【摘要】：如今中小跨徑梁橋以預(yù)應(yīng)力混凝土結(jié)構(gòu)占據(jù)主導(dǎo)地位,因?yàn)轭A(yù)應(yīng)力能提高結(jié)構(gòu)的抗裂性能,是改善工作性能的重要手段,是在役預(yù)應(yīng)力混凝土結(jié)構(gòu)的可靠性評(píng)估的最重要的指標(biāo)之一。然而,目前還沒有成熟的檢測(cè)在役預(yù)應(yīng)力混凝土結(jié)構(gòu)有效預(yù)應(yīng)力的方法,較多根據(jù)規(guī)范中預(yù)應(yīng)力損失理論估算得有效預(yù)應(yīng)力,預(yù)應(yīng)力損失各項(xiàng)因素間各自獨(dú)立且非線性,導(dǎo)致了計(jì)算的復(fù)雜性。也可以結(jié)構(gòu)建設(shè)期間事先埋入測(cè)試設(shè)備,該種方法雖有較高精度,但是其需要在建設(shè)期安裝的特點(diǎn),使其缺乏實(shí)用性且增加工程成本。因此,研究一種快速且無損的在役預(yù)應(yīng)力混凝土結(jié)構(gòu)有效預(yù)應(yīng)力的檢測(cè)方法,具有重要的工程意義。首先,列出了預(yù)應(yīng)力與動(dòng)剛度關(guān)系的理論模型,包括基本振動(dòng)理論模型、傳統(tǒng)分析模型、Kirchhoff動(dòng)力模型、Kim Jeong-Tae理論、李瑞鴿理論,對(duì)比理論模型的原理及前人對(duì)預(yù)應(yīng)力與頻率間關(guān)系的試驗(yàn)研究,最終選定合理理論模型作為本文研究依據(jù)。同時(shí),總結(jié)了運(yùn)用實(shí)際動(dòng)剛度、靜剛度進(jìn)行有效剛度修正的公式,為試驗(yàn)后續(xù)數(shù)據(jù)分析提供思路啟發(fā)。另外,介紹了磁通量傳感器的工作原理,為后續(xù)研究提供理論依據(jù)。按照應(yīng)力等效原則,預(yù)應(yīng)力混凝土T梁模型采用標(biāo)準(zhǔn)T梁縮尺比例設(shè)計(jì)而成,詳細(xì)介紹了模型尺寸設(shè)計(jì)情況。然后,介紹了試驗(yàn)方法、測(cè)點(diǎn)布置、數(shù)據(jù)采集及注意事項(xiàng)。為保證試驗(yàn)測(cè)試數(shù)據(jù)的精確度,研究并對(duì)比了多種力錘激勵(lì)方法,探討影響頻率測(cè)試的各種因素,提出最優(yōu)方案進(jìn)行試驗(yàn)。建立有限元模型進(jìn)行模態(tài)分析,介紹了模態(tài)分析建模的注意要點(diǎn)及提供了實(shí)驗(yàn)頻率理論值。實(shí)驗(yàn)采用靜剛度(撓度)、動(dòng)剛度(頻率)、磁通量三種測(cè)試手段,對(duì)三片預(yù)應(yīng)力混凝土T梁進(jìn)行試驗(yàn)研究,推出靜剛度與預(yù)應(yīng)力之間的關(guān)系、動(dòng)剛度與預(yù)應(yīng)力之間的關(guān)系,嘗試提出一種測(cè)試結(jié)構(gòu)的靜剛度或動(dòng)剛度,再對(duì)在役預(yù)應(yīng)力混凝土結(jié)構(gòu)有效預(yù)應(yīng)力進(jìn)行評(píng)價(jià)的方法。另外,確定了磁通量傳感器測(cè)試精度及其適用性,為有效預(yù)應(yīng)力的檢測(cè)方法及評(píng)價(jià)提供了一定的參考。
[Abstract]:Nowadays, prestressed concrete structure dominates the small and medium span beam bridge, because prestress can improve the crack resistance of the structure, is an important means to improve the working performance, and is one of the most important indexes to evaluate the reliability of in-service prestressed concrete structure. However, at present, there is no mature method to detect the effective prestress of prestressed concrete structures in service. According to the prestress loss theory in the code, the effective prestress is estimated. The factors of prestress loss are independent and nonlinear, which leads to the complexity of calculation. The test equipment can also be embedded in advance during the construction of the structure. Although this method has high accuracy, it needs to be installed in the construction period, so that it is lack of practicability and increases the cost of the project. Therefore, it is of great engineering significance to study a fast and nondestructive method for detecting the effective prestress of prestressed concrete structures in service. Firstly, the theoretical models of the relationship between prestress and dynamic stiffness are listed, including basic vibration theoretical model, traditional analysis model, Kirchhoff dynamic model, Kim Jeong-Tae theory, Li Rui pigeon theory, the principle of comparative theoretical model and the previous experimental research on the relationship between prestress and frequency. Finally, the reasonable theoretical model is selected as the basis of this paper. At the same time, the formulas of effective stiffness correction by using actual dynamic stiffness and static stiffness are summarized, which provides inspiration for the subsequent data analysis of the test. In addition, the working principle of magnetic flux sensor is introduced, which provides a theoretical basis for further research. According to the principle of stress equivalence, the prestressed concrete T-beam model is designed by standard T-beam scale ratio, and the size design of the model is introduced in detail. Then, the test method, the layout of measuring points, data acquisition and matters needing attention are introduced. In order to ensure the accuracy of the test data, a variety of force hammer excitation methods are studied and compared, the factors affecting the frequency test are discussed, and the optimal scheme is put forward to carry out the test. The finite element model is established for modal analysis, and the key points for attention of modal analysis modeling are introduced and the theoretical values of experimental frequency are provided. In the experiment, three test methods of static stiffness (deflection), dynamic stiffness (frequency) and magnetic flux are used to study the three prestressed concrete T-beams. The relationship between static stiffness and prestress and the relationship between dynamic stiffness and prestress are deduced. A method of testing the static stiffness or dynamic stiffness of the structure and then evaluating the effective prestress of the in-service prestressed concrete structure is proposed. In addition, the test accuracy and applicability of magnetic flux sensor are determined, which provides a certain reference for the detection method and evaluation of effective prestress.
【學(xué)位授予單位】：長(zhǎng)沙理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U445.57

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 劉齡嘉,賀拴海,趙小星;在役混凝土簡(jiǎn)支梁有效預(yù)應(yīng)力計(jì)算[J];交通運(yùn)輸工程學(xué)報(bào);2005年03期

，

本文編號(hào)：2502133