【摘要】：改革開放以來特別是近十幾年新中國的懸索橋發(fā)展十分迅速,隨著經(jīng)濟(jì)發(fā)展的需要全國各地新建了很多的懸索橋,懸索橋日漸成為我國交通的重要組成部分。研究懸索橋的動(dòng)力特性及自振特性對(duì)于了解懸索橋在地震作用下的動(dòng)力反應(yīng)具有十分重要的意義,也是懸索橋抗震設(shè)計(jì)的基礎(chǔ)。雖然到目前為止還沒有懸索橋在地震中遭到破壞,但是由于懸索橋的造價(jià)十分高昂,一旦破壞修護(hù)起來非常困難且維修費(fèi)用很高,并且由此造成的交通中斷也會(huì)給社會(huì)經(jīng)濟(jì)發(fā)展帶來巨大的損失。況且,由于地震作用的復(fù)雜性和懸索橋結(jié)構(gòu)自身的特點(diǎn),目前并沒有具有普遍適用意義的關(guān)于懸索橋抗震設(shè)計(jì)的規(guī)范。因此,研究橋梁結(jié)構(gòu)參數(shù)對(duì)自振特性及地震動(dòng)響應(yīng)的影響,分析懸索橋結(jié)構(gòu)在地震作用下的薄弱環(huán)節(jié),找到最優(yōu)結(jié)構(gòu)形式,進(jìn)而為今后懸索橋設(shè)計(jì)提供依據(jù),就具有非常重要的現(xiàn)實(shí)意義。本文依托青草背長江大橋?yàn)槌跏寄Ｐ?根據(jù)其工程概況采用大型有限元分析軟件Midas/civil建立了分析模型,依次分析了橋面質(zhì)量、主梁剛度、主纜剛度、主塔剛度以及矢跨比的變化對(duì)懸索橋自振特性的影響。通過分析得到:橋面系質(zhì)量和矢跨比對(duì)于懸索橋自振特性的影響是最大的,加勁梁剛度次之;而主塔剛度對(duì)體系的頻率和固有振型幾乎沒有任何影響。主梁豎向振動(dòng)和橫向振動(dòng)受橋面系質(zhì)量的影響較大,隨著橋面系質(zhì)量的增加,橫向自振頻率和豎向自振頻率減少。主纜剛度的變化對(duì)豎彎的影響比較明顯。改變懸索橋的矢跨比,會(huì)使懸索橋自振特征階次重新排序,減小矢跨比將使各主要振型的頻率升高。然后計(jì)算分析橋面系恒載、主梁剛度、主纜剛度和主塔剛度對(duì)懸索橋地震動(dòng)響應(yīng)的影響。得出改變不同的參數(shù),在不同方向的地震波作用下,懸索橋關(guān)鍵部位的響應(yīng)敏感性不盡相同,進(jìn)而運(yùn)用能力/需求比法,對(duì)青草背大橋主塔在順橋向+豎向地震波和橫橋向+豎向地震波作用下進(jìn)行易損性分析,得到了青草背大橋該橋主塔薄弱環(huán)節(jié)發(fā)生在順橋向+豎向地震波作用下,主塔根部、主塔塔高在0m~24m和80m~140m處。
[Abstract]:Since the reform and opening up, especially in recent years, the suspension bridge in New China has developed very rapidly. with the needs of economic development, many new suspension bridges have been built all over the country, and suspension bridges have increasingly become an important part of traffic in our country. It is of great significance to study the dynamic and natural vibration characteristics of suspension bridges for understanding the dynamic response of suspension bridges under earthquake, and it is also the basis of seismic design of suspension bridges. Although up to now, no suspension bridge has been damaged in the earthquake, but because of the high cost of the suspension bridge, once the damage and repair is very difficult and the maintenance cost is very high, and the traffic interruption will also bring great losses to the social and economic development. Moreover, due to the complexity of seismic action and the characteristics of suspension bridge structure, there is no code for seismic design of suspension bridge. Therefore, it is of great practical significance to study the influence of bridge structural parameters on natural vibration characteristics and ground motion response, to analyze the weak links of suspension bridge structure under earthquake action, to find the optimal structural form, and to provide the basis for the design of suspension bridge in the future. In this paper, based on the Qingcaobi Yangtze River Bridge as the initial model, according to its engineering situation, the analysis model is established by using the large-scale finite element analysis software Midas/civil. The effects of bridge deck mass, main beam stiffness, main cable stiffness, main tower stiffness and rise-span ratio on the natural vibration characteristics of suspension bridge are analyzed in turn. Through the analysis, it is found that the mass of the bridge deck system and the ratio of rise to span have the greatest influence on the natural vibration characteristics of the suspension bridge, followed by the stiffness of the stiffened beam, while the stiffness of the main tower has little effect on the frequency and natural vibration mode of the system. The vertical vibration and transverse vibration of the main beam are greatly affected by the quality of the bridge deck system. With the increase of the quality of the bridge deck system, the transverse natural vibration frequency and vertical natural vibration frequency decrease. The influence of the stiffness of the main cable on the vertical bending is obvious. By changing the rise-span ratio of the suspension bridge, the natural vibration characteristic order of the suspension bridge will be reordered, and the frequency of the main vibration modes will be increased by reducing the rise-span ratio. Then the effects of bridge deck system dead load, main beam stiffness, main cable stiffness and main tower stiffness on the ground motion response of suspension bridge are calculated and analyzed. It is concluded that the response sensitivity of the key parts of the suspension bridge is not the same under the action of different seismic waves in different directions, and then the vulnerability of the main tower of Qingcaobi Bridge under the action of vertical seismic wave and vertical seismic wave of the bridge is analyzed by using the capacity / demand ratio method. It is obtained that the weak link of the main tower of Qingcaobei Bridge occurs under the action of vertical seismic wave along the bridge and the root of the main tower. The main tower is high at 0m~24m and 80m~140m.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U442.55

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本文編號(hào)：2506515