EXPERIMENTAL STUDY ON AXIAL COMPRESSION BEHAVIOR OF CONCRETE COLUMNS CONFINED BY GRID STIRRUPS
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摘要: 为研究使用网格箍筋强度不同、素混凝土轴心抗压强度不同的约束混凝土的轴压受力性能,完成了39个网格箍筋约束混凝土方柱的轴心受压试验。混凝土设计强度等级为C20、C30、C40、C50,箍筋分别选用HRB335、HRB400、HRB500、HRB600钢筋,体积配箍率范围为1.0%~2.2%。试验结果表明:约束混凝土压应力达到峰值时,受压试件的约束箍筋屈服;随着配箍特征值增大,网格箍筋约束混凝土峰值压应力和峰值压应变提高幅度增大,受压应力-应变曲线下降段变缓。根据试验结果,通过回归分析获得了网格箍筋约束混凝土峰值压应力、峰值压应变的计算公式;建立了相应的轴心受压应力-应变模型,与几种具有代表性的箍筋约束混凝土应力-应变模型的对比表明,建立的模型与试验结果吻合较好;提出了约束混凝土极限压应变计算方法。Abstract: In order to study the axial compression behavior of the confined concrete with grid stirrups of different strength and plain concrete of different axial compressive strength, the axial compression tests of 39 concrete square columns confined by grid stirrups were completed. The stirrups are made of HRB335, HRB400, HRB500 and HRB600 reinforced bar. The volume stirrup ratio is between 1.0% and 2.2%. The design strength grades of concrete are C20, C30, C40 and C50. The test results show that stirrups yield under the peak stress of confined concrete. With the increase of the stirrup characteristic value, the increasing degree of peak stress and peak strain of the concrete confined by grid stirrups increases and the descending branch of stress-strain curve become flat. According to the test results, formulas for calculating peak stress and peak strain of concrete confined by grid stirrups are obtained. The corresponding axial compression stress-strain model is established. The comparison with several typical stress-strain models of concrete confined by stirrups shows that: the results calculated by the axial compressive stress-strain model are in a good agreement with the test results, thusly another method for calculating the ultimate compressive strain of confined concrete is proposed.
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表 1 试件设计参数
Table 1. Design parameters of specimens
试件编号 混凝土设计强度等级 a/mm H/mm 箍筋牌号 ρv /(%) s/mm d/mm 箍筋形式 ρs /(%) C-1 C20 400 1300 HRB335 1.40 80 8 双向四肢箍 0.71 C-2 C20 400 1300 HRB335 1.80 60 8 双向四肢箍 0.71 C-3 C20 400 1300 HRB335 2.20 50 8 双向四肢箍 0.71 C-4 C20 400 1300 HRB400 1.10 75 8 双向三肢箍 0.47 C-5 C20 400 1300 HRB400 1.35 60 8 双向三肢箍 0.47 C-6 C20 400 1300 HRB400 1.60 50 8 双向三肢箍 0.47 C-7 C20 400 1300 HRB500 1.00 80 8 双向三肢箍 0.47 C-8 C20 400 1300 HRB500 1.25 65 8 双向三肢箍 0.47 C-9 C20 400 1300 HRB500 1.50 55 8 双向三肢箍 0.47 C-10 C30 400 1300 HRB335 1.40 80 8 双向四肢箍 0.71 C-11 C30 400 1300 HRB335 1.80 60 8 双向四肢箍 0.71 C-12 C30 400 1300 HRB335 2.20 50 8 双向四肢箍 0.71 C-13 C30 400 1300 HRB400 1.10 75 8 双向三肢箍 0.47 C-14 C30 400 1300 HRB400 1.35 60 8 双向三肢箍 0.47 C-15 C30 400 1300 HRB400 1.60 50 8 双向三肢箍 0.47 C-16 C30 400 1300 HRB500 1.00 80 8 双向三肢箍 0.47 C-17 C30 400 1300 HRB500 1.25 65 8 双向三肢箍 0.47 C-18 C30 400 1300 HRB500 1.50 55 8 双向三肢箍 0.47 C-19 C40 400 1300 HRB335 1.40 80 8 双向四肢箍 0.71 C-20 C40 400 1300 HRB335 1.80 60 8 双向四肢箍 0.71 C-21 C40 400 1300 HRB335 2.20 50 8 双向四肢箍 0.71 C-22 C40 400 1300 HRB400 1.10 75 8 双向三肢箍 0.47 C-23 C40 400 1300 HRB400 1.35 60 8 双向三肢箍 0.47 C-24 C40 400 1300 HRB400 1.60 50 8 双向三肢箍 0.47 C-25 C40 400 1300 HRB500 1.00 80 8 双向三肢箍 0.47 C-26 C40 400 1300 HRB500 1.25 65 8 双向三肢箍 0.47 C-27 C40 400 1300 HRB500 1.50 55 8 双向三肢箍 0.47 C-28 C40 400 1300 HRB600 1.00 65 6 双向四肢箍 0.70 C-29 C40 400 1300 HRB600 1.20 50 6 双向四肢箍 0.70 C-30 C40 400 1300 HRB600 1.40 40 6 双向四肢箍 0.70 C-31 C50 400 1300 HRB400 1.10 75 8 双向三肢箍 0.47 C-32 C50 400 1300 HRB400 1.35 60 8 双向三肢箍 0.47 C-33 C50 400 1300 HRB400 1.60 50 8 双向三肢箍 0.47 C-34 C50 400 1300 HRB500 1.00 80 8 双向三肢箍 0.47 C-35 C50 400 1300 HRB500 1.25 65 8 双向三肢箍 0.47 C-36 C50 400 1300 HRB500 1.50 55 8 双向三肢箍 0.47 C-37 C50 400 1300 HRB600 1.00 65 6 双向四肢箍 0.70 C-38 C50 400 1300 HRB600 1.20 50 6 双向四肢箍 0.70 C-39 C50 400 1300 HRB600 1.40 40 6 双向四肢箍 0.70 注:a为方柱截面边长;H为柱高;ρv为柱中间区段体积配箍率;s为柱中间区段箍筋间距;d为箍筋直径;ρs为纵筋核心截面配筋率(纵筋总截面面积与核心截面面积之比)。 表 2 混凝土基本力学性能
Table 2. Basic mechanical properties of concrete
混凝土设计强度等级 fcu/MPa fco/MPa Ec/MPa εco/(×10−6) C20 23.7 18.0 27 286 1434 C30 32.2 24.5 30 507 1550 C40 38.3 29.1 32 199 1626 C50 60.6 47.4 36 069 1883 注:fcu为边长150 mm立方体抗压强度;fco为轴心抗压强度;Ec为弹性模量;εco为峰值压应变。 表 3 钢筋基本力学性能
Table 3. Basic mechanical properties of steel bars
钢筋牌号 fy/MPa fu/MPa εy/(×10−6) εu/(%) Es/(×105 MPa) HRB335 370 550 1850 17.6 2.00 HRB400 480 640 2400 15.8 2.00 HRB500 527 721 2635 11.7 2.00 HRB600 657 873 3285 10.7 2.00 注:fy为钢筋的屈服强度;fu为钢筋极限强度;εy为与fy相应的钢筋屈服应变;εu为与fu相应的钢筋峰值应变;Es为钢筋的弹性模量。 表 4 试件参数及试验结果
Table 4. Parameters and test results of specimens
试件编号 fco/MPa fyv/MPa ρv/(%) fcco/MPa εcco/(×10−6) εcc85/(×10−6) fcco/fco εcco/εco εsvo/(×10−6) Nccu/Ncc/(%) 约束程度 C-1 18.0 360 1.40 28.0 6848 13 238 1.56 4.91 2846 − 中 C-2 18.0 360 1.80 30.3 7360 30 340 1.68 6.07 4174 75 中 C-3 18.0 360 2.20 32.3 8802 40 429 1.79 6.14 3932 61 中 C-4 18.0 480 1.10 25.6 7004 19 934 1.42 5.67 3106 − 中 C-5 18.0 480 1.35 27.2 8136 35 143 1.51 5.67 3969 − 中 C-6 18.0 480 1.60 29.1 8666 43 742 1.62 6.04 4142 − 中 C-7 18.0 527 1.00 25.0 6981 21 560 1.39 4.90 3129 54 中 C-8 18.0 527 1.25 28.7 6886 18 086 1.59 4.96 3523 − 中 C-9 18.0 527 1.50 29.6 7037 − 1.64 5.16 3538 − 中 C-10 24.5 360 1.40 32.4 5844 8568 1.32 3.90 3231 − 中 C-11 24.5 360 1.80 35.5 6405 21 081 1.45 3.93 3505 55 中 C-12 24.5 360 2.20 40.6 6324 24 104 1.66 4.17 3285 64 中 C-13 24.5 480 1.10 32.5 5736 9304 1.33 3.93 3325 − 中 C-14 24.5 480 1.35 35.0 4853 9531 1.43 3.74 3577 − 中 C-15 24.5 480 1.60 36.4 4309 11 365 1.49 3.98 2856 − 中 C-16 24.5 527 1.00 31.7 4556 9099 1.29 3.41 5470 − 中 C-17 24.5 527 1.25 36.7 4491 9991 1.50 2.91 3139 − 中 C-18 24.5 527 1.50 39.3 6129 11 514 1.60 3.97 4892 − 中 C-19 29.1 360 1.40 38.5 4631 7763 1.32 3.62 3243 − 中 C-20 29.1 360 1.80 39.0 6119 18 709 1.34 3.73 3956 − 中 C-21 29.1 360 2.20 41.5 6284 22 484 1.43 3.86 3983 58 中 C-22 29.1 480 1.10 37.0 4232 6686 1.27 2.69 2827 − 中 C-23 29.1 480 1.35 40.7 5739 7641 1.40 3.64 3662 − 中 C-24 29.1 480 1.60 42.2 5788 11 097 1.45 3.73 4112 − 中 C-25 29.1 527 1.00 36.3 4458 6791 1.25 3.50 4109 25 中 C-26 29.1 527 1.25 38.7 4852 5288 1.33 1.89 4852 54 中 C-27 29.1 527 1.50 41.8 5678 18 121 1.44 4.16 4228 − 中 C-28 29.1 657 1.00 38.7 5676 10 687 1.33 3.49 3795 − 中 C-29 29.1 657 1.20 46.8 6387 14 444 1.61 3.93 4703 − 中 C-30 29.1 657 1.40 50.7 8904 18 288 1.74 5.48 4708 35 中 C-31 47.4 480 1.10 56.1 3797 5699 1.18 2.06 3256 − 低 C-32 47.4 480 1.35 56.1 4054 5508 1.18 2.42 4173 28 低 C-33 47.4 480 1.60 58.8 4712 8114 1.24 2.50 4100 − 中 C-34 47.4 527 1.00 52.3 5620 6396 1.10 3.11 4649 37 低 C-35 47.4 527 1.25 56.7 5230 11 040 1.20 3.04 3524 41 低 C-36 47.4 527 1.50 60.2 6444 8542 1.27 3.42 4704 43 中 C-37 47.4 657 1.00 57.4 8066 10 611 1.21 4.28 3705 − 低 C-38 47.4 657 1.20 59.5 6025 14 271 1.26 3.26 4257 − 中 C-39 47.4 657 1.40 60.0 9800 15 927 1.27 5.20 5687 − 中 注:fyv为箍筋屈服强度;fcco为约束混凝土峰值压应力;εcco为约束混凝土峰值压应变;εcc85为约束混凝土压应力下降至0.85fcco时的压应变;εsvo为约束混凝土峰值压应力下的箍筋拉应变;Nccu/Ncc为试件的第一根箍筋被拉断时的荷载与峰值荷载之比。 -
[1] RICHART F E, BRANDTZAEG A, BROWN R L. A study of the failure of concrete under combined compressive stresses [R]. Urbana: University of Illinois, 1928. [2] SHEIKH S A, UZUMERI S M. Strength and ductility of tied concrete column [J]. Journal of Structural Engineering, 1980, 106(5): 1079 − 1102. [3] MANDER J B, PRIESTLEY M J N. Theoretical stress-strain model for confined concrete [J]. Journal of Structural Engineering, 1988, 114(8): 1804 − 1826. doi: 10.1061/(ASCE)0733-9445(1988)114:8(1804) [4] RAZVI S, SAATCIOGLU M. Confinement model for high-strength concrete [J]. Journal of Structural Engineering, 1999, 125(3): 281 − 289. doi: 10.1061/(ASCE)0733-9445(1999)125:3(281) [5] BOUSALEM B, CHIKH N. Development of a confined model for rectangular ordinary reinforced concrete columns [J]. Materials and Structures, 2007, 40(6): 605 − 613. doi: 10.1617/s11527-006-9172-2 [6] 张秀琴, 过镇海, 王传志. 反复荷载下箍筋约束混凝土的应力-应变全曲线方程[J]. 工业建筑, 1985, 15(12): 16 − 20.ZHANG Xiuqin, GUO Zhenhai, WANG Chuanzhi. Complete stress-strain curves equation of stirrups confined concrete under recurring loading [J]. Industrial Architecture, 1985, 15(12): 16 − 20. (in Chinese) [7] 赵作周, 张石昂, 贺小岗, 等. 箍筋约束高强混凝土受压应力-应变本构关系[J]. 建筑结构学报, 2014, 35(5): 96 − 103. doi: 10.14006/j.jzjgxb.2014.05.016ZHAO Zuozhou, ZHANG Shiang, HE Xiaogang, et al. Stress-strain relationship of stirrup-confined high-strength concrete [J]. Journal of Building Structures, 2014, 35(5): 96 − 103. (in Chinese) doi: 10.14006/j.jzjgxb.2014.05.016 [8] 赵宪忠, 温福平. 钢骨约束混凝土的约束机制及其应力-应变模型建立[J]. 工程力学, 2018, 35(5): 36 − 46. doi: 10.6052/j.issn.1000-4750.2017.02.0109ZHAO Xianzhong, WEN Fuping. Theoretical study on confinement mechanism and stress-strain model for steel confined concrete in src columns [J]. Engineering Mechanics, 2018, 35(5): 36 − 46. (in Chinese) doi: 10.6052/j.issn.1000-4750.2017.02.0109 [9] POUR A F, GHOLAMPOUR A, OZBAKKALOGLU T. Influence of measurement methods on the axial strains of FRP-confined concrete [J]. Composite Structures, 2018, 188: 415 − 424. doi: 10.1016/j.compstruct.2018.01.017 [10] 史庆轩, 杨坤, 刘维亚, 等. 高强箍筋约束高强混凝土轴心受压力学性能试验研究[J]. 工程力学, 2012, 29(1): 141 − 149.SHI Qingxuan, YANG Kun, LIU Weiya, et al. Experimental study on mechanical behavior of high strength concrete confined by high-strength stirrups under concentric loading [J]. Engineering Mechanics, 2012, 29(1): 141 − 149. (in Chinese) [11] 史庆轩, 王南, 王秋维, 等. 高强箍筋约束高强混凝土轴心受压本构关系研究[J]. 工程力学, 2013, 30(5): 131 − 137. doi: 10.6052/j.issn.1000-4750.2011.12.0894SHI Qingxuan, WANG Nan, WANG Qiuwei, et al. Uniaxial compressive stress-strain model for high-strength concrete confined with high-strength lateral ties [J]. Engineering Mechanics, 2013, 30(5): 131 − 137. (in Chinese) doi: 10.6052/j.issn.1000-4750.2011.12.0894 [12] GB 50010−2010, 混凝土结构设计规范 [S]. 北京: 中国建筑工业出版社, 2015.GB 50010−2010, Code for design of concrete structures [S]. Beijing: China Architecture Industry Press, 2015. (in Chinese) [13] CUSSON D, PAULTRE P. Stress-strain model for confined high-strength concrete [J]. Journal of Structural Engineering, 1995, 121(3): 468 − 477. doi: 10.1061/(ASCE)0733-9445(1995)121:3(468) [14] BADUGE S K, MENDIS P, NGO T, et al. Understanding failure and stress-strain behavior of very-high strength concrete (>100 MPa) confined by lateral reinforcement [J]. Construction and Building Materials, 2018, 189: 62 − 77. doi: 10.1016/j.conbuildmat.2018.08.192 [15] 吴涛, 魏慧, 刘喜, 等. 箍筋约束高强轻骨料混凝土柱轴压性能试验研究[J]. 工程力学, 2018, 35(2): 203 − 213. doi: 10.6052/j.issn.1000-4750.2016.10.0814WU Tao, WEI Hui, LIU Xi, et al. Experimental study on axial compression behavior of confined high-strength light weight aggregate concrete under concentric loading [J]. Engineering Mechanics, 2018, 35(2): 203 − 213. (in Chinese) doi: 10.6052/j.issn.1000-4750.2016.10.0814 [16] 余波, 陶伯雄, 刘圣宾. 一种箍筋约束混凝土峰值应力的概率模型[J]. 工程力学, 2018, 35(9): 135 − 144. doi: 10.6052/j.issn.1000-4750.2017.05.0398YU Bo, TAO Boxiong, LIU Shengbin. A probabilistic model for peak stress of concrete confined by ties [J]. Engineering Mechanics, 2018, 35(9): 135 − 144. (in Chinese) doi: 10.6052/j.issn.1000-4750.2017.05.0398 [17] 邓宗才, 姚军锁. 高强钢筋约束超高性能混凝土柱轴心受压本构模型研究[J]. 工程力学, 2020, 37(5): 120 − 128. doi: 10.6052/j.issn.1000-4750.2019.07.0344DENG Zongcai, YAO Junsuo. The axial compression stress-strain model for ultra-high performance concrete columns confined by high-strength stirrups [J]. Engineering Mechanics, 2020, 37(5): 120 − 128. (in Chinese) doi: 10.6052/j.issn.1000-4750.2019.07.0344 [18] 史庆轩, 戎翀, 张婷, 等. 约束混凝土实用本构关系模型[J]. 建筑材料学报, 2017, 20(1): 49 − 54. doi: 10.3969/j.issn.1007-9629.2017.01.009SHI Qingxuan, RONG Chong, ZHANG Ting, et al. A practical stress-strain model for confined concrete [J]. Journal of Building Materials, 2017, 20(1): 49 − 54. (in Chinese) doi: 10.3969/j.issn.1007-9629.2017.01.009 [19] POPOVICS S. A numerical approach to the complete stress-strain curve of concrete [J]. Cement and Concrete Research, 1973, 3(5): 583 − 599. [20] 过镇海, 张秀琴, 张达成, 等. 混凝土应力-应变全曲线的试验研究[J]. 建筑结构学报, 1982, 3(1): 1 − 12.GUO Zhenhai, ZHANG Xiuqin, ZHANG Dacheng, et al. Experimental investigation of the complete stress-strain curve of concrete [J]. Journal of Building Structures, 1982, 3(1): 1 − 12. (in Chinese) [21] BADUGE S K, MENDIS P, NGO T. Stress-strain relationship for very-high strength concrete (>100 MPa) confined by lateral reinforcement [J]. Engineering Structures, 2018, 177: 795 − 808. doi: 10.1016/j.engstruct.2018.08.008 [22] DHAKAL R P, MAEKAWA K. Modeling for postyield buckling of reinforcement [J]. Journal of Structural Engineering, 2002, 128(9): 1139 − 1147. doi: 10.1061/(ASCE)0733-9445(2002)128:9(1139) [23] SAATCIOGLU M, RAZVI S. Strength and ductility of confined concrete [J]. Journal of Structural Engineering, 1992, 118(6): 1590 − 1607. doi: 10.1061/(ASCE)0733-9445(1992)118:6(1590) [24] 钱稼茹, 程丽荣, 周栋梁. 普通箍筋约束混凝土柱的中心受压性能[J]. 清华大学学报(自然科学版), 2002, 42(10): 1369 − 1373. doi: 10.3321/j.issn:1000-0054.2002.10.026QIAN Jiaru, CHENG Lirong, ZHOU Dongliang. Behavior of axially loaded concrete columns confined with ordinary hoops [J]. Journal of Tsinghua University (Science and Technology), 2002, 42(10): 1369 − 1373. (in Chinese) doi: 10.3321/j.issn:1000-0054.2002.10.026 -