Study of the Interfacial Bond Behavior between CFRP Grid–PCM Reinforcing Layer and Concrete via a Simplified Mechanical Model
Abstract
:1. Introduction
2. Experimental Program
2.1. Details of Specimens
2.2. Load Program
3. Experimental Results and Discussion
3.1. Failure Patterns and Maximum Loads
3.2. Strain Distribution of CFRP Grids
4. Interface Bond Mechanism
4.1. General
4.2. Load–Strain Difference Curves
5. Simplified Interface Model
5.1. Simplified Mechanical Model
5.2. Finite Element Analysis
5.2.1. Establishment of the Model
5.2.2. Model Verification
5.2.3. Strain Analysis of CFRP Grids
5.2.4. Strain Difference Analysis
6. Conclusions
- (1)
- The tensile strength utilization ratio of the CFRP grid in specimen C6D50 was 81% higher than in specimen C6D100, and the tensile strength utilization ratio of the CFRP grid in specimen C8D50 was 23% higher than in specimen C8D100. Meanwhile, the maximum load of specimen C8D50 with the CR8@50-type CFRP grid was nearly 2.5 times higher than that of specimen C6D50 with the CR6@50-type CFRP grid, and the maximum load of specimen C8D100 with the CR8@100-type CFRP grid was 3.5 times higher than that of specimen C6D100 with the CR6@100-type CFRP grid. The use of a CFRP grid with a larger cross-sectional area and smaller grid interval can significantly improve the interfacial bearing capacity between the CFRP grid–PCM reinforcing layer and the concrete. Moreover, the interfacial bond behavior between the reinforcing layer and the concrete can be effectively enhanced by using an interfacial binding agent;
- (2)
- The tensile stress in the CFRP grid deceased gradually from the loaded edge to the free edge. The tensile stress borne by the CFRP grid was transferred to the PCM by the resistant action of the horizontal grid and the bond action of the vertical grid, and then to the concrete by the interface bond between the PCM and the concrete. The interfacial bearing capacity between the CFRP grid–PCM reinforcing layer and the concrete depended on the tensile strength of the CFRP grid, the anchorage action of the CFRP grid in the PCM, and the bond behavior between the PCM and the concrete;
- (3)
- The simplified interface model with a nonlinear spring system could effectively reflect the mechanical behavior of the concrete specimens with the CFRP grid–PCM reinforcing layer, indicating that it can be used to simulate the stress transfer modes and interface bond mechanisms between the CFRP grid, PCM, and concrete;
- (4)
- The stress was gradually transferred from the loaded edge to the free edge through the grid action in the process of drawing the load. There was an obvious turning point in the load–strain difference curve in the CFRP grid, indicating the change in the tendency of the resistance of transverse reinforcement—that is, the stress transfer mode changes with the failure of the springs.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
- Gonzalez-Libreros, J.H.; Sneed, L.; D’Antino, T.; Pellegrino, C. Behavior of RC beams strengthened in shear with FRP and FRCM composites. Eng. Struct. 2017, 150, 830–842. [Google Scholar] [CrossRef]
- Tetta, Z.C.; Bournas, D.A. TRM vs. FRP jacketing in shear strengthening of concrete members subjected to high temperatures. Compos. Part B Eng. 2016, 106, 190–205. [Google Scholar] [CrossRef]
- Ye, L.P.; Feng, P. Application and development of fiber-reinforced polymer in engineering structures. China Civ. Eng. J. 2006, 39, 25–37. [Google Scholar]
- Engel, R.S.; Bakis, C.E.; Nanni, A.; Croyle, M.G. FRP Grids for reinforced concrete: An investigation of fiber architecture. In Proceedings International Composites Expo’ 97; Soc. Plastics Industry: New York, NY, USA, 1997; pp. 6E1–6E6. [Google Scholar]
- Guo, R.; Pan, Y.; Cai, L.; Hino, S. Bonding behavior of CFRP grid-concrete with PCM shotcrete. Eng. Struct. 2018, 168, 333–345. [Google Scholar] [CrossRef]
- Guo, R.; Pan, Y.; Cai, L.; Hino, S. Study on design formula of shear capacity of RC beams reinforced by CFRP grid with PCM shotcrete method. Eng. Struct. 2018, 166, 427–440. [Google Scholar] [CrossRef]
- Liang, J.; Uji, K.; Matsumura, S.; Sato, K. Shear strengthening of RC beam with CFRP grid and sprayed mortar. Proc. Jpn. Concr. Inst. 2008, 30, 607–612. [Google Scholar]
- Brunton, J.J.; Bank, L.C.; Oliva, M.G. Punching shear failure in double-layer pultruded FRP grid reinforced concrete bridge decks. Adv. Struct. Eng. 2012, 15, 601–613. [Google Scholar] [CrossRef]
- Jeong, S.K.; Lee, S.S.; Kim, C.H.; Ok, D.M.; Yoon, S.J. Flexural behavior of GFRP reinforced concrete members with CFRP grid shear reinforcements. Key Eng. Mater. Trans. Technol. Publ. 2006, 306, 1361–1366. [Google Scholar] [CrossRef]
- Wei, Y.; Ji, J.; Zhang, M. Experimental investigation on tensile performance of FRP grids and its application as strengthening materials for underwater concrete. Fiber. Reinf. Plast. Compos. 2014, 47, 10–15. [Google Scholar]
- Yost, J.R.; Goodspeed, C.H.; Schmeckpeper, E.R. Flexural performance of concrete beams reinforced with FRP grids. J. Compos. Constr. 2001, 5, 18–25. [Google Scholar] [CrossRef]
- Wan, B.L.; Petrou, M.F.; Harries, K.A. The effect of the presence of water on the durability of bond between CFRP and concrete. J. Reinf. Plast. Compos. 2006, 25, 875–890. [Google Scholar] [CrossRef]
- Chen, W.Y.; Chen, X.B.; Ding, Y. The shear behavior of beams strengthened with FRP grid. In Advances in FRP Composites in Civil Engineering; Springer: Berlin/Heidelberg, Germany, 2011; pp. 772–775. [Google Scholar]
- Cai, S.H.; Tang, L.F. Study on polymer cement mortar in concrete patching. J. Yangtze River Sci. Res. Inst. 2007, 24, 44–47. [Google Scholar]
- Zhang, D.; Ueda, T.; Furuuchi, H. Intermediate crack debonding of polymer cement mortar overlay-strengthened RC beam. J. Mater. Civil. Eng. 2011, 23, 857–865. [Google Scholar] [CrossRef]
- Ding, L.; Rizkalla, S.; Wu, G.; Wu, Z.S. Bond mechanism of carbon fiber reinforced polymer grid to concrete. In Advances in FRP Composites in Civil Engineering; Springer: Berlin/Heidelberg, Germany, 2010; pp. 589–592. [Google Scholar]
- Thamboo, J.A.; Dhanasekar, M. Characterisation of thin layer polymer cement mortared concrete masonry bond. Constr. Build. Mater. 2015, 82, 71–80. [Google Scholar] [CrossRef] [Green Version]
- Zhang, D.W.; Ueda, T.; Furuuchi, H. Concrete cover separation failure of overlay-strengthened reinforced concrete beams. Constr. Build. Mater. 2012, 25, 735–774. [Google Scholar] [CrossRef]
- Patnaik, G.; Kaushik, A.; Rajput, A.; Prakash, G. Numerical Study on Perforation Characteristics of Carbon-Fiber Reinforced Composite Laminates Subjected to Impact Loading. In International Conference on Structural Engineering and Construction Management; Springer: Cham, Switzerland, 2021; pp. 249–263. [Google Scholar]
- Salem, B.; Mkaddem, A.; Rubaiee, S.; Bin Mahfouz, A.S.; Al-Zahrani, A.; Jarraya, A. Combined Approach for Modeling Progressive Damage in Unidirectional CFRP Composites. In International Conference on Advances in Materials, Mechanics and Manufacturing; Springer: Singapore, 2021; pp. 308–316. [Google Scholar]
- Róyo, P.; Dbski, H.; Teter, A. Buckling and limit states of thin-walled composite columns under eccentric load. Thin Walled Struct. 2020, 149, 106627. [Google Scholar]
- Guo, R.; Hu, W.H.; Li, M.Q.; Wang, B. Study on the flexural strengthening effect of RC beams reinforced by CFRP grid with PCM shotcrete. Compos. Struct. 2020, 239, 112000. [Google Scholar] [CrossRef]
- Zinno, A.; Lignola, G.P.; Prota, A.; Manfredi, G.; Cosenza, E. Influence of free edge stress concentration on effectiveness of FRP confinement. Compos. Part B Eng. 2010, 41, 523–532. [Google Scholar] [CrossRef]
- Sugiyama, K.; Yamaguchi, K.; Nakamura, S.; Hino, S. Stress transfer mechanism of the reinforced interface and seismic retrofit existing RC pier by polymer cement mortar for shotcrete with CFRP grid. J. Struct. Eng. 2011, 57, 1042–1051. [Google Scholar]
- Banjara, N.K.; Ramanjaneyulu, K. Experimental and numerical investigations on the performance evaluation of shear deficient and GFRP strengthened reinforced concrete beams. Constr. Build. Mater. 2017, 137, 520–534. [Google Scholar] [CrossRef]
- Dung, T.V. Numerical Analysis of the Shear Behavior of Reinforced Concrete Beam Strengthened with CFRP and Sprayed Mortar. Ph.D. Thesis, Tokyo Metropolitan University, Tokyo, Japan, 2016. [Google Scholar]
- ACI Committee Report. Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars; ACI 440.1R-06; American Concrete Institute: Farmington Hills, MI, USA, 2001. [Google Scholar]
- Japan Society of Civil Engineerings. JSCE/E539-2007 Standard Specification for Concrete Structures; JSCE: Tokyo, Japan, 2007. [Google Scholar]
- Wang, B.; Uji, K.; Wu, T.; Dai, H.; Yan, D.; Guo, R. Experimental investigation of stress transfer and failure mechanism between existing concrete and CFRP grid-sprayed PCM. Constr. Build. Mater. 2019, 215, 43–58. [Google Scholar] [CrossRef]
- Wang, B.; Wang, Z.; Uji, K. Experimental verification of a novel anchorage method of CFRP grid in mortar. Structures 2020, 28, 1646–1660. [Google Scholar] [CrossRef]
Specimen | CFRP Grid Type | Grid Interval (mm) | Dimension of Concrete (mm) | Dimension of PCM (mm) |
---|---|---|---|---|
C6D50 | CR6 | 50 | 300 × 270 × 90 | 250 × 250 × 40 |
C6D100 | CR6 | 100 | ||
C8D50 | CR8 | 50 | 300 × 270 × 90 | 250 × 250 × 40 |
C8D100 | CR8 | 100 |
Specimen | Gmax * (mm) | SL * (mm) | W/C (%) | Air Content (%) | Unit Content (kg/m3) | |||
---|---|---|---|---|---|---|---|---|
W * | C * | S * | G * | |||||
C6D50 C6D100 | 20 | 80 | 58 | 4.5 | 174 | 300 | 823 | 985 |
C8D50 C8D100 | 20 | 120 | 55.6 | 4.5 | 158 | 284 | 792 | 1099 |
Ready-Mixed Mortar (kg/m3) | Polymer (kg/m3) | Water (kg/m3) |
---|---|---|
1450 | 70 | 239 |
Material | Specimen | Compressive Strength (N/mm2) | Tensile Strength (N/mm2) | Elastic Modulus (kN/mm2) |
---|---|---|---|---|
Concrete | C6D50 C6D100 | 33.2 | 3.0 | 25.3 |
C8D50 C8D100 | 36.7 | 2.87 | 30.1 | |
PCM | C6D50 C6D100 C8D50 C8D100 | 47.1 | 3.21 | 16.8 |
Grid Type | Cross-Sectional Area (mm2) | Tensile Strength (N/mm2) | Elastic Modulus (kN/mm2) |
---|---|---|---|
CR8 | 26.4 | 1400 | 100 |
CR6 | 17.5 | 1400 | 100 |
Specimen | Maximum Load (kN) | Test Ultimate Tensile Load of CFRP Grid (kN) | Tensile Strength Utilization Ratio of CFRP Grid (%) | Failure Pattern of CFRP Grid | Failure Pattern of PCM | Interface Failure Pattern between Concrete and PCM |
---|---|---|---|---|---|---|
C6D50 | 14.92 | 28.6 | 52.2 | The vertical grid was pulled out | No significant cracks were observed | Kept intact |
C6D100 | 8.11 | 28.4 | ||||
C8D50 | 34.72 | 45.07 | 77.04 | Cracks occurred on the surface | ||
C8D100 | 28.12 | 62.39 |
Specimens | Grid Interval (mm) | Location of Spring | Rmax (N) |
---|---|---|---|
C6D50 C8D50 | 50 | Non-bottom | 453 |
Bottom | 307 | ||
C6D100 C8D100 | 100 | Non-bottom | 747 |
Bottom | 307 |
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Dai, H.; Wang, B.; Zhang, J.; Zhang, J.; Uji, K. Study of the Interfacial Bond Behavior between CFRP Grid–PCM Reinforcing Layer and Concrete via a Simplified Mechanical Model. Materials 2021, 14, 7053. https://0-doi-org.brum.beds.ac.uk/10.3390/ma14227053
Dai H, Wang B, Zhang J, Zhang J, Uji K. Study of the Interfacial Bond Behavior between CFRP Grid–PCM Reinforcing Layer and Concrete via a Simplified Mechanical Model. Materials. 2021; 14(22):7053. https://0-doi-org.brum.beds.ac.uk/10.3390/ma14227053
Chicago/Turabian StyleDai, Huijuan, Bo Wang, Jiawei Zhang, Junlei Zhang, and Kimitaka Uji. 2021. "Study of the Interfacial Bond Behavior between CFRP Grid–PCM Reinforcing Layer and Concrete via a Simplified Mechanical Model" Materials 14, no. 22: 7053. https://0-doi-org.brum.beds.ac.uk/10.3390/ma14227053