Research On Damage Identification Technology Of Structure Based On Class-flexibility Difference Curvature

Structural damage identification is one of the core contents of bridge health monitoring.There are many methods to identify structural damage.Because the flexibility damage identification index only needs low-order modes to identify damage,low-order modes are easy to measure in engineering and have high accuracy,so the flexibility damage identification method has attracted a lot of attention of scholars,and many research work has been carried out.Damage identification technology has been gradually applied in civil engineering since 1970.Many scholars have put forward various damage identification methods with different characteristics through the study and analysis of different structural parameters,so as to judge whether the structure is damaged or not,determine the damage location and identify the damage degree.This paper summarizes the related research on structural damage identification,introduces the research status at home and abroad,and illustrates the characteristics and advantages and disadvantages of various structural damage identification methods.At present,a single damage index can not meet the requirements of structural damage identification.Comprehensive information should be considered to develop a multi-index combined damage identification technology.In order to identify structural weak damage better,a structural damage identification technique based on quasi-flexibility differential curvature and frequency perturbation is proposed.The numerical simulations of various damage conditions without boundary damage elements are carried out,and the first and second order frequency perturbations are calculated.The results show that only the first order modal test data are needed to diagnose the damage location and quantitatively identify the damage degree.At the same time,the LFCF index of flexibility difference curvature established by the first mode has a good diagnostic effect on damage location of beam structure,and the calculation workload of this method is small.When the damage degree is less than 25%,the maximum error of damage degree of second-order frequency perturbation calculation is less than 5.85%,which proves the validity and accuracy of this method.In order to further verify the practicability and effectiveness of this method,a damage identification method based on quasi-flexibility difference curvature and frequency perturbation is used to simulate single damage and multi-damage conditions for typical beam members of through arch bridge.The results show that for single damage simulation,the accuracy of second-order perturbation identification results is significantly higher than that of first-order perturbation identification results.In injury simulation,the results of the first two order frequency perturbation recognition are similar,and the first order perturbation recognition effect is better.It is proved that this method has good effect on structural damage identification and has certain research significance,which can provide reference for practical engineering application.