典型桥梁主梁断面气动特性风洞试验研究
发布时间：2018-08-18 18:02
【摘要】：大跨桥梁结构的抗风性能是影响其施工和运营安全的控制因素,主梁断面气动特性是大跨度桥梁抗风性能研究的重要问题。风洞试验是研究结构气动特性非常重要、且不可替代的手段。本文对桥梁两种典型主梁断面,即钝体断面和类流线型断面,进行抗风性能分析与试验研究。主要研究内容如下：(1)对两种典型断面的主梁节段模型进行风洞测压试验,研究其静力三分力系数,总结不同工况下三分力系数的变化规律并分析原因；并对断面在静止状态不同工况下的表面测压信号进行偏斜度与峭度分析,研究模型表面风压的偏斜度与峭度在施工阶段及成桥阶段随攻角变化规律并分析原因。试验数据表明,施工状态升力系数绝对值及扭矩系数绝对值大于成桥状态对应值；成桥状态阻力系数明显大于施工状态；类流线型断面的扭矩系数大于钝体断面。与施工状态相比,两种断面成桥状态的偏斜度值在各攻角下均出现了较大偏斜；模型后半部分信号表现出较强的非高斯性；类流线型断面表现出较好的高斯性；攻角越大,信号的非高斯性越强。(2)对两种主梁节段模型在典型工况下的系统阻尼比、不同工况信号的发散率和收敛率、软颤振时程响应及稳态振幅进行分析,研究系统阻尼比的影响因素及模型在软颤振发生过程中的振动特点。分析发现,随着风速提高,振动系统稳态振幅不断增大,达到稳态振幅所需时间更短；当断面发生软颤振时,同一工况下,无论施加何种形式的初始激励,系统最终的稳态扭转振幅都相同。(3)对比分析模型静止状态及软颤振状态下表面压力分布,风压系数均值、标准差的变化规律及变化产生的原因,探究气流对模型表面的静力作用和脉动作用。对比不同状态模型表面风压分布特性,研究振动对模型表面风压的影响。试验表明,类流线型断面表面压强分布与钝体断面相比较少出现涡旋附着与分离的情况；两种断面顶板风压系数根方差均随着测点向下游移动,呈现先增大后减小至平稳的趋势,峰值随着攻角从负到正逐渐向下游移动；软颤振状态下,随着风速的不断提高,两种断面表面风压系数均值均随之增大；由于气动负刚度影响,软颤振过程中的卓越频率低于扭转固有模态频率。
[Abstract]:The anti-wind performance of long-span bridge structure is the control factor of its construction and operation safety. The aerodynamic characteristics of the main girder section is an important problem in the study of the wind-resistant performance of long-span bridges. Wind tunnel test is an important and irreplaceable means to study aerodynamic characteristics of structures. In this paper, the wind-resistant performance of two typical main beam sections of bridges, namely blunt body section and streamlined section, are analyzed and tested. The main research contents are as follows: (1) the wind tunnel pressure test is carried out on the main girder segment model of two typical sections, the static three-point force coefficient is studied, and the variation law of the three-point force coefficient under different working conditions is summarized and the reasons are analyzed. The deflections and kurtosis of the surface pressure signals under different static conditions are analyzed, and the variation law of the model surface wind pressure with the angle of attack in the construction stage and the bridge completion stage is studied and the reasons are analyzed. The test data show that the absolute value of lift coefficient and torque coefficient of construction state is larger than that of bridge state, the resistance coefficient of bridge state is obviously larger than that of construction state, and the torque coefficient of quasi-streamlined section is larger than that of blunt body section. Compared with the construction state, the skew degree of the two types of cross-section bridge states is larger at each angle of attack; the signal at the back half of the model shows strong non-Gao Si property; the quasi-streamlined section shows better Gao Si property; the larger the attack angle, the greater the angle of attack. The non-Gao Si property of the signal is stronger. (2) the system damping ratio of the two main beam segment models under typical conditions, the divergence rate and convergence rate of the signals under different working conditions, the time-history response of soft flutter and the steady-state amplitude are analyzed. The factors affecting the damping ratio of the system and the vibration characteristics of the model in the process of soft flutter are studied. It is found that with the increase of wind speed, the steady amplitude of the vibration system increases continuously, and the time required to achieve the steady amplitude is shorter, and when soft flutter occurs in the section, no matter what form of initial excitation is applied under the same condition, The final steady-state torsional amplitude of the system is the same. (3) the variation of surface pressure distribution, mean wind pressure coefficient and standard deviation under static and soft flutter state of the model are analyzed. To explore the static and pulsating effects of airflow on the surface of the model. The influence of vibration on the surface wind pressure of the model was studied by comparing the distribution characteristics of wind pressure on the surface of different state models. The experimental results show that the surface pressure distribution of the streamlined section is less than that of the obtuse section, and the root variance of the wind pressure coefficient of the two sections moves downstream with the measured points. The peak value moves from negative to positive to downstream gradually with the angle of attack, and the mean value of wind pressure coefficient increases with the increasing of wind speed in soft flutter state. Due to the negative aerodynamic stiffness, the excellent frequency of soft flutter is lower than that of torsional natural mode.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446.1
本文编号：2190254
[Abstract]:The anti-wind performance of long-span bridge structure is the control factor of its construction and operation safety. The aerodynamic characteristics of the main girder section is an important problem in the study of the wind-resistant performance of long-span bridges. Wind tunnel test is an important and irreplaceable means to study aerodynamic characteristics of structures. In this paper, the wind-resistant performance of two typical main beam sections of bridges, namely blunt body section and streamlined section, are analyzed and tested. The main research contents are as follows: (1) the wind tunnel pressure test is carried out on the main girder segment model of two typical sections, the static three-point force coefficient is studied, and the variation law of the three-point force coefficient under different working conditions is summarized and the reasons are analyzed. The deflections and kurtosis of the surface pressure signals under different static conditions are analyzed, and the variation law of the model surface wind pressure with the angle of attack in the construction stage and the bridge completion stage is studied and the reasons are analyzed. The test data show that the absolute value of lift coefficient and torque coefficient of construction state is larger than that of bridge state, the resistance coefficient of bridge state is obviously larger than that of construction state, and the torque coefficient of quasi-streamlined section is larger than that of blunt body section. Compared with the construction state, the skew degree of the two types of cross-section bridge states is larger at each angle of attack; the signal at the back half of the model shows strong non-Gao Si property; the quasi-streamlined section shows better Gao Si property; the larger the attack angle, the greater the angle of attack. The non-Gao Si property of the signal is stronger. (2) the system damping ratio of the two main beam segment models under typical conditions, the divergence rate and convergence rate of the signals under different working conditions, the time-history response of soft flutter and the steady-state amplitude are analyzed. The factors affecting the damping ratio of the system and the vibration characteristics of the model in the process of soft flutter are studied. It is found that with the increase of wind speed, the steady amplitude of the vibration system increases continuously, and the time required to achieve the steady amplitude is shorter, and when soft flutter occurs in the section, no matter what form of initial excitation is applied under the same condition, The final steady-state torsional amplitude of the system is the same. (3) the variation of surface pressure distribution, mean wind pressure coefficient and standard deviation under static and soft flutter state of the model are analyzed. To explore the static and pulsating effects of airflow on the surface of the model. The influence of vibration on the surface wind pressure of the model was studied by comparing the distribution characteristics of wind pressure on the surface of different state models. The experimental results show that the surface pressure distribution of the streamlined section is less than that of the obtuse section, and the root variance of the wind pressure coefficient of the two sections moves downstream with the measured points. The peak value moves from negative to positive to downstream gradually with the angle of attack, and the mean value of wind pressure coefficient increases with the increasing of wind speed in soft flutter state. Due to the negative aerodynamic stiffness, the excellent frequency of soft flutter is lower than that of torsional natural mode.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446.1
【参考文献】
相关硕士学位论文 前1条
1 高斐;典型断面节段模型风洞试验影响因素研究[D];长安大学;2013年
，本文编号：2190254
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