Experiment on crack resistance of prestressed CFRP tendons-steel reinforced concrete eccentrically tensioned members under low-cyclic reversed loading
-
摘要: 为研究预应力碳纤维增强树脂复合材料(CFRP)筋-型钢/混凝土(SRC)偏拉构件的抗裂性能,以不同的预应力张拉水平、偏心距、预应力筋类型及竖向拉力等参数制作了11个试件,并对其进行低周反复加载试验。结果表明:相比于普通SRC偏拉构件,预应力SRC偏拉构件的抗裂度和裂缝控制能力显著提升,其开裂荷载提高约1.5倍,抗裂性能与预应力张拉水平正相关,与偏心距负相关,预应力筋类型对开裂荷载影响不大。另外直径7 mm的预应力CFRP筋在控制构件裂缝数量方面强于直径15 mm的预应力精轧螺纹钢筋,适当增大竖向拉力可提高试件抗裂性能。参照现有理论和试验结果,推导出试件开裂荷载的计算公式,其计算结果与试验值吻合度较高。Abstract: In order to investigate the crack resistance of prestressed carbon fiber reinforced polymer (CFRP) reinforced steel concrete eccentrically tensioned members, eleven specimens were fabricated with different parameters such as eccentricity, level of prestress, type of prestressed tendons and vertical tension were tested under low cyclic reversed loading. The results show that the crack resistance and crack control ability of prestressed steel reinforced concrete (SRC) biased tensioning members are significantly improved compared with the ordinary SRC biased tensioning members, and the cracking load is increased by about 1.5 times. The crack resistance of prestressed SRC biased tensioning members is positively related to the prestress level, and negatively related to the eccentricity. The type of prestressed tendons has little effect on the cracking load. In addition, the 7 mm diameter prestressed CFRP tendons are stronger than the 15 mm diameter prestressed fine rolled threaded rods in controlling the number of cracks in the members, and the crack resistance of the specimens can be improved by increasing the vertical tensile force appropriately. According to the existing theory and test results, the calculation formula of cracking load is derived, and the calculated results are in good agreement with the test values.
-
图 6 预应力CFRP筋-SRC试件截面应力和应变分布
Figure 6. Cross section and strain distribution of prestressed CFRP tendons-SRC specimens
h—Length of the section; b—Breadth of section; x—Distance from neutral axis to edge of tension side;as, ap, aa—Distance between tensile longitudinal bar, prestressed tendon, section steel and section edge; As, A's, As—Section area of compression and tension longitudinal reinforcement; Aa—Section area of section steel; Ap—Section area of prestressed reinforcement; εcr—Concrete cracking strain; εs, ε's, εaf, ε'af, ε'p, ε'c—When concrete cracks, tensile and compressive longitudinal bars, tensile and compressive flanges, prestressed tendons and the corresponding strains of concrete in the compressive zone; Ns, N's—Tension and pressure of longitudinal bars; Naf, N'af, Naw, N'aw—Tension and pressure of steel flanges and webs under tension and compression; N'p—Pressure of prestressed tendons; N'c—Pressure of concrete in compression zone; M—Cracking moment; T—Partial tensile load; e—Eccentric distance
表 1 预应力碳纤维增强树脂复合材料(CFRP)筋-型钢/混凝土(SRC)试件主要设计参数
Table 1. Main design parameters of prestressed carbon fiber reinforced polymer (CFRP) tendons-steel reinforced concrete (SRC) specimens
Specimen Prestressed
tension level/%Eccentricity/
mmVertical pull/
kNDiameter of prestressed
tendon/mmType of prestressed
tendonXPL-CFRP7-T1-P1/C 40 50 30 7 CFRP XPL-CFRP7-T1-P2/C 60 50 30 7 CFRP DPL-CFRP7-T1-P1/C 40 150 30 7 CFRP XPL-CFRP7-T2-P1/C 40 50 50 7 CFRP XPL-R15-T1-P1/C 40 50 30 15 Rebar XPL-R15-T1-P2/C 60 50 30 15 Rebar DPL-R15-T1-P1/C 40 150 30 15 Rebar DPL-R15-T1-P2/C 60 150 30 15 Rebar ZL-T1/C 0 0 30 - - XPL-T1/C 0 50 30 - - DPL-T1/C 0 150 30 - - Notes: ZL—Axial tension member; XPL—Small eccentric member; DPL—Large eccentric member; CFRP7—CFRP tendons; R15—Finely-rolled threaded bars; T1 and T2—Eccentric tension of the specimens, which are 30 kN and 50 kN; P1 and P2—Tensioning level of the prestressed tendons, which are 40%fptk and 60%fptk; fptk—Ultimate tensile strength; C—C40 concrete. 表 2 钢材力学性能指标
Table 2. Mechanical properties of steel
Type Yield
strength/MPaUltimate
strength/MPaModulus of
elasticity/105 MPaYield strain/10-6 Profile steel Q235 312.5 447.5 2.0 1555 Q345 395.6 556.6 2.0 1 978 HRB400 steel bar C6 492.0 608.0 2.1 2262 C10 475.0 690.0 2.1 2086 C12 438.0 618.0 2.0 2460 表 3 预应力筋力学性能指标
Table 3. Mechanical properties of prestressed tendons
Type Diameter/mm Yield
strength/MPaUltimate
strength/MPaModulus of
elasticity/105 MPaCFRP tendon 7 1624 1910 1.54 Fine rolled steel bar 15 817 1026 2.10 Note: Yield strength of CFRP tendons is the nominal yield strength, which is the ultimate strength of 85%. 表 4 预应力 CFRP 筋-SRC试件开裂荷载试验值
Table 4. Cracking load test value of prestressed CFRP tendons-SRC specimens
Specimen Positive cracking
load/kNNegative
cracking
load/kNCracking
load/kNXPL-CFRP7-T1-P1/C 24.17 12.04 18.11 XPL-CFRP7-T1-P2/C 32.08 10.16 21.12 DPL-CFRP7-T1-P1/C 18.10 14.03 16.07 XPL-CFRP7-T2-P1/C 21.04 18.10 19.57 XPL-R15-T1-P1/C 26.11 13.84 19.98 XPL-R15-T1-P2/C 30.01 12.10 21.06 DPL-R15-T1-P1/C 23.01 15.10 19.06 DPL-R15-T1-P2/C 26.10 13.74 19.92 ZL-T1/C 8.84 10.01 9.03 XPL-T1/C 4.27 12.10 8.19 DPL-T1/C 2.01 13.23 7.58 Note: Cracking load is the average value of positive and negative cracking loads. 表 5 预应力筋总的预应力损失实测值
Table 5. Measured value of total prestress loss of prestressed tendon
Specimen ε0 ε14 σ14/MPa XPL-CFRP7-T1-P1/C 5215 3994 188.1 XPL-CFRP7-T1-P2/C 7880 6498 212.8 DPL-CFRP7-T1-P1/C 5208 4076 174.3 XPL-CFRP7-T2-P1/C 5231 4062 180.1 XPL-R15-T1-P1/C 2067 1149 192.8 XPL-R15-T1-P2/C 3087 2152 196.3 DPL-R15-T1-P1/C 2 032 1124 190.6 DPL-R15-T1-P2/C 3103 2092 212.4 Notes: ε0—Microstrain value after tensioning; ε14—Microstrain value after 14 days; σ14—Total stress loss measured value. 表 6 预应力CFRP筋-SRC试件开裂荷载试验值与计算值比较
Table 6. Comparing the test value with the calculated value of cracking load of prestressed CFRP tendons-SRC specimens
Specimen Trival value
/kNCalculated value
/kNTrival value/Calculated value XPL-CFRP7-T1-P1/C 18.11 17.37 1.04 XPL-CFRP7-T1-P2/C 21.12 19.14 1.10 DPL-CFRP7-T1-P1/C 16.07 15.34 1.05 XPL-CFRP7-T2-P1/C 19.57 21.76 0.90 XPL-R15-T1-P1/C 19.98 18.42 1.08 XPL-R15-T1-P2/C 21.06 19.69 1.07 DPL-R15-T1-P1/C 19.06 17.72 1.08 DPL-R15-T1-P2/C 19.92 17.97 1.11 ZL-T1/C 9.03 8.79 1.03 XPL-T1/C 8.19 7.44 1.10 DPL-T1/C 7.58 6.53 1.16 -
[1] 尹世平, 华云涛, 徐世烺. FRP配筋混凝土结构研究进展及其应用[J]. 建筑结构学报, 2021, 42(1): 134-150.YIN Shiping, HUA Yuntao, XU Shilang. Research progress and application of FRP reinforced concrete structures[J]. Journal of Building Structures, 2021, 42(1): 134-150(in Chinese). [2] SELVACHANDRAN P, ANANDAKUMAR S, MUTHURAMU K L. Modified frosch crack width model for concrete beams prestressed with CFRP bars[J]. Polymers and Polymer Composites,2016,24(7):587-596. doi: 10.1177/096739111602400719 [3] CAO Q, ZHOU J P, WU Z M, et al. Flexural behavior of prestressed CFRP reinforced concrete beams by two different tensioning methods[J]. Engineering Structures,2019,189:411-422. [4] 程东辉, 郑文忠. 无粘结CFRP筋部分预应力混凝土连续梁试验与分析[J]. 复合材料学报, 2008, 25(5):104-113. doi: 10.3321/j.issn:1000-3851.2008.05.018CHENG Donghui, ZHENG Wenzhong. Test and analysis of unbonded CFRP bars partially prestressed concrete continuous beams[J]. Acta Materiae Compositae Sinica,2008,25(5):104-113(in Chinese). doi: 10.3321/j.issn:1000-3851.2008.05.018 [5] 傅传国, 李玉莹, 梁书亭. 预应力型钢混凝土简支梁受弯性能试验研究[J]. 建筑结构学报, 2007, 28(3):62-73. doi: 10.3321/j.issn:1000-6869.2007.03.009FU Chuanguo, LI Yuying, LIANG Shuting. Experimental study on the flexural behavior of prestressed steel reinforced concrete beams[J]. Journal of Building Structures,2007,28(3):62-73(in Chinese). doi: 10.3321/j.issn:1000-6869.2007.03.009 [6] 熊学玉, 高峰, 徐晓明. 预应力型钢混凝土结构理论研究[J]. 工业建筑, 2012, 42(4): 113-117.XIONG Xueyu, GAO Feng, XU Xiaoming. Theoretical research on prestressed steel concrete structure[J]. Industrial Building, 2012, 42(4): 113-117(in Chinese). [7] HAIJAR J F. Composite steel and concrete structural systems for seismic engineering[J]. Steel Construction,2008,58(5):703-723. [8] 薛建阳. 组合结构设计原理[M]. 北京: 中国建筑工业出版社, 2010: 99-101.XUE Jianyang. Design principles of composite structures[M]. Beijing: China Architecture & Building Press, 2010: 99-101(in Chinese). [9] 张鹏, 桂金洋, 邓宇, 等. 偏心受拉作用下预应力CFRP筋-型钢混凝土构件抗裂试验[J]. 复合材料学报, 2021, 38(3):920-931.ZHANG Peng, GUI Jinyang, DENG Yu, et al. Experimental study on crack resistance of prestressed CFRP reinforced steel concrete members under eccentric tension[J]. Acta Materiae Compositae Sinica,2021,38(3):920-931(in Chinese). [10] 邓宇, 武晓彤, 张鹏. 预应力型钢混凝土柱偏心受拉性能试验研究[J]. 建筑结构学报, 2019, 40(5):115-123.DENG Yu, WU Xiaotong, ZHANG Peng. Experimental study on eccentric tensile behavior of prestressed SRC columds[J]. Journal of Building Structures,2019,40(5):115-123(in Chinese). [11] 薛建阳, 马辉, 刘义. 反复荷载下型钢再生混凝土柱抗震性能试验研究[J]. 土木工程学报, 2014, 47(1):36-46.XUE Jianyang, MA Hui, LIU Yi. Experimental study on seismic performance of shaped steel recycled concrete columns under repeated loading[J]. China Civil Engi neering Journal,2014,47(1):36-46(in Chinese). [12] 李俊华, 王新堂, 薛建阳, 等. 低周反复荷载下型钢高强混凝土柱受力性能试验研究[J]. 土木工程学报, 2007, 40(7):11-18. doi: 10.3321/j.issn:1000-131x.2007.07.003LI Junhua, WANG Xintang, XUE Jianyang, et al. Experimental study on mechanical behavior of steel high-strength concrete column under low cyclic cyclic load[J]. China Civil Engineering Journal,2007,40(7):11-18(in Chinese). doi: 10.3321/j.issn:1000-131x.2007.07.003 [13] 唐锦蜀, 韩文涛, 张堃, 等. 偏心受拉型钢-混凝土组合梁的受力性能试验研究[J]. 工业建筑, 2015, 45(8):170-174.TANG Jinshu, HAN Wentao, ZHANG Kun, et al. Experimental study on mechanical properties of eccentrically tensioned steel-concrete composite beams[J]. Industrial Building,2015,45(8):170-174(in Chinese). [14] 谭园, 薛伟辰, 王晓辉. 有粘结预应力FRP筋混凝土梁抗裂计算方法[J]. 建筑结构, 2008, 26(3):117-120.TAN Yuan, XUE Weichen, WANG Xiaohui. Calculation method of crack resistance of bonded prestressed FRP reinforced concrete beams[J]. Building Structure,2008,26(3):117-120(in Chinese). [15] 熊学玉, 高峰, 李亚明. 预应力型钢混凝土框架梁试验研究及抗裂度分析[J]. 工业建筑, 2011, 41(12):16-19.XIONG Xueyu, GAO Feng, LI Yaming. Experimental research and crack resistance analysis of prestressed steel concrete frame beams[J]. Industrial Building,2011,41(12):16-19(in Chinese). [16] 中华人民共和国住房和城乡建设部. 建筑抗震试验规程: JGJ/T101—2015[S]. 北京: 中国建筑工业出版社, 2015.Ministry of Housing and Urban-Rural Development of the People’s Republic of China. Code for seismic test of buildings: JGJ/T101—2015[S]. Beijing: China Architecture and Building Press, 2015(in Chinese). [17] JOHN N, AMIN G, GAMIL T. Concrete flexural members reinforced with fiber reinforced polymer: Design for cracking and deformability[J]. Canadian Journal of Civil Engi-neering,2002,29(1):125-134. doi: 10.1139/l01-085 [18] 邓宇, 孙仁中, 张鹏, 等. 拉-弯-剪复合作用下型钢混凝土柱抗震性能研究及损伤量化分析[J]. 振动与冲击, 2021, 40(4):195-204.DENG Yu, SUN Renzhong, ZHANG Peng, et al. Seismic behavior and damage quantification analysis of steel reinforced concrete columns under tension-bending-shear composite action[J]. Journal of Vibration and Shock,2021,40(4):195-204(in Chinese). [19] 杨勇, 薛亦聪, 于云龙. 部分预制装配型钢混凝土柱抗震性能试验研究[J]. 建筑结构学报, 2019, 40(8):42-50.YANG Yong, XUE Yicong, YU Yunlong. Experimental study on seismic performance of partially precast steel concrete columns[J]. Journal of Building Structures,2019,40(8):42-50(in Chinese). [20] 薛建阳, 马辉. 低周反复荷载下型钢再生混凝土短柱抗震性能试验研究[J]. 工程力学, 2013, 30(12):123-131. doi: 10.6052/j.issn.1000-4750.2012.08.0571XUE Jianyang, MA Hui. Experimental study on seismic performance of shaped steel recycled concrete short columned under low cyclic repeated load[J]. Engineering Mechanics,2013,30(12):123-131(in Chinese). doi: 10.6052/j.issn.1000-4750.2012.08.0571