本文選題：結(jié)構(gòu)參數(shù)識別　切入點：模態(tài)坐標　出處：《中國地震局工程力學研究所》2017年碩士論文

【摘要】：結(jié)構(gòu)模態(tài)參數(shù)識別是結(jié)構(gòu)動力特性研究、結(jié)構(gòu)損傷診斷和結(jié)構(gòu)安全性評估等方面研究工作的基礎和前提,其在機械工程、航空工程和土木工程等領域受到了廣泛的關注和研究。在地震工程學領域,通過結(jié)構(gòu)在實際地震中測得的響應數(shù)據(jù)來準確的識別出結(jié)構(gòu)參數(shù)成為熱門的研究課題,眾多的模態(tài)參數(shù)識別方法及其改進算法被提出和應用。本文通過數(shù)值模擬和振動臺試驗地震響應記錄,對多種模態(tài)參數(shù)識別方法進行了比較分析,主要研究工作和結(jié)論如下:1、對國內(nèi)外結(jié)構(gòu)模態(tài)參數(shù)識別方法的發(fā)展和現(xiàn)狀進行了探討,針對本文中用到的模態(tài)參數(shù)方法,詳細介紹了其理論基礎,包括物理坐標和模態(tài)坐標的相互轉(zhuǎn)換、頻響函數(shù)和脈沖響應函數(shù)的概念、相關函數(shù)及其應用等。2、通過一個三層平面框架模型算例,驗證了自然環(huán)境激勵法這一時域信號預處理方法的可行性,該方法利用結(jié)構(gòu)在白噪聲激勵下響應的互相關函數(shù)來替代結(jié)構(gòu)的自由衰減信號,并指出在相關函數(shù)計算的過程中,需要一定的原始輸入數(shù)據(jù)長度來降低白噪聲隨機性的影響,其次要設置合理的自由衰減信號長度以降低信噪比的影響。3、重點研究了ITD、STD、ARX這三種模態(tài)參數(shù)識別方法,并應用于數(shù)值模擬結(jié)構(gòu)的模態(tài)參數(shù)識別。通過數(shù)值模擬算例結(jié)果分析得出:1)三種方法在以結(jié)構(gòu)地震響應為輸入數(shù)據(jù)時,能準確的識別出結(jié)構(gòu)頻率,STD法相對于ITD法的識別精度更高,且計算速度更快;2)STD法和ITD法方法都受白噪聲平穩(wěn)隨機性的影響,需要足夠的信號長度來降低誤差,ARX方法直接利用結(jié)構(gòu)響應和輸入數(shù)據(jù),穩(wěn)定性更高。4、以一個3層RC框架結(jié)構(gòu)模型的振動臺試驗為研究對象,采用STD法和ARX法分別對不同工況后的試驗結(jié)構(gòu)模型進行了參數(shù)識別,并與試驗現(xiàn)象進行了對比分析。結(jié)果表明:1)當結(jié)構(gòu)處于完好或輕微破壞時,這兩種方法對頻率的識別結(jié)果比較接近,進一步說明了這兩種方法及計算程序的可靠性;2)隨著結(jié)構(gòu)破壞的加深,結(jié)構(gòu)各階頻率逐漸下降,各階阻尼比增加,此時兩種方法在階數(shù)較低時會丟失真實模態(tài),在階數(shù)較高時又會產(chǎn)生虛假模態(tài),阻尼比識別效果變差,方法的準確性有待改進。
[Abstract]:Structural modal parameter identification is the foundation and premise of structural dynamic characteristics structural damage diagnosis and structural safety assessment. It has been widely concerned and studied in the fields of mechanical engineering aviation engineering and civil engineering.In the field of seismic engineering, it has become a hot research topic to identify structural parameters accurately by the response data of structures measured in actual earthquakes. Many modal parameter identification methods and their improved algorithms have been proposed and applied.In this paper, several modal parameter identification methods are compared and analyzed by numerical simulation and seismic response record of shaking table test.The main research work and conclusions are as follows: 1. The development and present situation of structural modal parameter identification methods at home and abroad are discussed. The theoretical basis of modal parameter identification method used in this paper is introduced in detail.Including the transformation of physical coordinate and modal coordinate, the concept of frequency response function and impulse response function, the correlation function and its application.The feasibility of the natural environment excitation method as a time domain signal preprocessing method is verified. The cross-correlation function of the structure response under white noise excitation is used to replace the free attenuation signal of the structure, and it is pointed out that in the process of calculating the correlation function,In order to reduce the random effect of white noise, it is necessary to set a reasonable free attenuation signal length to reduce the influence of signal-to-noise ratio (SNR) .3.Three modal parameter identification methods (ITDX / STDARX) are studied.And applied to the modal parameter identification of the numerical simulation structure.The result of numerical simulation shows that the three methods can accurately identify the frequency of the structure compared with the ITD method when the seismic response of the structure is taken as the input data, and the accuracy of the three methods is higher than that of the ITD method.The speed of calculation is faster. Both the ITD method and the ITD method are affected by the stationary randomness of white noise. It is necessary to reduce the error by using the structural response and input data directly.The stability is higher. Taking the shaking table test of a three-story RC frame structure model as the research object, the parameters of the test structure model under different working conditions are identified by STD method and ARX method, and the results are compared with the experimental phenomena.The results show that when the structure is in good condition or slightly damaged, the results of the two methods are close to each other, which further explains the reliability of the two methods and the calculation program.The frequency of each order of the structure decreases gradually, and the damping ratio of each order increases. In this case, the two methods will lose the true mode when the order is lower, and the false mode will be produced when the order is higher, the effect of the damping ratio will become worse, and the accuracy of the method needs to be improved.
【學位授予單位】：中國地震局工程力學研究所
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU317

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