Repair and Reinforcement of Industrial Factory Structures Damage

This project involves a 3-story reinforced concrete frame structure factory building with a total construction area of approximately 5200 square meters. The fire, caused by an electrical short circuit, resulted in serious damage to the building structure.

Based on on-site testing and analysis:

• Columns: The concrete on the surface of the columns in the bottom and middle layers has spalled extensively, exposing and corroding the reinforcing steel. The concrete strength in the core area is less than 45% of the original design value, and some columns have reached their ultimate load-bearing capacity.

• Beams and Slabs: The carbonation depth of the concrete at the bottom of the beams and on the surface of the slabs exceeds the standard, the protective layer is cracked and spalled, and the reinforcing steel is corroded; multiple through-cracks have appeared at the bottom of the slabs, resulting in a significant decrease in structural rigidity.

• Enclosing Structures: The infill walls, doors, windows, and decorative layers are essentially destroyed and require complete demolition and reconstruction.

Based on the inspection report and on-site conditions, a targeted reinforcement and repair plan was developed:

• Column：Concrete Replacement and Reinforcement

For severely damaged columns, a segmented replacement process was adopted: the failed concrete was removed, corroded rebar was derusted and treated with rust inhibitors, new rebar was installed, and then high-strength grouting material was poured to restore the column's load-bearing capacity.

• Beam and Slab：Carbon Fiber Reinforcement

Carbon fiber fabric was applied to the bottom of the beams to improve flexural load-bearing capacity; carbon fiber U-shaped stirrups were applied to the sides of the beams to enhance shear resistance.

Carbon fiber was applied to the bottom of the slabs to seal cracks and improve overall stiffness, preventing secondary cracking.

• Structural Repair and Restoration

The surfaces of the beams and slabs were treated with fire-resistant and anti-corrosion coatings to restore the concrete cover.

Infill walls, doors and windows, and the roof waterproofing system were reconstructed, and electrical wiring was updated simultaneously to eliminate fire hazards.

After the reinforcement was completed, static load tests and rebound-core drilling combined inspections were commissioned from an authoritative institution. The results showed that:

The column bearing capacity was restored to 110% of the original design;

The stiffness of the beams and slabs increased by 30%, and the deflection met the usage requirements;