起波钢筋高速动态拉伸力学性能研究

刘思嘉; 陈力; 曹铭津; 周东雷; 樊源; 陈欣

doi:10.11883/bzycj-2021-0328

起波钢筋高速动态拉伸力学性能研究

doi: 10.11883/bzycj-2021-0328

刘思嘉^1,,
陈力^1, ,,
曹铭津¹,
周东雷¹,
樊源¹,
陈欣²

1.
东南大学爆炸安全防护教育部工程研究中心，江苏南京 211189
2.
解放军93204部队，北京 100068

基金项目: 国家自然科学基金（51978166）；中央高校基本科研业务费专项资金（2242021R10131）

详细信息

作者简介:
刘思嘉（1998－　），男，硕士研究生，17801121102@163.com

通讯作者:
陈　力（1982－　），男，博士，博士生导师，li.chen@seu.edu.cn

中图分类号: O383.2
计量
- 文章访问数: 300
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- PDF下载量: 44
- 被引次数: 0
出版历程
- 收稿日期: 2021-07-30
- 修回日期: 2021-11-11
- 网络出版日期: 2022-03-11
- 刊出日期: 2022-05-27

Study on mechanical properties of the kinked rebar under high speed dynamic tension

1.
Engineering Research Center of Safety and Protection of Explosion and Impact of Ministry of Education, Southeast University, Nanjing 211189, Jiangsu, China
2.
The People’s Liberation Army Unit 93204, Beijing 100068, China

摘要

摘要: 针对提高混凝土梁抗冲击爆炸性能的起波配筋新技术，采用理论分析与动态冲击拉伸试验相结合的方法，揭示了起波钢筋的快速拉伸变形作用机理，分析了拉伸速度、起波矢高等因素对起波钢筋抗拉强度的影响规律，确定了起波钢筋静态弹性极限强度计算方法。提出了起波钢筋等效拉伸应变率新概念，建立了弹性极限强度动力放大系数（dynamic increase factors，DIF）计算模型。研究结果表明，预先弯折起波使得钢筋在受力拉直过程中产生截面弯矩，起波钢筋的力学性能存在明显的应变率效应；起波钢筋弹性抗拉极限强度DIF随起波矢高的增高先增大后减小，存在一个最优起波设计矢高，可以使起波钢筋抗拉强度动态放大系数达到最大。研究成果可为进一步推动起波配筋技术在防护工程中的应用提供依据。
- 起波钢筋 /
- 动态拉伸 /
- 等效应变率 /
- 动力放大系数 /
- 应变率效应
Abstract: Aiming at new technology of the kinked rebar which can improve the resistance of concrete beams to impact and blast loading, the mechanism of rapid tensile deformation of the kinked rebar was revealed through theoretical analysis combined with dynamic impact tensile tests. The influences of the tensile velocity and the bending height of the kinked rebar on its tensile strength were analyzed. According to the mechanism of tensile deformation, the calculation method of the static elastic ultimate strength of the kinked rebar was determined by using the classical plastic mechanics theory, and the proposed calculation method was modified based on the existing literature data to consider the error caused by the Bauschinger effect. A new concept of equivalent tensile strain rate of the kinked rebar was put forward, the kinked rebar was regarded as an equivalent material, and the average strain rate of the bending part of the rebar was defined as the equivalent tensile strain rate of the kinked rebar. Considering the influence of the tensile velocity and the bending height of the kinked rebar, the calculation model of dynamic increase factors (DIF) of the elastic ultimate strength was established, referring to the form of the Johnson-Cook material constitutive model. The results show that the pre-bending kink results in the section bending moment of the steel bar during force straightening and the mechanical properties of the kinked rebar have an obvious strain rate effect. The tensile yield strength first increases and then decreases with the increase of the bending height of the kinked rebar. There is an optimal bending height for the kinked rebar at high strain rates, which can maximize the dynamic amplification factor of the tensile strength of the kinked rebar. The research results can provide a basis for further promotion of the application of the kinked rebar technology in protection engineering.
- kinked rebar /
- dynamic tension /
- equivalent strain rate /
- dynamic increase factors (DIF) /
- strain rate effect

HTML全文

图 1 传统钢筋与起波钢筋示意图

Figure 1. Kinked rebar compared with traditional rebar

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图 2 弯折位置受力示意图

Figure 2. Forces at the bending position

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图 3 起波钢筋四折线模型

Figure 3. Four-line model of kinked rebar

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图 4 起波形状变化示意图

Figure 4. Diagram of the shape change of kink

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图 5 起波钢筋试件

Figure 5. Specimens of the kinked rebars

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图 6 试验加载系统

Figure 6. Loading system

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图 7 加速等待装置

Figure 7. Accelerated holding device

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图 8 各组起波钢筋等效应力-等效伸长率曲线

Figure 8. Equivalent stress-equivalent elongation curves of each group

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图 9 起波钢筋弹性极限强度DIF-等效应变率曲线

Figure 9. DIF-equivalent strain rate curves of the kinked rebars

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图 10 起波钢筋发生塑性变形过程

Figure 10. The plastic deformation process

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图 11 第2个塑性铰出现后起波钢筋的受力分析

Figure 11. Force analysis of the steel bar after the second plastic hinge appears

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图 12 端部支持力出现后起波钢筋受力分析

Figure 12. Force analysis after the occurrence of end support force

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表 1 试验工况

Table 1. Test parameters

试件	起波矢高 h/mm	起波间距 s/mm	拉伸速度 v/(m·s⁻¹)	试件数量
W1-2.5	40	150	2.5	3
W1-5	40	150	5.0	3
W1-10	40	150	10.0	3
W1-15	40	150	15.0	3
W2-2.5	50	150	2.5	3
W2-5	50	150	5.0	3
W2-10	50	150	10.0	3
W2-15	50	150	15.0	3
W3-2.5	60	150	2.5	3
W3-5	60	150	5.0	3
W3-10	60	150	10.0	3
W3-15	60	150	15.0	3
注：试件编号中W表示起波钢筋，字母后第1个数字表示不同起波矢高的钢筋组号，第2个数字表示拉伸速度值。

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表 2 起波钢筋的静态弹性极限强度和抗拉极限

Table 2. Elastic ultimate strength and tensile capacity of the kinked rebar under static loading

钢筋参数	σ/MPa	F/KN
d=10 mm(直筋)	400.00	31.40
h=40 mm	127.66	32.50
h=50 mm	92.49	23.54
h=60 mm	71.99	18.32

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表 3 各组起波钢筋的弹性极限强度

Table 3. Elastic ultimate strengths of the kinked rebars

拉伸速率 v/(m·s⁻¹)	弹性极限强度σ/MPa
拉伸速率 v/(m·s⁻¹)	h=40 mm	h=50 mm	h=60 mm
2.5	159.46	105.78	93.50
5.0	193.99	140.19	111.03
10.0	201.13	198.50	137.56
15.0	255.40	261.14	175.61

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表 4 三组DIF拟合公式中的$a $、$b $值

Table 4. Values of a and b of the three groups of the kinked rebars

起波失高h/mm	a	b
40	0.85	0.029700
50	1550	0.000033
60	6.086	0.013100

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表 5 起波钢筋静态弹性极限强度理论值与试验值对比

Table 5. Comparison between the theoretical and experimental values of the static elastic ultimate strength

试件	极限强度σ/MPa		误差/ %	修正后强度 σ_r/MPa	修正后的误差/%
试件	试验^[1]	理论	误差/ %	修正后强度 σ_r/MPa	修正后的误差/%
F10-30	81.917	119.260	31.3	95.41	14.1
F10-45	67.486	61.586	9.6	49.27	37.0
F10-60	96.457	46.027	109.6	−	−
S10-30	34.127	46.167	26.1	36.93	7.6
S10-45	35.903	43.825	18.1	35.06	2.4
S10-60	17.850	24.140	26.1	19.31	7.6

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参考文献(13)

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