Research On Structural Damage Identification Method Based On Static Parameters

The structural damage identification method based on static parameters is a global and damage-free damage identification method.It has outstanding advantages.After many years of development,structural damage identification has developed numerous new methods based on structural parameters identification of static parameters.Although there are countless damage identification methods based on static parameters,many problems remain unresolved.At present,lots of damage identification methods have achieved the quantitative estimation of damage location and damage degree.There are various methods for identifying damage location by means of curvature index,but there is no damage identification method that directly determines the damage quantitatively by the curvature index.Therefore,this paper considers the combination of curvature and static parameters to enable the index to accurately locate the damage and quantify the damage of the structure,and to locate the damage and ruin of the structure based deflection,bearing reaction and strain index.Conducting research and developing the following main contents:1.Based on the simply supported beam,cantilever beam and fixed beam structure model,the damage recognition theory based on deflection curvature was derived.It was verified that the deflection curvature identification theory can be applied to different load forms and different beam structure forms,and the curvature and damage degree were established.The expression of the degree of damage can be calculated from the index to determine theoretical damage of the structure.Aiming at the problem that the elemental damage of the deflection inflection point of the statically indeterminate structure such as the fixed beam and the three-span continuous beam was not recognized,the superimposed symmetric curvature index and the superimposed load curvature index were proposed to solve the problem that the unit damage at the inflection point cannot be identified.The correctness of the theory was verified by different beam structure example models,and the deflection curvature index has certain anti-noise ability.2.Based on previous studies,taking a simply supported beam as an example.The expression of strain and damage degree was derived,and the damage degree can be directly quantified by the strain index.Aiming at the interference peaks appearing in the multi-span continuous beam identification index,a superposition-by-span strain index,was proposed to eliminate the interference peak.The applicability of the strain damage theory was verified by the simply supported beam and the three-span continuous beam model,and the index has definite anti-noise ability.3.Taking the two-span continuous beam as an example,the variation of the influence line of the bearing reaction force in the single damage was theoretically derived.It was found that the reaction force of the bearing at the damage location has an extreme value.The curvature of the bearing influence line curve has a peak value only at the damage location,so it can be used to locate the damage.Further,the relationship between the curvature of the support and the degree of damage was established,and the degree of damage can be accurately quantified.For multi-span continuous beams with three spans and above,it is possible to use the anti-force of the two supports to the influence line curvature superposition for damage identification.Through the numerical simulation analysis of multiple damage conditions of a two-span and three-span continuous beam,the feasibility of the damage identification of the continuous beam support was verified.The index has certain anti-noise ability.4.Selecting a three-span variable-section continuous beam engineering example,use the Midas software to carry out modeling and simulation analysis,verify the applicability of the three indicators of the actual structure of damage identification,and compare and analyze the anti-noise ability of the three indicators.Identify issues such as accuracy.The results shown that all three indicators can effectively identify the structural damage,and they all have certain anti-noise ability,which verifies the effect of index damage recognition.Based on the bearing reaction force,the line curvature index not only has the best recognition effect,but also has good anti-noise ability.It can improve the damage identification only by superimposing the two-span cross-support index,which can save the detection cost,and the indicator has good test accuracy is conducive to damage identification in engineering practice.