Methods for Strengthening Reinforced Concrete Columns Using Carbon Fiber in China

Introduction. China's construction industry developed in three phases: the first peak occurred in the 1950s, and the second one in the 1980s and 1990s. Generally, buildings constructed during the construction boom were characterized by relatively low design and construction standards resulting in poor quality. Currently, buildings constructed during the first and second phases are entering a phase of "aging" due to some factors such as low construction standards and outdated construction methods. Both the buildings themselves and their structures are flawed. Over time, most buildings exhibit varying degrees of deterioration and serious damage requiring urgent inspection, repair, and reinforcement. To meet the needs of social development, proper repair, reinforcement, and reconstruction of existing buildings is essential. The aim of this study is to identify the possibilities of reinforcing defective building structures with modern composite materials manufactured in China.

Materials and Methods. The object of the research are methods of strengthening reinforced concrete pillars. The author suggests using a systematic approach that accounts for the adjacent functional areas, their mutual influence and an expert assessment of their significance.

Research Results. The analysis showed that the strengthening mechanism for reinforced concrete columns subjected to axial compression and strengthened with carbon fiber sheets is a combination of carbon fiber sheets and concrete influenced by a host of factors. The strengthening method is strictly regulated, and the lateral restraint provided by the carbon fiber sheets under loading is capable of improving the compressive strength, structural stability, and durability of the columns.

Discussion and Conclusion. The strengthening methods for existing buildings vary widely, each with its own unique advantages and limitations. For example, bonded steel is fast to construct but requires a high quality; section enlargement is cost-effective but reduces space; carbon fiber strengthening offers numerous advantages but has limitations in investigating nodes and calculating load-bearing capacity. Although extensive research has been conducted on strengthening reinforced concrete axial compressed columns, the effectiveness depends on a host of factors. The discussion demonstrates that the choice of a strengthening method should be tailored to actual conditions. Carbon fiber strengthening requires further research, while strengthening axial compressed columns requires technological optimization. Furthermore, existing standards and regulations should be revised to reflect new advances and best practices.

1. Xu Qingfu, Tang Xiangtan, Wang Yun Research of Design and Technology of Reinforcement of Structures of Residential Buildings. Ceramics. 2025;10:212–214. https://doi.org/10.19397/j.cnki.ceramics.2025.10.042

2. Xiang Bingquan, Li Ruilin, Xu Dan, et. A Study of Rapid Verification of Earthquake Resistance and Reinforcement Methods of Brick-and-Concrete Buildings in the area of Chuzhou. Sichuan Cement. 2025;(11):73–77. https://doi.org/10.20198/j.cnki.scsn.2025.11.026.

3. Zhao Weijie, Cheng Yangyang, Zhang Zhen Research of Methods of Inspection, Assessment and Reinforcement of Building Structures. Metal Structures in Chinese Construction. 2025;24(16):79–81. https://doi.org/10.20080/j.cnki.ISSN1671-3362.2025.16.027

4. Li Genmo, Luo Kaihai, Huang Shimin, et. Review of Research and Practical Application of Seismic Reinforcement Methods for Existing Stone Buildings. Earthquake Resistance and Reinforcement of Building Structures. 2025;47(03):139–147. https://doi.org/10.16226/j.issn.1002-8412.2025.03.016

5. Chen Incan Investigation of Earthquake Resistance and Seismic Insulation Reinforcement of Historical Buildings with Brick and Wooden Structures in Lingnan District. Guangzhou University, 2025. https://doi.org/10.27040/d.cnki.ggzdu.2025.000677

6. Yu Hongjun, Zhang Nan Research of Reinforcement Methods of Building Structures Based on Optimal Design and Application Examples. Metal Structures in Chinese Construction. 2025;24(06):130–132. https://doi.org/10.20080/j.cnki.ISSN1671-3362.2025.06.044

7. Gao Xing, Wang Weiyu Investigation of the Mechanism of Operation and Methods of Reinforcement of Residential Buildings of the "Xuanyao" Type (Vaulted Cave Dwellings). Building Structures. 2025;55(02):143–150. https://doi.org/10.19701/j.jzjg.20220914

8. Yang Shuaimin Research of Technologies for Reinforcing Structures of Existing Buildings and their Economic Efficiency. East China University of Technology, 2024. https://doi.org/10.27145/d.cnki.ghddc.2024.000872

9. Liu Liying, Ou Zhenfeng, Yang Chunshan, et. Numerical Modeling and Analysis of Full-Scale Measurements of Deformations of Coastal Structures Caused by the Development of a Foundation Pit for Lowering Sections. Prevention and Elimination of Accidents in Tunnels and Underground Structures. 2024;6(04):12–19. https://doi.org/10.19952/j.cnki.2096-5052.2024.04.02

10. Wang Yaohan A Brief Analysis of the Application of Reinforcement Technologies for Building Structures. Metal Structures in Chinese Construction. Proceedings of the Forum on Intellectual Construction and Economic Development from the Perspective of New Qualitative Productive Forces (I). Wuhan Institute of Municipal Construction Design, LLC. 2024:156–157. https://www.chndoi.org/Resolution/Handler?doi=10.26914/c.cnkihy.2024.036623