本文關(guān)鍵詞：阻尼器對懸索橋吊索減振效果的數(shù)值研究　出處：《湖南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 懸索橋吊索 阻尼器 模態(tài)阻尼比 有限差分法 振動控制

【摘要】：隨著懸索橋的跨度不斷增大,其吊索的長度也不斷增長。由于吊索屬于細長結(jié)構(gòu),其阻尼小、質(zhì)量輕、頻率低的特點,極易在風(fēng)荷載、橋面或主纜的激勵作用下發(fā)生大幅振動。本文采用數(shù)值方法研究阻尼器對懸索橋吊索振動的控制效果,主要內(nèi)容如下:(1)采用數(shù)值方法,以單根吊索為研究對象,研究了阻尼器支架剛度、阻尼器剛度和吊索彎曲剛度對懸索橋吊索減振效果的影響。首先,推導(dǎo)了支架-阻尼器-吊索系統(tǒng)的運動偏微分方程。其次,采用有限差分方法對支架-阻尼器-吊索系統(tǒng)的運動微分方程進行數(shù)值離散求解,與已有的結(jié)果驗證了方法的可靠性,研究了阻尼器支架剛度、阻尼器剛度和吊索彎曲剛度對無量綱阻尼比曲線、可實現(xiàn)的最優(yōu)阻尼比及其對應(yīng)的最優(yōu)阻尼系數(shù)等的影響,研究了阻尼器支架模態(tài)質(zhì)量的影響,并與相關(guān)文獻結(jié)果進行比較。研究結(jié)果表明,隨著阻尼器支架剛度的減小,能實現(xiàn)的最優(yōu)阻尼比減小,對應(yīng)的最優(yōu)阻尼系數(shù)也減小,會影響阻尼器效率,且各階模態(tài)的無量綱阻尼比曲線不一致,阻尼器支架的模態(tài)質(zhì)量對阻尼器效率影響很小;隨著阻尼器剛度的增大,能實現(xiàn)的最優(yōu)阻尼比減小,對應(yīng)的最優(yōu)阻尼系數(shù)則增大,也會影響阻尼器效率;隨著吊索彎曲剛度的減小,能實現(xiàn)的最優(yōu)阻尼比先減小后增大,對應(yīng)的最優(yōu)阻尼系數(shù)增大,但是實際懸索橋的吊索彎曲剛度很小,對阻尼器效率的影響可忽略。(2)采用數(shù)值方法,以平行雙吊索為研究對象,研究了雙吊索之間安裝阻尼器對雙吊索系統(tǒng)動力特性的影響。首先,推導(dǎo)了雙吊索-阻尼器系統(tǒng)的運動偏微分方程。其次,采用有限差分方法對雙吊索-阻尼器系統(tǒng)的運動微分方程進行數(shù)值離散求解,研究了雙吊索之間安裝單個和多個阻尼器情況下,對結(jié)構(gòu)頻率、振型和模態(tài)阻尼比的影響。研究結(jié)果表明:平行雙吊索之間安裝阻尼器僅能對雙吊索反向振型提供模態(tài)阻尼,對雙吊索同向振型不能提高模態(tài)阻尼;在雙吊索之間安裝阻尼器,能夠改變結(jié)構(gòu)振型的排列次序,提高單根吊索的振動頻率,對于吊索的振動控制有利,當(dāng)阻尼器阻尼系數(shù)無窮大時,相當(dāng)于剛性分隔器的作用。(3)以四根吊索為研究對象,吊索之間以剛性分隔器連接,在吊索端部安裝雙阻尼器,以控制吊索的扭轉(zhuǎn)振動。采用ANSYS有限元軟件平臺,建立了安裝剛性分隔器的四根吊索模型,研究了阻尼器對四吊索-分隔器系統(tǒng)扭轉(zhuǎn)振動的控制效果。研究了四吊索-分隔器-阻尼器系統(tǒng)的扭轉(zhuǎn)模態(tài)無量綱阻尼比曲線,研究了阻尼器支架剛度和阻尼器剛度對扭轉(zhuǎn)模態(tài)無量綱阻尼比曲線、可實現(xiàn)的最優(yōu)阻尼比及其對應(yīng)的最優(yōu)阻尼系數(shù)等的影響,結(jié)果表明:阻尼器自身剛度和阻尼器支架剛度都會使系統(tǒng)扭轉(zhuǎn)模態(tài)阻尼比減小,其無量綱阻尼比曲線與單根吊索-阻尼器系統(tǒng)的無量綱阻尼比曲線相同。
[Abstract]:With the increasing span of suspension bridge, the length of sling is also increasing. Because the slings belong to slender structure, its damping is small, light weight, low frequency, so it is easy to wind load. Large vibration occurs under excitation of bridge deck or main cable. In this paper, numerical method is used to study the control effect of suspension cable vibration of suspension bridge by damper. The main contents are as follows: 1) numerical method. The effects of damper support stiffness, damper stiffness and sling bending stiffness on the vibration reduction of suspension bridge are studied with single sling as the research object. The partial differential equations of motion of the brace-damper-sling system are derived. Secondly, the finite difference method is used to solve the differential equations of motion of the brace-damper-sling system. The reliability of the method is verified by the existing results. The stiffness of the damper bracket, the damper stiffness and the curve of the sling bending stiffness to the dimensionless damping ratio are studied. The effect of the realizable optimal damping ratio and its corresponding optimal damping coefficient on the modal mass of the damper bracket is studied and compared with the results of related literatures. With the decrease of the stiffness of the damper, the optimal damping ratio and the corresponding optimal damping coefficient are reduced, which will affect the efficiency of the damper, and the dimensionless damping ratio curve of the different modes is not consistent. The modal mass of the damper bracket has little effect on the damper efficiency. With the increase of damper stiffness, the optimal damping ratio decreases and the corresponding optimal damping coefficient increases, which also affects the efficiency of the damper. With the decrease of the bending stiffness of sling, the optimal damping ratio decreases first and then increases, the corresponding optimal damping coefficient increases, but the actual suspension bridge sling bending stiffness is very small. The effect of dampers on the efficiency of double slings is negligible. (2) A numerical method is used to study the effect of dampers on the dynamic characteristics of double sling systems by taking parallel double slings as the object of study. The partial differential equations of motion of double sling dampers are derived. Secondly, the differential equations of motion of double slings dampers are solved numerically by finite difference method. In the case of single and multiple dampers mounted between two slings, the frequency of the structure is studied. The results show that the damper installed between parallel double slings can only provide modal damping for the reverse mode of double slings, but can not increase the modal damping for the same mode of double slings. The installation of dampers between the two slings can change the arrangement order of the structural modes and increase the vibration frequency of the single sling, which is beneficial to the vibration control of the sling, when the damping coefficient of the dampers is infinite. Equivalent to the role of rigid separator. 3) take the four sling as the object of study, the slings are connected by rigid separator, and double dampers are installed at the end of the sling. In order to control the torsional vibration of the sling, four sling models with rigid separator are established by using the ANSYS finite element software platform. The effect of damper on torsional vibration of four-sling separator system is studied, and the dimensionless damping ratio curve of four-sling separator damper system is studied. The effects of the stiffness of the damper bracket and the damper stiffness on the dimensionless damping ratio curve of torsional mode, the optimal damping ratio and the corresponding optimal damping coefficient are studied. The results show that both the stiffness of the damper and the stiffness of the damper bracket can reduce the damping ratio of the torsional mode, and the dimensionless damping ratio curve is the same as the dimensionless damping ratio curve of the single sling-damper system.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441.3;U448.25

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