| Large-span space structure with unique beautiful shape and complex structural system is one of the most important criteria measuring the construction technological level of countries, and it is usually the place holding large-scale events and the crowd gathered. So ensuring the construction and service security is particularly important. Structural health monitoring is a method which can obtain the structural responses and give the estimation of the structures'working status by measuring different types of sensors arranged on the structures, so the unsafe factors of the structures are warned in the early stage and the service security of the structures is ensured. Structural health monitoring system is one of the useful methods to ensure the service and construction security of important structures in civil engineering.It is a common method to achieve the health monitoring with the changes of stress and strain in the structures, because any unsafe factor will result in the changes of the bearing capacity in the structures, while induce the variations of stress and strain in the structures. To take full use of the information obtained by the strain sensors arranged on the structures, learn the stress distribution of the key region, and ensure the security of structures, stress identification of the key region in large-span space structure is studied. In the paper, a stress identification method using fuzzy pattern recognition and information fusion technique is proposed, and the Numerical study on a lattice shell modal and the Nation Swimming Center is carried out to validate the effectiveness and feasibility of the proposed method.The contents of this dissertation are mainly as follows(1) The stress identification method based on limited sensor information is studied. By fuzzy pattern recognition, the stress distribution of the key region of is obtained based on the measurements of the strain sensors located on the structure. In addition, to increase the accuracy of identification, the improved fuzzy pattern recognition method is proposed.(2) The information fusion technique is used in the stress identification of the key region in the structure to improve the reliability of the results. First, the structure is divided into several regions according to the similarity and the most unfavorable region is selected to be the key region for stress identification; secondly, the different stress distribution of the key region are obtained based on the measurements of the strain sensors located on the key region and the normal regions separately, in which the fuzzy pattern recognition is used to identify the different stress distributions; thirdly, the stress distributions obtained by the measurements of sensors in normal regions are selected to calculated the synthesized stress distribution of the key region by D-S evidence theory; fourthly, the synthesized stress distribution is obtained based on the weighted fusion algorithm.(3) The numerical study on a lattice shell model is carried out. The selection of relevant parameters of fuzzy pattern recognition and information fusion is discussed, and the feasibility of the method is evaluated. In addition, the influence of measuring noise and the faults of sensors to the accuracy of the identification results is also analyzed.(4) The numerical study on the structural health monitoring system of National Swimming Center is carried out, the effectiveness and feasibility of the proposed method to the complex structures is evaluated.A stress identification method of the key region in large-span space structure is proposed in this paper, which provides a new way to ensure the construction and service security of the large-span space structures. The proposed method has high identification accuracy, even considering the influence of measuring noise and the faults of sensors, the stress identification results of the key region can also achieve relative high accuracy. |
