本文選題：鋼管混凝土 + 壓電智能骨料��； 參考：《沈陽建筑大學(xué)》2013年碩士論文

【摘要】：近年來,隨著建筑高度的不斷提高,鋼管混凝土結(jié)構(gòu)突顯其獨特的優(yōu)勢。然而,由于鋼管內(nèi)部隔板的存在,導(dǎo)致混凝土在澆筑完成之后,隔板下部存在局部孔洞等不密實的情況。此外,由于混凝土本身的收縮,使鋼管與核心混凝土在界面處脫開或者是核心混凝土出現(xiàn)空洞、不密實等現(xiàn)象。混凝土的密實性是保證鋼管混凝土結(jié)構(gòu)可靠性的重要前提,直接影響整個結(jié)構(gòu)的可靠性能。因此,對鋼管混凝土密實性進(jìn)行檢測將為結(jié)構(gòu)承載力評估提供參考。本文重點研究利用壓電智能骨料及波動法對混凝土密實性的進(jìn)行識別,并對其密實狀態(tài)進(jìn)行評估。主要有以下內(nèi)容： 第一部分,利用壓電陶瓷對鋼管混凝土柱內(nèi)部混凝土密實性進(jìn)行試驗研究,以確定不密實的位置和程度。將一組壓電陶瓷(如鎬鈦酸鉛,簡稱PZT)預(yù)埋在小體積混凝土中,制成具有驅(qū)動和傳感雙重功能的“智能骨料”,并將其預(yù)埋在混凝土柱內(nèi)的指定位置。將一對“智能骨料”作為測試組,分別作為驅(qū)動器和傳感器激勵和接收信號。通過比較兩骨料處接收信號并以歐式距離確定兩個信號之間的差別,從而實現(xiàn)鋼管混凝土密實性的評估。此外本文以超聲法對混凝土密實性進(jìn)行同步測試,同樣能準(zhǔn)確反映鋼管內(nèi)核心混凝土的密實性情況,表明本文提出的密實性檢測新方法是可行的、有效的。 第二部分,通過現(xiàn)代聲學(xué)時間反轉(zhuǎn)概念將導(dǎo)波傳播應(yīng)用到鋼管混凝土結(jié)構(gòu)密實性的識別中。為了有效描述混凝土密實性程度,定義兩個損傷指數(shù)：TR和SYM。激發(fā)“智能骨料”產(chǎn)生監(jiān)測信號,另一組“智能骨料”接收監(jiān)測信號,同時對接收信號在時域內(nèi)反轉(zhuǎn)再次激勵,接收重構(gòu)信號。共制作6組足尺試件,分別進(jìn)行人工缺陷和實際形成的不密實區(qū)域的測試。通過選擇合適的窄帶波激勵信號和有效的信號處理,評估混凝土的密實性。試驗結(jié)果表明：該方法的可行性,可以用這兩個損傷指數(shù)很好地表達(dá)不密實區(qū)域和程度。 第三部分,采用大型通用有限元分析軟件ANSYS模擬人工缺陷在不同信號激勵頻率下的響應(yīng),為混凝土激勵頻率的選取提供參考。通過施加激勵波形的位移,采用瞬態(tài)分析,并改變激勵波形的周期,模擬結(jié)果與實驗測試選取的頻率相一致。
[Abstract]:In recent years, with the continuous improvement of building height, concrete filled steel tube (CFST) structure highlights its unique advantages. However, due to the existence of the internal partition of the steel tube, there are local holes in the lower part of the partition plate after the completion of concrete pouring. In addition, due to the shrinkage of the concrete itself, the steel pipe and the core concrete are separated at the interface or the core concrete is hollow and undense. The compactness of concrete is an important prerequisite to ensure the reliability of concrete-filled steel tube (CFST) structure, which directly affects the reliability of the whole structure. Therefore, testing the compactness of concrete-filled steel tube (CFST) will provide a reference for the evaluation of structural bearing capacity. In this paper, piezoelectric intelligent aggregate and wave method are used to identify and evaluate the compactness of concrete. The main contents are as follows: in the first part, the concrete compactness of concrete-filled steel tubular columns is studied by using piezoelectric ceramics to determine the position and degree of uncompaction. A group of piezoelectric ceramics (such as lead pick titanate, PZT) are preburied in small volume concrete to make "intelligent aggregate" with dual functions of driving and sensing, and it is preburied in the designated position of concrete column. A pair of "smart aggregates" are used as test groups, as actuators and sensors to excite and receive signals, respectively. By comparing the received signals between the two aggregates and determining the difference between the two signals with the Euclidean distance, the compactness of concrete-filled steel tubular (CFST) can be evaluated. In addition, the simultaneous testing of the compactness of concrete by ultrasonic method can also accurately reflect the compactness of the core concrete in the steel tube, which shows that the new method proposed in this paper is feasible and effective. In the second part, guided wave propagation is applied to identify the compactness of concrete-filled steel tubular structures through the concept of modern acoustic time reversal. In order to describe the compactness of concrete effectively, two damage indices: TR and Sym are defined. The "intelligent aggregate" is stimulated to generate the monitoring signal, the other group of "intelligent aggregate" receives the monitoring signal, and at the same time, the received signal is reexcited in the time domain to receive the reconstructed signal. Six groups of full-scale specimens were made and the artificial defects and the actual undense areas were tested. The compactness of concrete is evaluated by selecting appropriate narrowband wave excitation signal and effective signal processing. The experimental results show that the proposed method is feasible and can be used to express the undense region and degree. In the third part, the finite element analysis software ANSYS is used to simulate the response of artificial defects under different signal excitation frequencies, which provides a reference for the selection of concrete excitation frequency. By applying the displacement of the excitation waveform, using transient analysis, and changing the period of the excitation waveform, the simulation results are consistent with the frequency selected by the experimental test.
【學(xué)位授予單位】：沈陽建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU398.9

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