【摘要】：荷載試驗(yàn)評定橋梁雖然可以全面反映結(jié)構(gòu)的實(shí)際工作狀況，但耗費(fèi)較大，因此動力測定試驗(yàn)快速評定法就成了目前研究的熱點(diǎn)。由于動力法進(jìn)行鋼筋混凝土結(jié)構(gòu)的評估更能真實(shí)反映其與結(jié)構(gòu)在移動荷載作用下的實(shí)際工作狀況，因此動力測試方法和系統(tǒng)識別理論的研究與應(yīng)用具有廣闊的前景。本文從動靜力試驗(yàn)著手，以探索鋼筋混凝土矩形梁快速動力評定的可行性。 闡述了動態(tài)損傷識別的典型方法，沖擊彈性波檢測技術(shù)的基本理論，振動結(jié)構(gòu)測試與頻譜分析方法�；谏鲜隼碚撨M(jìn)行模型試驗(yàn)的設(shè)計(jì)，包括試驗(yàn)梁的參數(shù)、測點(diǎn)布置、試驗(yàn)流程安排及數(shù)據(jù)采集等方面。 運(yùn)用實(shí)測回彈值對試驗(yàn)梁的強(qiáng)度進(jìn)行計(jì)算，測試各個(gè)工況下試驗(yàn)梁的加載全過程應(yīng)變云圖、裂縫開展情況及分布特征，計(jì)算出裂縫的寬度大小，并測試出梁體破壞時(shí)的極限承載力，從而全面分析了梁體從彈性階段到破壞階段的工作特性。 對沖擊彈性波的測試和梁的應(yīng)變分布及裂縫特征的分析，其規(guī)律可以歸結(jié)為梁體在試驗(yàn)加載前，錘擊所產(chǎn)生的沖擊彈性波信號存在著初始的微小時(shí)間差。當(dāng)采用兩個(gè)較小量級荷載對梁進(jìn)行反復(fù)加載后，，所測得的彈性沖擊波的信號的時(shí)間差與梁體空載前的激振結(jié)果并無明顯的變化。梁體產(chǎn)生裂縫后，彈性沖擊波的信號出現(xiàn)了比較明顯的差異，這種差異主要與裂縫的分布位置及裂縫的寬度的大小有關(guān)。這樣，就可以實(shí)現(xiàn)對結(jié)構(gòu)的完整性檢測，識別損傷的位置和損傷程度的大小。 通過對梁的跨中最大沖擊動撓度的測試，計(jì)算出瞬態(tài)沖擊曲率均處在較小的水平，而且破壞后梁的曲率較彈性階段有所增大，這正是動位移增大的另一方面的反映。再者，通過數(shù)學(xué)上的多元線性回歸分析，梁體瞬態(tài)沖擊最大動撓度和梁的極限承載力之間存在著線性關(guān)系。試驗(yàn)梁在破壞階段較彈性工作階段的跨中最大沖擊動撓度有一定的增量，這種增量與裂縫寬度之間存在著線性關(guān)系。從而，在確定的沖擊荷載作用下，結(jié)構(gòu)損傷前后的動撓度增量可以識別結(jié)構(gòu)的完整性及損傷程度的大小。 最后基于研究成果，建立了一套鋼筋混凝土和預(yù)應(yīng)力混凝土梁橋的動力評定方法，為實(shí)際橋梁結(jié)構(gòu)安全性能快速評定提供指導(dǎo)。
[Abstract]:Although the load test evaluation bridge can reflect the actual working condition of the structure completely, but the cost is large, so the fast evaluation method of dynamic measurement test has become the hot spot of the research at present. Because the evaluation of reinforced concrete structure by dynamic method can reflect the actual working condition of the reinforced concrete structure and the structure under moving load, the research and application of dynamic test method and system identification theory have a broad prospect. In this paper, the feasibility of rapid dynamic evaluation of reinforced concrete rectangular beams is explored by means of dynamic and static tests. The typical methods of dynamic damage identification, the basic theory of shock elastic wave detection technology, the method of vibration structure test and spectrum analysis are described. Based on the above theory, the design of the model test is carried out, including the parameters of the test beam, the layout of the measuring points, the arrangement of the test flow and the data acquisition. The strength of the test beam is calculated by using the measured rebound value, the strain cloud diagram of the whole loading process of the test beam under various working conditions is tested, the crack development and distribution characteristics are calculated, and the width of the crack is calculated. The ultimate bearing capacity of the beam is tested, and the working characteristics of the beam from the elastic stage to the failure stage are analyzed. The measurement of the shock elastic wave and the analysis of the strain distribution and crack characteristics of the beam can be attributed to the initial small time difference of the impact elastic wave signal produced by the hammer before the test loading. The time difference between the measured elastic shock wave signals and the excitation results before the beam is left unloaded has no obvious change after repeated loading on the beam with two smaller loads. There are obvious differences in the signals of elastic shock waves after the cracks occur in the beam body, which are mainly related to the distribution of the cracks and the width of the cracks. In this way, the integrity of the structure can be detected and the damage location and damage degree can be identified. Through the measurement of the maximum impact dynamic deflection of the beam in the span, it is found that the transient impact curvature is at a smaller level, and the curvature of the beam after the failure is larger than that of the elastic stage, which is another reflection of the increase of the dynamic displacement. Furthermore, through multiple linear regression analysis, there is a linear relationship between the maximum dynamic deflection of the beam and the ultimate bearing capacity of the beam. There is a certain increment in the maximum impact deflection of the test beam in the failure stage than in the elastic working stage, and there is a linear relationship between the increment and the crack width. Therefore, the dynamic deflection increment before and after damage can identify the integrity of the structure and the magnitude of the damage under a certain impact load. Finally, based on the research results, a set of dynamic assessment method of reinforced concrete and prestressed concrete beam bridges is established, which provides guidance for rapid evaluation of the safety performance of practical bridge structures.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U448.33;U441

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