本文關(guān)鍵詞： 圓鋼管平面K型間隙節(jié)點 極限承載力 有限元 應(yīng)力強度因子 疲勞壽命　出處：《長沙理工大學》2014年碩士論文　論文類型：學位論文

【摘要】：隨著鋼管結(jié)構(gòu)在土木工程中的廣泛應(yīng)用,圓鋼管K型節(jié)點也大量的出現(xiàn)在桁架、網(wǎng)架等結(jié)構(gòu)中。盡管,目前有關(guān)K型節(jié)點受力性能方面的研究已取得了大量的研究成果,但仍有許多問題并沒有得到完美的解決,仍需進一步關(guān)注。近年來,對K型節(jié)點受力性能的研究主要圍繞節(jié)點極限承載力的問題而展開的,而對節(jié)點疲勞壽命方面的研究相對而言較少。此外,在國家鋼結(jié)構(gòu)規(guī)范中有關(guān)計算節(jié)點極限承載力的公式也并未考慮邊界條件的影響,整體上偏于保守。因此,本文將以圓鋼管平面K型間隙節(jié)點為研究對象,主要對節(jié)點的極限承載力、破壞模式以及疲勞壽命方面的問題進行了相關(guān)研究。首先,利用有限元方法對圓鋼管平面K型間隙節(jié)點的極限承載力與破壞模式進行了探討,并應(yīng)用規(guī)范公式對部分圓鋼管平面K型間隙節(jié)點的承載力進行了計算。分析時主要考慮了支、主管軸線間角度θ,支、主管直徑比β(d/D),主管徑厚比γ(D/T)以及四種不同邊界條件與加載方式對節(jié)點極限承載力與破壞模式的影響。然后,將規(guī)范公式計算結(jié)果與有限元分析結(jié)果進行了對比,并分析了產(chǎn)生計算偏差的原因。研究表明節(jié)點的幾何影響參數(shù)θ、β、γ對節(jié)點的極限承載力與破壞模式有不同程度的影響,并且γ是影響節(jié)點破壞模式的主要參數(shù)；當β、γ較小時,邊界條件對節(jié)點極限承載力的影響基本可以忽略,當β、y較大時,邊界條件對節(jié)點極限承載力的影響逐漸體現(xiàn)出來。其次,分析了圓鋼管平面K型間隙節(jié)點的疲勞壽命問題,利用了Paris公式定量反推了節(jié)點疲勞擴展階段的剩余壽命。分析中,一方面采用有限元軟件建立了含二維表面穿透裂紋標準三點彎曲試樣的有限元模型,并計算了試樣的應(yīng)力強度因子,另一方面應(yīng)用理論公式法對試樣應(yīng)力強度因子進行了計算。然后將有限元分析結(jié)果與理論公式計算結(jié)果進行對比,驗證了建立含裂紋體模型思路及方法的合理性。最后,將借鑒上述思路與方法建立含初始表面半橢圓裂紋圓鋼管平面K型間隙節(jié)點有限元模型,并將節(jié)點應(yīng)力強度因子有限元分析結(jié)果通過公式換算成有效應(yīng)力強度因子代入Paris公式中計算節(jié)點的疲勞壽命。分析節(jié)點的疲勞壽命時,主要考慮了支、主管直徑比β,主管徑厚比γ以及裂紋深度與主管壁厚比a/T對節(jié)點疲勞壽命的影響。研究表明節(jié)點的疲勞壽命隨γ、a/T值的增大而減小,隨β值的增大而增大；對于主管較薄或支管直徑較小的節(jié)點,β、γ的影響更加明顯；對于主管較薄或初始裂紋a較大的節(jié)點,a增大,節(jié)點的疲勞壽命將急劇減小。
[Abstract]:With the wide application of steel pipe structure in civil engineering, K-joints of circular steel tube are also widely used in truss, grid structure and so on. However, there are still many problems that have not been solved perfectly and need further attention. In recent years, the research on the mechanical behavior of K-type joints is mainly focused on the ultimate bearing capacity of the joints. In addition, the formulas for calculating the ultimate bearing capacity of joints in the national code for steel structures do not take into account the influence of boundary conditions and are generally conservative. In this paper, the ultimate bearing capacity, failure mode and fatigue life of the joints with plane K clearance of circular steel pipe are studied. In this paper, the ultimate bearing capacity and failure mode of plane K type gap joints of circular steel pipe are discussed by using finite element method, and the bearing capacity of K type gap joints in plane plane of circular steel pipe is calculated by using the standard formula. The influence of angle 胃, branch, diameter ratio 尾 d / D, diameter ratio 緯 D / T) and four different boundary conditions and loading modes on ultimate bearing capacity and failure mode of joints. The calculation results of the specification formula are compared with the results of the finite element analysis, and the causes of the calculation deviation are analyzed. The results show that the geometric influence parameters 胃, 尾, 緯 of the joints have different effects on the ultimate bearing capacity and failure mode of the joints. When 尾, 緯 is small, the effect of boundary conditions on ultimate bearing capacity of joints can be neglected, and when 尾 = y is larger, the effect of boundary conditions on ultimate bearing capacity of joints is gradually reflected. Secondly, when 尾 and 緯 are small, the effect of boundary conditions on ultimate bearing capacity of joints can be neglected. In this paper, the fatigue life of plane K clearance joints of circular steel tubes is analyzed. The residual life of joints in fatigue growth stage is quantitatively deduced by using Paris formula. On the one hand, the finite element model of the standard three-point bending specimen with two-dimensional surface penetrating crack is established by using the finite element software, and the stress intensity factor of the specimen is calculated. On the other hand, the stress intensity factor of the specimen is calculated by the method of theoretical formula, and the result of finite element analysis is compared with the result of theoretical formula, which verifies the rationality of the idea and method of establishing the model of cracked body. The finite element model of plane K-type gap joints with initial surface semi-elliptic cracks of circular steel pipe is established by using the above ideas and methods. The results of finite element analysis of the joint stress intensity factor are converted into the effective stress intensity factor into the Paris formula to calculate the fatigue life of the node. In the analysis of the fatigue life of the node, the support is mainly considered. The effects of diameter ratio 尾, diameter thickness ratio 緯, crack depth to wall thickness ratio a / T on the fatigue life of joints are studied. The results show that the fatigue life of joints decreases with the increase of 緯 -a / T ratio, and increases with the increase of 尾 value. The effect of 尾, 緯 on the joints with thinner supervisor or smaller branch diameter is more obvious, and the fatigue life of the joints with thin supervisor or larger initial crack a increases sharply.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU392.3
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本文編號：1534014