Research Of Structural Damage Detection Based On BP Network And EMD Method

The morbidity states of existing structures are increasingly highlighting while the construction industry develops rapidly and lots of new building are constructed. The target of sustainable development and green architecture assists the urgency of damage detection of existing building structures. In recent years, many domestic and overseas scholars have conducted some researches on it and put forward lots of damage detection methods that are mainly dynamic detection, while, All detection methods have their practicability and defects. For the deficiency of structures detection damage information by Back Propagation Neural Network often covered by other information and the characteristic that Empirical Mode Decomposition can decompose signal to single component including the pronounced damage information,this paper put forward a new methods to combine BP with EMD and apply it to structures damage detection.The main contents of the paper are as follows:(1)The necessity of making the damage detection of existing structure and the characteristic of common detection methods by domestic and overseas are summarized;(2)The BP network training methods—the steepest BP descent methods has been detailed derived, the basic concepts and decomposition process of EMD methods also have been detailed introduced, and then,the stationary curve of simulated signals with time have been draw;(3)The program of EMD, acceleration time history with energy calculation and BP network damage detection based on MATLAB2012 a have been compiled;(4)A 2F reinforced concrete frame structure have been set as an example to conduct dynamic response based on SAP2000, then contrastively analyze the acceleration peak 、 response spectra and the difference of energy carried by acceleration time history at difference structure damage parts and with different levels.the influence regularity that the structure damage parts and levels respond to the structure earthquakes have been discussed, as well the sensitivity that the peak 、response spectra and energy damage the structure while the joints respond time history have been analyzed.(5)The feasibility of combining BP network with EMD method on theory have been demonstrate. by using the compiled program to simulating frame structure,the difference of the result that make the test by using directly BP network and combining BP network with EMD method have been analyzed contrastively and the influence of synaptic weights and threshold use the gradient modification learning algorithms and additional momentum learning method as well have been analyzed contrastively.