叠合梁悬索桥的抗风性能研究

发布时间：2019-03-31 20:17

【摘要】：钢混叠合梁桥主梁为开口断面。因具有均匀合理的受力特性、造价低及施工方便等优势，在结构抗扭刚度相对较大的斜拉桥中有越来越多的应用。但叠合梁悬索桥由于抗扭刚度的降低，导致其颤振临界风速显著降低，并且在较低的风速下很容易出现涡激共振现象。为了发挥出叠合梁悬索桥的优势，提高抗风稳定性，因此就有必要对叠合梁悬索桥的涡激振动与颤振特性进行研究。本文以在建的主跨838m的宜昌庙嘴长江大桥的主梁形式为基础，通过节段模型风洞试验及理论分析，研究叠合梁悬索桥涡激振动和颤振特性，主要工作包括以下几个方面： (1)详细综述了桥梁的风致振动的基本概念和基本理论，以及桥梁气动性能的影响因素和气动措施，在参考相似桥梁相关研究的基础上提出了本文所要研究的主要内容。 (2)研究了在主梁不同位置设置稳定板对叠合梁涡激振动和颤振稳定性的影响。本文共设计了5组稳定板典型位置的对比试验，通过对5组试验数据的分析对比发现，不同位置的稳定板对叠合梁悬索桥涡激振动影响不同，特别是对扭转振动影响较大；在主梁设置两道下稳定板能显著改善其涡振性能。增加稳定板后断面的颤振稳定性也显著提高。 (3)利用基于有限元的三维颤振分析方法对叠合梁悬索桥进行颤振稳定性分析，预测了复模态频率及阻尼随风速的变化，并基于复特征值摄动理论首次对三维颤振分析中出现的特征值的变化做出定量理论解释。分析表明，①基于颤振导数得到的颤振临界风速比主梁节段模型风洞试验值略大，，可能是由于颤振判据差异引起的；②颤振分析中出现的扭转振动频率下降现象是气动刚度和非经典的气动阻尼共同作用的结果。 (4)分析比较了3种涡激力经验模型的参数识别方法及涡激力形式。利用节段模型涡激振动风洞试验得到的试验数据，对涡激力气动参数进行识别。研究发现，在同一风速下不同涡激力模型识别的涡激力幅值相同；利用识别的涡激力反算涡激响应能满足识别精度。
[Abstract]:The main beam of steel hybrid bridge is an open section. Due to the advantages of uniform and reasonable mechanical characteristics, low cost and convenient construction, the cable-stayed bridges with relatively large torsional stiffness are more and more used in cable-stayed bridges. However, due to the reduction of torsional stiffness, the critical flutter velocity of superimposed suspension bridge decreases significantly, and vortex-induced resonance is easy to occur at lower wind speed. In order to give full play to the advantages of superimposed beam suspension bridges and improve wind stability, it is necessary to study the vortex-induced vibration and flutter characteristics of superimposed beam suspension bridges. Based on the main beam form of the Yichang Miaozui Yangtze River Bridge with a main span of 838m under construction, the vortex-induced vibration and flutter characteristics of the superimposed beam suspension bridge are studied by the segmental model wind tunnel test and theoretical analysis. The main work includes the following aspects: (1) the basic concepts and theories of wind-induced vibration of bridges are summarized in detail, as well as the influencing factors and aerodynamic measures of bridge aerodynamic performance. The main contents of this paper are put forward on the basis of reference to the related research of similar bridges. (2) the effects of stability plates at different positions on vortex-induced vibration and flutter stability of laminated beams are studied. Through the analysis and comparison of five groups of test data, it is found that the vortex-induced vibration of superimposed beam suspension bridge is affected by the stability plate at different positions, especially on the torsional vibration of the suspension bridge with superimposed beams. The results show that the stability plate at different positions has different effects on the vortex-induced vibration of superimposed beam suspension bridges, especially on the torsional vibration of suspension bridges. The vortex vibration performance of the main beam can be significantly improved by setting two stable plates under the main beam. The flutter stability of the rear section of the plate is also improved significantly. (3) the three-dimensional flutter analysis method based on finite element method is used to analyze the flutter stability of superimposed beam suspension bridge, and the variation of complex modal frequency and damping with wind speed is predicted. Based on the perturbation theory of complex eigenvalues, the variation of eigenvalues in three-dimensional flutter analysis is explained quantitatively for the first time. The results show that (1) the flutter critical wind speed based on flutter derivative is slightly larger than the wind tunnel test value of the main beam segment model, which may be due to the difference of flutter criterion; (2) the frequency drop phenomenon of torsional vibration in flutter analysis is caused by the combination of aerodynamic stiffness and non-classical aerodynamic damping. (4) the parameter identification methods and vortex force forms of three kinds of empirical models of vortex excitation are analyzed and compared. The aerodynamic parameters of vortex-induced force are identified by using the wind tunnel test data of segment model vortex-induced vibration. It is found that the amplitude of vortex excitation force identified by different vortex excitation models under the same wind speed is the same, and the identification accuracy can be satisfied by calculating the vortex excitation response by using the identified vortex excitation force.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.25;U441.3

【参考文献】