Study On Damage Identification And Condition Evaluation Method For Curved Ramp Continuous Rigid Frame Bridges Based On Modal Analysis

Structural damage appears during normal use of bridges, the type and degree of whichwill bring negtive effects to the stability, reliability and durability of bridges, even reduce theservice life of the bridge.Slope curved continuous rigid frame bridges are widely used inmountain plateau. Variours structure damages caused by the special type of the structure, theuneven distribution of mass and the torsional effect might appear during the serve life ofbridges. If early dectetion and reasonable treatment were not taken steps, the bridge will fallinto risk.Therefore, the study of the identification and estimate theory is significant.The curvature mode analysis method about damage identification applied in bridges isrelatively mature, but the applicability, sensitivity and effectiveness of this method in thecurved slope bridge remains to be further explored.In addition, the present assessmentmethods of bridge structure damage are ensemble assessment methods mainly based onreliability theory, fuzzy theory, neural network and expert system etc. And the local damageassessment is limited to qualitative assessment.How to accurately, effectively andquantitatively evaluate the local damage, and evaluate its effect on the performance of bridgeare worthy deep research.The bridge damage identification correction theory based on the curvature mode analysistheory is expounded in this paper. This paper takes the absolute difference of curvature modeas identification factors, discusses the relationship between the protuberant position of the ofthe absolute difference of curvature mode curve and the damage position of bridge, researchesthe function relation between the summit value of absolute difference of curvature mode anddegree of the damage.First of all, taking the Feilong bridge in Yunnan Province as the research object, thewhole bridge model is established by using finite element program MIDAS/CIVIL. The singledamage and multiple damages are respectively researched in this paper. And the interferencesof the multiple damages and the factors beyond structure damages are analyzed. The absolutedifference of curvature mode identification method is corrected.Second, through optimizing of damage identification parameters and refining theidentification section, the damage identification methods of special position in curved slopecontinuous rigid-framed bridge is studied, the applicability and sensitivity of curvature modeabsolute difference method are improved.Again, based on the research of the curvature mode absolute difference method, thequantitative evaluation method local damage based on the direct stiffness method of bridge is researched, and the function relation between the summit value of curvature mode absolutedifference and damage degree is given out.The results of this paper improve the identification and evaluation theory about bridgedamage, and guide the inspection, maintenance and repair work of existing bridge.