焊接箍筋网多重配筋混凝土柱力学性能研究

发布时间：2018-08-23 10:23

【摘要】：本文的研究对象是焊接箍筋网多重配筋混凝土柱,具有箍筋采用焊接箍筋网和箍筋网内部布置多重纵筋两大特点。采用焊接箍筋网代替普通绑扎箍筋可有效节省施工时间和劳动力。箍筋网内部多重配筋的作用类似于型钢混凝土柱中布置型钢,试验试件最大内部纵筋配筋率达到5.5%,大大增加柱的轴压承载力储备,有效减小框架柱的截面尺寸。本文设计制作了8种截面的混凝土柱,分别进行了轴压试验和低周反复试验,结合试验结果、有限元计算和理论分析,得到以下结论:(1)完成了8个混凝土柱的轴压试验研究。试验结果表明,焊接箍筋网柱内部布置高强纵筋后,柱的轴压承载力大大提高。说明通过内部配置高强纵筋增加柱轴压承载力储备的方案可行,焊接箍筋网对内部纵筋及混凝土均具有良好的约束作用,可以保证纵筋和混凝土的材料强度得到充分利用。(2)采用Abaqus通用有限元软件对轴压试验构件进行受力机理研究。根据混凝土柱在轴压作用下核心混凝土应力及箍筋应力的发展趋势,对柱进行受力分析,对试验承载力结果进行验算。结合已有文献中关于箍筋约束作用下混凝土强度的计算模型,对焊接箍筋网形式的复合箍筋对混凝土的约束效应进行分析。结果显示,C60混凝土试件的混凝土强度提高系数试验结果高于有限元及理论计算结果;但C80高强混凝土试件的试验结果低于C60混凝土试件,原因可能是C80混凝土脆性较大,试验结果离散型较大,构件容易发生提前破坏。(3)完成了8个混凝土柱的低周反复试验研究,得到滞回性能、延性、变形恢复能力和耗能能力等力学指标。结果显示采用焊接箍筋网形式及多重配筋形式均对混凝土柱的滞回性能和耗能能力有提高作用。增加内部配筋率后,混凝土柱的水平承载力有一点提高,延性有所降低,但仍满足抗震设计要求。即使内部配筋率最大为5.5%的构件WRC-9,在设计轴压比为0.8、剪跨比1.6的条件下位移延性系数仍然达到4.6,满足规范中二级抗震设计要求。(4)在试验结果和理论分析的基础上,参考目前的结构设计规范,对多重配筋混凝土柱形式的构件提出正截面分析方法,主要包括一般设计规定、极限抗弯承载力和轴压比限值等内容。按照抗震设计要求,本文提出多重配筋混凝土柱在不同抗震等级下的轴压比限值,并建议多重配筋混凝土柱的轴压比限值应根据内部配筋率及剪跨比进行适当调整。
[Abstract]:The research object of this paper is welded stirrups with multiple reinforcement concrete columns, which has the characteristics of welding stirrups and multiple longitudinal bars arranged inside the stirrups. Welding stirrups net instead of common binding stirrups can save construction time and labor. The effect of multiple reinforcement in stirrups is similar to that in steel reinforced concrete columns. The maximum longitudinal reinforcement ratio of test specimens is up to 5.5, which greatly increases the axial bearing capacity reserve of columns and effectively reduces the section size of frame columns. In this paper, eight kinds of concrete columns with different sections have been designed and made, and axial compression tests and low-cycle repeated tests have been carried out respectively. Combined with the test results, finite element calculation and theoretical analysis, the following conclusions have been obtained: (1) the axial compression tests of eight concrete columns have been completed. The experimental results show that the axial compression capacity of welded stirrups is greatly improved after the high strength longitudinal reinforcement is arranged inside the column. It shows that it is feasible to increase the bearing capacity reserve of columns with high strength longitudinal reinforcement, and the welding stirrups net has a good restraint effect on both longitudinal reinforcement and concrete. It can ensure that the material strength of longitudinal reinforcement and concrete can be fully utilized. (2) the stress mechanism of axial compression test members is studied by using Abaqus universal finite element software. According to the development trend of core concrete stress and stirrups stress of concrete columns under axial compression, the stress analysis of columns is carried out, and the results of test bearing capacity are checked and calculated. Based on the existing model of concrete strength under stirrups restraint, the restraint effect of welded stirrups net composite stirrups on concrete is analyzed. The results show that the concrete strength enhancement coefficient of C60 concrete specimen is higher than that of finite element method and theoretical calculation, but the test result of C80 high strength concrete specimen is lower than that of C60 concrete specimen, which may be due to the brittleness of C80 concrete. The test results show that the discrete type is large and the members are prone to early failure. (3) the low cycle repeated test of 8 concrete columns has been completed and the mechanical indexes such as hysteretic performance ductility deformation recovery ability and energy dissipation capacity have been obtained. The results show that the hysteretic performance and energy dissipation capacity of concrete columns are improved by welding stirrups and multiple reinforcement. With the increase of internal reinforcement ratio, the horizontal bearing capacity of concrete columns is improved a little, and the ductility is decreased, but it still meets the requirements of seismic design. Even for WRC-9 with the maximum internal reinforcement ratio of 5.5%, the displacement ductility coefficient is still up to 4.6 when the design axial compression ratio is 0.8 and the shear span ratio is 1.6. (4) on the basis of experimental results and theoretical analysis, the displacement ductility coefficient still reaches 4.6. (4) on the basis of experimental results and theoretical analysis, Referring to the current structural design code, a method of normal section analysis for multi-reinforced concrete columns is proposed, including general design provisions, ultimate flexural bearing capacity and limit value of axial compression ratio and so on. According to the requirements of seismic design, this paper puts forward the limit value of axial compression ratio of multi-reinforced concrete columns under different seismic grades, and suggests that the limit value of axial compression ratio of multi-reinforced concrete columns should be adjusted appropriately according to internal reinforcement ratio and shear span ratio.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375.3

【相似文献】