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1.
郭辉  张新军 《市政技术》2011,29(3):42-44
采用三维非线性空气动力稳定性分析程序,分析三塔悬索桥施工全过程空气动力稳定性的变化规律,揭示了不同主梁施工顺序对三塔悬索桥施工过程空气动力稳定性的影响,并探讨具有良好空气动力稳定性的主梁施工顺序。  相似文献   

2.
In this paper, a nonlinear method is proposed to analyze the flutter stability of cable-supported bridges, in which structural geometric nonlinearity and the nonlinear effects due to the static wind-structure interactions are fully considered. A computer program NFACSB is also developed. With the criteria of total mode damping including both structural and aerodynamic damping less than zero, the critical condition of flutter can be obtained. Through the analyses on two cable-supported bridges with streamlined and bluff deck sections, flutter characteristics is explained and the intrinsic consistence of different flutter types is clarified. The effects of each aerodynamic derivative and mode coupling on flutter instability are further investigated.  相似文献   

3.
As the span length of suspension bridges increases, the diameter of cables and thus the wind load acting on them, the nonlinear wind-structure interaction and the spatial non-uniformity of wind speed (including the vertical and horizontal variations) all increase consequently, which may have unnegligible influence on the aerostatic and aerodynamic behavior of long-span suspension bridges. In this paper, the models of aerostatic and aerodynamic forces are established, in which the nonlinear wind-structure interaction and the spatial non-uniformity of wind speed are both considered. By taking the Runyang Bridge over the Yangtze River as example, effects of the nonlinear wind-structure interaction, wind speed spatial non-uniformity, and the cable's wind load on the aerostatic and aerodynamic behavior of the bridge are investigated analytically. The results show that the aerostatic behavior is significantly influenced by these factors, but for the aerodynamic stability, it is greatly influenced by the nonlinear wind-structure interaction and the horizontal variation of wind speed, and the other factors have no influence on it.  相似文献   

4.
随着桥梁跨径的增大 ,各种非线性因素对大跨径悬索桥颤振特性的影响将不容忽视。在线性颤振分析方法的基础上 ,考虑风速的空间非均匀分布、结构以及作用于结构上的气动力随结构变形的非线性变化影响因素 ,建立了大跨径桥梁的三维非线性颤振分析方法。以某悬索桥为例 ,进行了考虑风速空间非均匀分布、结构动力特性以及气动力随结构变形的非线性变化等因素的颤振分析 ,揭示了各种非线性因素对大跨径悬索桥颤振影响的机理和规律  相似文献   

5.
风雨联合作用下大跨桥梁颤振稳定性试验研究   总被引:3,自引:0,他引:3  
针对风雨联合作用下的大跨桥梁颤振稳定性,以一开槽双箱梁桥梁为研究对象,通过在大气边界层风洞中搭建的风雨联合作用试验系统,完成基于自由振动法的节段模型颤振试验。通过分析不同雨强下该桥梁主梁的颤振导数以及颤振临界风速,进而获取降雨对大跨桥梁颤振稳定性的影响规律。试验结果显示:颤振导数随雨强变化而变化,其中体现扭转气动阻尼特性的颤振导数变化较为显著,随雨强增大,颤振临界风速先增大后减小。试验结果表明:降雨对大跨桥梁的颤振导数以及颤振临界风速均有一定影响。  相似文献   

6.
This paper introduces the state-of-the-art of longspan bridge engineering in China with emphases on recent long-span bridge projects, bridge deck configuration and material, design codes of long-span bridges and improvement of aerodynamic performance. The recent long-span bridge projects include thirty-eight completed suspension bridges, cable-stayed and arch bridges with a main span over 400 m, and eighteen major bridges are under construction. The bridge deck configuration and material, with prestressed concrete decks, steel-concrete composite decks and steel box decks together with several popular cross-sections, are presented. The third part briefly outlines four design codes, including static and dynamic design for highway long-span bridges, and the recent engineering experiences gained from several aerodynamic vibration control projects of long-span bridges are shared in the last part.  相似文献   

7.
The aerodynamic stability becomes a governing factor in designing long-span suspension bridges. In this paper, using the method of three-dimensional nonlinear aerodynamic stability analysis, parametric analyses on the aerodynamic stability of the Runyang bridge over the Yangtze River are performed including the structural system, the cable sag, the side span length, the depth, dead load and supporting system of the deck, etc. Some important design parameters that affect the aerodynamic stability of the bridge are pointed out, and the favorable structural system of the bridge is also discussed based on the wind stability.  相似文献   

8.
应用碳纤维缆索的大跨度悬索桥抗风稳定性研究   总被引:6,自引:0,他引:6  
为了探讨碳纤维复合材料缆索在大跨度悬索桥中应用的可能性,以主缆等轴向刚度为原则,拟定了一座主跨为1490m的碳纤维复合材料主缆悬索桥,并运用三维非线性计算理论进行了空气静力和动力稳定性分析。通过与同跨度钢主缆悬索桥的比较,讨论了不同主缆材料对大跨度悬索桥抗风稳定性的影响。分析结果表明:大跨度悬索桥采用碳纤维复合材料主缆后,静风作用下结构的变形增大,但其静风稳定性却与钢主缆悬索桥基本接近;由于结构自振频率特别是扭转频率有显著的提高,使得其空气动力稳定性要比钢主缆悬索桥好。因此从抗风稳定性角度而言,大跨度悬索桥采用碳纤维复合材料主缆是可行的,但是主缆截面尺寸的确定应采用等轴向刚度的准则。  相似文献   

9.
为确保斜风作用下大跨度悬索桥的抗风稳定性,采用考虑静风效应和全模态耦合影响的斜风下大跨度桥梁三维精细化颤振分析程序,以润扬长江大桥南汊悬索桥为工程背景,在0°和±3°初始风攻角下,分析了斜风下成桥状态和加劲梁从跨中向两侧桥塔对称架设全过程的颤振稳定性,并揭示了斜风作用和静风效应对成桥和施工状态大跨度悬索桥颤振稳定性的影响。结果表明:悬索桥成桥和施工状态的颤振临界风速随着风偏角的增加呈现波动起伏变化特征,且主要在斜风情况下达到最低值;斜风作用和静风效应不会影响悬索桥施工期颤振稳定性的演变规律,但会显著降低悬索桥成桥和施工状态的颤振稳定性;斜风作用使得成桥和施工状态颤振临界风速的最大降幅平均值分别达到了8.0%和19.6%,而斜风和静风的综合效应则进一步劣化悬索桥成桥和施工状态的颤振稳定性,最大降幅平均值分别达到了11.5%和22.4%,因此大跨度悬索桥成桥尤其是施工状态的颤振稳定性分析必须考虑静风和斜风综合效应的不利影响。  相似文献   

10.
A time domain approach for predicting the flutter response of long-span bridges was presented. The unsteady aerodynamic forces were presented by the indicial functions through a convolution integral, whereas the nonlinear least square method was used to calculate the aerodynamic indicial parameters. The nonlinear dynamic analysis which includes both the geometric and material nonlinearities due to the unsteady self excited aerodynamics force was considered. Numerical analyses were then performed using three dimensional finite element model of the suspension bridge. The results show that the geometric and material nonlinearities have a significant influence on the critical velocity and the response of long-span bridges.  相似文献   

11.
Wind actions on long-span bridges are commonly considered as the superimposition of buffeting forces and self-excited forces, depending on the aerodynamic admittance functions and on the flutter derivatives, respectively. Since bridge deck sections are bluff bodies, the aerodynamic admittance functions and the flutter derivatives have to be determined experimentally by wind tunnel tests. This paper introduces a generalized quasi-static theory, defining new relationships among the flutter derivatives and the aerodynamic admittance functions. All the relationships are theoretically verified for the zero circular frequency; based upon experimental results, the validation of the relationships among the flutter derivatives is also provided for non-zero values of the frequency.  相似文献   

12.
为了探索理想的大跨度悬索桥的缆索体系以提高其横向及扭转刚度,以大跨度地锚式悬索桥——润扬长江公路大桥南汊桥为工程背景,采用不同缆索空间布置形式试设计三座具有空间缆索体系的方案桥,采用三维非线性空气静力和动力稳定性分析方法,分别对其动力特性、空气静力和动力稳定性进行分析和比较,并探讨具有良好抗风稳定性的大跨度悬索桥的合理缆索体系。结果表明:悬索桥采用内倾式空间缆索体系后,结构的侧弯及扭转频率增大,结构的空气动力稳定性增强;而采用外倾式空间缆索体系时,结构的侧弯及扭转频率减小,但结构的静风稳定性增强;考虑到悬索桥的空气动力稳定性一般比静风稳定性差,因此从总体抗风稳定性考虑,大跨度悬索桥采用内倾式空间缆索体系则比较有利。  相似文献   

13.
悬索桥跨径的空气动力极限   总被引:9,自引:0,他引:9  
桥梁建设已经进入了一个建造跨海大桥的新时代。在跨海大桥工程的可行性研究中存在许多技术方面的挑战 ,对于桥梁设计者来说 ,超大跨径悬索桥的气动稳定问题始终是必须十分关注的问题。本文首先研究超大跨径悬索桥的技术可行性及潜在的要求 ,然后讨论各种气动措施的性能 ,其中包括缆索系统的调整、中央开槽方案、垂直及水平稳定板以及振动控制措施等。从技术及航运要求出发 ,设计了一个接近极限跨径的主跨为5 0 0 0m的悬索桥方案 ,以此为基础研究并阐述解决其空气静动力稳定性的方法  相似文献   

14.
The potential requirement of extreme bridge spans is firstly discussed according to horizontal clearances for navigation and economical construction of deep-water foundation. To ensure the technological feasibility of suspension bridges with longer spans, the static estimation of feasible span length is then made based on current material strength and weight of cables and deck. After the performances of the countermeasures for raising the aerodynamic stability are reviewed, a trial design of a 5 000 m suspension bridge, which is estimated as a reasonable limitation of span length, is finally conducted to respond to the tomorrow’s challenge in span length of suspension bridges with the particular aspects, including dynamic stiffness, aerodynamic flutter and aerostatic stability. Selected and modified from Proceedings of the 11th International Conference on Wind Engineering, 2003, 65–80  相似文献   

15.
The nonlinear characteristics of bridge aerodynamics preclude a closed-form solution of limit-cycle oscillation (LCO) amplitude and frequency in the post-flutter stage. To address this issue, a long short-term memory (LSTM) network is utilized as the reduced-order modeling of nonlinear aeroelastic forces on the bridge deck section, and it is repeatedly employed to generate force inputs at spanwise nodes of a three-dimensional (3D) finite element model (FEM) of the long-span bridge (using spatial beam elements). All LSTM networks are dynamically coupled through FEM, and the 3D nonlinear flutter response is accordingly obtained. To improve the simulation accuracy and reduce the required training data of the standard LSTM network, both general knowledge (motivated by the gating mechanism and mathematical models for information processing) and domain knowledge (resulting from the basic understanding of bridge aerodynamics) are leveraged to, respectively, customize the LSTM cell and network architecture. In addition, a fast-training algorithm effectively combining the linear convergence of stochastic gradient descent and superlinear convergence of modified Broyden–Fletcher–Goldfarb–Shanno is developed to improve the training efficiency of the obtained knowledge-enhanced LSTM network. To further advance the computational efficiency of the coupled LSTM-FEM nonlinear flutter analysis, the convolution-based numerical integration is adopted in the finite element modeling of long-span bridge dynamics. A case study of a long-span suspension bridge under strong winds demonstrates the proposed 3D nonlinear flutter analysis presents high simulation efficiency and accuracy and can be utilized to effectively obtain the nonlinear LCO characteristics in a wide range of post-flutter wind speeds.  相似文献   

16.
郭辉  孙华卿 《市政技术》2011,29(5):50-52,55
以在建主跨为1080m的三塔双跨悬索桥——泰州长江公路大桥为工程背景,采用三维非线性空气静力稳定性分析方法,分析不同的主梁架设顺序对三塔悬索桥施工阶段空气静力稳定性的影响,确定具有良好抗风稳定件的施工方案。结果表明:三塔悬索桥主梁拼装采用从桥塔处至跨中施工时,可以获得较好的空气静力稳定性。  相似文献   

17.
共收集到截止2015年1月的已建和在建的钢管混凝土拱桥413座(跨径不小于50m)。统计分析表明,钢管混凝土拱桥在我国修建的数量不断增多、跨径不断增大。从行业分布来看,在公路、城市桥梁中的应用仍是主体,在铁路尤其是高速铁路中的应用不断增多。在结构体系方面,上承式、中承式、拱梁组合式、飞鸟式和下承式刚架系杆拱5大类,仍为主要应用的桥型,占总数的85%。在截面形式方面,以圆钢管混凝土为基本单元组成的单圆管、哑铃形和桁式是应用的主流。提篮拱被应用于各种桥型,尤其是大跨度铁路桥。无风撑拱主要应用于120m跨径以下的桥梁,且以斜靠拱和拱梁组合桥为主,截面多采用横向刚度较大的形式。拱肋的材料强度不断地提高,钢管以Q345钢为主,混凝土以C40、C50为主。虽然对桥面系强健性的重视在不断提高,然而强健性好的整体式和具有加劲纵梁的悬吊桥面系的应用还不够普及。钢管拱的架设方法仍以支架法、悬臂法和转体法3种为主,其中悬臂拼装法应用最多,适用跨径最大范围也最广。  相似文献   

18.
An overview of wind tunnel activities and methodologies to support the design of long-span suspension bridges is proposed. The most important aspects of the wind-bridge interaction are investigated considering the aerodynamic phenomena affecting the different parts of the bridge (mainly deck and towers). The experimental activities and results are proposed in the framework of a synergic approach between numerical and experimental methodologies that represent the common practice in defining the full scale aeroelastic behaviour of the bridge starting from scaled reproduction of the wind-bridge interaction. Static and dynamic wind loads, aeroelastic stability, vortex-induced vibrations will be investigated.  相似文献   

19.
An aerodynamic study is described showing the stability of a new type of double deck cable-stayed bridge having both upper and lower flat, shallow, streamlined box girder decks connected by vertical members only. In long span, cable-stayed bridges the longer the span, the more important the aerodynamic stability of the structure becomes. Even though cable-stayed bridges evidence structural damping, the measure of the aerodynamic stability of such a bridge is whether or not a cross-sectional shape of the suspended structure is stable against flutter oscillation and vortex-excited oscillation. The experiments presented in this paper, therefore, focus on the aerodynamic stability against these phenomena in a partial scale model of a cable-stayed bridge of new design. The three aerodynamic components of force have also been measured. For comparison, a wind-tunnel experiment has been carried out using a partial model of a conventional suspended structure of a typical truss type double deck cable-stayed bridge. It is shown that the new system is superior to the truss type from an aerodynamic stability viewpoint.  相似文献   

20.
The paper describes the addition of actively controlled aerodynamic appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suspension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to make use of control analysis and design techniques, a linear model of the structural and aerodynamic motion around equilibrium is developed. The model is validated through comparison with finite element calculations and wind tunnel experimental data on the Great Belt East Bridge in Denmark. The developed active control scheme is local in that the flap control signal at a given longitudinal position along the bridge only depends on local motion measurements. The analysis makes use of the Nyquist stability criteria and an analysis of the sensitivity function for stability analysis. The analysis shows that the critical wind speed for flutter instability and divergence is increased substantially by active control.  相似文献   

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