【摘要】：隨著社會的快速發(fā)展,鋼管混凝土這種復(fù)合材料在拱橋的領(lǐng)域中發(fā)展迅速,由于鋼管和混凝土之間的良好配合,使鋼管混凝土具有抗壓性能強,耐火性能好,塑性和韌性好等特點。鋼管混凝土材料首次應(yīng)用在19世紀(jì)80年代英國的賽文鐵路橋的橋墩中,但是鋼管混凝土在橋梁中的真正得到發(fā)展是在我國,迄今為止,我國已經(jīng)建成和正在建的鋼管混凝土拱橋就達(dá)到了300多座,并且朝著大跨度的方向進(jìn)行發(fā)展,那么拱肋的穩(wěn)定問題就隨之出現(xiàn),由于拱肋主要是受壓的結(jié)構(gòu),尤其是拱肋的面外穩(wěn)定問題,通過大量的試驗和理論分析得出拱肋的的橫向剛度要小于豎向剛度,也就是說拱肋很容易在面內(nèi)失穩(wěn)前發(fā)生面外失穩(wěn)。同時鋼管混凝土拱橋在運營期間暴露了一些問題,其中比較突出的問題之一就是鋼管和混凝土之間的脫空問題,脫空問題的存在使鋼管和混凝土之間的緊箍作用失效,不同程度的影響了鋼管混凝土拱橋的承載力,現(xiàn)階段對鋼管混凝土拱肋脫空問題的防治對策和解決辦法諸多,但是后期的混凝土的徐變收縮引起的脫空卻是不可避免的。由于混凝土后期脫空是不可避免的,并且鋼管混凝土拱肋在受力過程中更容易發(fā)生面外失穩(wěn),因此本文研究混凝土脫空對鋼管混凝土拱肋的平面外穩(wěn)定性的影響。通過大型通用軟件ANSYS對鋼管混凝土拱肋進(jìn)行建模分析,以陳寶春的單圓管拱肋的試驗作為研究對象來建立有限元的模型,使有限元的結(jié)果與試驗的結(jié)果相對比,在驗證所建立的有限元模型的正確性和可靠性之后,在脫空的情況下研究長細(xì)比、含鋼率、矢跨比和套箍系數(shù)等參數(shù)對鋼管混凝土拱肋的面外穩(wěn)定承載力的影響,同時對脫空率的大小、脫空的位置、脫空的長度以及荷載的作用位置進(jìn)行了研究。研究表明:拱肋長細(xì)比越大,其極限承載力就越小,相反,拱肋的極限承載力隨著含鋼率、鋼材強度等級和混凝土的強度的增大而增大,拱肋的極限承載力隨著矢跨比的增大呈現(xiàn)出先增大后減小的趨勢,最佳矢跨比在0.25-0.3之間。在拱肋發(fā)生脫空時,脫空率和脫空長度的增大使拱肋的極限承載力大幅度下降,應(yīng)引起足夠的重視,脫空的位置以及荷載的加載方式對拱肋的極限承載力影響較大,在對稱荷載的作用下拱肋的極限承載力要明顯高于非對稱荷載作用下的極限承載力。在研究拱肋各參數(shù)的基礎(chǔ)上,對現(xiàn)階段的GB50936-2014《鋼管混凝土結(jié)構(gòu)技術(shù)規(guī)范》中構(gòu)件空間受力的計算公式為研究對象,考慮在脫空的情況下引入脫空折減系數(shù)Kn和Km,通過對各參數(shù)的影響數(shù)據(jù)進(jìn)行匯總,擬合得到了脫空折減系數(shù)的簡化計算公式,簡化計算公式所計算的結(jié)果與有限元計算結(jié)果相比較,二者之間的誤差在10%左右,說明該公式具有較好的精度,可供實際工程參考。
[Abstract]:With the rapid development of society, concrete filled steel tube (CFST) is developed rapidly in the field of arch bridge. Due to the good coordination between CFST and CFST, CFST has strong compressive performance and good fire resistance. Good plasticity and toughness. Concrete filled steel tube (CFST) is first used in the pier of Severn railway bridge in Britain in the 1880s. However, the concrete filled steel tube (CFST) has been developed in China, so far, the concrete filled steel tube (CFST) has been developed in China. More than 300 concrete-filled steel tube arch bridges have been built and are being built in China, and the arch ribs are developed in the direction of long span, then the stability problem of arch ribs will appear, because the arch ribs are mainly compressed structures. Especially for the out-of-plane stability of arch rib, the lateral stiffness of arch rib is smaller than that of vertical stiffness through a lot of tests and theoretical analysis, that is to say, the out-of-plane instability of arch rib is easy to occur before in-plane instability. At the same time, the concrete-filled steel tube arch bridge has exposed some problems during the operation, one of the more prominent problems is the void between the steel tube and concrete, the existence of the void problem makes the fastening between the steel tube and the concrete invalid, The bearing capacity of concrete-filled steel tube arch bridge is affected in different degrees. At present, there are many preventive measures and solutions to the void problem of concrete-filled steel tube arch rib. However, the void caused by creep shrinkage of concrete in the later stage is inevitable. In this paper, the influence of concrete void on the out-of-plane stability of concrete-filled steel tube arch rib is studied because it is inevitable that the concrete-filled steel tube arch rib is out-of-plane instability in the process of loading. The finite element model of concrete-filled steel tube arch rib is established by means of large-scale general software ANSYS. The finite element model is established by taking Chen Baochun's single circular pipe arch rib test as the research object, and the results of the finite element method are compared with the experimental results, and the results of the finite element method are compared with the experimental results. After verifying the correctness and reliability of the established finite element model, the influence of the parameters such as slenderness ratio, steel content ratio, rise-span ratio and hoop coefficient on the out-of-plane stability bearing capacity of concrete-filled steel tube arch rib is studied under the condition of void. At the same time, the size, the position, the length and the action position of the emptying rate are studied. The research shows that the greater the slenderness ratio of arch rib is, the smaller the ultimate bearing capacity is. On the contrary, the ultimate bearing capacity of arch rib increases with the increase of steel content, steel strength grade and concrete strength. The ultimate bearing capacity of arch ribs increases first and then decreases with the increase of the rise-span ratio, and the optimum rise-span ratio is between 0.25 and 0.3. When the arch rib is emptied, the ultimate bearing capacity of the arch rib decreases greatly with the increase of the void ratio and the length of the void, which should be paid enough attention. The location of the void and the loading mode of the arch rib have a great influence on the ultimate bearing capacity of the arch rib. Under the action of symmetric load, the ultimate bearing capacity of arch rib is obviously higher than that under asymmetric load. On the basis of studying the parameters of arch rib, the calculation formula of spatial force of members in GB50936-2014 (Technical Code for concrete filled Steel Tubular structures) at present is studied, and the void reduction factor Kn and Km, are taken into account in the case of emptying. By summarizing the influence data of each parameter, the simplified calculation formula of void reduction coefficient is obtained. Compared with the results calculated by finite element method, the error between the simplified calculation formula and the results of finite element calculation is about 10%, and the error between the simplified formula and the finite element method is about 10%. It is shown that the formula has good accuracy and can be used for reference in practical engineering.
【學(xué)位授予單位】：吉林建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U441

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1 王卓琦,吳齊正;鋼管混凝土拱肋施工技術(shù)[J];華東公路;2003年04期

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本文編號：2430940