Column, Beam Strengthening

Project overview

The project is seven - layer half frame structure, the pile foundation is immersed tube pile, and the superstructure uses universal silicon 425# cement. It was found that the cement strength was qualified for 3 days and 7 days, but the cement strength was not qualified for 28 days because of the test of the performance of the same batch of cement. The test results show that the strength of the 1~3 layers of most beam and column concrete is lower than the original C25 design strength grade.

After research, it is decided to externally bonded steel plate.

Calculation of bearing capacity of bonded steel reinforcement method

fcmbx=fyAs+0.9fayAa

—

fy/As/ 

Mu=fcmbx(h01-x/2)+ fy/As/(h01-as/) 

fcmbx=fyAs+0.9fayAa—fy/As/ 

Mu=fcmbx(h01-x/2)+ fy/As/(h01-as/) 

Calculation of bonding length for steel plate reinforcement

L1≥2fayta/fcv

Reinforcement of columns

Considering the column concrete strength is not up to the design requirements, the bearing capacity of the columns and the axial compression ratio is less than the standard requirements, concrete columns reinforced by steel plate and bottom paste or column as a whole to the bottom of beam, not only improves the bearing capacity of column, meet the axial compression ratio, and can effectively improve the concrete the deformation stress, improve the ductility of the column

Reinforcement of beams

The strengthening and bonding is used in two forms, the bottom of the beam or the side of the beam. At the bottom of the beam, we must destroy the painting layer, leave the reinforcement protection layer, and attach the steel plate to the column edge or beam side. The beam measuring surface can not pasted to l/3 higher than the beam height. If we encounter windows and doors, we can avoid it.

Reinforcement of the main beam of side span support

The main beam of the side span support is reinforced according to the articulated node. In the first column with 3mm thick steel plate of a plate, and then paste the 6mm thick plate piece, size is 600mm * 300mm, and with the expansion bolt through the anchor plate into the column; then choose 6mm thick isosceles triangle axillary plate two block is welded on the steel plate column, axillary plate size is 600mm x 600mm, finally at the end of the beam is pasted a 3mm thick steel plate, the size of 600mm * 300mm, the girder ends through the plate supported by axillary plate.

Reinforcement of the main beam on both sides of the middle column

The main frame of the engineering framework is continuous beam. The side faces of the frame columns are convex. For the beam side, the floor is supported by the floor. The sides of the upper part should be hung around the column to paste the steel plate, and the steel plate should be designed for 1:3. The steel plate width below 100mm, in order to strengthen the effect of a cushion in the paste steel plate, steel plate bending, bolt tightening, triangular gap plate and beam column angle formed by filling the epoxy mortar.