In the construction of industrial plants, due to the needs of production technology, environmental sanitation and other aspects, many ventilation, smoke exhaust, and fire-fighting pipe openings are designed on the structural roof. However, due to the change of construction technology, a hole needs to be opened behind the structural roof, and the size of the hole varies. Most of them are above 1000mm. Such rear openings are difficult to excavate. Although it satisfies the needs of the construction process, it has caused great hidden dangers to the safety of the structure, which requires the reinforcement of the structural roof at the position of the rear opening.

Use the steel frame and carbon fiber cloth combination to reinforce and open the hole, mainly to draw the edge line of the hole after drawing the corresponding position on the board and under the board where the hole is to be made. After drawing the line, arrange the corresponding steel frame and carbon fiber reinforcement range according to the size of the opening. The corresponding openings are opened after the combined reinforcement of the steel frame and carbon fiber cloth. This reinforcement method not only retains the advantages of the carbon fiber cloth reinforcement technology, but also integrates the high strength and good rigidity of the combined steel frame. This makes the reinforcement of the hole safer and more convenient.

1 Construction characteristics

1) Simple construction (no need for large construction machinery and turnover materials), easy operation, good economy, and short construction period.

2) After reinforcement, the corrosion resistance and durability of the rear opening structure and the integrity of the roof around the opening are greatly improved.

2 Reinforcement construction process

Confirmation of the reinforcement method-laying out the line to determine the opening and reinforcement location-concrete structure and section steel surface treatment / profile steel frame production and carbon fiber cloth cutting-glue-bonding-fixing-opening... a hole and profile steel frame surface treatment and protection.

3 Operation points

The confirmation of the reinforcement method is to use a combined steel frame and carbon fiber cloth to reinforce the opening. This method has passed through the original design unit to open the roof of the opening structure.

Set the line to determine the opening and reinforcement position

Surface treatment of concrete structures, openings and steel frames

Combined steel frame installation

Carbon fiber cloth reinforcement

Open a hole

Surface treatment and protection of openings and section steel frames

4 Quality assurance measures

1) The carbon fiber cloth binder uses carbon fiber impregnated glue, which is Grade A glue. After entering the site, it should be sampled on-site for quality inspection and can be used only after being qualified.

2) The strength grade of the concrete base reinforced by the profiled steel frame shall not be lower than C15.

3) After the hole is cut and chiseled, the roof hood should be built on the upper part of the hole according to the requirements of production and construction technology. After the installation of the opening pipe, the gap between the hood masonry and the pipe should be filled with polyurethane foam, and a galvanized steel plate cover should be installed on the upper part. An additional waterproof layer is provided on the periphery of the hood, and the detailed structure meets the requirements of relevant specifications to ensure the use of the rear opening.

5 Benefit Analysis

1) This construction method adopts the combined reinforcement method of steel frame and carbon fiber cloth for the opening of the cast-in-situ slab, which not only retains the advantages of carbon fiber cloth reinforcement technology, but also integrates the high strength and high rigidity characteristics of the steel frame. This makes the reinforcement of the hole safer and more convenient. The new construction method technology will promote the construction technology progress of the opening reinforcement project behind the structural slab, and the social benefits will be obvious.

2) Compared with similar structural slab reinforcement engineering methods, this construction method integrates various factors, while ensuring the quality of the project, it also reduces the cost, saves the construction period, and forms a better economic benefit.