The Redundancy Optimization Research On Single-layer Spherical Latticed Shell

Latticed shell structures are widely used in large civil engineering structures such as stadiums,train stations and terminal buildings.Occurrences of collapse accidents occur occasionally under the sudden action of earthquakes and typhoons.In order to ensure the safety of the structure under emergencies and to improve the overall force performance of the structure,the robust performance of the structure needs to be studied.Structural redundancy is an important part of robustness,reflecting the impact of local damage on the overall performance of the structure,while redundancy also reflects the importance of the component in the structure.The difference of redundancy between components is the component’s role in the structure and its concentrated reflection on the contribution to structural collapse resistance.If the distribution of structural redundancy is not balanced,the collapse of partial components can easily lead to the collapse of the disproportionate damage.In this paper,based on the redundancy of structural components,the optimization algorithm is adopted to diminish the redundancy difference between components by optimizing the cross-section of components to achieve the purpose of improving the overall mechanical performance and robustness of the structure.In order to diminish the redundancy difference between structural components and to control the growth of the total volume of the structure,based on the sensitivity redundancy calculation theory,taking the section size of the component as a optimization variable,setting the minimum of the redundancy difference between the components and the total volume of the structure as a optimization goal,the Genetic Algorithm is used to optimize the cross-sectional dimensions of the components to get the feasible components,then the optimal components that meet the requirements of cross-section from the feasible components are selected to form a new latticed shell structure so that the latticed shell structure has good overall force and robustness.This paper mainly studies the analysis method of structural redundancy,the structural optimization measures based on redundancy and its application in the size optimization of largescale latticed shell structure.The research content mainly includes:Firstly,it is discussed the importance of studying the redundancy and robustness of the structure,and pointed out the importance of structural redundancy optimization in the maintenance of structural safety.Furthermore,the research course and research status in the aspects of robustness,seismic design and structural optimization are described,as well as the main research contents,key issues,research methods and ideas of this paper.Secondly,based on the sensitivity analysis,taking the cross-sectional area of the structural components as a parameter,the sensitivity of the structural response to this parameter is deduced in detail,then the evaluation index of the structural redundancy is established.On the basis of that discussion above,taking plane truss and star-shaped spherical latticed shell under static load as examples,the redundancy distribution of them is given and analyzed.Moreover,the basic theory of Genetic Algorithm,the construction of objective function and constraints condition in structural redundancy optimization and the optimization procedure of Genetic Algorithm in structural redundancy optimization is introduced.Taking the plane truss and the star-shaped spherical lattice shell as examples,the Genetic Algorithm compiled by Matlab for redundancy optimization is utilized to optimize the structure redundancy and the optimization results are analyzed.The results show that through structural redundancy genetic optimization,a balanced distribution of structural redundancy can be achieved then the overall mechanical performance and robustness of the structure can be improved.Furthermore,applying the method of structural redundancy optimization based on Genetic Algorithm to the long-span spatial structure,Taking The Ribbed single-layer spherical latticed shell and The Kewitte single-layer spherical latticed shell as examples,the finite element software is used to simulate the structure before and after optimization then to analyze the mechanical performance,seismic performance and stability of the structure before and after optimization.The results show that the redundancy evaluation method based on the structural response sensitivity and the genetic optimization strategy of structural redundancy are feasible in the optimization of the redundancy of long-span spatial structure,the method to reduce the structural redundancy difference between components by optimizing the cross-sectional area of components can make the weak parts of the structure be strengthened,which can effectively improve the overall mechanical performance and robustness of the structure so that the anticollapse performance of the structure is enhanced ultimately.Finally,it is all about the conclusion and prospect.It is mainly summarized the main contents and the main conclusions of this paper and pointed out the imperfections of this paper in the calculation of redundancy optimization indicators,the construction of structural redundancy optimization model and the research level.The results show that: the structure redundancy genetic optimization strategy adopted in this paper can optimize the structural redundancy by automatically searching for the cross-section size of the structural components to diminish the redundancy difference between the components,which can realize the optimal control of the structural redundancy and achieve the optimization of the force mode of the structure so that ensure the safety of the structure under the failure of the partial components;by the means of optimal selection of the cross-section size of the components,which can make full use of structural materials to reinforce the key components of the structure and improve the overall performance of the structure;structural redundancy optimization method based on structural response sensitivity can realize the failure process control of the structure under load and improve the overall structure Robust performance.