纤维改性再生混凝土框架中节点抗震性能试验研究

发布时间：2018-07-29 10:34

【摘要】：再生混凝土技术不仅能够减少对天然砂石资源的开采，还可以很好地解决大量固体建筑垃圾造成的生态环境日益恶化等问题，对生态环境建设和经济建设的长远有序发展具有重要的意义。但再生骨料特殊的形成过程往往使其存在一些内部缺陷，用其制备的再生混凝土各项力学性能与普通混凝土相比也有一定差异。因此，为了弥补再生混凝土的不足，扩大其在实际工程中的应用，，对改性再生混凝土及改性再生混凝土构件抗震性能的研究势在必行。本文以硅粉、聚丙烯纤维和钢纤维混合而成的二元纤维作为外掺料对再生混凝土进行改性，研究了硅粉及二元混杂纤维改性再生混凝土试块的力学性能，并以此为基础，设计制作了3榀不同混杂纤维掺量下的改性再生混凝土框架中节点，通过对其进行拟静力试验，研究了纤维改性再生混凝土框架中节点的抗震性能及其承载力性能。主要工作和研究内容如下：（1）以硅粉和混杂纤维掺量为主要参数，设计制备了15组共45个混凝土试块。通过力学性能试验，对比研究了硅粉、混杂纤维对再生混凝土立方体抗压强度、轴心抗压强度和弹性模量的影响，分析了硅粉、混杂纤维影响再生混凝土力学性能的作用机理，同时还给出了改性再生混凝土单轴受压本构关系模型的上升段曲线方程。（2）采用强构件弱节点的方法设计制作了3榀框架中节点模型，使其发生核心区剪切破坏，并按1/1的比例原型制作框架节点试验模型，对其进行拟静力加载试验。研究了再生粗骨料取代率为100%时，不同混杂纤维掺量下再生混凝土框架中节点的破坏形态、刚度退化、延性和耗能性能等，对试验结果进行分析，探讨了各抗震性能指标随混杂纤维掺量变化的一般规律，得出了一些可供参考的结论和建议。（3）依据现有混凝土框架中节点的抗裂承载力计算公式和现行混凝土规范中的抗剪承载力计算公式，采用本次试验结果并结合已有研究成果，通过引入影响参数和加入纤维作用项的方法，得出适用于纤维改性再生混凝土框架中节点的抗裂及抗剪承载力计算公式。（4）采用本文纤维改性再生混凝土的本构关系，应用有限元软件ABAQUS对节点试件的试验过程进行模拟分析，得出其破坏形态、滞回曲线及骨架曲线，并与试验结果进行对比，两者吻合较好，说明本文建立的节点模型合理，可以较为准确的模拟纤维改性再生混凝土框架节点在低周反复荷载作用下的受力性能。通过对以上工作的开展及内容的研究，得出了如下结论：（1）掺入硅粉可显著提高再生混凝土的抗压强度；本文中采用的二元混杂纤维（钢纤维、聚丙烯纤维），当其掺量较低时对再生混凝土的抗压强度提升较小，而当掺量增大后对其抗压强度则有明显的提升；混杂纤维中的钢纤维属于高弹性模量纤维，使得掺入混杂纤维后再生混凝土的弹性模量增大。（2）纤维改性再生混凝土框架节点的破坏过程与普通再生混凝土框架节点相同，主要不同在于纤维节点最终破坏时核心区混凝土呈现碎而不落藕断丝连的现象；混杂纤维的掺入可明显改善再生混凝土框架节点的抗震性能，增强其延性和耗能性能等，同时还提高了再生混凝土框架节点的抗裂及抗剪承载力，是一种改善再生混凝土材料性能的有效途径。
[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.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375.4;TU352.11

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