本文選題：三室箱梁　切入點(diǎn)：數(shù)值模型　出處：《蘭州交通大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：薄壁箱形截面梁在客運(yùn)專線中的廣泛使用,使得局部畸變效應(yīng)在橋梁結(jié)構(gòu)設(shè)計(jì)和受力分析越來越受人們重視。從理論推導(dǎo)和有限元數(shù)值模擬相結(jié)合對單箱三室箱梁在正對稱荷載作用下基于閉口薄壁桿件理論的局部畸變效應(yīng)的相關(guān)問題,進(jìn)行了大量對比分析及研究,主要研究內(nèi)容如下:(1)針對單箱三室箱梁在中腹板對稱加載模式和邊腹板對稱加載模式來研究正對稱作用下的受力情況。通過將單箱三室箱梁在中腹板對稱加載模式下的荷載分解可看出,箱梁截面總體可看做約束扭轉(zhuǎn)、畸變效應(yīng)與剪力滯效應(yīng)的組合變形;本文通過截開單箱三室箱形梁截面,截開后單室截面上的畸變豎向荷載與等效荷載計(jì)算公式利用截面剪力流平衡來推導(dǎo)出,以此為基礎(chǔ)利用彈性地基比擬法可得到中腹板對稱模式下單箱三室截面的約束扭轉(zhuǎn)、畸變效應(yīng)與剪力滯效應(yīng)等組合變形下的應(yīng)力;而邊腹板對稱加載模式下的單箱三室箱梁可通過荷載分解成中腹板對稱加載模式進(jìn)行計(jì)算。(2)針對單箱三室截面的簡支梁和懸臂梁在中腹板對稱加載模式下,數(shù)值模型采用ANSYS中SHELL63單元建立。數(shù)值解是通過疊加數(shù)值模型中提取的應(yīng)力值得到的,并對畸變縱向應(yīng)力及畸變橫向應(yīng)力解析解與數(shù)值解分別從(1)橫向:不同截面各關(guān)鍵點(diǎn)部位;(2)縱向:各關(guān)鍵點(diǎn)部位沿跨度方向上的分布等兩方面進(jìn)行了大量的對比分析,結(jié)論如下:解析解和數(shù)值解無論從數(shù)值還是變化規(guī)律均基本吻合,證實(shí)了本文中相關(guān)理論推導(dǎo)是正確性與精確性。(3)針對單箱三室箱梁在邊腹板對稱加載模式下,利用荷載分解的方法將其等效成中腹板對稱加載模式,單箱三室箱形梁截面局部畸變縱向應(yīng)力及畸變橫向應(yīng)力的解析解與數(shù)值解進(jìn)行了對比分析,分析結(jié)果表明,解析解和數(shù)值解基本吻合,同時(shí)說明,中腹板對稱加載模式與邊腹板對稱加載模式利用荷載分解的方法相互等效的方法是可行的,同時(shí)也證明了本文相關(guān)理論推導(dǎo)的正確性。(4)本文中引入了畸變率的概念為了更加清晰的反映畸變應(yīng)力占考慮剪力滯效應(yīng)的彎曲應(yīng)力的比值的大小。通過對截面畸變率的分析得到結(jié)論如下:單箱三室截面最大的畸變率出現(xiàn)在頂板懸臂部位,而畸變率最小的部位為頂板和邊腹板交接處。中腹板對稱加載模式下,簡支梁L/2截面最小畸變率為15.21%,最大畸變率為43.7%;懸臂梁L/8截面最小畸變率為12.52%,最大畸變率為70.57%。邊腹板對稱加載模式下,簡支梁L/2截面最小畸變率為6.42%,最大畸變率為22.4%;懸臂梁L/8截面最小畸變率為6.85%,最大畸變率為38.83%。結(jié)果表明,單箱三室箱梁在正對稱加載模式下個(gè)別部位畸變率相對較大,在結(jié)構(gòu)計(jì)算中應(yīng)予以重視,同時(shí),正對稱荷載作用下荷載在橫截面上分布越靠近頂板中心,截面局部畸變效應(yīng)越明顯。
[Abstract]:The wide use of thin-walled box section beam in passenger dedicated line, People pay more and more attention to local distortion effect in the design and stress analysis of bridge structure. Based on closed thin-walled member mechanism of single box and three-room box girder under normal symmetric load, the theoretical derivation and finite element numerical simulation are combined. On the related problems of local distortion effect, A large number of comparative analyses and studies have been carried out. The main contents of this study are as follows: (1) in view of the symmetrical loading mode of the single box and three chambers box girder under the symmetrical loading mode of the middle web and the symmetrical loading mode of the edge web plate, the loading modes of the single box and three room box girder under the normal symmetrical action are studied by using the symmetrical loading mode of the single box and three chambers box girder in the middle web. As can be seen from the decomposition of the load under the formula, The cross section of box girder can be regarded as the combined deformation of restrained torsion, distortion effect and shear lag effect. The formula for calculating the distorted vertical load and equivalent load on the section of a single chamber after cutting is derived by using the cross-section shear flow balance. Based on this formula, the constrained torsion of the three-compartment section of the order box can be obtained by using the elastic foundation analogy method. The stress under the combined deformation such as distortion effect and shear lag effect; The single box and three compartment box girder under symmetrical loading mode can be decomposed into the symmetrical loading mode of the middle web plate to calculate. (2) for the simple supported beam and cantilever beam of the single box and three compartment section under the symmetrical loading mode of the middle web, the single box and three compartment section of the box can be calculated under the symmetrical loading mode of the middle web. The numerical model is established by SHELL63 element in ANSYS. The numerical solution is worth the stress extracted from the superposition numerical model. The analytical solution and numerical solution of distortion longitudinal stress and distortion transverse stress are compared and analyzed respectively from two aspects: transverse: different key points of different sections and distribution of key points along the span direction, etc. The conclusions are as follows: both the analytical solution and the numerical solution are in good agreement with each other, which proves that the theoretical derivation in this paper is correct and accurate. By using the method of load decomposition, it is equivalent to the symmetrical loading mode of middle web. The analytical and numerical solutions of local distortion longitudinal stress and distortion transverse stress of single box and three compartment box beam are compared and analyzed. The results show that, The analytical and numerical solutions are in good agreement with each other. At the same time, it is shown that it is feasible to use the method of load decomposition for the symmetric loading mode of the mesosecond and the symmetrical loading of the edge web, which is equivalent to each other by the method of load decomposition. It also proves the correctness of the theoretical derivation in this paper. (4) the concept of distortion rate is introduced in this paper in order to more clearly reflect the magnitude of the ratio of distortion stress to the bending stress considering shear lag effect. The conclusions are as follows: the maximum distortion rate of the section of a single box and three chambers appears in the cantilever part of the roof. The lowest distortion rate is at the junction of the top plate and the edge web. Under the symmetrical loading mode of the middle web, The minimum distortion rate of L- / 2 section of simply supported beam is 15.21, the maximum distortion rate is 43.7, the minimum distortion rate of L- / 8 section of cantilever beam is 12.52 and the maximum distortion rate is 70.57. The minimum distortion rate of L / 2 section is 6.42 and the maximum distortion rate is 22.40.The minimum distortion rate of cantilever beam L / 8 section is 6.85 and the maximum distortion rate is 38.83.The results show that the distortion rate of individual parts of single box and three chambers box girder is relatively large in normal symmetric loading mode. At the same time, the distribution of the load on the cross section is closer to the center of the roof, and the local distortion effect of the section is more obvious.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441

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