【摘要】：大跨橋梁結(jié)構(gòu)的抗風(fēng)性能是影響其施工和運(yùn)營(yíng)安全的控制因素,主梁斷面氣動(dòng)特性是大跨度橋梁抗風(fēng)性能研究的重要問題。風(fēng)洞試驗(yàn)是研究結(jié)構(gòu)氣動(dòng)特性非常重要、且不可替代的手段。本文對(duì)橋梁兩種典型主梁斷面,即鈍體斷面和類流線型斷面,進(jìn)行抗風(fēng)性能分析與試驗(yàn)研究。主要研究?jī)?nèi)容如下：(1)對(duì)兩種典型斷面的主梁節(jié)段模型進(jìn)行風(fēng)洞測(cè)壓試驗(yàn),研究其靜力三分力系數(shù),總結(jié)不同工況下三分力系數(shù)的變化規(guī)律并分析原因；并對(duì)斷面在靜止?fàn)顟B(tài)不同工況下的表面測(cè)壓信號(hào)進(jìn)行偏斜度與峭度分析,研究模型表面風(fēng)壓的偏斜度與峭度在施工階段及成橋階段隨攻角變化規(guī)律并分析原因。試驗(yàn)數(shù)據(jù)表明,施工狀態(tài)升力系數(shù)絕對(duì)值及扭矩系數(shù)絕對(duì)值大于成橋狀態(tài)對(duì)應(yīng)值；成橋狀態(tài)阻力系數(shù)明顯大于施工狀態(tài)；類流線型斷面的扭矩系數(shù)大于鈍體斷面。與施工狀態(tài)相比,兩種斷面成橋狀態(tài)的偏斜度值在各攻角下均出現(xiàn)了較大偏斜；模型后半部分信號(hào)表現(xiàn)出較強(qiáng)的非高斯性；類流線型斷面表現(xiàn)出較好的高斯性；攻角越大,信號(hào)的非高斯性越強(qiáng)。(2)對(duì)兩種主梁節(jié)段模型在典型工況下的系統(tǒng)阻尼比、不同工況信號(hào)的發(fā)散率和收斂率、軟顫振時(shí)程響應(yīng)及穩(wěn)態(tài)振幅進(jìn)行分析,研究系統(tǒng)阻尼比的影響因素及模型在軟顫振發(fā)生過程中的振動(dòng)特點(diǎn)。分析發(fā)現(xiàn),隨著風(fēng)速提高,振動(dòng)系統(tǒng)穩(wěn)態(tài)振幅不斷增大,達(dá)到穩(wěn)態(tài)振幅所需時(shí)間更短；當(dāng)斷面發(fā)生軟顫振時(shí),同一工況下,無論施加何種形式的初始激勵(lì),系統(tǒng)最終的穩(wěn)態(tài)扭轉(zhuǎn)振幅都相同。(3)對(duì)比分析模型靜止?fàn)顟B(tài)及軟顫振狀態(tài)下表面壓力分布,風(fēng)壓系數(shù)均值、標(biāo)準(zhǔn)差的變化規(guī)律及變化產(chǎn)生的原因,探究氣流對(duì)模型表面的靜力作用和脈動(dòng)作用。對(duì)比不同狀態(tài)模型表面風(fēng)壓分布特性,研究振動(dòng)對(duì)模型表面風(fēng)壓的影響。試驗(yàn)表明,類流線型斷面表面壓強(qiáng)分布與鈍體斷面相比較少出現(xiàn)渦旋附著與分離的情況；兩種斷面頂板風(fēng)壓系數(shù)根方差均隨著測(cè)點(diǎn)向下游移動(dòng),呈現(xiàn)先增大后減小至平穩(wěn)的趨勢(shì),峰值隨著攻角從負(fù)到正逐漸向下游移動(dòng)；軟顫振狀態(tài)下,隨著風(fēng)速的不斷提高,兩種斷面表面風(fēng)壓系數(shù)均值均隨之增大；由于氣動(dòng)負(fù)剛度影響,軟顫振過程中的卓越頻率低于扭轉(zhuǎn)固有模態(tài)頻率。
[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.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U446.1

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

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本文編號(hào)：2190254