Project

A training hall covers an area of 6411 square meters, with a construction area of 18474.6 square meters, and adopts a prestressed frame structure. The size of the column mesh is 9000mmx9000mm, the column height is 5.8m, and the cross-section is divided into three specifications: 800mmx700mm, 800mmx600mm and 600mmx600mm. C40 concrete was used for on-site mixing of concrete. Due to inaccurate measurement, inspection was issued when the construction reached the third floor. At present, the rebound strength of 12 columns in the foundation is lower than the design value. Among them, the concrete strength grade of two columns is only about C25, which is 60% of the original design strength.

Determination of reinforcement plan

According to the concrete structure design specification, the carbon fiber sheet reinforced concrete structure specification, the building structure design specification and the structural reinforcement technical specification, the carbon fiber sheet and the enlarged section method reinforcement calculation are carried out. After a comprehensive assessment, it was decided to use unidirectional carbon fiber sheet for reinforcement. This method is economical and easy to construct. It also has extremely high resistance to fatigue, acid and alkali, creep resistance and high temperature resistance. It has a long service life after reinforcement and has long-term comprehensive benefits:

Preparation of reinforcement materials for frame column structure

1 Unidirectional carbon fiber sheet

(1) The standard value of tensile strength of carbon fiber sheet ≥3 000 MPa, elastic modulus ≥2 .1X10⁵ MPa, elongation ≥1.4%:

(2) Weight per unit area of single-layer carbon fiber sheet 200g/m² ,300g/m².

2 Adhesive

The basic performance of the adhesive requires: compressive strength ≥ 70 MPa, tensile strength ≥ 30 MPa, bending strength ≥ 40 MPa, elastic modulus ≥ 3.0x10³ MPa, and bonding ability≥ 2. 01 MPa.

Externally bonding carbon fiber sheet on frame column

Concrete bonding surface treatment

Configure primer

Primer

Configure repair leveling glue

Paste surface repair and leveling

Unloading

Configure carbon fiber dipping glue

Cutting unidirectional carbon fiber sheet

Paste one-way carbon fiber sheet

Project results

After the concrete frame column is reinforced with unidirectional carbon fiber sheet, the strength is restored and improved, meeting the design requirements.