Digital Modeling And Optimization Analysis Of Single-layer Lattice Shel

In the context of the era of digital construction,computer technology is profoundly influencing the construction industry and the associated field of structural engineering.Parametric design is just an emerging design method developed from computer-aided design.Its emergence not only changes the design methods of architects and structural designers,but also increases the efficiency of communication and collaboration between them.Large-span spatial mesh shell organizational models are the best objects for collaborative work between architecture and structure in parametric platforms in the design field because of their light self-weight,reasonable forces and large-span.The thesis focuses on the parametric design of single-storey mesh-shell structural models and the study of optimisation methods for large span stadium space mesh-shell structures,with the following main elements:(1)The general approach,process and current status of application of parametric design and parametric modelling are discussed,and the shortcomings of research and application of parametric modelling and the current status of research on structural optimisation are outlined.Finally,based on the Rhino platform plug-in grasshopper parametric modelling software as an example,a parametric variable design approach is proposed,and the basic parametric design process and the parametric design method for single-layer mesh shell structures are described in detail.(2)Based on the results obtained from the parametric modelling of the single-storey mesh shell structure,six single-storey mesh shell structures of different vector heights of the Kiewitt type,the joint square type and the Schwedler type were selected for the selection of large-span stadium dome structures,and finite element models were established by combining Rhino and ANSYS software.Stability,seismic response time,modal and static characteristics analyses were carried out for six single-storey mesh shell structures,and the corresponding structural displacements and stresses were extracted and compared.The results show that both the Schwedler type and the Kiewitt type single-layer shell structures meet the design requirements,but the performance of the(2)Kiewitt single-layer shell structure is superior,which also proves that the parametric design selection can improve the efficiency of the project.(3)In order to further compare the advantages and disadvantages of different single-layer shell structures,based on the advantages and disadvantages of the above study,the Schwedler type and the joint square type single-layer shell structures were improved,and the above-mentioned better performance of the(2)Kiewitt type single-layer shell structure was selected,in addition,the same vector height of the Kiewitt type single-layer shell structure and the two improved single-layer shell structures were generated using parametric design,totaling four dome structures.The four types of dome structures were applied to the actual large-span stadium project,and the overall stability,seismic response time,dynamic characteristics and static characteristics of the stadium were compared and analysed,and the results showed that:in the actual project,the three types of mesh-shell structures all meet the design requirements,among which the Kiewitt type space mesh structure has the best ultimate bearing capacity in terms of non-linear buckling analysis in overall stability,and is not greatly affected by the initial The ultimate load carrying capacity of the Kiewitt type spatial mesh structure is the best in terms of non-linear buckling analysis in overall stability and is not greatly affected by the initial defects.However,compared to the Schwedler type,the Schwedler type spatial mesh structure is superior in all other aspects,and the Schwedler type large-span stadium structure is finally selected.(4)Theoretical analysis is carried out for four optimisation methods:Multi-objective genetic algorithm,screening method,sequential quadratic programming method and mixed integer sequential quadratic programming method.Four optimisation methods are also used to optimise the Schwedler type large-span stadium structure and to compare the optimisation results.The results show that the multi-objective genetic algorithm wastes resources.So a suitable optimisation method needs to be selected according to the actual situation.In addition,both the sequential quadratic programming method and the mixed integer sequential quadratic programming method can only optimise a single objective,and may ignore the influence of other objectives.The screening method was chosen as the final optimisation solution,resulting in a 0.82 %reduction in maximum combined stress,0.37 % reduction in total deformation and31.47 % reduction in total mass of the Schwedler-type large-span stadium structure,achieving the goal of structural optimisation.This proved that structural optimisation has a significant impact on the cost savings of the project.