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The Studies on Structural Damage Detection Based on Probability Statistics Method

Author: LinXiuPing
Tutor: CaoZuo
School: Chongqing University
Course: Disaster Prevention and Reduction Engineering and Protective Engineering
Keywords: Damage Identification Modal parameters Measurement noise Cell damage variable Statistical Methods
CLC: TU312.3
Type: Master's thesis
Year: 2009
Downloads: 171
Quote: 3
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Abstract


For various reasons, the civil service structure will be different degrees of damage, to protect the safety of the structure, integrity and durability, the need for structure health monitoring, where the core content is to the structure damage identification . Structural damage identification process, the presence of measurement noise seriously affected the stability and reliability of recognition results. In this paper, bridge health monitoring system to obtain data continuity (along the time axis monitoring system can provide sufficient monitoring data) characteristics, the injury indicators and the method of combining probability and statistics for damage identification, efforts to solve the most current identification method for measuring noise sensitive issue. This paper selected cell damage improved damage identification variables as indicators, combined with simply supported beam and continuous beam study examines the mode number, extent of damage location and damage effect on damage identification. The results show that without considering the effects of noise in the case of the improved cell damage variable, using only the low order mode can accurately locate damage, including damage to the small extent of 5%, which shows the modal truncation does not affect cell damage Variable positioning performance. But for injury, because the impact of modal truncation, cell damage variable can only characterize the different degree of injury between the relative size of the damage level of absolute quantitative results very satisfactory. Taking into account the structural response of the test data will inevitably contain measurement noise, and measure the presence of noise on the adverse effects of damage identification results, this paper focuses on the numerical simulation method of measurement noise and the noise level of control, the establishment of signal noise levels and modal correspondence between the noise level parameters, combined with Charpy example examines the single sample cell damage variable noise on recognition results. The presence of measurement noise to damage variable cell-based damage identification method caused serious interference, discrimination need to set a damage threshold. In this paper, probabilistic method, using statistics and hypothesis testing method to determine the damage threshold discrimination, and gives a wrong judgment test probability. This method can eliminate the adverse effects of measurement noise, according to the structure before and after damage parametric statistical value changes, statistical significance given recognition result of the damage. In this paper, respectively Charpy and continuous beams simulation example of the feasibility of the method and the results of its identification with the Monte Carlo method for the comparative analysis of the recognition result. Studies have shown that the probability of damage variable cell-based statistical method is robust to noise, can effectively prevent damage to the occurrence of false positives.

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CLC: > Industrial Technology > Building Science > Building structure > Structure theory to calculate > Structural loads and structural capacity > Structural damage and accident analysis
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