焊接箍筋網(wǎng)多重配筋混凝土柱力學性能研究
發(fā)布時間：2018-08-23 10:23
【摘要】：本文的研究對象是焊接箍筋網(wǎng)多重配筋混凝土柱,具有箍筋采用焊接箍筋網(wǎng)和箍筋網(wǎng)內(nèi)部布置多重縱筋兩大特點。采用焊接箍筋網(wǎng)代替普通綁扎箍筋可有效節(jié)省施工時間和勞動力。箍筋網(wǎng)內(nèi)部多重配筋的作用類似于型鋼混凝土柱中布置型鋼,試驗試件最大內(nèi)部縱筋配筋率達到5.5%,大大增加柱的軸壓承載力儲備,有效減小框架柱的截面尺寸。本文設計制作了8種截面的混凝土柱,分別進行了軸壓試驗和低周反復試驗,結合試驗結果、有限元計算和理論分析,得到以下結論:(1)完成了8個混凝土柱的軸壓試驗研究。試驗結果表明,焊接箍筋網(wǎng)柱內(nèi)部布置高強縱筋后,柱的軸壓承載力大大提高。說明通過內(nèi)部配置高強縱筋增加柱軸壓承載力儲備的方案可行,焊接箍筋網(wǎng)對內(nèi)部縱筋及混凝土均具有良好的約束作用,可以保證縱筋和混凝土的材料強度得到充分利用。(2)采用Abaqus通用有限元軟件對軸壓試驗構件進行受力機理研究。根據(jù)混凝土柱在軸壓作用下核心混凝土應力及箍筋應力的發(fā)展趨勢,對柱進行受力分析,對試驗承載力結果進行驗算。結合已有文獻中關于箍筋約束作用下混凝土強度的計算模型,對焊接箍筋網(wǎng)形式的復合箍筋對混凝土的約束效應進行分析。結果顯示,C60混凝土試件的混凝土強度提高系數(shù)試驗結果高于有限元及理論計算結果;但C80高強混凝土試件的試驗結果低于C60混凝土試件,原因可能是C80混凝土脆性較大,試驗結果離散型較大,構件容易發(fā)生提前破壞。(3)完成了8個混凝土柱的低周反復試驗研究,得到滯回性能、延性、變形恢復能力和耗能能力等力學指標。結果顯示采用焊接箍筋網(wǎng)形式及多重配筋形式均對混凝土柱的滯回性能和耗能能力有提高作用。增加內(nèi)部配筋率后,混凝土柱的水平承載力有一點提高,延性有所降低,但仍滿足抗震設計要求。即使內(nèi)部配筋率最大為5.5%的構件WRC-9,在設計軸壓比為0.8、剪跨比1.6的條件下位移延性系數(shù)仍然達到4.6,滿足規(guī)范中二級抗震設計要求。(4)在試驗結果和理論分析的基礎上,參考目前的結構設計規(guī)范,對多重配筋混凝土柱形式的構件提出正截面分析方法,主要包括一般設計規(guī)定、極限抗彎承載力和軸壓比限值等內(nèi)容。按照抗震設計要求,本文提出多重配筋混凝土柱在不同抗震等級下的軸壓比限值,并建議多重配筋混凝土柱的軸壓比限值應根據(jù)內(nèi)部配筋率及剪跨比進行適當調(diào)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.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU375.3
[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.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU375.3
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