanical parking garage of steel structures.Taking a SMPG project as an example,this paper uses MIDAS/FEA and MIDAS/GEN finite element software to study the influence of the roof and horizontal support on the overall structure seismic performance.Using MIDAS/FEA,the feasibility of the rod + shell element model of rod + plate shell element in the study of new structures and complex structures is studied.The main work and research result of this article is as follows:(1)The development history of mechanical parking garages and the basic principles of structural seismic analysis theory and elastoplastic analysis are summarized,and the related contents of the analysis software are introduced.(2)The MIDAS/GEN finite element software is used to establish 4 models with,without roof,and horizontal support.An artificial wave and two natural waves are selected in this paper to conduct the elastoplastic time history analysis of the model.The influence of roof and horizontal support on the seismic performance of a mechanical parking lot is studied.After setting the horizontal support,the shear force and the minimum shear-to-weight ratio of the structure are all increased,and the displacement angle between the floors is reduced.Results show that adding the horizontal support can improve the seismic performance of the parking garage.After the roof is set,the top layer quality of the structure,the shear force between layers,the displacement angle between layers,and the displacement of the top node increase,while the minimum shear ratio and the acceleration at the top node decrease.The roof is detrimental to the seismic performance of a three-dimensional parking garage.However,considering the architectural function of the top floor of a general parking garage,lightweight roof is recommended SMPG design.(3)The MIDAS/GEN finite element software is used to analyze the seismic response of the mechanical parking garage with roof and horizontal support.By analyzing the stress distribution and yield of key components such as beams,columns,and horizontal supports under various operating conditions,the structural weaknesses are studied.It is found that the degree of the elastic plasticity of the structural components is not too large,but the maximum stress appear in the frame column and the beam column joint area.Therefore,to ensure better safety goals,we should further strengthen these areas.(4)By taking out a frame from the parking garage model,the MIDAS/FEA software is used to establish the rod + plate shell element model and the pure rod(beam)element model respectively.On the basis of verifying the basic consistency of the two models,the elastoplastic time history analysis of the two models is carried out.The study shows that: the bar + plate shell element analysis model can be used for the analysis of the parking garage.It can reflect more detailed consideration of the local structure and the detail of the stress.The stress and strain at any position can be easily seen,the stress at each detail in the whole section can be read and analyzed,and more details can be analyzed on the impact of the overall seismic performance.Rod element + shell element analysis model has higher accuracy than pure rod element model,and faster than the pure shell element model.