Structural Damage Identification Under Ambient Temperature

Damage identification is one of the core contents of structural health monitoring.Various existing traditional identification methods have been developed,but the damage identification of structures under ambient temperature has not been very satisfactory.In this regard,this paper studies the damage identification method based on ambient temperature and its application,and explores the use of appropriate methods to eliminate temperature effects,or to find structural damage identification methods that are not affected by the environment temperature.Research shows that the mode curvature and its improved method can effectively solve this problem.In view of the limitations and shortcomings of the application of the mode curvature index,the paper introduces the uniform load surface curvature difference(ULSCD)index to identify the structural damage under the influence of ambient temperature.The analysis results show that the mode curvature index can effectively identify and locate the damage of the simply supported beam structure,but it is not sensitive to temperature effects.The ULSCD index has better ability to identify and locate the structural damage state than the vibration mode curvature index,which can effectively characterize the damage degree.It is also applicable to the continuous beam structure and is not sensitive to temperature changes.The ULSCD index can be used as an effective method for structural damage identification under ambient temperature.The research focus of this paper is divided into the following aspects:(1)Explain the research background and significance,and introduce the theoretical background,development history and research application status of three bridge structure damage identification methods based on dynamic characteristics,environmental factors and temperature effects;(2)Introduce the theoretical basis of structural damage identification,study the damage process of beam structure,analyze the stress change,and then define the damage degree,and select the damage level determination method;(3)Establishing the finite element model of simply supported beam under the influence of ambient temperature,and numerically analyzing the ability of the shape curvature index to identify the structural damage state at ambient temperature;(4)Based on the deficiency of modal curvature in identifying structural damage under environmental temperature impact,the improved ULSCD index is obtained to identify structural damage under temperature impact.Simply supported beam andcontinuous beam models are used to verify the improved method;(5)Summarize the content of the work and propose a vision for the limitations of the method.