The Principle Of Damage Detection Of Mast Structural Bars

Mast structure is a kind of high structure, it is widely applied in important national economy domain,such as wireless communication, broadcast television, sea and air navigation, environmental development. In recent years, masts had been applied more and more widely in our country,However,mast structure destruction accidents occurred frequently, the member's failure is the main intrinsic reason of its destruction, The problem of how to carry on the damage diagnosis to the medium-scale and large-scale mast structure has attracted engineering and academic circles's attention in recent years. Groping for the damage detection principle of mast structural bars is just the research purpose of this article. Detection every bars for the damage with partial detection methods is not practical.It is valuable and significative to research for the damage detection methods based on the whole structural vibrational test signal.This article firstly introduces the main engineering application of mast structure and the destruction accident examples, summarizing the former mast structure destruction reason, the external causes is mostly wind load and the ice load, the intrinsic reason is mostly the structural own member damage.Then this article summarizes the mast structural dynamic performance research situation in and out abroad and the main large-scale structural damage detection method. Domestic and foreign researchers have done much work to the mast structure dynamic performance research, but the mast structural non-linearity has not been completely discovered, therefore, it is very difficult to detect damage through indentification of structural physical parameters.At present, the damage detection methods based on frequency domain have been developed very well, but actually not suit for the high non-linear mast structure, damage detection methods based on time domain and time-frequency distribution is deserved to research further.This article establishes the mast structural numerical model, this model uses non-linear element, and it had considered the guy's large deflection and stress stiffening and coupling effect between the mast body and guys, then carry on the non-linear dynamic analysis to this model to obtained the mast body node's response signal, and compares the displacement and velocity and acceleration and displacement spectrum with and without damage of bars, the results indicate that the mast body's response is extremely sensitive to the bar's damage.This article introduces main signal time-frequency analysis methods,time-frequency distribution can reflect the signal's characteristic, therefore, it becomes a important method to study the non-steady signal, but many problems still exist to utlize the time-frequency anlysis method to detect structural damage,such as management of disturbing item and selection of window function. this article utilizes the SPWD to analyze the nodal displacement response signal with and without bar damage, the results reflect the non-linearity of the mast structural vibration,then proposes the bar damage detection index P based on the spectrogram, calculated examples indicate this index's efficiency to bar damage.This article mainly analyzes the influence of mast bars' damage to mast body section inetia-moment , and establishes the relation between mast body inetia-moment and nodes' response, proposes the bars' damage index H based on time domain,and testified the index's validity with different load inspiritment and different damage bars and different damage degree.and proposes the measured nodes' number optimization method from the index's characteristic,the number is much lower through optimization,and this aricle discusses the influence of noise disturbance to the detection index value.then utilizes this index to another mast numerical model, also accurately detect the damage bars,finally, has infers the index based on the velocity response.