The Research Of Health Monitoring And Damage Identification Based On The Difference Of Modal Curvature For Simply Supported Beam

Most of the engineering structures,when subjected to the natural disasters such as earthquake, fire and the action of the long-term fatigue loading or erosion, the damage of the structure is caused.With the accumulation of the damage,its criticality will be enhanced gradually.After judging the structure damage and confirming the locality of the damage, real time repair can be done or the means of the operation of changing the structure can be changed,so as to reduce the accumulation degree of the damage of the structure and the economy loss.Structural damage detection in civil engineering is a new research field, which has not yet formed a unified theory and method of solving, and is still in the initial stage of development. In this paper, damage identification of bridge structure is studied by using the difference of modal curvature methods.The paper is divided into five chapters.Specific studies are as follows:(1)Described the significance, contents and methods of the damage identification of bridge structure, research status and results of damage identification in China and abroad, and the scope of the paper and the main research contents.(2)Discussed the health monitoring of large bridge and the contents of safety testing, as well as the theories of health monitoring and safety testing, and explaining the great significance of bridge structural health monitoring.(3)While simply supported beam suffer with different load conditions,the virtual work principle of structural mechanics are used to deduce the damage formula of simple beam bridge before and after the curvature difference, obtain index of the modal curvature difference and damage location and degree of injury of simple supported beams. The relationship between strain and curvature, which can work out the curvature by using mode shape and strain are described, and provided a theoretical basis for the process of the curvature difference in the actual detection, which proves the higher positioning accuracy and sensitivity of the method of locating the damage of structure.(4) Discussed the theoretical basis of curvature modal analysis in detail,analyzed the relationship of curvature modal, strain mode and mode shapes;respectively used mode shape and strain method to seek curvature mode, and used the curvature difference modal method to do analogy computation to the damage of simply supported beam.The working conditions are divided into five types to analyze research and compare the identification capabilities of single damage location and multiple damage locations under different conditions,and the impact of different injury degrees to structural damage detection etc.The changes of the damage before and after the natural frequency are also studied.Numerical simulation results show the feasibility, validity and applicability of the index of curvature difference modal damage detection to bridge damage identification.(5)The effectiveness and applicability of curvature difference modal in the real test is verified by experimental method.(6)Summarized the contents and results of this paper, and pointed out the problem in using the difference of mode curvature damage identification in the bridge structure damage identification and health monitoring.