Application Of PCA In Structural Damage Identification Under Environmental Impact

The normal operation of the bridge structure is related to the safety of people's lives and property.Early detection of structural damage and degradation maximizes bridge life and reduces overall life cycle costs,ensuring structural safety and reliability.Therefore,it is imperative to conduct health monitoring on in-service bridges.In the current bridge health monitoring system,most of the sensors are installed to collect structural response signals,extract the sensitive features of structural damage,establish corresponding indicators,and discriminate structural damage.However,in actual engineering,environmental factors(temperature,humidity,noise,etc.)also cause changes in structural vibration characteristics like structural damage,which in turn affects structural damage identification accuracy.Therefore,how to accurately identify structural damage under the influence of environmental factors is the paper of this topic.The main research work of the thesis is as follows.(1)Explain the background and significance of the research,summarize the research status of structural damage identification at home and abroad,and discuss the shortcomings of some damage identification methods at this stage.(2)The influence of ambient temperature and damage on the structural modal is studied by numerical simulation method.The conclusion is drawn that the influence of temperature on the structure is much greater than the damage,and the modal parameters are not sensitive to structural damage,and a new damage identification indicator is needed.(3)Using the wavelet packet decomposition to process the structural response signal to obtain the wavelet packet energy spectrum,establish the damage index and identify the damage.Studies have shown that the wavelet packet method can effectively identify structural damage conditions.(4)Using wavelet packet energy spectrum combined with PCA algorithm to eliminate the influence of environmental factors on the structure,and then identify structural damage.The results show that the method can effectively eliminate the influence of environmental factors,and the recognition accuracy of structural damage is greatly improved.