Experimental Investigation on the Creep Property of Carbon Fiber Reinforced Polymer Tendons under High Stress Levels
Abstract
:1. Introduction
2. Literature Review
3. Materials and Methods
3.1. Specimen Preparation and Anchoring System
3.2. Testing Setups
3.2.1. Static Test Setup
3.2.2. Creep Test Setup
3.3. Loading Procedure
3.3.1. Static Test Loading Procedure
3.3.2. Creep Test Loading Procedure
4. Results and Discussion
4.1. Static Tensile Properties
4.2. Creep Properties
4.2.1. Creep Curve
4.2.2. Creep Coefficient
4.2.3. Residual Tensile Strength and after-Creep Elastic Modulus
4.2.4. Creep Coefficient Prediction
5. Conclusions
- (1)
- The creep curves for all the specimens under sustained stresses from 0.69 fu to 0.85 fu are similar and can be divided into two stages. The creep strain increases quickly in the first stage and becomes stable in the second stage. Generally, a higher creep stress leads to a larger creep coefficient. The creep coefficients at 1000 h vary from 1.08 to 1.16%.
- (2)
- Compared to their static properties, the CFRP tendons’ residual strength after creep tests of 1000 h is 4.54% lower, while the after-creep elastic modulus is 6.99% higher.
- (3)
- A semi-logarithm relationship is found to fit the creep data within 1000 h with an acceptable precision. Through the extrapolation of this relationship, the creep coefficients at 1 million hours under stress levels of 0.69–0.85 fu are 1.83–1.91%. However, under stress levels close to or exceeding the creep rupture stress of CFRP tendons, the creep coefficients predicted by this relationship are smaller than the actual values.
- (4)
- No premature failure at the anchorage zone was observed in any of the tests. The 8 mm wedge-type anchorage developed by the authors’ research group performed well in both the static and creep tests.
Supplementary Materials
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Creep Specimen ID | Creep Stress Level |
---|---|
CC1-i (i = 1~3) | 0.69 fu |
CC2-i (i = 1~3) | 0.76 fu |
CC3-i (i = 1~3) | 0.85 fu |
Tensile Capacity/kN | Tensile Strength/MPa | Elastic Modulus/GPa | Rupture Strain/% | |
---|---|---|---|---|
Mean value | 108.6 | 2159 | 147.3 | 1.47 |
Standard deviation | 4.51 | 89.57 | 1.39 | 0.054 |
Variation coefficient | 0.041 | 0.041 | 0.0095 | 0.037 |
Specimen ID | CC1 (0.69 fu) | CC2 (0.76 fu) | CC3 (0.85 fu) | ||||||
---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 | |
Creep coefficient (1000 h, %) | 1.12 | 1.10 | 1.03 | 1.11 | 1.15 | 1.06 | 1.19 | 1.16 | 1.13 |
Mean value (%) | 1.08 | 1.11 | 1.16 | ||||||
Standard deviation (%) | 0.047 | 0.045 | 0.030 | ||||||
Variation coefficient | 0.0436 | 0.0407 | 0.0259 |
Tensile Capacity/kN | Tensile Strength/MPa | Elastic Modulus/GPa | Rupture Strain/% | |
---|---|---|---|---|
Mean value | 103.7 | 2061 | 157.6 | 1.28 |
Standard deviation | 4 | 79.5 | 1.88 | 0.047 |
Variation coefficient | 0.039 | 0.039 | 0.012 | 0.037 |
Specimen ID | Constants | Regression Coefficient | Creep Coefficient (%) | |||||
---|---|---|---|---|---|---|---|---|
a | b | 50 Year | Mean Value | 106 h | Mean Value | |||
CC1 (0.69 fu) | 1 | 12.14 | 25.50 | 0.966 | 1.81 | 1.75 | 1.91 | 1.84 |
2 | 12.07 | 24.67 | 0.965 | 1.79 | 1.89 | |||
3 | 11.09 | 22.94 | 0.959 | 1.65 | 1.74 | |||
CC2 (0.76 fu) | 1 | 13.04 | 29.70 | 0.967 | 1.77 | 1.74 | 1.87 | 1.83 |
2 | 12.99 | 28.56 | 0.962 | 1.76 | 1.85 | |||
3 | 12.46 | 24.94 | 0.958 | 1.66 | 1.76 | |||
CC3 (0.85 fu) | 1 | 15.32 | 31.11 | 0.964 | 1.84 | 1.81 | 1.94 | 1.91 |
2 | 15.85 | 26.54 | 0.943 | 1.86 | 1.96 | |||
3 | 14.76 | 26.44 | 0.952 | 1.74 | 1.84 |
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Yang, D.; Zhang, J.; Song, S.; Zhou, F.; Wang, C. Experimental Investigation on the Creep Property of Carbon Fiber Reinforced Polymer Tendons under High Stress Levels. Materials 2018, 11, 2273. https://doi.org/10.3390/ma11112273
Yang D, Zhang J, Song S, Zhou F, Wang C. Experimental Investigation on the Creep Property of Carbon Fiber Reinforced Polymer Tendons under High Stress Levels. Materials. 2018; 11(11):2273. https://doi.org/10.3390/ma11112273
Chicago/Turabian StyleYang, Dong, Jiwen Zhang, Shoutan Song, Fei Zhou, and Chao Wang. 2018. "Experimental Investigation on the Creep Property of Carbon Fiber Reinforced Polymer Tendons under High Stress Levels" Materials 11, no. 11: 2273. https://doi.org/10.3390/ma11112273