Fracture behaviors of lightly reinforced concrete beams under different loading rates

SONG Min; ZHANG Jie; CHEN Qingqing; WANG Zhiyong; WANG Zhihua

doi:10.11883/bzycj-2020-0121

Volume 41 Issue 6

Jun. 2021

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SONG Min, ZHANG Jie, CHEN Qingqing, WANG Zhiyong, WANG Zhihua. Fracture behaviors of lightly reinforced concrete beams under different loading rates[J]. Explosion And Shock Waves, 2021, 41(6): 063102. doi: 10.11883/bzycj-2020-0121

Citation:

SONG Min, ZHANG Jie, CHEN Qingqing, WANG Zhiyong, WANG Zhihua. Fracture behaviors of lightly reinforced concrete beams under different loading rates[J]. Explosion And Shock Waves, 2021, 41(6): 063102. doi: 10.11883/bzycj-2020-0121

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Fracture behaviors of lightly reinforced concrete beams under different loading rates

doi: 10.11883/bzycj-2020-0121

SONG Min^{1, 2
,},
ZHANG Jie^{1, 2},
CHEN Qingqing^{1, 2},
WANG Zhiyong^{1, 2},
WANG Zhihua^{1, 2, 3
,
,}

1.
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China
2.
Shanxi Key Laboratory of Material Strength & Structural Impact, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
3.
School of Civil Engineering, Qinghai University, Xining 810016, Qinghai, China

Received Date: 2020-04-24
Rev Recd Date: 2020-10-29

Available Online: 2021-06-01

Publish Date: 2021-06-05

Abstract

Abstract

Under impact loads, the crack resistance of reinforcement in concrete is the focus of impact dynamics research. In this study, the three-point bending tests of lightly reinforce concrete beams with notch were conducted with a drop hammer testing machine. The high speed camera and digital image correlation (DIC) technology were applied to catch the fracture process and analyse the displacement field. The shape and geometry of the specimen followed the RILEM recommendation, i.e., 150 mm × 150 mm in cross section, 800 mm in length, notch-depth ratio was around 1/3 and span was kept constant 600 mm. And the impact force, mid-span deflection, steel strain beneath the loading point and concrete strain at the notch tip were measured over four loading rates. The experiment results showed that the crack initiation strain rate increased linearly with the loading rate, and the growth trend weakened when loading rate was 1.771 m/s. Based on the test results, the empirical formula of crack initiation strain rate with respect to loading rate was given, which was meaningful to simulate the crack initiation in concrete under dynamic loading. In addition, with the increase of loading rate, the steel yielded gradually, which resulted in the response time difference between impact force and steel strain decreased. With the recovery of elastic deformation of steel bars, the crack started to close and the macro crack became visible clearly. Meanwhile, the crack mouth opening displacement (CMOD) declined to a constant value after reaching the maximum value. Then, the crack mouth opening displacement rate was obtained from the fitting curve, and a linear growth relationship between CMOD rate and loading rate was founded. The failure process of the lightly reinforced beams was analyzed based on the CMOD rate, which provided an idea for comparing the fracture process of the beam under dynamic and static loads.
- steel concrete,
- lightly-reinforced beam,
- drop hammer machine,
- three-point bending test,
- crack initiation strain rate,
- CMOD rate

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References(22)

References

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