本文關(guān)鍵詞： 鋼管混凝土 力學(xué)性能 膨脹劑 試驗(yàn)研究 理論分析　出處：《蘭州交通大學(xué)》2016年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：鋼管混凝土以其承載力高、延性好、澆筑方便、經(jīng)濟(jì)效益高等優(yōu)點(diǎn)被廣泛應(yīng)用于各種結(jié)構(gòu)物中。目前工程界對(duì)鋼管混凝土基本力學(xué)性能的研究比較多,多數(shù)研究主要集中在承載力方面。從施工的角度來(lái)看,由于溫度與混凝土收縮等原因,鋼管混凝土容易發(fā)生脫黏,一般通過(guò)內(nèi)摻膨脹劑來(lái)補(bǔ)償核心混凝土的收縮,而內(nèi)摻膨脹劑又會(huì)一定程度地影響鋼管混凝土的力學(xué)性能。核心混凝土徐變也會(huì)使鋼管混凝土工作狀態(tài)產(chǎn)生變化。國(guó)內(nèi)對(duì)這些問(wèn)題的研究還比較少。針對(duì)上述的問(wèn)題,本文在前人的基礎(chǔ)上,主要做了如下工作:(1)對(duì)鋼管混凝土構(gòu)件進(jìn)行了軸壓試驗(yàn)研究,主要包括軸壓瞬時(shí)變形試驗(yàn)、軸壓徐變?cè)囼?yàn)和軸壓承載力試驗(yàn)。以鋼管壁厚(試件外徑不變)和膨脹劑摻量(0%、4%、8%)為自變量,考察了試件軸壓瞬時(shí)變形、由核心混凝土徐變引起的軸向變形和承載力隨鋼管壁厚以及膨脹劑摻量的變化規(guī)律。(2)借助Rapid Air型氣孔結(jié)構(gòu)分析儀,對(duì)不同膨脹劑摻量下的鋼管核心混凝土進(jìn)了氣孔結(jié)構(gòu)測(cè)試,通過(guò)氣孔結(jié)構(gòu)參數(shù)分析對(duì)比,發(fā)現(xiàn)膨脹劑對(duì)鋼管混凝土軸壓性能的影響機(jī)理主要是內(nèi)摻膨脹劑提高了核心混凝土的密實(shí)度。(3)介紹了一些混凝土徐變理論和影響鋼管混凝土徐變效應(yīng)的常見(jiàn)因素�；谟�(jì)算混凝土徐變的齡期調(diào)整有效模量法,推導(dǎo)了鋼管混凝土徐變效應(yīng)計(jì)算公式。通過(guò)所推導(dǎo)的公式,計(jì)算了鋼管混凝土由核心混凝土徐變引起的軸向變形、混凝土軸向應(yīng)力、鋼管軸向應(yīng)力隨時(shí)間的變化曲線,分析了核心混凝土徐變對(duì)鋼管混凝土工作狀態(tài)的影響。分析、比較了不同含鋼率和加載齡期對(duì)鋼管混凝土徐變效應(yīng)的影響。(4)介紹了鋼管混凝土軸壓短柱有限元模型的建立方法與基本原理,通過(guò)考慮核心混凝土損傷塑性的有限元模型,分析了鋼管脫黏對(duì)構(gòu)件軸壓性能的影響,比較了脫黏構(gòu)件和正常粘結(jié)構(gòu)件的荷載—變形曲線、接觸壓力—變形曲線,發(fā)現(xiàn)脫黏減弱了構(gòu)件的整體性,從而降低了軸壓承載力。
[Abstract]:Concrete-filled steel tubular (CFST) has been widely used in various structures because of its high bearing capacity, good ductility, convenient pouring and high economic benefit. At present, there are many researches on the basic mechanical properties of CFST in engineering circles. Most of the research focuses on bearing capacity. From the point of view of construction, due to temperature and concrete shrinkage, concrete filled steel tube is prone to debonding. Generally, the shrinkage of core concrete is compensated by adding expansion agent. However, the mechanical properties of concrete-filled steel tube (CFST) will be affected to a certain extent by the addition of expansive agent. The creep of core concrete will also change the working state of CFST. There are few researches on these problems in China. The problem. In this paper, based on the previous work, mainly do the following work: 1) the concrete filled steel tube members of the axial compression test, including axial compression transient deformation test. Axial compression creep test and axial compression bearing capacity test. Taking the wall thickness of steel tube (without change in external diameter of the specimen) and the amount of dilatant as independent variables, the instantaneous deformation of the specimen under axial compression is investigated. Axial deformation and bearing capacity caused by creep of core concrete with the change of wall thickness of steel tube and the content of expansive agent. (2) Rapid Air type pore structure analyzer is used. The pore structure of steel tube core concrete with different amount of expansive agent was tested, and the pore structure parameters were analyzed and compared. It is found that the influence mechanism of expansion agent on axial compression performance of concrete filled steel tube is that the density of core concrete is improved by adding expansion agent. Some concrete creep theory and common factors affecting creep effect of concrete-filled steel tube (CFST) are introduced. Based on the calculation of concrete creep, the age adjusted effective modulus method is introduced. The formula for calculating creep effect of concrete filled steel tube (CFST) is derived. The axial deformation and axial stress of concrete filled steel tubular (CFST) caused by creep of core concrete are calculated. The influence of the creep of the core concrete on the working state of the concrete filled steel tube is analyzed. The influence of different steel content and loading age on creep effect of concrete-filled steel tubular (CFST) is compared. The method and basic principle of the finite element model of CFST short columns under axial compression are introduced. Through the finite element model considering the damage plasticity of core concrete, the influence of steel tube debonding on the axial compression behavior of steel tube is analyzed, and the load-deformation curves of debonding members and normal bonded members are compared. The contact pressure-deformation curve shows that debonding weakens the integrity of the member and thus reduces the axial compression capacity.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TU398.9

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