本文選題：結(jié)構(gòu)參數(shù)識(shí)別　切入點(diǎn)：模態(tài)坐標(biāo)　出處：《中國(guó)地震局工程力學(xué)研究所》2017年碩士論文

【摘要】：結(jié)構(gòu)模態(tài)參數(shù)識(shí)別是結(jié)構(gòu)動(dòng)力特性研究、結(jié)構(gòu)損傷診斷和結(jié)構(gòu)安全性評(píng)估等方面研究工作的基礎(chǔ)和前提,其在機(jī)械工程、航空工程和土木工程等領(lǐng)域受到了廣泛的關(guān)注和研究。在地震工程學(xué)領(lǐng)域,通過(guò)結(jié)構(gòu)在實(shí)際地震中測(cè)得的響應(yīng)數(shù)據(jù)來(lái)準(zhǔn)確的識(shí)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(shí)別方法及其改進(jìn)算法被提出和應(yīng)用。本文通過(guò)數(shù)值模擬和振動(dòng)臺(tái)試驗(yàn)地震響應(yīng)記錄,對(duì)多種模態(tài)參數(shù)識(shí)別方法進(jìn)行了比較分析,主要研究工作和結(jié)論如下:1、對(duì)國(guó)內(nèi)外結(jié)構(gòu)模態(tài)參數(shù)識(shí)別方法的發(fā)展和現(xiàn)狀進(jìn)行了探討,針對(duì)本文中用到的模態(tài)參數(shù)方法,詳細(xì)介紹了其理論基礎(chǔ),包括物理坐標(biāo)和模態(tài)坐標(biāo)的相互轉(zhuǎn)換、頻響函數(shù)和脈沖響應(yīng)函數(shù)的概念、相關(guān)函數(shù)及其應(yīng)用等。2、通過(guò)一個(gè)三層平面框架模型算例,驗(yàn)證了自然環(huán)境激勵(lì)法這一時(shí)域信號(hào)預(yù)處理方法的可行性,該方法利用結(jié)構(gòu)在白噪聲激勵(lì)下響應(yīng)的互相關(guān)函數(shù)來(lái)替代結(jié)構(gòu)的自由衰減信號(hào),并指出在相關(guān)函數(shù)計(jì)算的過(guò)程中,需要一定的原始輸入數(shù)據(jù)長(zhǎng)度來(lái)降低白噪聲隨機(jī)性的影響,其次要設(shè)置合理的自由衰減信號(hào)長(zhǎng)度以降低信噪比的影響。3、重點(diǎn)研究了ITD、STD、ARX這三種模態(tài)參數(shù)識(shí)別方法,并應(yīng)用于數(shù)值模擬結(jié)構(gòu)的模態(tài)參數(shù)識(shí)別。通過(guò)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(yīng)為輸入數(shù)據(jù)時(shí),能準(zhǔn)確的識(shí)別出結(jié)構(gòu)頻率,STD法相對(duì)于ITD法的識(shí)別精度更高,且計(jì)算速度更快;2)STD法和ITD法方法都受白噪聲平穩(wěn)隨機(jī)性的影響,需要足夠的信號(hào)長(zhǎng)度來(lái)降低誤差,ARX方法直接利用結(jié)構(gòu)響應(yīng)和輸入數(shù)據(jù),穩(wěn)定性更高。4、以一個(gè)3層RC框架結(jié)構(gòu)模型的振動(dòng)臺(tái)試驗(yàn)為研究對(duì)象,采用STD法和ARX法分別對(duì)不同工況后的試驗(yàn)結(jié)構(gòu)模型進(jìn)行了參數(shù)識(shí)別,并與試驗(yàn)現(xiàn)象進(jìn)行了對(duì)比分析。結(jié)果表明:1)當(dāng)結(jié)構(gòu)處于完好或輕微破壞時(shí),這兩種方法對(duì)頻率的識(shí)別結(jié)果比較接近,進(jìn)一步說(shuō)明了這兩種方法及計(jì)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(shí)兩種方法在階數(shù)較低時(shí)會(huì)丟失真實(shí)模態(tài),在階數(shù)較高時(shí)又會(huì)產(chǎn)生虛假模態(tài),阻尼比識(shí)別效果變差,方法的準(zhǔn)確性有待改進(jìn)。
[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(xué)位授予單位】：中國(guó)地震局工程力學(xué)研究所
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU317

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