獨塔混合梁斜拉橋摘要.doc

摘 要混合梁斜拉橋是指斜拉橋的主梁沿梁的長度方向由兩種不同材料組成,主跨的梁體為鋼梁,邊跨(或伸入主跨的一部分)的梁體為混凝土梁?；旌狭盒崩瓨蛴捎谄渲骺绮捎娩摿?所以具有跨越能力大的優(yōu)點,而邊跨采用混凝土梁從而起到了很好的錨固作用且兼有可降低建橋成本的特點。斜拉橋與其它一般梁式橋在結構體系、材料受力性能等方面都有明顯的差異，其抗風、抗震性能以及車振性能等均有其自身的特點。橋梁結構的動力學特性主要包括橋跨結構的自振頻率、振型、阻尼比以及在車輛、風、地震等動荷載作用下的動力響應等。斜拉橋的動力特性分析是研究斜拉橋動力行為的基礎，其自振特性決定其動力反應特性，分析斜拉橋自振特性意義重大。近半個世紀以來，斜拉橋的設計理論、結構風動穩(wěn)定試驗和減振控制、計算機技術的應用、有限元分析和施工質量的控制、檢測技術日趨成熟，與上述較成熟的理論相比，斜拉橋的動力特性分析方面較落后。目前，斜拉橋正不斷的向大跨度、輕型化方向發(fā)展，對其在動荷載(如車輛、風和地震等)作用下的動力響應研究更顯得十分迫切。橋梁結構的地震反應分析是一個抗震動力學問題。對橋梁結構進行地震反應分析，必須從抗震動力學出發(fā)來思考問題、解決問題，而橋梁結構的地震反應分析必須以地震場地的運動為依據。但是由于實際強震記錄的不足，這個關鍵問題還未能很好的解決，因此仍然是結構抗震設計計算中最薄弱的環(huán)節(jié)。斜拉橋動力學分析的方法大致可以分為兩類，一類為傳統(tǒng)的理論解析方法，對結構作一定的簡化后作解析分析，最后得出解析公式。另一類是有限元數(shù)值分析方法，利用電子計算機強大的計算功能采用有限單元法分析，該方法能夠更為真實地模擬實際結構，分析結果精度高。本橋采用有限元數(shù)值分析方法。本文在現(xiàn)有研究的基礎上，以廣州東沙特大橋為背景，圍繞獨塔混合梁斜拉橋動力特性及地震響應的分析，展開進一步的研究?；旌狭盒崩瓨蛴捎谄渲髁貉亓旱拈L度方向由兩種不同材料組成,主跨的梁體為鋼梁,邊跨為混凝土梁。因此混合梁斜拉橋的動力特性及抗震性能方面與混凝土斜拉橋及鋼箱梁斜拉橋相比，有其相似處，但亦有其自身的特色。本文在現(xiàn)有研究的基礎上，以廣州東沙特大橋作為計算背景，圍繞混合梁斜拉橋動力特性及混合梁斜拉橋地震響應的計算分析，展開了以下幾個方面的工作：1、以廣州東沙特大橋為背景，運用大型通用軟件ANSYS建立該橋的動力分析模型，對設置輔助墩和不設置輔助墩情況下的動力特性做比較分析。2、建立考慮在不同的參數(shù)影響下對其自振頻率的影響程度。如斜拉索的稀密程度、索塔、鋼混比等。3、基于地震響應時程反應分析基本理論，對獨塔混合梁斜拉橋分別在橫向+豎向地震波、縱向+豎向地震波、三向地震波作用下的地震時程影響做出分析，并對比考慮輔助墩相互作用和不考慮輔助墩相互作用兩種模型的地震時程影響本文以東沙大橋為例,利用ANSYS建立空間動力計算模型，分析了橋梁主要結構參數(shù)對其振動特性的影響，結果表明：對于獨塔混合梁斜拉橋，邊垮輔助墩可以大幅提高結構的整體剛度，而且斜拉索的稀密程度、索塔、鋼混比對其自振頻率均有不同程度影響。獨塔混合梁斜拉橋根據自身結構形式的不同,其動力特性也隨之變化。1,輔助墩的設置使得結構的整體剛度有較大的提高,改善了結構的動力性能; 除個別振型外(例如第六階主塔側彎 耦合主跨主梁側彎振型有無輔助墩其頻率基本相同) ,有無輔助墩對整體振型的出現(xiàn)次序及對應頻率影響較大。有輔助墩情況下，邊垮主梁沒有振動現(xiàn)象，而沒有輔助墩的情況下，邊垮有振動現(xiàn)象，如模型B的3、5、7、9、10階。2，斜拉索的稀密程度對結構面外振動頻率影響不明顯，而面內振動頻率影響稍大這說明斜拉索布置的稀密程度對提高結構的橫向剛度作用很小，而對全橋的豎向剛度作用很大。密索還能大大增加塔和梁的耦合現(xiàn)象。3，索塔剛度的加大對橋梁的面內頻率提高不明顯，對面外的頻率的提高顯著。4，鋼混比的減小會增大基礎頻率，但卻明顯的降低了其他振型的頻率。斜拉橋動力學特性的研究為橋梁的抗震設計、抗風設計以及車輛振動分析等方面的內容提供理論基礎。通過動力學分析能夠更真實地揭示斜拉橋的橋跨結構在汽車車輛荷載作用下的受力與變形狀況，并能夠描述橋跨結構在地震作用和風荷載作用下的結構響應。時程分析，建立了考慮輔助墩相互作用和不考慮輔助墩相互作用兩種模型，比較并分析了在三組地震波作用下，兩種模型的時程響應情況?；诘卣痦憫獣r程反應分析基本理論，對獨塔混合梁斜拉橋分別在橫向+豎向地震波、縱向+豎向地震波、三向地震波作用下的地震時程影響做出分析，并對比考慮輔助墩相互作用和不考慮輔助墩相互作用兩種模型的地震時程影響，得出以下結論：1、比較三組地震波情況下的位移及受力情況，對于獨塔混合梁斜拉橋塔梁墩固結體系，在地震波作用下，主要以豎向及縱向地震時程的影響為主，橫向地震時程影響相對較小。這是因為本橋的一階基本振型是主跨主梁豎彎，所以此結論符合本橋的振型規(guī)律。2、對比考慮輔助墩相互作用和不考慮輔助墩相互作用兩種模型，考慮輔助墩相互作用時，本橋剛度明顯增大，使得在三種地震類型激勵下本橋的位移、軸力、剪力、彎矩峰值增量較不考慮輔助墩相互作用時有不同程度減小。3、某些峰值大小與在何種類型地震激勵影響下有密切關系，例如無橫向地震波激勵情況下的塔底面外彎矩峰值和塔頂橫向位移峰值明顯小于有橫向地震波激勵情況下的塔底面外彎矩峰值和塔頂橫向位移峰值。4、對三組地震波情況下，獨塔混合梁斜拉橋關鍵截面處的應力進行了驗算，經驗算，部分關鍵截面處的應力已超出允許范圍，因此，在地震活動比較活躍的地區(qū)應用此種橋型時應慎重考慮，且應做進一步的抗震分析。本文以廣州東沙特大橋為背景，借助有限元軟件ANSYS，重點分析了獨塔混合梁斜拉橋的動力特性、獨塔混合梁斜拉橋的地震時程反應特性。考慮了橋梁主要結構參數(shù)對其振動特性的影響。并對有無輔助墩相互作用情況下的動力特性進行了對比分析；在地震時程反應特性中分別分析了三種地震波情況下，不考慮輔助墩相互作用和考慮輔助墩相互作用時對獨塔混合梁斜拉橋地震反應的影響，并進行了橫向比較。根據本文的研究，結合前人研究的成果，得出以下結論：1、考慮輔助墩作用時獨塔混合梁斜拉橋的基頻比不考慮輔助墩時普遍偏大，這是因為邊跨沒有輔助墩的約束, 使得主梁豎彎剛度降低。2、斜拉索布置的稀密程度對本橋的自振頻率也有影響，密索可以降低基頻即面內振動頻率，稀索提高了面外振動頻率。但是這種變化非常的小。索塔剛度的加大可以有效的提高獨塔混合梁斜拉橋的自振頻率。鋼混比的減小增大基礎頻率，但卻明顯的降低了其他振型的頻率。3、比較三組地震波情況下的位移及受力情況，對于獨塔混合梁斜拉橋塔梁墩固結體系，在地震波作用下，主要以豎向及縱向地震時程的影響為主，橫向地震時程影響相對較小。這是因為本橋的一階基本振型是主跨主梁豎彎，所以此結論符合本橋的振型規(guī)律。4、對比考慮輔助墩相互作用和不考慮輔助墩相互作用兩種模型，考慮輔助墩相互作用時，本橋剛度明顯增大，使得在三種地震類型激勵下本橋的位移、軸力、剪力、彎矩值較不考慮輔助墩相互作用時有不同程度減小。5、某些峰值大小與在何種類型地震激勵影響下有密切關系，例如無橫向地震波激勵情況下的塔底面外彎矩峰值和塔頂橫向位移峰值明顯小于有橫向地震波激勵情況下的塔底面外彎矩峰值和塔頂橫向位移峰值。6、對三組地震波情況下，獨塔混合梁斜拉橋關鍵截面處的應力進行了驗算，經驗算，部分關鍵截面處的應力已超出允許范圍，因此，在地震活動比較活躍的地區(qū)應用此種橋型時應慎重考慮，且應做進一步的抗震分析。關鍵詞：獨塔混合梁斜拉橋；動力特性；有限元法；ANSYS ；動力響應ABSTRACT The girder of hybrid girder cable-stayed bridge is composed of two different materials along the length of beam direction. The material of the main span is steel , while the side bay (or part of the main span) is concrete. Hybrid girder cable-stayed bridge has the advantage of large capacity across because of its main span is steel, and the characteristics of playing the anchor role and reducing the cost of bridge construction because of the side span is concrete. Cable-stayed bridge have significant differences in the general structure of the system and mechanical properties of materials with the other beam bridge, which has its own characteristics about the wind, seismic performance, as well as vehicle vibration performance, and so on. The dynamics of the bridge structure includes a bridge structure of natural frequencies, mode shapes, damping ratio, and the dynamic response in vehicles, wind, earthquake and other dynamic loads . The dynamic characteristics of cable-stayed bridge is the foundation to study the dynamic behavior of cable-stayed bridge, determine the vibration characteristics of its dynamic response characteristics, vibration characteristics of cable-stayed bridge is significant. Nearly half a century, cable-stayed bridge design theory, structural stability tests and wind vibration control, computer technology, finite element analysis and construction quality control, detection technology has matured, and compared to the more mature theory , Dynamic analysis of cable-stayed bridge over backward. At present, the cable-stayed bridge span is constantly to light in the direction of development, its in the dynamic load (such as vehicles, wind and earthquakes) under the dynamic response of more particularly pressing. Seismic response analysis of bridge structures is a seismic dynamics problem. Regarding the structure of the bridge seismic response analysis, we must proceed from the earthquake dynamics to think, solve problems, and seismic response analysis of bridge structure to earthquake sites must be based on the movement. However, due to lack of actual earthquake records, the key issue is also not well resolved, so calculation of seismic design is still the weakest link. Bridge dynamic analysis methods can be divided into two categories, one for the traditional method of theoretical analysis, simplified the structure to be made after analysis of a certain conclusion that analytical formulas. The other is the finite element numerical analysis method, using powerful computing computer using the finite element method analysis, the method could be more true to simulate the actual structure, analysis and high precision. The bridge by finite element numerical analysis. Taking the Dongsha super major bridge in Guangzhou as an instance, this paper has a further research around the analysis of dynamic characteristic and Seismic Response of hybrid girder cable-stayed bridge with single pylon on the foundation of existing research.Hybrid girder cable-stayed bridge due to the length of the main beam along the beam direction by two different materials, a main span of the beam to beam, side spans of concrete beams. Therefore, the dynamic characteristics of hybrid girder cable-stayed bridge and seismic performance of concrete and steel box girder cable-stayed bridge in comparison with their similarities, but it have their own characteristics. In this paper, based on existing research to the calculation of Guangzhou bridge in the background, around the hybrid girder cable-stayed bridge dynamic characteristics and seismic response of mixed-beam calculation and analysis, carried out the following areas: 1 Taking Guangzhou Dongsha bridge in the background, Use large-scale general-purpose software ANSYS dynamic analysis model to establish the bridge, on the set does not set the auxiliary supporting piers and pier in case of a comparative analysis of dynamic characteristics. 2, Establishes under the influence of different parameters of the natural frequencies of its extent. the cable density level, tower, steel mixing ratio. 3, Based on time history analysis of seismic response of the basic theory of single tower cable-stayed bridge beams were mixed in the horizontal + vertical seismic waves, vertical + vertical seismic waves, seismic waves under three-time history of seismic effects make analysis and comparison consider the auxiliary pier pier supporting the interaction and does not consider the interaction of the two models affect the earthquake processDongSha bridge in GuangZhou City is taken as an example to establish space dynamic calculaing models with ANSYS. and the influence of primary structural parameters to the self-vibration characteristics is analyzed through the application of the finite element analysis software. The results show that the arrangements of the auxiliary piers in the side spans can increase the structure rigidity greatly. And dilute the extent of cable stayed、tower、steel-concrete ratio have varying degrees of influence on self-vibration frequency.Hybrid single tower cable-stayed bridge girder structure according to their own different characteristics also change its momentum. 1, Supporting piers set makes the whole structure has greatly improved rigidity and improved the dynamic properties; addition to individual modes of foreign (eg, the sixth-order main tower main span girder bending coupled lateral bending mode with or without auxiliary Piers the same frequency), with or without auxiliary pier on the overall appearance of the order of vibration mode and the corresponding frequency greater impact. With auxiliary pier case, the edge collapse is not the main beam vibration phenomenon, where no auxiliary pier, side collapse with vibration phenomena, such as the Model B, 3,5,7,9,10-order. 2, Cable of thin dense level was not obvious to inside vibration frequency on the structure, and the vibration frequency of the larger plane. This shows that the cable arrangement of the thin dense level of lateral rigidity on the role of improving the structure of very small, while the full bridge vertical rigidity markedly. Cable can also greatly increase the density towers and beam coupling. 3, Increase the stiffness of the bridge tower the inside frequency did not differ, across the outside of the frequency increased significantly. 4, Reduce the steel-concrete ratio increase the basis of frequency, but significantly reduced the frequency of other modes.The study of cable-stayed bridge dynamic property provides fundamental theory for aseismatic design, wind resistance and analysis of vehicle vibration. Through the analysis of dynamic, it can reveal more truly the structure stresses and deflection under the effect of vehicles. Then it can figure the responses of bridge structure when earthquake and wind loads affected.The time-history analysis applied to the hybrid girder cable-stayed bridge, establish two kinds of model, which one consider the the auxiliary piers interaction and another not, compare and analyze the situation of the time analysis of them under three groups of seismic waves. Based on seismic response analysis of the basic theory ,single tower cable-stayed bridge beams were mixed in the horizontal + vertical seismic waves, vertical + vertical seismic waves, seismic waves under three-time history of seismic effects make analysis and comparison to consider supporting Tun Tun interaction and does not consider supporting the interaction of the two models affect the earthquake process, the following conclusions: 1, Compared three groups of seismic waves in case of displacement and force conditions, the single tower cable-stayed bridge tower Piers hybrid beam consolidation system, the seismic waves, mainly in the vertical and longitudinal range of the main earthquake, horizontal earthquake process was relatively small. This is because the bridge of the first order fundamental mode shape is a main span girder vertical bending, so this conclusion is consistent with the law of the bridge mode. 2, Compared to consider supporting piers supporting the interaction and does not consider the interaction of two model pier, consider the interaction between auxiliary pier, the bridge stiffness significantly increased, making the three types of excitation of the bridge seismic displacement, axial force, shear force, peak moment to consider supporting pier increment less interaction reduced to varying degrees. 3, Some of the peak size and what type of influence of earthquake excitation is closely related to, for example, no case of transverse earthquake waves tower and the tower bottom bending moment peak lateral displacement of the peak is smaller than a transverse earthquake waves tower case bottom and top of the tower outside the peak moment of peak lateral displacement. 4,Three sets of seismic waves on the circumstances, the key single tower cable-stayed section of mixed beam was checking the stress, experience counted, some of the key section of the stress is beyond the allowable range, therefore, more active in the areas of seismic activity apply should carefully consider the bridge is, and should do further seismic analysis. In this paper, Guangzhou bridge in the background, using finite element software ANSYS, focused analysis of the single tower cable-stayed bridge in the dynamic characteristics of hybrid girder, single girder cable-stayed bridge tower mixed-time history characteristics of the earthquake. Considered the main structural parameters of the bridge vibration characteristics. And the interaction with or without supporting piers under the dynamic characteristics were analyzed; the earthquake response characteristics of the process were analyzed under three different seismic waves, do not take into account the interaction and to consider supporting piers supporting the interaction between pairs of single tower pier hybrid girder bridge seismic response, and had horizontal comparison. According to this study, combined with the results of previous studies, the following conclusions: 1, Consider the role of supporting piers single tower cable-stayed bridge of the fundamental frequency of composite beam than not generally too large when considering supporting piers, because there is no supporting pier side cross-bound, so the main girder vertical bending stiffness decreased. 2, Cable layout level sparse density of the natural frequency of the bridge also have an impact, secret cable that can reduce the baseband frequency plane, thin Suoti plane high frequency. But this change is very small. Tower stiffness increase can effectively improve the single tower cable-stayed bridge mixed beam natural frequency. Steel and larger than the decrease of the fundamental frequency, but significantly reduced the frequency of other modes. 3, Compared three groups of seismic waves in case of displacement and force conditions for the single tower cable-stayed bridge tower Piers hybrid beam consolidation system, the seismic waves, mainly in the vertica