【摘要】：正交異性鋼橋面板因具有自重輕、施工便捷等優(yōu)點(diǎn),被廣泛應(yīng)用于各種類型的橋梁中。然而正交異性鋼橋面板受力復(fù)雜,加之通行橋梁的車輛超載嚴(yán)重,各種焊接細(xì)節(jié)易出現(xiàn)疲勞開裂。研究車輛活載作用下的正交異性鋼橋面板受力行為,分析構(gòu)造細(xì)節(jié)的疲勞開裂機(jī)理,提出更為合理的正交異性鋼橋面板構(gòu)造設(shè)計(jì),對(duì)橋梁的運(yùn)營(yíng)安全和耐久性顯得尤為重要。論文從評(píng)價(jià)方法和實(shí)例分析兩方面著手,討論了正交異性鋼橋面U肋-橫隔板構(gòu)造細(xì)節(jié)處的疲勞應(yīng)力。主要研究?jī)?nèi)容和取得的成果如下:(1)介紹了正交異性鋼橋面板的工程應(yīng)用和疲勞開裂問題,回溯了疲勞的相關(guān)研究和實(shí)際鋼橋的健康檢測(cè),并提出了本文的研究?jī)?nèi)容。(2)分別概述了名義應(yīng)力法、熱點(diǎn)應(yīng)力法、零點(diǎn)結(jié)構(gòu)應(yīng)力法、缺口應(yīng)變法及基于線彈性斷裂力學(xué)的原理、使用條件、計(jì)算方法以及相對(duì)應(yīng)的規(guī)范標(biāo)準(zhǔn)。另外,著重指出了上述方法存在的優(yōu)缺點(diǎn)。(3)采用有效缺口應(yīng)力法并以十字角焊縫為參考,分別計(jì)算單元類型、網(wǎng)格大小、焊根區(qū)域的網(wǎng)格劃分方式對(duì)有效缺口應(yīng)力的影響。結(jié)果表明:為避免解鎖現(xiàn)象,有效缺口應(yīng)力法計(jì)算時(shí)盡量使用高階單元;網(wǎng)格大小必須滿足IIW規(guī)定的最小要求,且無需過細(xì)劃分導(dǎo)致工作量增加;當(dāng)荷載平行于缺口時(shí),可采用鑰匙孔或U型孔建模;當(dāng)荷載垂直于缺口時(shí),應(yīng)采用鑰匙孔建模。(4)以某工程試驗(yàn)為例,分別采用熱點(diǎn)應(yīng)力法和有效缺口應(yīng)力法計(jì)算關(guān)鍵點(diǎn)處的疲勞應(yīng)力。結(jié)果表明有效缺口應(yīng)力法可以適用于正交異性橋面板的疲勞評(píng)價(jià),且比熱點(diǎn)應(yīng)力法具有一定的優(yōu)越性。文章比較兩種不同的橫隔板過渡形式的有效缺口應(yīng)力,得到了更加合理的方案;U肋-橫隔板弧形切口焊趾處的有效缺口應(yīng)力顯著大于焊根處,證明焊趾處更易萌生裂紋;比較不同的U肋厚度,發(fā)現(xiàn)U肋厚度的增加會(huì)導(dǎo)致U肋-橫隔板弧形切口焊縫處疲勞強(qiáng)度的降低。(5)現(xiàn)場(chǎng)實(shí)測(cè)某橋的應(yīng)力時(shí)程曲線,采用雨流計(jì)數(shù)法、Miner準(zhǔn)則并結(jié)合AASHTO規(guī)范條文計(jì)算正交異性鋼橋面板典型易開裂處焊縫的等效應(yīng)力幅,給出了疲勞壽命的估算值。結(jié)果表明:U肋-橫隔板弧形切口焊縫處,靠近U肋側(cè)和靠近橫隔板側(cè)疲勞壽命均不滿足規(guī)范要求。該處疲勞開裂的原因是焊縫未打磨處理,導(dǎo)致焊縫質(zhì)量降低。
[Abstract]:Orthotropic steel bridge face is widely used in various types of bridges because of its advantages of light weight and convenient construction. However, the orthotropic steel bridge face is complicated, and the vehicle overloading of the bridge is serious, so various welding details are prone to fatigue cracking. It is very important for the operation safety and durability of orthotropic steel bridge to study the stress behavior of orthotropic steel bridge slab under the action of live load, analyze the fatigue cracking mechanism of structural details, and put forward a more reasonable structural design of orthotropic steel bridge slab. In this paper, the fatigue stress of orthotropic steel deck U rib-transverse partition is discussed from two aspects of evaluation method and example analysis. The main research contents and achievements are as follows: (1) the engineering application and fatigue cracking of orthotropic steel bridge face are introduced. The research contents of this paper are also presented. (2) the nominal stress method, the hot spot stress method, the zero point structure stress method, the notch strain method and the principle and conditions based on linear elastic fracture mechanics are summarized respectively. Calculation method and corresponding specification standard. In addition, the advantages and disadvantages of the above methods are emphatically pointed out. (3) the effective notch stress method and the cross-fillet weld are used to calculate the cell type and mesh size, respectively. The effect of mesh generation on effective notch stress in soldering root region. The results show that, in order to avoid the unlocking phenomenon, the high-order element is used in the effective notch stress method, the mesh size must meet the minimum requirement of IIW, and the workload is increased without too much division. When the load is parallel to the notch, the model of keyhole or U-hole can be used. When the load is perpendicular to the notch, the keyhole model should be adopted. (4) the hot spot stress method and the effective notch stress method are used to calculate the fatigue stress at the key points in an engineering experiment. The results show that the effective notch stress method can be applied to the fatigue evaluation of orthotropic bridge deck, and it is superior to the hot spot stress method. In this paper, the effective notch stress of two different transversal plate transition forms is compared, and a more reasonable scheme is obtained, and the effective notch stress at the arc notch of U-rib transverse diaphragm is significantly larger than that at the welding root, which proves that the crack initiation is easier in the weld toe. Compared with the different thickness of U rib, it is found that the increase of thickness of U rib will lead to the decrease of fatigue strength at the weld seam of arc notch of U rib transverse partition plate. (5) the stress time history curve of a bridge is measured on the spot, and the rain flow counting method is used. The Miner criterion and the AASHTO code are used to calculate the equivalent stress amplitude of the weld seam where the orthotropic steel bridge face is prone to crack, and the estimated fatigue life is given. The results show that the fatigue life of the arc notch weld near the U-rib and the transverse partition does not meet the requirements of the specification. The reason of fatigue cracking is that the weld seam is not polished and the quality of weld is reduced.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U441.4

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