| The double-layer cylindrical reticulated shell structure is widely used in stadiums,airports,stockyards and other places.Because of its excellent characteristics of space and safety,it has been widely concerned and has a promising spatial structure.This paper intends to study the system and design optimization of closed cylindrical reticulated shell structures with lower edge constraints,which will enrich and improve the design and optimization methods of existing cylindrical reticulated shell structures,and provide reference for practical engineering design.In this paper,by studying the three optimization schemes of support position and constraint form,reticulated shell evacuation,and grid structure system on the mechanical and economic performance of the closed reticulated cylindrical reticulated shell structure,the following four aspects of work are mainly done:(1)By using the 3D3 S steel structure design software,a variety of support spacing arrangements were established.Based on structural performance analysis,combined with the support spacing distance of the reticulated shell structure,the basic model was determined for subsequent research.The research shows that the supports in the longitudinal direction and span gable direction of the double-layer cylindrical reticulated shell are spaced by 2 grids,and the number of supports and the reaction force of the supports are significantly reduced.(2)Based on the existing horizontal sliding bearings,a new type of vertical sliding bearings is proposed,which takes structural performance as the main objective optimization function,releases multiple bearings in different directions,and changes the position of the bearings as optimization variables.The structure and the node displacement are similar when the structure is optimized to obtain the optimal support position and constraint form.The results of the study show that the vertical sliding bearing is installed from the second to third grids along the length of the gable end,and the pressure in the X,Y,and Z directions is less than the maximum support reaction force of the model without the bearing optimization About 30%,the tensile force in the Z direction can be reduced by about 60%.(3)Based on the existing reticulated shell evacuation form,further study is made on the optimized evacuated form suitable for cylindrical reticulated shell structure,with the structural mechanical properties as the target optimization function,and the number of multi-directional continuous evacuated grids as the optimized variables,to analyze the structural mechanical properties Economic performance.Through comparison,it is found that the cylindrical reticulated shell structure continuously evacuates the quadrangular pyramid cone edge and the lower chord only retains a few spaced quadrangular cones.The effect of reducing the steel consumption is more obvious,and based on the evacuation plan,combined with the optimized support For the position and restraint form,the vertical sliding bearing is set from the second to third grids along the length of the model near the gable end,which can effectively reduce the bearing reaction force and the amount of structural steel.(4)On the basis of the existing double purlin grid structure system and no purlin grid structure system,a single purlin bolt ball joint grid structure system that replaces the upper chord in the span direction from a circular tube to a rectangular tube is proposed,and through the double purlin,The comparison of the single purlin grid structure system is determined to analyze the structural performance when the node displacements are similar.Through optimization analysis,it is known that the new single purlin grid structure system can reduce the total steel consumption and maximum support force of the lattice structure by about 5% ~ 10% compared with the double purlin grid structure system. |
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