Overview of Structural Repair and Strengthening Design
In the construction industry, reinforced concrete structures play an essential role and are widely used. In Vietnam, for projects such as high-rise buildings, factories, schools, and hospitals, reinforced concrete structures are often preferred. With the continuous development of the construction sector, the demand for repairing and strengthening existing structures is also increasing due to factors such as changes in load requirements, renovation needs, and structural deterioration over time.
In this article, we will present the process and common design approaches for structural strengthening and repair services.
I. When Structural Strengthening and Repair Are Needed
During their service life, buildings gradually lose structural resistance due to various external factors such as physical impacts, chemical corrosion, or unexpected incidents. When this occurs, structural repair and strengthening become necessary. In some cases, project owners may also wish to change the load capacity or functional use of the building, requiring adjustments to the structure to ensure safety and extend its service life.
Figure 1: Relationship between Structural Resistance and Building Service Life over Time
II. Structural Repair and Strengthening Design Process
The process of structural repair and strengthening typically begins with a site survey, followed by investigation and the development of a detailed design plan. This process can be summarized in the following steps:
1. Survey: Identify the scope and extent of structural damage.
2. Investigation and Analysis: Determine suitable repair and strengthening options.
3. Design: Develop a detailed design plan for the repair and strengthening work.
Figure 2: Strengthening Design Process
Depending on the extent of damage and the improvement goals of the client, the selection of a repair and strengthening method can sometimes start directly from the third step. Before beginning the strengthening design, the existing structure is usually thoroughly inspected, and all damages are repaired to ensure structural integrity. For example, concrete crack injection or reinforcement rust removal is often part of this stage.
Compared to designing a new structure, the calculation process for repair and strengthening at the third step requires assessing the original load-bearing capacity and deformation of the existing structure. This step is critical and forms the basis for all strengthening calculations. For instance, if a beam is strengthened using FRP material, its initial deformation, existing load capacity, and fire resistance must all be considered. The same principle applies to other methods such as section enlargement and external prestressing. Without thorough evaluation, the post-strengthening load capacity of the structure could be inaccurately assessed.
Figure 3: Consideration of key factors for developing a strengthening plan
There are various methods and techniques for structural repair and strengthening, often involving a combination of approaches rather than relying on a single method to achieve the desired goals. Common options include:
Strengthening Design Using FRP Materials:
FRP materials offer advantages such as light weight, high strength, and excellent corrosion resistance, making them widely used in the repair industry today. (For further reference, see: https://minhduccorp.com.vn/vat-lieu-frp-trong-sua-chua-gia-cuong-ket-cau )
Figure 4: Cross-section bending analysis model at ULS strengthened with CFRP material
Application: Strengthening reinforced concrete columns, beams, slabs, and prestressed concrete in high-rise buildings, factories, bridges, etc.
External Prestressed Cable Strengthening Design
Figure 5: Load Transfer Model for Existing Structures Using External Prestressed Cables
Figure 6: Flexural Section Analysis Model of Structures with External Prestressed Cables
- Application: Reducing deflection and increasing the load-bearing capacity of reinforced concrete (RC) slabs and prestressed concrete slabs in high-rise buildings, industrial plants, bridges, etc.
Strengthening Structures by Section Enlargement
It is commonly applied to reinforced concrete beams or columns to enhance load-bearing capacity.
Figure 7: Calculation model of the flexural resistance of an enlarged cross-section after strengthening
In addition to the aforementioned solutions, there are many other structural strengthening methods, such as using jacks and steel structures.
- Using jacks: This method is often applied to raise or adjust the position of structural parts that have settled, shifted, or experienced any other type of deformation.
- Using steel structures: Steel structures are often used as an effective means of strengthening, especially for enhancing the load-bearing capacity of reinforced concrete elements. By adding or replacing parts of the structure with steel material, the structural strength and durability of the project can be significantly improved.
III. Summary and Conclusion:
- Structural repair and strengthening is a field with significant growth potential in the future, especially in the context of a rapidly developing construction industry and the increasing need to maintain and upgrade aging structures.
- Structural strengthening analysis and design is a complex process that requires high-level expertise and practical experience. It is a critical step in repairing and improving the durability of a structure.
- Each project has its own specific characteristics, and strengthening solutions can be diverse and flexible to meet the unique requirements of each structure. A combination of different methods is often necessary to achieve the best results.
- At SSC, we take pride in our team of experts, equipped with the knowledge, experience, and dedication to deliver high-quality structural repair and strengthening services. Contact us today for consultation and to experience our professional solutions — partnering with you in every construction project.
