本文選題：大寧河峽谷　切入點：大跨度鋼桁拱橋　出處：《重慶大學》2014年博士論文　論文類型：學位論文

【摘要】：鋼桁架拱橋具有結(jié)構(gòu)輕巧、受力合理、便于節(jié)段拼裝和施工快捷等優(yōu)勢，在我國西部溝壑縱橫的山區(qū)橋梁建設(shè)中獲得了越來越廣泛的應(yīng)用。由于跨越峽谷的需要，拱橋的跨度一般超過300m。跨度的提升將導致拱橋整體剛度的下降、阻尼比的減小，使得結(jié)構(gòu)對風的敏感性增加，風致振動對結(jié)構(gòu)設(shè)計和施工的影響變得重要，尤其對于剛度較弱的懸臂施工階段。而現(xiàn)行《公路橋梁抗風規(guī)范》條文中對于山區(qū)橋梁抗風問題未給出相關(guān)的細則，不便于山區(qū)橋梁的抗風設(shè)計。論文以位于西部山區(qū)的大寧河特大橋為研究對象，開展了橋位風觀測，分析了橋址區(qū)域風場分布的規(guī)律。利用現(xiàn)場實測獲得的風場特性參數(shù)，參考規(guī)范中的建議風譜，，擬合了符合橋位區(qū)風場特性的風譜參數(shù)。利用橋位區(qū)風場的風譜，開展了大跨度桁架拱橋成橋狀態(tài)、合龍施工態(tài)和最大懸臂施工態(tài)結(jié)構(gòu)的抖振響應(yīng)，并與規(guī)范中建議風譜的計算結(jié)果進行了對比分析，以檢驗現(xiàn)行規(guī)范對于山區(qū)橋梁抗風計算的指導程度。本文的工作主要有以下幾個方面： 1）利用C#程序開發(fā)語言，采用WPF（Windows Presentation Foundation）框架開發(fā)了風特性觀測和分析處理軟件。程序具有數(shù)據(jù)文件分割處理的功能，能夠快速準確地對風觀測數(shù)據(jù)進行計算分析，輸出風場特性參數(shù)，可為橋址處海量的風場觀測數(shù)據(jù)的處理工作提供便利的分析工具。 2）通過對風特性數(shù)據(jù)的分析得到了大寧河峽谷區(qū)橋位處風場的分布規(guī)律。橋址處平均風速沿高度的變化規(guī)律不符合規(guī)范給出的指數(shù)分布或?qū)?shù)分布。對于西部山區(qū)的這類山地地貌來說，風的脈動成分比較大，離拱腳10m高度測得的水平向湍流強度超過了40%，離拱腳90m高度所測得的也可達20%，遠大于規(guī)范中D類地表粗糙度下的參考值。此結(jié)論表明西部山區(qū)的橋梁抗風設(shè)計需要考慮大紊流度影響。 3）采用數(shù)理統(tǒng)計方法對大橋橋址處的實測風速譜進行擬合，得到水平脈動風速譜和垂直脈動風速譜表達式，發(fā)現(xiàn)該橋橋址處實測脈動風速譜與我國橋梁抗風規(guī)范中建議使用的脈動風速譜存在差異，其低頻段的能量小于規(guī)范風譜的值。該現(xiàn)象將直接影響低頻段模態(tài)對抖振共振響應(yīng)的貢獻。 4）利用ANSYS有限元分析軟件，建立了大寧河特大橋成橋態(tài)、合龍態(tài)和懸臂施工態(tài)三類空間有限元模型，獲得了結(jié)構(gòu)動力特性。分別利用實測擬合風譜和規(guī)范建議風譜，開展了三種狀態(tài)下結(jié)構(gòu)的抖振響應(yīng)分析。 5）抖振響應(yīng)結(jié)果表明，該橋成橋狀態(tài)的側(cè)向位移較大，豎向和扭轉(zhuǎn)向抖振位移響應(yīng)較小，且跨中位移顯著大于兩側(cè)位移。成橋態(tài)和合龍態(tài)的抖振響應(yīng)主要受到對稱和反對稱模態(tài)共同作用，而最大懸臂施工態(tài)基本只受到對稱模態(tài)影響，其抖振響應(yīng)幅值顯著大于另外兩個狀態(tài)，且其扭轉(zhuǎn)抖振受到的是對稱扭轉(zhuǎn)模態(tài)影響，而非附帶扭轉(zhuǎn)形態(tài)的橫向彎曲模態(tài)影響。 6）三種狀態(tài)結(jié)構(gòu)的抖振計算結(jié)果表明，規(guī)范建議風譜的計算值要顯著大于現(xiàn)場實測擬合風譜的計算值，且在剛度相對較弱的橫向差異較大。通過對比抖振響應(yīng)譜可以進一步發(fā)現(xiàn)，兩類風譜對于結(jié)構(gòu)背景響應(yīng)的貢獻是相當?shù)�，在共振模態(tài)的階次和分布上也是一致的；不同的是規(guī)范風譜所引起的共振響應(yīng)更大，尤其對于低頻段模態(tài)。計算結(jié)果也表明，現(xiàn)行規(guī)范關(guān)于抖振計算的條文可以指導山區(qū)大跨度拱橋的抗風計算，但其在山區(qū)橋梁抖振計算中的通用性還需要通過更多研究結(jié)果的證明。
[Abstract]:The steel truss arch bridge has a compact structure, reasonable stress, easy segmental and quick construction and other advantages, is widely used in the construction of bridges in mountainous areas in Western China. Due to the ravines across the canyon, the span of arch bridge is generally more than 300m. span lifting arch bridge will lead to the overall stiffness decreased, the damping ratio decreases, increased sensitivity makes the structure of the wind, the wind-induced vibration of structure design and construction become important, especially for the cantilever construction stage stiffness is weak. While the current rules for highway bridges Standard < > the provision of mountain bridge wind resistance are not related, for the wind resistant design of bridges in mountainous areas the thesis is located in the western mountainous area. The Daning River Bridge as the research object, carry out the bridge wind observation, analysis of the bridge site area wind field distribution. The wind field obtained by field test The characteristic parameters, reference standard in wind spectrum, fitting with the bridge area wind field characteristics of wind spectrum parameters. By using the bridge area of the wind field wind spectrum, to carry out a large span truss arch bridge, buffeting state and maximum closure construction of cantilever construction structure response, and code proposed the calculation of wind spectrum results were analyzed. The degree of guidance to test the existing standard for mountain bridge wind calculation. The main work of this paper are as follows:
1) the use of C# programming language, using WPF (Windows Presentation Foundation) framework for the development of Wind Characteristics Observation and analysis software. The program has a data file segmentation function, can quickly and accurately calculate the wind observation data, the characteristic parameters of wind field output, provide convenient analysis tool for wind field observation data can work for the bridge site is massive.
2) by analyzing the characteristics of data obtained in the Daning River Valley area, the bridge is located at the bridge site of the wind field. The average wind velocity along the height variation with exponential or logarithmic distribution specification is given. For this type of mountain landscape in western mountains, the wind ripple component is relatively large, from the arch height of 10m levels measured by more than 40% to the turbulence intensity, from up to 20% foot arch height of 90m as measured by the standard is far greater than the D of the surface roughness of the reference value. The conclusion shows that the wind resistant design of bridges in western mountains to consider large turbulence effects.
3) the actual wind speed of the bridge at the bridge site by using mathematical statistic method spectral fitting, horizontal wind spectrum and vertical wind spectrum expression, found on the bridge site measured wind spectrum and our bridges in standard use of pulsating wind spectrum differences, the low frequency energy is less than the standard the wind spectrum value. This phenomenon will directly influence the low-frequency mode on the buffeting resonant response contribution.
4) using ANSYS finite element analysis software, the establishment of the Daning River Bridge bridge state, the closure of three kinds of state space finite element model and cantilever construction state, the dynamic characteristics of the structure. By fitting measured wind spectrum and standard wind spectrum, carried out three kinds of buffeting response analysis under the condition of the structure.
5) the buffeting response results show that the bridge's lateral displacement is large, vertical and torsional buffeting response to small and mid span displacement was significantly greater than that on both sides of displacement. The completion and closure state of the buffeting response is mainly affected by the symmetric and antisymmetric interaction mode, while the maximum cantilever construction state only by symmetry mode, the buffeting response amplitude was significantly greater than that of the other two states, and the torsional buffeting by the symmetrical torsional mode, rather than the transverse bending mode of incidental torsion form.
6) the three state structure buffeting calculation results show that the proposed calculation specification wind spectrum value is significantly greater than the calculated fitting measured wind spectrum field value, and larger in the lateral stiffness difference is relatively weak. By comparing the buffeting response spectrum can be found, two kinds of wind spectrum is equivalent to the structure background the contribution of the response, is consistent in resonance mode order and distribution; the difference is caused by the resonance specification wind spectrum response is larger, especially for low frequency mode. The calculation results also show that the current standard about wind buffeting calculation can guide the provisions of mountain long span arch bridge calculation, but its versatility in the calculation of buffeting of bridges in mountainous area also need to prove through more research results.

【學位授予單位】：重慶大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U441.3

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