Study On The Structure Of Long-Span Hybrid Grid Hangar Based On Lever Principle

With the continuous development of China from a large civil aviation country to a strong civil aviation country,more and more large aircraft are put into use.In order to meet the actual needs of the simultaneous maintenance of multiple large aircraft in the hangar,it is urgent to study a new spatial structure with smaller thickness and greater stiffness to realize the large span spatial structure.The structure of a large span aircraft maintenance hangar generally adopts a structure with three sides supporting and one opening.The problem of large deflection at the opening of a conventional flat grid under such support conditions will be highlighted,and the hangar span will be limited.At present,the research on the buckling capacity of the hangar roof space rod structure does not consider restraint joints.If this is taken into account,it will cause changes in the buckling capacity,which will affect the capacity of the hangar roof structure.Therefore,in order to meet the needs of the current hangar construction,it is necessary to propose a new form of grid hangar structure.In this paper,a grid hangar structure of large span hybrid hangar based on lever principle is proposed.The support of the hangar structure is moved inward,and the support is used as the fulcrum of the lever.The cable is set at the left and right overhanging end,and the cable is anchored vertically with the ground.A modeling method of large span hybrid grid structure based on lever principle is proposed.Based on SAP2000 spatial structure design software,a plug-in for automatically creating large span hybrid grid structure based on lever principle is developed by using C # language.The large span hybrid grid structure based on lever principle is automatically generated by inputting the parameters such as the span of the hangar structure,the number of horizontal grids,the number of longitudinal grids and so on.A method for optimizing the design of a large span hybrid grid hangar structure based on particle swarm optimization was proposed.Using SAP2000 software,C # was used to develop a large span hybrid grid structure based on the principle of leverage.The optimization design was carried out,and the optimization design procedure of the hangar grid structure was developed a second time.Steel circular hollow section is widely used in the structure of hangar roof,and its axial force determines that the steel circular hollow section can bear high buckling capacity.The buckling modes are used as the initial geometrical imperfection forms of the steel circular hollow section when parametric analysis of the integral finite element model is carried out.Based on the probability and statistics method,a method for calculating the refined buckling capacity design value of the steel circular hollow section with uniform reliability considering the restraint of welded hollow spherical joints is established,and the error formula of this design value at a certain confidence level is also derived.The relationships between the refined buckling capacity design value of steel circular hollow section and the geometrical and material parameters of the member and joint are determined quantitatively by linear regression method.A practical formula for the refined buckling capacity design value of the steel circular hollow section considering the restraint of welded hollow spherical joints is derived.When the restraint of welded hollow spherical joints is finely considered,the buckling capacity value of steel circular hollow section could be quite different from that calculated based on the current code.If the difference of restraint effect which is caused by different welded hollow spherical joint is ignored,the buckling capacity value of steel circular hollow section calculated based on the unified effective length coefficient may be bigger or smaller than that of the actual case.Therefore,refined consideration should be placed on the different restraint of welded hollow spherical joints of different sizes on steel circular hollow section,and the restraint of the end joints should be accurately considered when determining the buckling capacity of steel circular hollow sections of the hangar roof.