高强钢绞线网/ECC加固RC梁二次受力试验研究

李可; 陈翔; 范家俊; 牛自立; 张哲

高强钢绞线网/ECC加固RC梁二次受力试验研究

李可¹,
陈翔¹,
范家俊^1, ,,
牛自立²,
张哲¹

1.
郑州大学　土木工程学院, 郑州 450001
2.
河南省城乡规划设计研究总院股份有限公司, 郑州 450001

基金项目: 国家自然科学基金(U1804137；51879243；52108183)；中国博士后基金(2020 M672236；2021 TQ0302)；河南省交通运输厅科技项目(2021 J3)

详细信息

通讯作者:
范家俊，博士，副教授,研究方向为新型复合材料性能及结构加固　E-mail: jiajun.fan@zzu.edu.cn

中图分类号: TU528.57
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出版历程
- 收稿日期: 2022-08-26
- 修回日期: 2022-10-10
- 录用日期: 2022-10-22
- 网络出版日期: 2022-11-04
- 刊出日期: 2023-08-15

Experimental study on RC beams strengthened with high-strength steel strand meshes and ECC under secondary load

LI Ke¹,
CHEN Xiang¹,
FAN Jiajun^{1
, ,},
NIU Zili²,
ZHANG Zhe¹

1.
School of Civil Engineering, Zhengzhou University, Zhengzhou 450001, China
2.
He'nan Country & Town Layout Design Research Institute, Zhengzhou 450001, China

Funds: National Natural Science Foundation of China(U1804137；51879243；52108183); China Postdoctoral Science Foundation(2020 M672236；2021 TQ0302); Science and Technology Project of Henan Provincial Department of Transportation(2021 J3)

摘要

摘要: 高强钢绞线网/ECC(Engineered Cementitious Composites)作为新型高性能复合材料，充分利用高强钢绞线网及ECC优良的物理力学性能，具有超高延性、高韧性、优异的裂缝控制能力及强度高等优点。而现阶段采用该新型复合材料加固RC梁的研究未考虑二次受力对加固梁受弯性能的影响。为完善现有研究成果，进一步将该新型复合材料应用于实际工程加固中，本文进行高强钢绞线网/ECC持载加固RC梁受弯性能的试验研究。试验结果表明：整个加载阶段并未发生剥离现象，说明加固层与原RC梁能较好的协同工作，充分发挥加固材料性能；持载加固梁破坏模式均为原梁钢筋首先屈服，之后受压区混凝土被压碎而达到极限承载力，紧接着加固层被拉断而破坏。采用高强钢绞线网/ECC持载加固RC梁后，其承载力、刚度、延性、韧性分别提升了38%-65%、20%-81%、0%-18%、33%-116%，且能很好约束RC梁裂缝而减小裂缝宽度；相比于卸载加固梁，持载加固梁的加固层由于存在明显应变滞后，对原梁混凝土裂缝约束效果变差，其受弯承载力、刚度、韧性有所降低，但其延性有所提高；持载加固梁的受弯承载力、刚度、延性、韧性随原梁损伤程度增加而降低，而随钢绞线配筋率的适当提高而增大。1弯矩-跨中挠度曲线2跨中弯矩-高强钢绞线应变曲线
- 高强钢绞线网/ECC /
- 二次受力 /
- 持载加固 /
- 损伤程度 /
- 钢筋混凝土梁
Abstract: As a new type of high performance composite material, high-strength steel wire strand (HSWS) meshes reinforced engineered cementitious composites (ECC), which makes full use of the excellent mechanical properties of HSWS meshes and ECC, has the advantages of ultra- high ductility and toughness, excellent crack-control ability and high strength. In order to explore the effect of secondary load on the flexural behavior of reinforced concrete (RC) beam strengthened with this new composite material, the bending test of RC beams strengthened with HSWS meshes reinforced ECC was conducted, considering the effects of strengthening in load-carrying state, damage degree of the original beam, and reinforcement ratio of longitudinal HSWS. The influence mechanism of secondary load on the flexural performance of strengthened RC beams was analyzed, and the influence laws of these factors on the flexural behavior of RC beams strengthened with HSWS meshes reinforced ECC in load-carrying state were explored. The results show that the flexural capacity, stiffness, ductility and toughness of RC beams strengthened with high-strength steel wire meshes reinforced ECC in load-carrying state are increased by 38%-65%, 20%-81%, 0%-18% and 33%-116%, respectively, and the crack development of RC beam can be well restrained, and the crack width can be reduced. Compared with the RC beams strengthened in unloading state, the beams strengthened in load-carrying state exhibit obvious strain hysteresis in the reinforcement layer, resulting in the worse constraint effect on the crack of the original beam, and its flexural capacity, stiffness and toughness decrease, but its ductility is improved. The flexural capacity, stiffness, ductility and toughness of the beams strengthened in load-carrying state decrease as the original beam damage degree increases, but grow as the reinforcement ratio of HSWS increases properly.
- high-strength steel wire strand meshes reinforced ECC /
- secondary load /
- strengthening in load-carrying state /
- degree of damage /
- reinforced concrete beam

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图 1 试件尺寸及配筋(单位：mm)

Figure 1. Specimen size and reinforcement (Unit: mm)

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图 2 高强钢绞线网及剪切销钉布置(单位：mm)

Figure 2. Arrangement of HSSWS meshes and shear pins (Unit: mm)

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图 3 典型ECC受拉应力-应变曲线

Figure 3. Typical tensile stress-strain curves of ECC

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图 4 试验加载装置

Figure 4. A picture of loading device

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图 5 高强钢绞线网/ECC加固RC梁典型破坏模式

Figure 5. Typical failure modes of RC beams strengthened with HSWS meshes reinforced ECC

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图 6 高强钢绞线网/ECC加固RC梁弯矩-跨中挠度曲线

Figure 6. Bending moment versus mid-span deflection curves of RC beams strengthened with HSWS meshes reinforced ECC

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图 7 高强钢绞线网/ECC加固RC梁跨中弯矩-钢筋拉应变曲线

Figure 7. Bending moment versus tensile strain curves of RC beams strengthened with HSWS meshes reinforced ECC

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图 8 高强钢绞线网/ECC加固RC梁跨中弯矩-高强钢绞线应变曲线

Figure 8. Bending moment versus HSWS strain curves of RC beams strengthened with HSWS meshes reinforced ECC

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图 9 高强钢绞线网/ECC加固RC梁弯矩-混凝土压应变曲线

Figure 9. Bending moment versus concrete compressive strain curves of RC beams strengthened with HSWS meshes reinforced ECC

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图 10 高强钢绞线网/ECC加固RC梁弯矩-混凝土裂缝宽度曲线

Figure 10. Bending moment versus maximum crack width curves of RC beams strengthened with HSWS meshes reinforced ECC

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图 11 高强钢绞线网/ECC加固RC梁截面刚度-挠度曲线

Figure 11. Stiffness-deflection curves of RC beams strengthened with HSWS meshes reinforced ECC

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表 1 试件设计参数

Table 1. Specimen design parameters

Group	Specimen number	d /mm	Preload level	ρ /%	s/mm (n)	Load reinforcement
A	CSLA0	2.4	0	0.413	30(5)	Y
	CSLA1	2.4	50%	0.413	30(5)	Y
	CSLA2	2.4	65%	0.413	30(5)	Y
	CSLA3	2.4	80%	0.413	30(5)	Y
B	CSLB1	2.4	65%	0.248	50(5)	Y
B	CSLB3	2.4	65%	0.579	21(5)	Y
C	USLC1	2.4	65%	0.413	30(5)	N
Notes: Specimen number (C—Loading status; U—Unloading Status; S—Strengthening; L—RC beam); d—Diameter of steel strand; ρ—Reinforcement ratio of longitudinal HSSWSs; s—Spacing of longitudinal steel strands; n—Number of longitudinal steel strands; N—Not load reinforcement; Y—Load reinforcement.

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表 2 ECC配合比

Table 2. Mix proportions of ECC

Cement	Sand	Fly ash	Silica powder	Water	PVA fiber	Water reducer	Thickening agent
1	0.4	2.5	0.073	0.893	0.072	0.0407	0.00182
Note: PVA—Polyvinyl alcohol.

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表 3 ECC材料性能

Table 3. Material properties of ECC

f_cu/ MPa	f_tc/ MPa	ε_tc/%	E_s/ GPa	f_et/ MPa	ε_u /%
45.8	2.97	0.046	18.1	4.55	2.13
Notes: f_cu—ECC compressive strength; f_tc—ECC Cracking strength; ε_tc—ECC cracking strain; E_s—ECC elastic modulus; f_et—ECC tensile strength; ε_u—ECC ultimate tensile strain.

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表 4 高强钢绞线网/ECC加固RC梁受弯试验结果

Table 4. Bending test results of RC beams strengthened with HSWS meshes reinforced ECC

Specimen number	M_c/ (kN·m)	M_ec-d/ (kN·m)	M_y/ (kN·m)	M_swy/ (kN·m)	M_u/ (kN·m)	Δ_y/ mm	Δ_u/ mm	${\mu _\Delta }$	D_max	ω_{c,0.8 y}/ mm	ω_{c,0.9 y}/ mm	ω_c,y/ mm
L0	2.86	—	12.78	—	14.98	7.46	23.30	3.12	876.03	0.20	0.27	0.36
CSLA0	6.60	2.62	19.97	22.06	24.30	9.04	30.29	3.35	1894.15	0.14	0.19	0.29
CSLA1	3.72	0.98	18.91	21.79	23.50	9.02	29.92	3.32	1744.05	0.18	0.21	0.29
CSLA2	3.39	0.93	17.08	21.12	22.77	8.82	28.50	3.23	1509.68	0.21	0.23	0.30
CSLA3	3.43	0.66	16.19	20.25	21.85	8.85	27.67	3.13	1384.42	0.3	0.31	0.34
CSLB1	3.31	0.68	15.17	19.56	20.70	7.74	24.53	3.17	1169.79	0.21	0.23	0.32
CSLB3	3.35	1.06	17.70	22.31	24.66	8.08	29.71	3.68	1710.61	0.21	0.22	0.29
USLC1	—	2.47	19.20	19.96	23.30	8.80	27.50	3.13	1519.75	0.21	0.22	0.29
Notes; M_c—cracking moment of concrete; M_ec-d—Absolute value of ECC cracking moment minus pre-damage moment; M_y—Yielding moment of the specimen; M_swy—Nominal yield moment of steel strand; M_u—Ultimate bending moment of the specimen; Δ_y—Deflection of the specimen at M_y; Δ_u—Deflection of the specimen at M_u; ${\mu _\Delta }$—Ductility coefficient of the specimen; D_max—Flexural toughness coefficient of the specimen; ω_{c,0.8 y}—concrete crack width at 80%M_y; ω_{c,0.9 y}—concrete crack width at 90%M_y; ω_c,y—concrete crack width at M_y.

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