The Method For The Enhancement Of Structural Anti-collapse Capacity Based On Component Redundancy And Nodal Well-formedness

Structural robustness reflects the safety of the structure after partial component damage.If the robustness of the structure is insufficient,it may cause continuous collapse of the structure after the initial damage occurs.Therefore,to ensure that the structure has high robust performance is to maintain an important measure of its safety.The redundancy of components is an important part of structural robustness,reflecting the influence of component failure on the overall performance of the structure;while structural vulnerability and robustness are a pair of opposite concepts.The fragility of components can comprehensively reflect the ease of structure damage.Research on the redundancy and vulnerability of structural components,by strengthening low-redundancy-high-vulnerability components,plays an important role in improving the overall performance of the structure and the ability to resist collapse.In this paper,the sensitivity analysis method is used to study the redundancy and vulnerability evaluation indicators of structural components,and the redundancy and vulnerability of the components are used to improve the overall performance of the structure.The main research contents and the obtained results are as follows:(1)In order to evaluate the importance of the components in a structure.An evaluation index was established in order to measure component redundancy based on the sensitivity of the strain energy of structural components to the structural design parameters(the cross-sectional area,material elastic modulus),as well as the changes in the structural strain energy after being damaged.The results show that structural component redundancy is indicative of its importance to structural stability and its influence on the performance of the structure when it is damaged.The smaller the redundancy value of a given component,the greater the impact on the structure and the lower the residual bearing capacity would be after the member was damaged.(2)According to the value of the component redundancy coefficient,then the structural components were divided into three subsets: important components,general components,and secondary components,according to the value of redundancy.The cross-section size of components were taken as the optimization variable,and the minimization of the sum of the standard deviations of the redundancy of all the structural components and the components in different subsets was taken as the objective function.In the optimization the particle swarm optimization method was used to search for the optimal solution of the size of structural components cross-section.The results show that the redundancy coefficient of structural component can reflects the importance of it in the structure and the influence on the structure performance after it was damaged accurately,a reasonable distribution of the cross-section size of components can be realized by reduce the difference of the redundancy of structural components,and the overall performance and ultimate bearing capacity of the structure can be improved effectively.(3)On the basis of component redundancy evaluation,the component vulnerability evaluation index was established under load.The components are divided into four types of components: high vulnerability-low redundancy components,high vulnerability-high redundancy components,low vulnerability-low redundancy components,and low vulnerability-high redundancy components.Then,the member with high vulnerability and low redundancy were strengthened,the ones with low vulnerability and high redundancy were weakened by adjusting the section area of member.The results show that the redundancy and vulnerability of structural member can reflect the fragility and the influence of its failure on the structure overall performance correctly.By adjusting the member section area according to the differences in redundancy and vulnerability of structural members,and the overall performance and the ultimate bearing capacity of the structure can be enhanced effectively.(4)In order to achieve a uniform distribution of nodal connection capacity of reticulated shell structure,and to enhance the performance and the ultimate bearing capacity of it.An index was proposed to measure the difference of the well-formedness between the structural nodes based on the structure vulnerability theory.Then the particle swarm optimization method(PSO)was used to optimize the cross-section size of structural members,in which the minimization of the difference between nodal well-formedness of structural nodes was taken as the optimization objective.In the optimization,constrains such as the structural maximum displacement,the member slenderness ratio,the strength and stability of members were considered.The results show that the defined difference coefficient of the structural nodal well-formedness can reflects the uniformity of the overall stiffness of the structure accurately.The uniform distribution of nodal connection performance can be realized by reducing the difference of the well-formedness of the structural nodes with the particle swarm optimization method to optimize the cross-section size of the structural members,the overall performance of the structure would be improved,and the failure model of the structure under earthquake has turn into the ductile failure mode.