【摘要】：野營折疊網(wǎng)殼帳篷被廣泛應(yīng)用于民用和軍事領(lǐng)域,此類房屋通過編織材料組成其防護(hù)層和構(gòu)造層,致使房屋自重在整個荷載中所占比重很小,屬于典型的輕型房屋,故風(fēng)和雪荷載是其結(jié)構(gòu)設(shè)計(jì)的主要控制荷載。針對風(fēng)荷載目前已有相對深入的研究,而對于雪荷載,風(fēng)致雪漂效應(yīng)會造成積雪在折疊網(wǎng)殼屋蓋表面產(chǎn)生不均勻分布,其結(jié)果常會導(dǎo)致結(jié)構(gòu)局部或整體坍塌,且現(xiàn)行《建筑結(jié)構(gòu)荷載規(guī)范》(GB50009-2012)僅根據(jù)以往的設(shè)計(jì)經(jīng)驗(yàn)和國際標(biāo)準(zhǔn)以及國外有關(guān)資料概括性地規(guī)定了典型規(guī)則屋面積雪分布系數(shù),并不能適用于目前大量涌現(xiàn)的外形獨(dú)特且對雪荷載敏感的輕質(zhì)屋蓋結(jié)構(gòu),故亟需對折疊網(wǎng)殼結(jié)構(gòu)的風(fēng)雪效應(yīng)進(jìn)行深入研究與探討。在風(fēng)致雪漂移的研究方法中,現(xiàn)場實(shí)測可以獲得最準(zhǔn)確的數(shù)據(jù),但是所需周期長,較大程度上受制于自然條件等因素;試驗(yàn)研究受到試驗(yàn)條件和相似準(zhǔn)則的限制致使耗費(fèi)成本過高。隨著計(jì)算機(jī)技術(shù)的高速發(fā)展,CFD(Computational Fluid Dynamics)數(shù)值模擬技術(shù)以其周期短、成本低、易滿足相似性和高重復(fù)性模擬的優(yōu)點(diǎn)被廣泛且深入地應(yīng)用于風(fēng)雪運(yùn)動的研究。為了深入研究風(fēng)致折疊網(wǎng)殼結(jié)構(gòu)表面積雪分布規(guī)律,本文基于歐拉-歐拉方法和空氣相與雪相均連續(xù)且單向耦合的基本假定,考慮風(fēng)雪漂移的躍移運(yùn)動模式和懸移運(yùn)動模式,運(yùn)用大型通用計(jì)算流體動力學(xué)軟件ANSYS Fluent中的Mixture多相流模型理論,采用自編C語言UDF解釋型程序與Fluent作接口實(shí)現(xiàn)邊界條件的嵌入,并計(jì)及壁面上積雪侵蝕與沉積,建立風(fēng)致雪漂的數(shù)值計(jì)算模型。首先模擬三維算例立方體模型周圍的積雪分布,探討與分析數(shù)值風(fēng)洞的關(guān)鍵技術(shù)與參數(shù),在與實(shí)測結(jié)果對比后驗(yàn)證所建立數(shù)值模型的可行性與有效性,分析表明三方程klk--ω湍流模型具有較優(yōu)模擬結(jié)果。在此基礎(chǔ)上,以風(fēng)速、風(fēng)向角和地貌類型為分析參數(shù),模擬折疊網(wǎng)殼結(jié)構(gòu)的風(fēng)致雪漂效應(yīng),求解風(fēng)雪流流場后分析風(fēng)雪耦合場規(guī)律,并獲得結(jié)構(gòu)表面風(fēng)致雪漂的積雪分布系數(shù),為近似該體型結(jié)構(gòu)的抗風(fēng)雪設(shè)計(jì)提供參考依據(jù)。結(jié)果表明:風(fēng)雪流繞流具有復(fù)雜體型的折疊網(wǎng)殼結(jié)構(gòu)異常紊亂,較低風(fēng)速的持續(xù)作用下對其表面積雪分布尤為不利,結(jié)構(gòu)表面積雪的侵蝕與沉積受風(fēng)向角影響會發(fā)生在不同區(qū)域,總體呈現(xiàn)以侵蝕為主、背風(fēng)面局部沉積的規(guī)律,因風(fēng)向角的變化引起同一分區(qū)雪荷載的改變對此類雪荷載敏感性結(jié)構(gòu)的抗風(fēng)雪設(shè)計(jì)至關(guān)重要,此外,結(jié)構(gòu)表面積雪沉積系數(shù)與四類地貌的開闊程度呈現(xiàn)負(fù)相關(guān)性。
[Abstract]:Camping folding reticulated shell tent is widely used in civil and military fields. This kind of house is composed of protective layer and structural layer through braided materials, which makes the proportion of building weight in the whole load very small, so it belongs to typical light building, so wind and snow load is the main control load of its structural design. At present, the wind load has been studied relatively deeply, but for the snow load, the snow drift effect caused by the wind will cause the uneven distribution of snow on the surface of the folded reticulated shell roof, and the results often lead to the local or overall collapse of the structure, and the current Code of Building structure load (GB50009-2012) only specifies the snow distribution coefficient of the typical regular roof according to the previous design experience and international standards, as well as the relevant foreign data. It is not suitable for a large number of lightweight roof structures with unique shape and sensitive to snow load, so it is urgent to study and discuss the snowstorm effect of folded reticulated shell structure. In the research method of wind-induced snow drift, the most accurate data can be obtained from the field measurement, but the required period is long, which is restricted to a large extent by natural conditions, and the experimental research is limited by the test conditions and similar criteria, resulting in too high cost. With the rapid development of computer technology, CFD (Computational Fluid Dynamics) numerical simulation technology has been widely and deeply used in the study of snow movement because of its short cycle, low cost, easy to meet the advantages of similarity and high repeatability simulation. In order to deeply study the snow distribution law on the surface of wind-induced folded reticulated shell structure, based on the Euler-Euler method and the basic assumption that the air phase and snow phase are continuous and unidirectional coupling, considering the jump motion mode and suspension motion mode of snow drift, the Mixture multiphase flow model theory in large-scale general computational fluid dynamics software ANSYS Fluent is used, and the interface between self-compiled C language UDF explanatory program and Fluent is used to realize the embedding of boundary conditions. Taking into account the erosion and deposition of snow on the wall, the numerical model of wind-induced snow drift is established. Firstly, the snow distribution around the cube model of a three-dimensional example is simulated, and the key techniques and parameters of the numerical wind tunnel are discussed and analyzed. The feasibility and effectiveness of the numerical model are verified by comparing with the measured results. The analysis shows that the three-equation klk-- 蠅 turbulence model has better simulation results. On this basis, taking wind speed, wind direction angle and geomorphological type as analysis parameters, the wind-induced snow drift effect of folded reticulated shell structure is simulated, the law of wind-snow coupling field is analyzed after solving the wind-snow flow field, and the snow distribution coefficient of wind-induced snow drift on the surface of the structure is obtained, which provides a reference for the anti-snow design of the similar structure. The results show that the folding reticulated shell structure with complex shape is abnormally disordered, and the snow distribution on the surface is particularly disadvantageous under the continuous action of low wind speed. The erosion and deposition of snow on the surface of the structure will occur in different areas under the influence of wind direction angle, which is dominated by erosion and local deposition on the leeward surface. The change of snow load in the same zone caused by the change of wind direction angle is very important to the anti-snow design of this kind of snow load sensitive structure. In addition, the snow deposition coefficient on the surface of the structure is negatively correlated with the openness of the four geomorphology.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU399;TU312.1

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