Research On Optimal Sensor Placement For Large-span Spatial Structure Health Monitoring System

The large-span spatial structure system is one of the most fast-developing structural types in the construction market at present,which is widely used in the construction of large-scale structures such as sports stadium,airport terminal,Convention and Exhibition centers,etc.Its development states can in a way reflect a nation’s architecture technique.These large-span spatial structures have the characteristics of complex spatial system,large-scale measurement points and long design service life.It could greatly threaten the safety of people’s lives and property if these structures are damaged or even collapsed.Therefore,how to ensure the service safety of long-span spatial structures has become an important research content in the field of structural health monitoring.In this paper,based on the actual monitoring requirements of large-span spatial structures,the basic problems of optimal placement of large-scale sensors are studied.The main research work of this paper is as follows:(1)Based on the monitoring requirements of real life structures,the dynamic principles of commonly used evaluation criteria for optimal sensor placement are explained,and the practical engineering significance of these criteria is analyzed and classified.Considering that the conventional criteria can only optimize one single direction out of three,a triaxial singular value ratio criteria(TSVR)is proposed and applied into the evaluation of three-dimensional optimal sensor placement.(2)In view of the large-scale measuring points for large civil engineering structures,a high efficiency algorithm for solving the problem of large-scale sensor placement optimization is established.Firefly algorithm is introduced and the coding system is improved so as to solve discrete variables optimization problem;The gradation system and immune system are introduced so as to maintain the diversity of the population,avoid the problem of premature convergence and greatly enhance the global searching ability of the algorithm;Finally,a full-scale benchmark cable-stayed bridge is employed as a case study to prove that the proposed algorithm is excellent in solving OSP problems.(3)Based on the requirements of optimal sensor placement for practical large span spatial structures,the commonly used evaluation criteria mentioned above and the high efficiency algorithm proposed in this paper are integrated to develop the MATLAB toolbox for the use of optimal sensor placement system(OSPS).The interactive interface between MATLAB and three finite element software ANSYS,MIDAS and ABAQUS is established and the function that reconstructing finite element modal in MATLAB is realized.Users canadd and open new projects,preset sensor number,choose candidate sensor locations and finally output visualized optimal configuration on the modal and export placement report.(4)Using Dalian Stadium as a practical engineering example,the finite element modal is established and the modal analysis is carried out by ANSYS.The mode shape,mass,stiffness,and frequency information are extracted.The optimal placement of one-dimensional and three-dimensional sensors are carried out separately based on the OSPS toolbox and chosen OSP criteria.The result shows that OSP problems of the large-span structure can be well solved by the OSPS toolbox.