本文關(guān)鍵詞：車輛作用下具有裂縫的中小跨徑梁式橋的自振特性分析　出處：《吉林大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 梁式橋 裂縫 車輛 自振特性

【摘要】：梁式橋的損傷不可避免的會(huì)導(dǎo)致其剛度發(fā)生變化,從而導(dǎo)致其自振頻率和振型等動(dòng)力特性發(fā)生變化,這便為基于動(dòng)力特性的梁式橋的損傷識(shí)別提供了理論基礎(chǔ)。由于橋梁結(jié)構(gòu)的動(dòng)力荷載試驗(yàn)具有測(cè)試時(shí)間短,客觀性強(qiáng),無(wú)需封閉交通,能夠發(fā)現(xiàn)隱蔽部位的病害等優(yōu)點(diǎn),因此基于動(dòng)力特性的橋梁結(jié)構(gòu)損傷識(shí)別備受人們的青睞。然而動(dòng)力特性的準(zhǔn)確性直接決定了損傷識(shí)別結(jié)果的優(yōu)劣。有關(guān)研究資料表明,動(dòng)力特性的準(zhǔn)確性并不是由測(cè)試方法本身所決定的,橋梁上的通行車輛和環(huán)境溫度改變都會(huì)導(dǎo)致動(dòng)力特性的變異,有時(shí)這種變異會(huì)完全掩蓋由結(jié)構(gòu)損傷引起的動(dòng)力特性變異。因此如何剔除外界因素引起的動(dòng)力特性變異或在損傷識(shí)別時(shí)考慮由外界因素引起的動(dòng)力特性變異是十分必要的。對(duì)于中小跨徑梁式橋而言,為了在動(dòng)力荷載試驗(yàn)過程中測(cè)得信噪比相對(duì)較高的動(dòng)力時(shí)程響應(yīng),往往采用車輛對(duì)橋梁進(jìn)行激勵(lì)。一般來說,車輛激勵(lì)可分為采用試驗(yàn)車輛對(duì)橋梁進(jìn)行沖擊(跳車試驗(yàn))以及采用通行車輛對(duì)橋梁進(jìn)行隨機(jī)激勵(lì)。無(wú)論是何種激勵(lì),測(cè)試到的動(dòng)力特性其實(shí)是以橋梁振動(dòng)為重要振動(dòng)形式的車-橋耦合系統(tǒng)的動(dòng)力特性,動(dòng)力特性中均包含了車輛的影響。裂縫是梁式橋最為常見的病害之一,裂縫是如何影響梁式橋的動(dòng)力特性的,至今還沒有形成統(tǒng)一的認(rèn)識(shí)。裂縫中小跨徑梁式橋同樣也采用車輛進(jìn)行激振,這時(shí)測(cè)試到的橋梁動(dòng)力特性其實(shí)是車輛和裂縫耦合影響下的動(dòng)力特性。建立車輛作用下、車輛和裂縫耦合作用下梁式橋的動(dòng)力特性計(jì)算方法,剖析車輛作用以及車輛和裂縫耦合作用對(duì)其動(dòng)力特性的影響機(jī)理和影響規(guī)律,是使得測(cè)試到的動(dòng)力特性能夠應(yīng)用到橋梁損傷識(shí)別中的技術(shù)保障。為了解決以上問題,本文結(jié)合國(guó)家自然科學(xué)基金項(xiàng)目“考慮車輛和溫度耦合作用的中小跨徑梁式橋固有頻率分析方法研究”和吉林大學(xué)種子基金項(xiàng)目“車輛作用下中小跨徑梁式橋固有頻率分析方法研究”,開展了車輛作用下具有裂縫的中小跨徑梁式橋的動(dòng)力特性分析方法研究,具體研究?jī)?nèi)容如下:1、依據(jù)車輛振動(dòng)方程和梁體振型函數(shù),基于中支點(diǎn)處變形連續(xù)和力的平衡條件,采用數(shù)值組裝方法建立了多個(gè)車輛作用下等截面連續(xù)梁的動(dòng)力特性特征方程。采用傳遞矩陣方法來表征變截面梁的振型函數(shù),根據(jù)車輛振動(dòng)方程和邊界條件得到了多個(gè)車輛作用下變截面簡(jiǎn)支梁的動(dòng)力特性特征方程。依據(jù)建立的動(dòng)力特性特征方程計(jì)算了多個(gè)車輛作用工況下等截面連續(xù)梁和變截面簡(jiǎn)支梁的動(dòng)力特性,并討論了車輛參數(shù)對(duì)其動(dòng)力特性的影響。2、采用無(wú)質(zhì)量扭轉(zhuǎn)彈簧來模擬裂縫,并形成了裂縫位置處梁體振型函數(shù)待定系數(shù)的傳遞關(guān)系。依據(jù)車輛的振動(dòng)方程以及采用傳遞矩陣方法表征的振型函數(shù),建立了采用待定系數(shù)表示的車輛和裂縫作用下簡(jiǎn)支梁橋的耦合體系振動(dòng)方程,并給出了其求解方法。根據(jù)建立的理論計(jì)算模型,計(jì)算了多種車輛作用、裂縫作用工況下的簡(jiǎn)支梁的動(dòng)力特性,并討論了車輛參數(shù)和裂縫參數(shù)對(duì)其動(dòng)力特性的影響。3、采用單自由度彈簧-質(zhì)量系統(tǒng)來模擬車輛,首先構(gòu)建了任意數(shù)量車輛作用下具有任意裂縫數(shù)量的連續(xù)梁的等效計(jì)算模型。通過對(duì)已有方法的改進(jìn),采用一組基函數(shù)來表征梁體的振型函數(shù),得到了單跨內(nèi)梁體振型函數(shù)的遞推關(guān)系。依據(jù)單跨內(nèi)梁體振型函數(shù)和中支點(diǎn)處變形連續(xù)和力的平衡條件,以及彈簧-質(zhì)量系統(tǒng)振動(dòng)方程,形成了任意數(shù)量車輛作用下具有任意裂縫數(shù)量的連續(xù)梁的動(dòng)力特性計(jì)算方法。同樣討論了車輛參數(shù)和裂縫參數(shù)對(duì)其動(dòng)力特性的影響。
[Abstract]:Liang Shiqiao's injury inevitably lead to the rigidity changes, leading to its natural frequency and modal shape change, which provides a theoretical basis for the damage identification of girder bridge based on dynamic characteristics. Due to the dynamic load test of bridge structure with short test time, strong objectivity, without closed to traffic to discover the advantages, the hidden parts of the disease, so the damage identification of bridge structure based on the dynamic characteristics of the popular with people of all ages. However the accuracy of dynamic characteristics directly determine the damage identification result. Relevant research data show that the dynamic characteristics of the accuracy is not determined by this test method itself, vehicles and the environment temperature of bridge the change will lead to the variation of dynamic characteristics, sometimes this variant will completely obscured by the structural damage caused by the variation of dynamic characteristics. So how to tick In addition to the dynamic characteristics or variation of external factors caused by considering the variation of dynamic characteristics caused by external factors in the damage identification is necessary. For the small and medium span bridge, in the dynamic load test in the process of the measured signal-to-noise ratio is relatively high dynamic response, often using the vehicle on the bridge for a general incentive. Motivation can be divided into the vehicle, the vehicle test impact on bridge (jumping test) and the use of vehicles of random excitation on the bridge. No matter what kind of motivation is to test dynamic characteristics of dynamic characteristics of the bridge vibration is an important form of vibration of vehicle bridge coupling system dynamic characteristics, which include the effect of vehicle. Crack is one of the most common diseases of beam bridge, crack is how to affect the dynamic characteristics of the bridge, has not yet formed a unified understanding. Small and medium span crack Diameter of beam bridge also uses the vehicle vibration, the bridge dynamic characteristics when it is tested to the dynamic characteristics of vehicle and crack under coupling. Vehicles built under the calculation method of dynamic characteristics of beam bridge and vehicle cracks under coupling effect of vehicles and vehicles and to analyze crack coupling effects on its dynamic characteristics the mechanism and effect of dynamic characteristics, is to make the test can be applied to guarantee the bridge damage identification. In order to solve the above problems, combined with the National Natural Science Fund Project "consider the vehicle and temperature coupling effect of small and medium span beam bridge natural frequency analysis method research and the Jilin University seed fund project" under the action of small vehicles span bridge natural frequency analysis method research, carry out dynamic medium span girder bridges with cracks under the action of the vehicle. Study on the method of analysis, the specific contents are as follows: 1, according to the vehicle vibration equation of beam and Tizhen type function, equilibrium conditions and continuous force in support of deformation based on the numerical method of assembly dynamics characteristics of continuous beam multiple vehicles for sectional process. Using the mode function to characterize the variable cross section beam the transfer matrix method, according to the vehicle vibration equation and boundary condition, dynamic characteristics of the characteristic equation of variable section beam under several vehicles. Based on the dynamic characteristics of the characteristic equation established multiple vehicle working conditions of uniform section continuous beam of variable cross section beam and calculated the dynamic characteristics, and discusses the influence of parameters on the dynamic characteristics of vehicle.2, the quality of the torsion spring to simulate cracks, and the formation of cracks at the position of the undetermined coefficient transfer function. On the basis of Tizhen beam type vibration of vehicle The process and the modal function of transfer matrix method for the characterization of the established system coupling vibration equation of beam bridge using undetermined coefficient and crack under the action of the vehicle, and gives the solving method. Calculation model is established according to the theory, a variety of vehicles is calculated, the dynamic characteristics of beam crack condition, and discuss the vehicle parameters and fracture parameters on the dynamic characteristics of.3, the single degree of freedom spring mass system to simulate vehicle, first constructed a calculation model with arbitrary number of cracks of arbitrary number of vehicles under the action of the equivalent continuous beam. Through the improvement of the existing methods, the modal function using a set of basis functions to characterize the beam the beam has been Tizhen type function of single span recursive relationship. According to the balance conditions and capacity of single span continuous beam Tizhen type function and support deformation, and spring - mass The dynamic equation of continuous beam with arbitrary number of cracks is formed when any number of vehicles is acted on. The influence of vehicle parameters and crack parameters on its dynamic characteristics is also discussed.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U441.3

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