Damage Detection In Derrick Structure By Modal Parameter Analysis

Modern project structures are proceeding at the direction of maximization complicationand automation. The complicated environments of service threat functional safety of thestructure. Moreover in the real life many disasters structural engineering accident occurrenceinitiates the people the "health" question widely pays attention to the structure. To guaranteethe safety and avoid disaster, the scholars, engineers and technicians are paying attention to theresearch of identification for the damage of structure real-timely, on-line and accurately.This article elaborates the technology of structural damage identification domestic andforeign research present situation, Introduced each kind of theory and the research techniquefor structural damage identification. And the mode parameter analysis carries on the structuraldamage identification to the petroleum derrick structure for the technical research and theapplied research;Based on the modal parameters, it discusses mostly the theory and techniqueof the damage identification for structure with the flexibility difference method and curvaturemodal method, then present the idea of damage identification for structure with flexibilitydifference curvature method. The application of the three damage identification techniquesabove for the derrick of drilling rig, confirm that vague or wrong location will occur in thedamage location method based on flexibility difference, and the curvature modal method neednot rely on the structural parameter before the damage, but has the hidden trouble of vaguelocation for small damage. It studies and puts forward the flexibility difference curvaturemethod, and many simulated damage examples show that the method has notable advantagessuch as high damage identification sensitivity, strong reliability, and visualization andsimplicity in amount and graph analysis.The use of Central insert law for modal parameter in the curvature modal and flexibilitydifference curvature method can solve the contradiction between decreasing measure pointsand the guarantee of identification precision;Developed the operation using Matlab softwareand the Excel tool and collects the chart procedure, as long as lower step vibration shape andfrequency rate of the structure are input, the value and the graphic representation of damageidentification will be obtained.