本文選題：時-頻特征參數(shù)　切入點：擬合功率譜　出處：《西南交通大學》2017年碩士論文

【摘要】：地震動輸入正確與否是決定結(jié)構(gòu)地震響應(yīng)準確性的關(guān)鍵因素,特別是對于平面尺寸很大的大跨度結(jié)構(gòu)物,比如橋梁、石油管線、海洋平臺等生命線工程,若采用一致地震激勵輸入來做抗震分析,顯然是不夠準確的,因為大跨結(jié)構(gòu)尺寸相對于地震波波長而言不可忽略,故各支點的地震動是不同的,且地震波數(shù)量有限性、隨機性和不確定性等限制了多點直接動力分析法應(yīng)用到實際工程。只有考慮了各支點的不同地震激勵,才能確保大跨度結(jié)構(gòu)地震響應(yīng)的準確性,因此模擬生成具有特性參數(shù)的多點地震動是本文研究的重要方向。本文為了較為真實地模擬實際地震動的多維性、空間性及非平穩(wěn)性,具體從以下幾個方面進行研究:(1)針對地震動加速度時程的特征參數(shù)的話題進行了討論,歸納和總結(jié)了地震動時域特征參數(shù)和頻域特征參數(shù)的統(tǒng)計模型和相應(yīng)的回歸參數(shù)。(2)研究了擬合功率譜和擬合設(shè)計反應(yīng)譜合成空間多點非平穩(wěn)地震動時程,首先將設(shè)計反應(yīng)譜轉(zhuǎn)化為當量功率譜(目標功率譜);然后將功率譜密度函數(shù)矩陣由一維擴展到三維考慮地震波的多維性;再添加包絡(luò)函數(shù)模型即考慮地震動非平穩(wěn)性,并利用逆傅里葉變換合成了非平穩(wěn)地震動時程;最后將合成的地震動時程采用頻域方法迭代修正時程幅值,得到了滿足精度要求的地震動時程曲線。(3)基于相位差譜合成空間多維多點非平穩(wěn)地震動時程,首先研究了相位譜與地震動時程非平穩(wěn)性的相互關(guān)系,采用計算機隨機生成[0,2π]均勻分布的相位譜不能使地震動時程具有非平穩(wěn)性;然后引入了相位差譜的概念,并研究分析了相位差譜的頻數(shù)分布情況;最后構(gòu)造相位差譜模型合成了空間多維多點非平穩(wěn)地震動時程。(4)對比研究了基于PEER地震動數(shù)據(jù)庫選取和人工合成兩類地震動作用下橋梁結(jié)構(gòu)的響應(yīng),驗證了人工地震動的準確性。最后將人工合成的多維多點非平穩(wěn)地震動用于甌江特大橋地震響應(yīng)計算。
[Abstract]:Whether the input of ground motion is correct or not is the key factor to determine the accuracy of seismic response of structures, especially for large span structures with large plane size, such as bridges, oil pipelines, offshore platforms and other lifeline projects. It is obviously not accurate to use uniform seismic excitation input to do seismic analysis, because the size of large span structure can not be ignored relative to the wavelength of seismic wave, so the ground motion of each fulcrum is different, and the number of seismic waves is limited. Randomness and uncertainty limit the application of direct multi-point dynamic analysis to practical projects. The accuracy of seismic response of long-span structures can only be ensured by considering the different seismic excitation at each fulcrum. Therefore, it is an important research direction to simulate the multi-point ground motion with characteristic parameters. In order to simulate the multi-dimensional, spatial and non-stationary of the actual ground motion, The topic of characteristic parameters of acceleration time history of ground motion is discussed from the following aspects. The statistical models of time-domain and frequency-domain characteristic parameters of ground motion and the corresponding regression parameters are summarized. The time history of multi-point nonstationary ground motion in space by fitting power spectrum and fitting design response spectrum is studied. First, the design response spectrum is transformed into equivalent power spectrum (target power spectrum); then, the power spectrum density function matrix is extended from one dimension to three dimensions to consider the multi-dimension of seismic wave, and then the envelope function model is added to consider the nonstationarity of ground motion. The time history of non-stationary ground motion is synthesized by inverse Fourier transform, and the amplitude of the time history is modified iteratively by frequency domain method. In this paper, the time-history curve of ground motion satisfying the precision requirement is obtained. Based on the phase difference spectrum, the multi-dimensional multi-point non-stationary motion time history is synthesized. The relationship between the phase spectrum and the nonstationarity of the motion process is studied. The random generation of phase spectrum by computer can not make the time history of ground motion nonstationary, then the concept of phase difference spectrum is introduced, and the frequency distribution of phase difference spectrum is studied and analyzed. Finally, the phase difference spectrum model is constructed to synthesize the multi-dimensional multipoint non-stationary ground motion time history. The responses of bridge structures under the action of PEER seismic database selection and artificial synthesis are compared and studied. The accuracy of artificial ground motion is verified. Finally, the synthetic multi-dimensional non-stationary ground motion is used to calculate the seismic response of Oujiang super bridge.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU311.3

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