Research Of Wavelet On The Damage Detection Of Structure Under Moving Load

The bridges may be damaged due to various loading applied and various accidents in their lives. The accumulated damage may give rise to the failure of structures and lead to the loss of properties and lives. Up to now, damage diagnosis technology is an active research domain in current structure engineering and has strong engineering background. The correlative theory and technology are developing continuously.Because of the complexity in damage identification of brige structures, it is difficult to apply to damage identification by the general method presently. In the thesis, based on wavelet analysis, combined the difference of each node time-curve acceleration under moving load, which is regard as the object to identify damage of structure. Based on simply supported beam curvature modal are proposed to finish damage identification. the experimental results which are obtained by dilapidated dynamic test on four model deck beam from intact state to destroyed state, combined with the dynamic theory on bridge structures, finish the damage identification by wavelet analysis. This paper provides important experimental basis while present research in damage identification on steel-concrete beam bridge lack experimental support. The research content as follows:(1) The properties of dynamic parameters are investigated when damage occurs in structure. Using finite-element method, this thesis get the modal parameters of simple sustain beam and also modified the modal according the prototype.(2) As the test data are usually polluted by noise, this thesis reduce-noise of the data by wavelet analysis to improve the precision.(3) This thesis make ANSYS simulation analysis of the test model, and simulate structural damage through the element stiffness reduction approach. After differing acceleration response of the node before and after damage, it make use of characteristics of wavelet multi resolution analysis to transform wavelet of acceleration margin curve and extract of singular points of the signal, as to identify the damage of structure and damage location in different conditions. (4) This thesis simulated moving loads with a iron ball based on the laboratory model of simply supported beam, at the same time it measure each node of the acceleration response before and after the damage of Simply supported beam based on LMS Dynamic Test System ,and make data processing analysis by the method of theoretical analysis, as to identify the damage of test beam.