本文選題：大跨度橋梁 + 流線型箱梁　； 參考：《西南交通大學(xué)》2015年博士論文

【摘要】：本論文首先回顧了大跨度橋梁抗風(fēng)研究的發(fā)展歷程,介紹了自激氣動力的研究現(xiàn)狀和獲取途徑。隨后基于CFD數(shù)值模擬,研究薄平板和流線型箱梁斷面的自激力特性,并通過流場顯示,考查自激力非線性成分與典型流場特征之間的關(guān)系。引入特定的假設(shè)條件,通過理論推導(dǎo),建立了橋梁二維非線性顫振響應(yīng)分析的一般方法,并在此基礎(chǔ)上討論結(jié)構(gòu)阻尼比模型的數(shù)學(xué)形式對橋梁非線性顫振幅值響應(yīng)的影響。本文的主要研究內(nèi)容有：(1)提出了多變形子區(qū)域的動網(wǎng)格方法,結(jié)合剛性網(wǎng)格技術(shù)和標(biāo)準(zhǔn)彈簧光順法,實(shí)現(xiàn)橋梁斷面大振幅變形運(yùn)動時網(wǎng)格質(zhì)量的良好控制。(2)研究大振幅條件下薄平板和流線型箱梁斷面的自激力。運(yùn)動振幅越大,高次諧波成分在整個氣動力中所占的比例也越大。同等振幅條件下,對純扭轉(zhuǎn)運(yùn)動而言,高折算風(fēng)速下的自激力非線性效應(yīng)更顯著,但對純豎彎運(yùn)動而言,則是低折算風(fēng)速下的自激力非線性更顯著。(3)研究薄平板大振幅條件下的流場。流動分離不是氣動自激力出現(xiàn)高頻分量的原因,平板前緣流動分離影響自激氣動力的基頻幅值,而氣動力高次諧波分量所占比例與流場中二次渦的強(qiáng)度成正相關(guān)。(4)研究流線型箱梁斷面大振幅條件下的流場。斷面單側(cè)流場出現(xiàn)漩渦反向的現(xiàn)象與氣動力出現(xiàn)高次諧波分量具備同時性。(5)在假設(shè)橋梁顫振是同一頻率簡諧豎向和簡諧扭轉(zhuǎn)運(yùn)動耦合的基礎(chǔ)之上,將顫振導(dǎo)數(shù)表述為折算頻率和運(yùn)動振幅的二維函數(shù)即非線性顫振導(dǎo)數(shù),以振動系統(tǒng)的總阻尼再次為零作為振動振幅穩(wěn)定的判據(jù),建立了一種非線性顫振分析的基本方法。(6)研究南京四橋斷面的非線性顫振幅值響應(yīng)。即使其顫振臨界風(fēng)速被超過后,顫振響應(yīng)也可能維持在一定的振幅水平上,對顫振響應(yīng)振幅起決定作用的是顫振導(dǎo)數(shù)A2*構(gòu)成的氣動正阻尼和與A1*、H3*有關(guān)的耦合氣動負(fù)阻尼。(7)研究結(jié)構(gòu)阻尼比模型的數(shù)學(xué)形式對非線性顫振響應(yīng)的影響。當(dāng)結(jié)構(gòu)阻尼比為常數(shù)型時,結(jié)構(gòu)阻尼無法抑制顫振發(fā)散。當(dāng)結(jié)構(gòu)阻尼比為線性比例型時,阻尼比隨振幅變化的斜率構(gòu)成了抑制顫振響應(yīng)的重要因素。當(dāng)結(jié)構(gòu)阻尼比為漸近型時,其振幅響應(yīng)曲線的形狀介于常數(shù)型阻尼比和線性比例阻尼比的振幅響應(yīng)曲線之間。
[Abstract]:In this paper, the development of wind resistance research of long span bridges is reviewed, and the research status and ways of obtaining self-excited gas dynamics are introduced. Then, based on CFD numerical simulation, the self-excited force characteristics of thin plate and streamlined box girder section are studied, and the relationship between the nonlinear components of self-excited force and the characteristics of typical flow field is investigated through the flow field. A general method for analyzing the nonlinear flutter response of a bridge is established by introducing specific assumptions and theoretical derivation. On the basis of this, the influence of the mathematical form of the damping ratio model on the amplitude response of the nonlinear vibration of the bridge is discussed. The main contents of this paper are as follows: (1) A dynamic mesh method for multi-deformed subregions is proposed, which combines rigid mesh technique and standard spring fairing method. The mesh quality can be controlled well under the condition of large amplitude deformation of bridge section. (2) the self-excited force of thin slab and streamlined box girder section is studied under the condition of large amplitude. The larger the amplitude of motion, the larger the proportion of higher harmonic components in the whole aerodynamic force. For pure torsional motion with the same amplitude, the nonlinear effect of self-excited force at high converted wind speed is more significant, but for pure vertical bending motion, It is more obvious that the self-excited force is nonlinear at low converted wind speed. (3) the flow field under the condition of large amplitude of thin plate is studied. Flow separation is not the cause of the high frequency component of aerodynamic self-excited force. The flow separation at the leading edge of the plate affects the fundamental frequency amplitude of the self-excited force. However, the proportion of aerodynamic high-order harmonic components is positively correlated with the intensity of secondary vortices in the flow field. (4) the flow field under the condition of large amplitude of streamlined box girder section is studied. The phenomenon of vortex reverse in the flow field on one side of the cross-section is simultaneous with the high harmonic component of aerodynamic force. (5) based on the assumption that the bridge flutter is coupled with the harmonic vertical and torsional motions of the same frequency, The flutter derivative is expressed as a two-dimensional function of the converted frequency and motion amplitude, that is, the nonlinear flutter derivative. The total damping of the vibration system is again zero as the criterion of vibration amplitude stability. A basic method of nonlinear flutter analysis is established. (6) the nonlinear vibration amplitude response of Nanjing fourth Bridge section is studied. Even if the critical flutter velocity is exceeded, the flutter response may be maintained at a certain amplitude level. The flutter response amplitude is determined by the aerodynamic positive damping formed by the flutter derivative A2 * and the coupled negative aerodynamic damping associated with A1H3 *. (7) the influence of the mathematical form of the structural damping ratio model on the nonlinear flutter response is studied. When the damping ratio of the structure is constant, the structure damping can not restrain the flutter divergence. When the damping ratio of the structure is linear proportional, the slope of the damping ratio with the amplitude is an important factor to suppress the flutter response. When the damping ratio of the structure is asymptotic, the shape of the amplitude response curve is between the constant damping ratio and the linear proportional damping ratio.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：U441.3
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本文編號：2093085