本文關(guān)鍵詞：斜腿框架體系的穩(wěn)定性分析　出處：《昆明理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 斜腿框架 諾模圖 計(jì)算長(zhǎng)度系數(shù) 二階位移法

【摘要】：斜腿框架相對(duì)于常見的直腿框架(普通框架)有其受力的特點(diǎn)和優(yōu)點(diǎn),在直腿框架中主要以桿件的彎曲來(lái)傳力,桿件中彎矩和剪力較大。而在斜腿框架中除了有彎曲傳力外,還多了一種“拱”的傳力方式,因此,在斜腿框架中軸力較大。由于有“拱”的傳力方式,斜腿框架的變形剛度比普通框架大,在同樣的荷載和桿件截面情況下,斜腿框架可跨越的空間(跨度)更大,或者在同樣的跨度下,斜腿框架的桿件截面可以做的更小。但這會(huì)使得斜腿框架的穩(wěn)定問(wèn)題變得突出和重要,加之斜腿框架中的軸力也相對(duì)較大。穩(wěn)定問(wèn)題的核心是評(píng)估和確定桿件或結(jié)構(gòu)的臨界力。對(duì)于普通框架可借助《鋼結(jié)構(gòu)設(shè)計(jì)規(guī)范》附錄D來(lái)確定框架柱的計(jì)算長(zhǎng)度系數(shù),而對(duì)于斜腿框架就沒(méi)那么幸運(yùn)了,在常用規(guī)范中還沒(méi)有見到相關(guān)的計(jì)算公式或表格。工程中也不可能針對(duì)具體的結(jié)構(gòu)去推導(dǎo)和求解穩(wěn)定臨界方程,因臨界方程式超越方程,無(wú)解析解,須迭代求解。雖然當(dāng)今可用軟件計(jì)算來(lái)取代大量的手算,但軟件計(jì)算結(jié)果的正確性也需要檢驗(yàn),用什么來(lái)檢驗(yàn),怎樣檢驗(yàn)?這些也是不能回避的問(wèn)題。因此工程設(shè)計(jì)還是迫切需要一些既方便又快速的計(jì)算工具。本論文就是針對(duì)這一現(xiàn)狀來(lái)開展工作:對(duì)斜腿框架的穩(wěn)定進(jìn)行研究,推導(dǎo)相關(guān)的臨界方程,進(jìn)而求解和大量求解,以獲得足夠多的數(shù)據(jù),來(lái)繪制能計(jì)算斜腿框架柱臨界力的諾模圖。因此本文最有價(jià)值的成果就是附表1至附表3中的諾模圖,這些諾模圖的計(jì)算結(jié)果經(jīng)過(guò)了有限元(ansys軟件)計(jì)算的檢驗(yàn),檢驗(yàn)結(jié)果是正確可靠,計(jì)算精度高。由于穩(wěn)定問(wèn)題比傳統(tǒng)的一階強(qiáng)度問(wèn)題復(fù)雜,要考慮結(jié)構(gòu)變形后的平衡,屬于二階問(wèn)題,是幾何非線性。精確推導(dǎo)結(jié)構(gòu)的穩(wěn)定臨界方程會(huì)隨著結(jié)構(gòu)桿件及節(jié)點(diǎn)數(shù)目的增多變得異常困難,因此本論文僅選取了單跨斜腿框架為研究對(duì)象,但本文研究方法可以擴(kuò)展到多跨的情況。值得一提的是:在研究斜腿框架的穩(wěn)定特點(diǎn)及規(guī)律時(shí),作者找到了合適的方法,可用來(lái)定性或定量的考察與斜腿框架臨界力密切相關(guān)的參數(shù)(約束和剛度)的影響,為此引入了新的概念,即全剛度約束、半剛度約束和零剛度約束。用這些概念包含的知識(shí)來(lái)考察結(jié)構(gòu)中桿件對(duì)柱子提供的約束大小,有很好的幫助。也能清晰的解釋為什么斜腿框架比同樣尺寸的直腿框架的臨界力低。
[Abstract]:The oblique leg frame has the characteristics and advantages of force compared with the common straight leg frame (common frame). In the straight leg frame, the bending of the bar is mainly used to transmit the force. The bending moment and shearing force are larger in the members. In addition to the bending force transmission in the oblique leg frame, there is also one kind of "arch" force transfer mode, therefore, the axial force is larger in the oblique leg frame. Because of the "arch" transmission mode. The deformation stiffness of the oblique leg frame is larger than that of the ordinary frame. In the case of the same load and member section, the inclined leg frame can span more space (span), or under the same span. The cross section of the inclined leg frame can be smaller, but this will make the stability of the inclined leg frame become prominent and important. The core of the stability problem is to evaluate and determine the critical force of the member or structure. For the common frame, the calculation length of the frame column can be determined by using Appendix D of the Code for Design of Steel structures. Degree coefficient. But for the oblique leg frame is not so lucky, there is no related calculation formula or table in the common specification, and it is impossible to deduce and solve the stability critical equation for the specific structure in the engineering. Because the critical equation transcends the equation and has no analytic solution, it has to be solved iteratively. Although a large number of manual calculations can be replaced by software calculation nowadays, the correctness of the software calculation results also needs to be tested. What should be used to test and how to test? Therefore, engineering design is in urgent need of some convenient and fast computing tools. This paper is aimed at this situation to carry out the work: to study the stability of oblique leg frame. The related critical equations are derived, then solved and solved in large quantities to obtain enough data. Therefore, the most valuable result of this paper is the Norm diagram in schedules 1 to 3. The calculation results of these Norm diagrams have been verified by finite element software ANSYS. The results are correct and reliable, and the calculation accuracy is high. The stability problem is more complicated than the traditional first-order strength problem. In order to consider the structural equilibrium after deformation, it belongs to the second order problem and is geometric nonlinear. It is very difficult to derive the stability critical equation of the structure with the increase of the number of structural members and nodes. Therefore, this paper only selects the single-span oblique leg frame as the research object, but this research method can be extended to the multi-span case. The author has found a suitable method for qualitative or quantitative investigation of the influence of parameters (constraints and stiffness) closely related to the critical force of the oblique leg frame. For this reason, a new concept is introduced, that is, full stiffness constraint. Semi-stiffness constraints and zero-stiffness constraints. The knowledge contained in these concepts is used to investigate the size of the constraints provided by the members of the structure to the columns. It also clearly explains why the oblique leg frame has a lower critical force than a straight leg frame of the same size.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU391

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