本文選題：鋼管混凝土　切入點：溫度沖擊　出處：《武漢理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：鋼管混凝土是在鋼管內(nèi)澆筑混凝土且由鋼管和混凝土共同承擔荷載的構(gòu)件。其優(yōu)異性能依賴于鋼管與混凝土間的復合增強作用,鋼管對核心混凝土的套箍作用提高了混凝土的塑性和延性,增加了鋼管的整體和局部的穩(wěn)定性。然而,鋼材和混凝土的熱工性能差異明顯,這導致在服役環(huán)境下鋼管混凝土界面產(chǎn)生脫粘和脫空現(xiàn)象,影響鋼管混凝土的工作性能與結(jié)構(gòu)安全。本文結(jié)合溫度沖擊試驗、有限元數(shù)值分析方法、熱彈性力學理論、非線性擬合理論等,完成了溫度沖擊作用下鋼管混凝土截面溫度場、界面性能與界面優(yōu)化理論等方面的研究工作。研究成果形成了基于核心混凝土膨脹性能精細化設計的鋼管混凝土界面優(yōu)化方法。主要研究內(nèi)容如下:(1)開展鋼管混凝土溫度沖擊試驗研究。試件的長徑比、徑厚比、套箍指標、材料強度等重要參數(shù)能夠滿足工程實際中的構(gòu)造要求,試驗結(jié)果能夠較好的反應實際鋼管混凝土構(gòu)件的服役狀態(tài)。得到了試件截面溫度場分布和變化規(guī)律,結(jié)果顯示鋼管和混凝土界面存在溫度差,有限元分析中需考慮鋼管與混凝土界面的接觸熱阻作用�？蛇\用實測溫度場與后期有限元模擬溫度場進行對比,以校驗有限元模型的有效性和精確性。(2)進行鋼管混凝土溫度沖擊和熱力耦合有限元分析研究。建立了有限元分析的試件傳熱模型和力學模型,并探討了鋼管混凝土溫度沖擊和熱力耦合有限元分析理論。數(shù)值計算得到了截面溫度場、界面響應和補償溫度引起的界面間隙所需的混凝土自由膨脹率。對比分析了實驗溫度場和計算結(jié)果,結(jié)果表明可以利用有限元模型進行鋼管混凝土界面特征的參數(shù)化分析和界面性能優(yōu)化設計。試件截面最大非線性溫差可達18.2℃,降溫階段鋼管Mises應力和混凝土徑向應力可分別達36.6MPa、-3.39MPa,環(huán)境溫度升高將劣化試件界面性能,適量的膨脹率摻量可緩解界面脫空和提高承載力,超過0.5Nu可使鋼材和混凝土產(chǎn)生的相對變形彌補溫度沖擊實驗中溫度變化引起的界面間隙,超過0.7Nu導致鋼管進入屈服階段且其承載力有所下降。(3)提出了鋼管混凝土界面優(yōu)化設計方法,建立了補償溫度沖擊引起的界面間隙所需的混凝土自由膨脹率公式,,,。首先,提出利用鋼管混凝土膨脹性能設計來實現(xiàn)鋼管混凝土界面優(yōu)化。然后,采用Python語言編寫了參數(shù)化分析程序,進行了270個不同幾何尺寸和溫變條件的未添加膨脹劑的鋼管混凝土溫度沖擊數(shù)值分析,分別得到構(gòu)件所對應的最大界面間隙,并換算得到補償界面間隙所需的混凝土自由膨脹率。最后,利用270個自由膨脹率離散數(shù)據(jù)擬合得到混凝土自由膨脹率公式。
[Abstract]:Concrete-filled steel tube (CFST) is a kind of concrete filled steel tube, whose excellent performance depends on the composite reinforcement between steel tube and concrete. The hoop effect of steel tube on the core concrete improves the plasticity and ductility of concrete, and increases the overall and local stability of the steel pipe. However, the thermal properties of steel and concrete are obviously different. This leads to the phenomenon of debonding and voids at the interface of concrete-filled steel tube (CFST) in service environment, which affects the working performance and structural safety of CFST. In this paper, combined with temperature shock test, finite element numerical analysis method, thermo elastic mechanics theory, The temperature field of concrete filled steel tube (CFST) section under the action of temperature shock is completed by nonlinear fitting theory. Research work on interface performance and interface optimization theory. The research results have formed a concrete filled steel tube interface optimization method based on the fine design of core concrete expansion performance. The main research contents are as follows: 1) Steel tube mixing. Experimental study on temperature shock of solidified soils. Ratio of length to diameter of specimens, The important parameters, such as diameter thickness ratio, hoop index, material strength and so on, can meet the construction requirements in engineering practice, and the test results can better reflect the service state of concrete filled steel tube members. The distribution and variation law of the temperature field of the section of the specimen are obtained. The results show that there is a temperature difference between the steel tube and concrete interface, and the contact thermal resistance between the steel tube and concrete interface should be considered in the finite element analysis. The measured temperature field can be compared with the later finite element simulation temperature field. By checking the validity and accuracy of the finite element model, the coupled finite element analysis of temperature shock and thermal mechanism of concrete-filled steel tube (CFST) is studied. The heat transfer model and mechanical model of the finite element analysis are established. The finite element analysis theory of temperature shock and thermal-mechanical coupling of concrete-filled steel tube (CFST) is discussed. The temperature field of section is obtained by numerical calculation. The free expansion rate of concrete required for interface gap caused by interface response and compensation temperature is compared and analyzed. The results show that the finite element model can be used to parameterize the interface characteristics of concrete-filled steel tube (CFST) and to optimize the interface properties. The maximum nonlinear temperature difference of the specimen section can reach 18.2 鈩，

本文編號：1560705