FRP非均匀约束海水海砂混凝土方柱轴压性能

杨俊龙; 王吉忠; 卢世伟; 张丽华; 王子茹

doi:10.13801/j.cnki.fhclxb.20210708.004

FRP非均匀约束海水海砂混凝土方柱轴压性能

doi: 10.13801/j.cnki.fhclxb.20210708.004

大连理工大学　海岸和近海工程国家重点实验室，大连 116024

基金项目: 中央高校基本科研业务费项目(DUT20JC02)

详细信息

通讯作者:
王吉忠，博士，教授，研究方向为FRP-混凝土组合结构　E-mail：wangjz@dlut.edu.cn

中图分类号: TU398+.9
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出版历程
- 收稿日期: 2021-05-19
- 修回日期: 2021-06-26
- 录用日期: 2021-06-30
- 网络出版日期: 2021-07-08
- 刊出日期: 2022-06-01

Axial compressive behavior of FRP nonuniformly wrapped seawater sea-sand concrete in square columns

State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

摘要

摘要: 为扩大纤维增强树脂复合材料(FRP)-海水海砂混凝土(SSC)组合结构的应用范围，改善FRP约束海水海砂混凝土柱脆性破坏特性，对碳纤维增强树脂复合材料(CFRP)非均匀约束海水海砂混凝土方柱的轴压性能进行了研究。试验结果表明：由于CFRP非均匀约束试件中沿高度方向CFRP厚度并不相等，因而整个破坏过程具有明显的预兆，故脆性行为得到明显改善。相比于相同体积率下的全包裹和条带约束试件，其具有更优越的力学性能，尤其是在净距比较小的情况下。随着外部CFRP条带净距的下降和层数的增加，试件的极限强度和变形能力显著提高。具体而言，由于FRP条带净距的降低导致试件的极限强度增幅在5.4%~18.5%不等，而在净距比固定状态下，当外部条带层数增大1倍后，极限强度与应变的最大增幅分别为15.8%和21.8%。最后基于试验数据，对现有部分代表性应力-应变模型对于非均匀约束混凝土的适用性进行了讨论，并给出了所有模型对于试件极限状态的预测精度与误差大小。
- 纤维增强树脂复合材料 /
- 非均匀约束 /
- 约束混凝土 /
- 海水海砂混凝土 /
- 应力-应变模型
Abstract: To facilitate the practical application of fiber-reinforced polymer (FRP) strengthened seawater sea-sand concrete (SSC) structures in marine infrastructures and alleviate the brittleness of abrupt failure of FRP confined SSC columns, the mechanical performance of carbon fiber-reinforced polymer (CFRP) nonuniformly wrapped square SSC columns under axial compression was explored. Test results show that the failure pattern of nonuniformly CFRP confined square SSC columns exhibits less brittle since the rupture of thinner CFRP band between two adjacent strips can provide a warning sign due to the inequivalent number of CFRP layers at different locations along the height of the specimens. Compared to the specimens uniformly wrapped with CFRP sheets and strips under the same volumetric ratio of CFRP, CFRP nonuniformly wrapped SSC columns possess superior mechanical properties, especially for the specimens with a smaller clear spacing. Besides, with the decrease of clear spacing ratio and the increment of the thickness of external CFRP strips, the ultimate strengths and strains of confined specimens increase obviously. In specific, the enhancement of ultimate strengths ranges from 5.4%-18.5% as the decreasing of clear spacing ratio. Moreover, under the same clear spacing ratio, the maximum ultimate strength improvement and strain improvement are equal to 15.8% and 21.8% respectively when the thickness of external CFRP strips doubles. Finally, several representative stress-strain models were selected to examine their validity in predicting the ultimate conditions of FRP nonuniformly wrapped concrete and the accuracy and reliability of each model were also assessed.
- FRP /
- nonuniform confinement /
- confined concrete /
- seawater sea-sand concrete /
- stress-strain model

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图 1 CFRP非均匀约束SSC试件加固方案

Figure 1. Nonuniform wrapping schemes of CFRP nonuniformly wrapped SSC tested specimens

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图 2 加载装置与测点布置

Figure 2. Test setup and instrumentations

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图 3 CFRP非均匀约束SSC试件破坏模式

Figure 3. Failure modes of CFRP nonuniformly wrapped SSC specimens

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图 4 CFRP非均匀约束SSC试件轴向应力-轴向应变曲线

Figure 4. Axial stress-axial strain curves of CFRP nonuniformly wrapped SSC specimens

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图 5 不同约束形式下CFRP非均匀约束SSC试件试验结果对比

Figure 5. Comparison of CFRP nonuniformly wrapped SSC specimens under different wrapping schemes

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图 6 不同净距比下CFRP非均匀约束SSC试件极限状态对比

Figure 6. Comparison of ultimate conditions of CFRP nonuniformly wrapped SSC specimens under different clear spacing ratios

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图 7 挑选模型对CFRP非均匀约束SSC试件极限状态的预测精度

Figure 7. Predicted accuracy of selected models in calculating ultimate conditions of CFRP nonuniformly wrapped SSC specimens

AAE—Average absolute error; SD—Standard deviation; AVE—Average

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图 8 各模型对CFRP非均匀约束SSC试件极限状态预测值与试验值对比

Figure 8. Comparison of ultimate conditions between test results and theoretical predictions of CFRP nonuniformly wrapped SSC specimens

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表 1 碳纤维增强树脂复合材料(CFRP)非均匀约束海水海砂混凝土(SSC)件参数和试验结果

Table 1. Details and test results of carbon fiber reinforced polymer (CFRP) nonuniformly wrapped seawater sea-sand concrete (SSC) specimens

Group	Specimen ID	w/mm	s/mm	s/b	n_P/ply	Test results
Group	Specimen ID	w/mm	s/mm	s/b	n_P/ply	f_cc/MPa	f_cc/f_co	f_cu/MPa	f_cu/f_co	ε_cu/%	ε_cu/ε_co	ε_h,rup/%
1	C(W3A2F)S-1	30	105	0.7	2	47.4	1.31	42.6	1.17	1.21	6.05	1.08
	C(W3A2F)S-2	30	105	0.7		49.2	1.36	43.7	1.20	1.39	6.93	1.17
	C(W4A2F)S-1	40	90	0.6		51.3	1.41	45.8	1.26	1.49	7.46	1.19
	C(W4A2F)S-2	40	90	0.6		50.7	1.40	45.1	1.24	1.37	6.83	1.20
	C(W5A2F)S-1	50	75	0.5		52.6	1.45	49.5	1.36	1.57	7.86	1.25
	C(W5A2F)S-2	50	75	0.5		51.9	1.43	46.9	1.29	1.43	7.14	1.02
	C(W6A2F)S-1	60	60	0.4		52.7	1.45	50.5	1.39	1.87	9.37	1.20
	C(W6A2F)S-2	60	60	0.4		51.8	1.43	48.8	1.34	1.72	8.62	1.15
	C(W3B2F)S-1	30	30	0.2		52.4	1.44	50.4	1.39	1.97	9.83	1.28
	C(W3B2F)S-2	30	30	0.2		53.0	1.46	51.9	1.43	2.03	10.15	1.30
2	C(W3A4F)S-1	30	105	0.7	4	50.5	1.39	50.5	1.39	1.62	8.08	1.11
	C(W3A4F)S-2	30	105	0.7		49.0	1.35	49.0	1.35	1.45	7.27	0.92
	C(W4A4F)S-1	40	90	0.6		51.7	1.43	51.7	1.43	1.62	8.12	1.22
	C(W4A4F)S-2	40	90	0.6		53.6	1.48	53.6	1.48	1.44	7.22	1.13
	C(W5A4F)S-1	50	75	0.5		53.0	1.46	53.0	1.46	1.74	8.69	1.16
	C(W5A4F)S-2	50	75	0.5		55.1	1.52	55.1	1.52	1.92	9.59	1.17
	C(W6A4F)S-1	60	60	0.4		58.0	1.60	58.0	1.60	2.23	11.16	1.21
	C(W6A4F)S-2	60	60	0.4		56.8	1.56	56.8	1.56	1.91	9.55	1.15
	C(W3B4F)S-1	30	30	0.2		59.2	1.63	59.2	1.63	2.17	10.87	1.26
	C(W3B4F)S-2	30	30	0.2		58.7	1.62	58.7	1.62	2.54	12.71	1.23
Notes: In specimen ID: C—CFRP; W3, W4, W5, W6—Width of CFRP are 30 mm, 40 mm, 50 mm and 60 mm, respectively; A, B—CFRP number are 3 and 5, respectively; 2, 4—Layer number of CFRP; F—Bottom is wrapped with CFRP; S—SSC; 1, 2—Specimen number. f_co—Compressive strength of unconfined concrete; w, s—Width and clear spacing of primary strips, respectively; b—Width of section edge; n_P—Number of layers of external CFRP strips; f_cc—Peak strength of confined concrete; f_cu, ε_cu—Ultimate strength and corresponding strain of confined concrete, respectively; ε_h,rup—Hoop rupture strain of primary strips at the midheight outside the overlapping zone.

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