本文選題：受壓構(gòu)件 + 畸變屈曲　； 參考：《蘭州大學(xué)》2015年博士論文

【摘要】：隨著結(jié)構(gòu)鋼屈服強度的提高,在結(jié)構(gòu)輕量化的要求下和節(jié)約鋼材的利益驅(qū)動下,冷彎型鋼受壓構(gòu)件的橫截面逐漸趨于開闊、纖薄,這致使畸變屈曲或畸變相關(guān)屈曲可能控制構(gòu)件的設(shè)計。本文在總結(jié)前人研究成果和分析前人研究不足的基礎(chǔ)上,以C形截面和帽形截面冷彎薄壁型鋼受壓構(gòu)件為研究對象,采用試驗研究、理論分析和數(shù)值模擬相結(jié)合的技術(shù)路線,主要完成了以下三方面的研究：1.建立了薄壁受壓構(gòu)件畸變屈曲的分析理論進行了4組共36個C形截面受壓構(gòu)件的試驗研究,考察了腹板和翼緣的寬度比h/b構(gòu)件幾何長度l對屈曲模式和極限荷載的影響,分析了構(gòu)件橫截面的變形特點、屈曲后強度等內(nèi)容；在試驗研究的基礎(chǔ)上并結(jié)合前人研究成果,提出了識別屈曲模式的判據(jù)。揭示了計算長度的物理意義,提出了畸變屈曲和局部屈曲的計算長度系數(shù)的概念,實現(xiàn)了畸變屈曲、整體屈曲和局部屈曲的統(tǒng)一表征。提出了受壓構(gòu)件畸變屈曲的分解分析方法,依據(jù)經(jīng)典的板的屈曲理論推導(dǎo)了局部屈曲計算長度的邊界條件影響系數(shù),采用能量法推導(dǎo)了彎扭屈曲的總勢能方程和平衡微分方程,進而推導(dǎo)了連續(xù)彈性支承構(gòu)件彎扭屈曲的平衡微分方程。研究表明,本文建立的薄壁受壓構(gòu)件畸變屈曲的分析理論概念明確、條理清晰。統(tǒng)一了屈曲問題的研究對象,解決了長期以來因截面形式、荷載工況或邊界約束條件的不同而研究對象不同的問題；突出了影響畸變屈曲的關(guān)鍵因素,為全面建立薄壁受壓構(gòu)件畸變屈曲的計算理論和計算方法奠定了基礎(chǔ)。2.建立了系統(tǒng)的薄壁受壓構(gòu)件畸變屈曲的計算理論和計算方法在畸變屈曲的臨界荷載方面,首先采用有限條軟件CUFSM分析了彈性模量、邊界約束條件和尺度參數(shù)對畸變屈曲臨界荷載的影響；繼而依據(jù)建立的畸變屈曲的分析理論和Lau和Hancock的分析模型,采用Galerkin法推導(dǎo)了畸變屈曲臨界荷載的統(tǒng)一公式,建立了畸變屈曲臨界荷載Pcr,D的統(tǒng)一理論,提出了Pcr,D的通用公式,并采用有限條軟件CUFSM驗證了Pcr,D通用公式的精度并確定了其適用范圍,同時還與其他數(shù)值軟件和現(xiàn)有的簡支構(gòu)件畸變屈曲臨界應(yīng)力的解析解的計算值進行了對比。結(jié)果表明,對于簡支構(gòu)件畸變屈曲臨界荷載,Pcr,D的通用公式較國際上廣泛使用的Lau和Hancock的公式、Schafer的公式精度更高、適用范圍更廣在畸變屈曲的極限荷載方面,根據(jù)結(jié)構(gòu)設(shè)計“窮舉”和“取小”的特點改寫了Schafer的固支受壓構(gòu)件畸變屈曲極限荷載Pu,D的計算公式；在提出簡支構(gòu)件Pu,D計算公式后,建立了畸變屈曲極限荷載Pu,D的統(tǒng)一理論并提出了Pu,D的通用公式。然后通過17個C形和17個帽形固支受壓構(gòu)件的ANSYS計算值進一步驗證了Pcr,D通用公式的精度,通過42個C形和42個帽形簡支受壓構(gòu)件的ANSYS計算值驗證了Pu,D的通用公式具有較高的精度。在畸變屈曲的發(fā)生條件和計算公式的本質(zhì)方面,建立了畸變屈曲與λD和λL的關(guān)系,提出了畸變屈曲的判據(jù)；對比了形式不同的Pu,D計算公式,揭示了畸變屈曲極限荷載計算理論的本質(zhì)是把強度問題轉(zhuǎn)化為穩(wěn)定問題進行求解的,同時也指出以有效寬度法或有效截面法形式給出的Pu,D計算公式與直接強度法的Pu,D計算公式無本質(zhì)區(qū)別。以上建立的薄壁受壓構(gòu)件畸變屈曲的計算理論和計算方法,解決了國內(nèi)外長期以來缺乏固支構(gòu)件的Pcr,D解析解的問題,拓展了簡支構(gòu)件Pcr,D計算公式的適用范圍,解決了臨界荷載Pcr,D和極限荷載Pu.D因邊界約束條件不同而無法對接的問題。3.建立了薄壁受壓構(gòu)件極限荷載的計算理論和計算方法基于本文提出的整體屈曲極限荷載Pu,G的實用公式和局部屈曲臨界荷載Pcr,L的實用公式以及建立的畸變屈曲的計算理論和計算方法,建立了薄壁受壓構(gòu)件極限荷載的統(tǒng)一化理論,提出了包含不同屈曲模式的3種極限狀態(tài)ULSⅣ,ULSⅥ和ULSⅧ。采用極限荷載的統(tǒng)一化理論分別計算了196個C形截面和32個帽形截面固支軸壓構(gòu)件以及45個C形截面簡支軸壓構(gòu)件的極限荷載Pu,Ⅳ,PuⅥ和pu,Ⅷ,并與試驗值Pu,Exp進行了對比。為提高極限荷載的計算精度和提高結(jié)構(gòu)材料的利用率,分別建立了屈曲模式和截面承載效率與λ和五的關(guān)系,提出了全面的局部-畸變相關(guān)屈曲的判據(jù)和極限狀態(tài)ULS的判據(jù),并根據(jù)如上判據(jù)確定了極限荷載的數(shù)值。最后提出了受壓構(gòu)件橫截面選形和構(gòu)件選材的建議。研究表明,極限荷載的計算精度和結(jié)構(gòu)材料的利用率受λD和λL的影響較大：限制構(gòu)件的λD≤1.290和(或)λL≤1.130不但可以由極限荷載的統(tǒng)一化理論較為準(zhǔn)確地計算其極限荷載,還能獲得較高的截面承載效率。而且,局部一畸變相關(guān)屈曲的承載效率較低,應(yīng)限制該屈曲模式的出現(xiàn)；為節(jié)約鋼材和提高極限荷載的計算精度,薄壁受壓構(gòu)件橫截面的尺度參數(shù)的選擇應(yīng)與構(gòu)件材料的選擇相協(xié)調(diào)。本文的創(chuàng)新點有：1.揭示了計算長度系數(shù)的物理意義,首次統(tǒng)一了屈曲問題的研究對象——兩端簡支且?guī)缀伍L度為屈曲半波長的構(gòu)件或構(gòu)件段。2.首次給出了簡支和固支構(gòu)件畸變屈曲臨界荷載統(tǒng)一計算公式,首次建立了畸變屈曲臨界荷載Pcr,D的統(tǒng)一理論和極限荷載Pu,,D的統(tǒng)一理論,提出了Pcr,D的通用公式和Pu,D的通用公式。3.首次建立了畸變屈曲、局部-畸變相關(guān)屈曲與λD和λL的關(guān)系,提出了全面的局部-畸變相關(guān)屈曲判據(jù)。
[Abstract]:With the increase of yield strength of structural steel, under the demand of lightweight structure and the benefit of saving steel, the cross section of the compression member of the cold bending steel gradually tends to be open and thin, which may lead to the design of the distortional buckling or distortion related buckling. On the basis of the research object, the C section and the cap shaped section cold bending thin-walled steel compression member are studied. The following three aspects are completed by the experimental research, the theoretical analysis and the numerical simulation. 1. the analysis of the distortion buckling of the thin-walled compression members is established, and 4 groups of 36 members of the compression members are tested. The effect of the width of the web and flange on the buckling mode and the ultimate load of the h/b member L is investigated. The deformation characteristics of the cross section of the component and the post buckling strength are analyzed. The criteria for the identification of the buckling mode are proposed on the basis of the experimental research and the previous research results. The physics of the calculation length is revealed. Meaning, the concept of calculating length coefficient of distortion buckling and local buckling is put forward. The unified characterization of distortion buckling, integral buckling and local buckling is realized. A decomposition analysis method for distorted buckling of compression members is proposed. The influence coefficient of boundary condition of local flexion calculation length is derived based on the classical plate buckling theory. The total potential energy equation and the equilibrium differential equation for flexural and torsional buckling are derived and the equilibrium differential equation of flexural and torsional buckling of continuous elastic supporting members is derived. The study shows that the theoretical concept of the distortion buckling of the thin-walled compression members is clear and the bar is clear. The research object of the buckling problem has been unified and the long term has been solved. The different problems of the object are studied in the form of cross section, load condition or boundary constraint conditions, and the key factors affecting the distortion buckling are highlighted. The foundation.2. is established to establish the calculation theory and calculation method of the distortion buckling of the thin-walled compression members. The calculation theory and calculation of the distorted buckling of the thin-walled compression members are established. In the critical load of distorted buckling, the finite strip software CUFSM is used to analyze the influence of elastic modulus, boundary constraint conditions and scale parameters on the critical load of distortional buckling, and then the critical load of distorted buckling is derived by Galerkin method, based on the analysis theory of distortion buckling and the analysis model of Lau and Hancock. The unified formula of the critical load of the distortion buckling load Pcr, D is established. The general formula of Pcr and D is put forward. The precision of Pcr, D general formula is verified by the finite strip software CUFSM, and its application range is determined. At the same time, the calculation value of the analytical solution of the critical stress of the existing simple supported components and the other numerical software and the existing simple supported components is also given. The results show that the general formula of Pcr and D is more accurate than that of Lau and Hancock, which is widely used in the world. The formula of Schafer is more accurate than the formula of Lau and Hancock, which is widely used in the world. The application range is more widely used in the limit load of distortional buckling, and the Schafer is rewritten according to the characteristics of "poor" and "small" structure design. The calculation formula of the limit load of the flexed buckling load Pu and D for the supported compression members; after putting forward the formula of Pu and D for the simply supported component, the unified theory of Pu, D for the ultimate load of the distorted buckling is established and the universal formula of Pu and D is put forward. Then the Pcr, the essence of the D general formula is further verified by the ANSYS calculation values of the 17 C and 17 cap solid supported compression members. Degree, verified by the ANSYS calculation values of 42 C shaped and 42 cap shaped simply supported compression members, the general formula of Pu and D has high accuracy. In terms of the condition of the distortion buckling and the essence of the formula, the relation between the distortion buckling and lambda D and lambda L is established, the criterion of the distortion buckling is put forward, and the different forms of Pu, D calculation formula are compared. The essence of the theory of the ultimate load calculation is to convert the strength problem to the stability problem, and also points out that the Pu, D formula given by the effective width method or the effective cross section method has no essential difference between the Pu and D formulas of the direct strength method. The calculation theory of the distortion buckling of the thin-walled compression members established above has been found. The theory and calculation method have solved the problem of Pcr and D analytical solution for a long time lack of solid supported components, expanded the scope of application of Pcr and D formula for simply supported components, and solved the calculation theory of critical load of Pcr, D and ultimate load Pu.D which can not be butted because of the different boundary constraints, and established the limit load of the thin-walled compression member. The theory and calculation method based on the proposed integral buckling limit load Pu, G's practical formula and the local buckling critical load Pcr, the practical formula of L and the calculation theory and calculation method established for the distortion buckling, establish the unified theory of the limit load of the thin-walled compression member, and put forward 3 extreme state UL containing different buckling modes. S IV, ULS VI and ULS VIII. Using the unified theory of limit load, the ultimate load of 196 C cross sections and 32 cap shaped cross section solid supported axial compression members and 45 C shaped section simply supported axial compression members are calculated respectively, Pu, IV, Pu VI and Pu, VIII, and are compared with the experimental values Pu and Exp. In order to improve the calculation precision of the limit load and improve the structural material The relation between the buckling mode and the cross section bearing efficiency with lambda and five is established respectively. The criterion of the comprehensive local distortion related buckling and the criterion of the limit state ULS are put forward, and the limit load values are determined according to the above criteria. Finally, the suggestion of the cross section selection and the material selection of the compression members is put forward. The research shows that the limit of the limit is the limit. The calculation accuracy of the load and the utilization of structural materials are greatly influenced by the lambda D and lambda L: the limit of the member's lambda D < 1.290 and (or) lambda L < 1.130 can not only calculate the ultimate load more accurately by the unified theory of the limit load, but also obtain higher cross section bearing efficiency. The emergence of the buckling mode should be limited. In order to save the steel and improve the calculation accuracy of the ultimate load, the selection of the scale parameters of the cross section of the thin-walled compression member should be coordinated with the selection of the component materials. The innovation points of this paper are as follows: 1. the physical meaning of the calculation length coefficient is revealed, and the research object of the buckling problem is first unified. .2. for the first time a member or component section with geometric length as a half wavelength, a unified calculation formula for the critical load of the flexural buckling of simply supported and supported components is given for the first time. For the first time, the unified theory of the critical load of the distorted buckling Pcr, the unified theory of D and the limit load Pu, the unified theory of D, and the general formula of Pcr, D, and the general formula.3. of D are proposed. For the first time, the relationship between distortional buckling, local distortion related buckling and lambda D and lambda L is established for the first time. A comprehensive local distortion correlation buckling criterion is proposed.

【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TU392.1

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