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纖維改性再生混凝土框架中節(jié)點抗震性能試驗研究

發(fā)布時間:2018-07-29 10:34
【摘要】:再生混凝土技術不僅能夠減少對天然砂石資源的開采,還可以很好地解決大量固體建筑垃圾造成的生態(tài)環(huán)境日益惡化等問題,對生態(tài)環(huán)境建設和經(jīng)濟建設的長遠有序發(fā)展具有重要的意義。但再生骨料特殊的形成過程往往使其存在一些內部缺陷,用其制備的再生混凝土各項力學性能與普通混凝土相比也有一定差異。因此,為了彌補再生混凝土的不足,擴大其在實際工程中的應用,,對改性再生混凝土及改性再生混凝土構件抗震性能的研究勢在必行。 本文以硅粉、聚丙烯纖維和鋼纖維混合而成的二元纖維作為外摻料對再生混凝土進行改性,研究了硅粉及二元混雜纖維改性再生混凝土試塊的力學性能,并以此為基礎,設計制作了3榀不同混雜纖維摻量下的改性再生混凝土框架中節(jié)點,通過對其進行擬靜力試驗,研究了纖維改性再生混凝土框架中節(jié)點的抗震性能及其承載力性能。主要工作和研究內容如下: (1)以硅粉和混雜纖維摻量為主要參數(shù),設計制備了15組共45個混凝土試塊。通過力學性能試驗,對比研究了硅粉、混雜纖維對再生混凝土立方體抗壓強度、軸心抗壓強度和彈性模量的影響,分析了硅粉、混雜纖維影響再生混凝土力學性能的作用機理,同時還給出了改性再生混凝土單軸受壓本構關系模型的上升段曲線方程。 (2)采用強構件弱節(jié)點的方法設計制作了3榀框架中節(jié)點模型,使其發(fā)生核心區(qū)剪切破壞,并按1/1的比例原型制作框架節(jié)點試驗模型,對其進行擬靜力加載試驗。研究了再生粗骨料取代率為100%時,不同混雜纖維摻量下再生混凝土框架中節(jié)點的破壞形態(tài)、剛度退化、延性和耗能性能等,對試驗結果進行分析,探討了各抗震性能指標隨混雜纖維摻量變化的一般規(guī)律,得出了一些可供參考的結論和建議。 (3)依據(jù)現(xiàn)有混凝土框架中節(jié)點的抗裂承載力計算公式和現(xiàn)行混凝土規(guī)范中的抗剪承載力計算公式,采用本次試驗結果并結合已有研究成果,通過引入影響參數(shù)和加入纖維作用項的方法,得出適用于纖維改性再生混凝土框架中節(jié)點的抗裂及抗剪承載力計算公式。 (4)采用本文纖維改性再生混凝土的本構關系,應用有限元軟件ABAQUS對節(jié)點試件的試驗過程進行模擬分析,得出其破壞形態(tài)、滯回曲線及骨架曲線,并與試驗結果進行對比,兩者吻合較好,說明本文建立的節(jié)點模型合理,可以較為準確的模擬纖維改性再生混凝土框架節(jié)點在低周反復荷載作用下的受力性能。 通過對以上工作的開展及內容的研究,得出了如下結論: (1)摻入硅粉可顯著提高再生混凝土的抗壓強度;本文中采用的二元混雜纖維(鋼纖維、聚丙烯纖維),當其摻量較低時對再生混凝土的抗壓強度提升較小,而當摻量增大后對其抗壓強度則有明顯的提升;混雜纖維中的鋼纖維屬于高彈性模量纖維,使得摻入混雜纖維后再生混凝土的彈性模量增大。 (2)纖維改性再生混凝土框架節(jié)點的破壞過程與普通再生混凝土框架節(jié)點相同,主要不同在于纖維節(jié)點最終破壞時核心區(qū)混凝土呈現(xiàn)碎而不落藕斷絲連的現(xiàn)象;混雜纖維的摻入可明顯改善再生混凝土框架節(jié)點的抗震性能,增強其延性和耗能性能等,同時還提高了再生混凝土框架節(jié)點的抗裂及抗剪承載力,是一種改善再生混凝土材料性能的有效途徑。
[Abstract]:Recycled concrete technology can not only reduce the exploitation of natural sand resources, but also solve the problems caused by a large number of solid construction waste. It is of great significance to the long-term and orderly development of ecological environment and economic construction. In order to make up for the shortage of recycled concrete and expand its application in practical engineering, it is imperative to study the earthquake resistance of the modified recycled concrete and the modified recycled concrete members.
In this paper, the two yuan fiber mixed with silicon powder, polypropylene fiber and steel fiber is used as the external admixture to modify the recycled concrete. The mechanical properties of the modified recycled concrete block with silica powder and two yuan hybrid fiber are studied. On the basis of this, the joints of the modified recycled concrete frame with 3 different mixed fibers are designed and manufactured. By the pseudo static test, the seismic performance and bearing capacity of the joints in the fiber modified recycled concrete frame are studied. The main work and research contents are as follows:
(1) 15 groups of concrete specimens were designed and prepared with silica powder and mixed fiber as the main parameters. Through mechanical properties test, the effects of silica powder and hybrid fiber on the compressive strength, axial compressive strength and modulus of elasticity of recycled concrete were compared, and the mechanical properties of recycled concrete affected by silica powder and hybrid fiber were analyzed. In addition, the ascending curve equation of the constitutive model of modified recycled concrete under uniaxial compression is presented.
(2) the joint model of 3 frames is designed and produced by the method of strong component and weak node to make the shear failure in the core area, and the test model of the frame node is made according to the proportional prototype of 1/1, and the static loading test is carried out. The regenerated aggregate ratio is 100%, and the middle section of the recycled concrete frame under the different mixing amount of mixed fiber is studied. The damage morphology, stiffness degradation, ductility and energy dissipation properties of the point are analyzed, and the general rules of the variation of various seismic performance indexes with the mixing amount of hybrid fibers are discussed, and some conclusions and suggestions for reference are obtained.
(3) according to the calculation formula of the crack resistance bearing capacity of the joints in the existing concrete frame and the calculation formula of the shear bearing capacity of the current concrete code, the results of this test are adopted and the existing research results are combined. By introducing the method of influencing the parameters and adding the effects of the fiber, the joints in the fiber modified recycled concrete frame are obtained. Calculation formula for crack resistance and shear bearing capacity.
(4) using the constitutive relation of the recycled fiber reinforced concrete, the finite element software ABAQUS is used to simulate the test process of the joints, and the failure mode, the hysteresis curve and the skeleton curve are obtained, and the results are compared with the experimental results. It is said that the node model established in this paper is reasonable and can be more accurate. Mechanical behavior of FRP modified recycled concrete frame joints under low cyclic loading.
Based on the above work, the following conclusions are drawn:
(1) the compressive strength of recycled concrete can be greatly improved by adding silica powder. The two element hybrid fiber (steel fiber, polypropylene fiber) used in this paper has a small increase in the compressive strength of recycled concrete when its content is low, but the compressive strength of the recycled concrete is obviously improved when the content is increased; the steel fiber in the hybrid fiber is of high elasticity. Modulus fiber increases the modulus of elasticity of recycled concrete after incorporation of hybrid fibers.
(2) the failure process of the fiber modified recycled concrete frame joints is the same as that of the common recycled concrete frame joints. The main difference is that the concrete in the core area is broken, not broken and connected when the fiber node is finally destroyed. The mixing of the hybrid fiber can obviously improve the seismic performance of the regenerated concrete frame joints and enhance their ductility. At the same time, it also improves the crack resistance and shear capacity of recycled concrete frame joints. It is an effective way to improve the properties of recycled concrete materials.
【學位授予單位】:西安建筑科技大學
【學位級別】:碩士
【學位授予年份】:2014
【分類號】:TU375.4;TU352.11

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