空腹式连续刚构桥静动力学特性

发布时间：2018-05-05 19:40

本文选题：桥梁工程 + 连续刚构　；参考：《长安大学》2014年博士论文

【摘要】：随着我国高等级公路的发展，高墩大跨的预应力混凝土连续刚构桥成为100～300m范围具有明显竞争优势的桥型。为了解决早期所建此类桥梁的开裂、下挠问题，近年来出现了改进型桥型----空腹式连续刚构桥，即在普通连续刚构桥基础上将桥墩附近箱梁腹板局部挖空，形成根部空腹式结构。本文针对空腹式连续刚构桥进行系统的静动力学特性研究，为其推广应用提供理论基础。本文以国内某建成的实桥为依托，建立了结构空间分析模型，利用Midas/Civil有限元程序，从静、动力学方面分析其结构反应特点。在静力学方面，以边中跨比、墩梁刚度比、腹板挖空率、曲率半径等为参数，研究内力变化规律。在动力学方面，研究了曲率半径、桥墩弯曲刚度、地震卓越频率、行波效应等因素对空腹式连续刚构桥的动力特性、关键截面水平和竖向地震响应的影响；通过风洞试验测定了空腹式箱梁的三分力系数，并与既有普通连续刚构的试验数据对比，分析了宽高比、宽悬比对空腹式箱梁三分力系数的影响；通过风洞试验与基于FLUENT平台的CFD数值模拟相结合，分析了双幅桥气动干扰效应，并研讨了腹板阻塞度对三分力系数的影响机理；通过最大双悬臂施工阶段的气弹模型风洞试验，给出了不同风偏角下空腹式与普通连续刚构施工状态的结构位移相响应和加速度响应特点。主要研究成果如下：（1）明晰了空腹式连续刚构桥的内力分布规律，指出了其与普通连续刚构桥的异同。空腹式连续刚构桥的最大负弯矩位于上下弦梁的结合处，数值上小于同跨径普通连续刚构；边中跨比小于等于0.5时，各构件内力分布均匀，其比值基本恒定，大于0.5时则相反；建议五跨以上空腹式连续刚构的跨径布置自中跨逐跨递减，跨径比取值为1：（0.5-0.8）：（0.25-0.4）；腹板挖空率越大，内力分布越均匀；上弦梁刚度比仅影响弦梁内力分配，，对实腹段内力影响较小；当曲率半径大于600米时，其对桥墩的扭矩影响可以忽略不计。（2）箱梁空腹段的弦梁是抗震设计的关键构件。曲率半径对空腹式连续刚构基频影响较大，而对高阶频率没有影响，桥墩的弯曲刚度变化对桥梁动力性能影响极小；桥梁对低频（2Hz）水平地震响应强烈；箱梁空腹段的弦梁对低频且存在行波效应的地震波激励响应强烈，是抗震设计的关键部位。（3）直腹板箱梁的三分力系数与宽高比满足线性关系，空腹式直腹板箱梁三分力系数变化规律比普通箱梁复杂，根据试验结果给出的拟合公式可以用于其风荷载的计算。双幅并置的空腹式箱梁存在影响其周边流场的巷道效应和遮挡效应以及干扰效应，这些因素导致空腹式箱梁的三分力系数随宽高比变化规律趋于复杂，从而探究了阻塞度与三分力系数间的相互关系。（4）施工状态悬臂端的风致响应最大值出现在风向与桥梁轴线夹角约60°斜风方向，空腹式箱梁在斜风作用下的悬臂端最大位移响应小于普通箱梁。
[Abstract]:With the development of high grade highway in our country, the prestressed concrete continuous rigid frame bridge with high piers and large span has become a bridge type with obvious competitive advantage in the range of 100 ~ 300m. In order to solve the problem of cracking and flex of the bridge built in the early stage, an improved bridge type - hollow continuous rigid frame bridge has appeared in recent years, that is, on the basis of the common continuous rigid frame bridge. In this paper, the static and dynamic characteristics of the hollow continuous rigid frame bridge are studied in this paper, which provides a theoretical basis for its popularization and application.
Based on a real bridge built in China, the structure space analysis model is established, and the structural response characteristics are analyzed from static and dynamic aspects by using the Midas/Civil finite element program. In the statics, the internal force changes are studied by the ratio of the side span to span, the rigidity ratio of the pier and beam, the hollowing rate of the web and the radius of curvature. The influence of the curvature radius, the pier bending stiffness, the earthquake excellent frequency and the traveling wave effect on the dynamic characteristics of the hollow continuous rigid frame bridge, the key section level and the vertical seismic response are investigated. The three force coefficient of the hollow box girder is measured by the wind tunnel test, and it is compared with the experimental data of the common continuous rigid frame. The effect of high ratio and wide suspension ratio on the triple force coefficient of the hollow box girder is obtained. Through the wind tunnel test and the CFD numerical simulation based on the FLUENT platform, the aerodynamic interference effect of the double amplitude bridge is analyzed, and the influence mechanism of the web block on the three force coefficient is discussed, and the aerodynamic model wind tunnel test of the maximum double cantilever construction stage is given. The structural displacement phase response and acceleration response characteristics of open and ordinary continuous rigid frame structures under different wind deflections are summarized.
(1) the internal force distribution of the hollow continuous rigid frame bridge is clarified, and the difference of the maximum negative moment of the continuous rigid frame bridge is pointed out. The maximum negative moment of the hollow continuous rigid frame bridge is located in the combination of the upper and lower chord beams. The numerical value is less than the common continuous rigid frame with the same span, and the internal forces of each component are evenly distributed and the ratio is basically constant when the side span ratio is less than or equal to 0.5. It is the opposite; it is suggested that the span layout of the five span hollow continuous rigid frame is reduced from middle to span, and the span ratio is 1: (0.5-0.8) (0.25-0.4); the greater the hollowing rate is, the more uniform the internal force distribution is, the rigidity ratio of the upper chord beam is only influenced by the internal force distribution of the string beam, and the internal force of the real abdomen is less; when the radius of curvature is greater than 60 The torque impact on the pier can be negligible at 0 meters.
(2) the chord beam of the empty section of the box girder is the key component of the seismic design. The curvature radius has great influence on the basic frequency of the hollow continuous rigid frame, but has no influence on the high order frequency. The change of the flexural rigidity of the pier has little effect on the dynamic performance of the bridge; the bridge should be strong for the low frequency (2Hz) horizontal earthquake, and the chord beam of the box beam to the hollow section of the box girder has a line to the low frequency. The seismic response of wave effect is strong, and it is the key part of aseismic design.
(3) the three force coefficient of the straight web box girder has a linear relationship with the width to height ratio. The variation law of the triple force coefficient of the empty belly straight web box girder is more complex than that of the ordinary box girder. The fitting formula given according to the test results can be used to calculate the wind load. These factors lead to the complexity of the three force coefficient of the hollow box girder with the variation of the width to height ratio, thus exploring the relationship between the blocking degree and the three force coefficient.
(4) the maximum wind-induced response of the cantilever end of the construction occurs in the direction of the wind direction and the axis of the bridge about 60 degrees of wind, and the maximum displacement response of the cantilever end of the hollow box girder is less than that of the ordinary box girder under the effect of the wind.

【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U441.3;U448.23

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