Retrofitting introduction 

Structural strengthening defines as taking some measures in necessary or by owners requirements to increase the strength, change the section parts, or adjust the internal force on those unreliable bearing structures, structural componentes, or related construction parts to realize the structures satified with the industrial design standard or owner request safety, durability, and suitable performance.

why retrofitting is needed?

1.Aging

2.Natural disasters

3.Design defects

4.Damage to structural member

5.Improve the standard

6.Use function changes

7.Save time and space

8.Seismic strengthening

9.Load increase

Retrofitting or not ?

1.Economical consideration

2.Immediate solution

3.Improved serviceability

4.Making building more suitable for intended use

5.More energy efficient

6.Loads may be immediately applied ,no cure time

7.Enhancement of strength to increase durability

Different strengthening method:retrofitting of existing concrete members

1.Carbon fiber reinforced polymer(CFRP)

2.Section enlargement or jacketing

3.Bonded steel plate

4.Pre-stressed CFRP laminate

5.Steel jacketing:structural strengthening epoxy 

1.Carbon fiber reinforced polymer(CFRP)

materials to be used:unidirectional carbon wrap; CFRP strip

Carbon fiber strengthening is a new advanced strengthening technical, materials include unidirectional carbon fiber and CFRP strip.

key feature of CFRP wrap

1.Light self weight
2.High strength
3.High modulus
4.Flexible
5.Environmental-friendly
6.Long shelf life
7.High toughness
8.Ani high temperature

9.Fire resistant

Where to use carbon fiber reinforced polymer(CFRP)?

1.Increased live loads in warehouses
2.Increased traffic volumes on bridges
3.Installation of heavy machinery in industrial buildings
4.Vibrating structures
5.Changes of building utilization
6.Column wrapping, beam, wall, slab strengthening
7.Masonry walls strengthening
8.Aging of construction materials
9.Vehicle impact
10.Fire
11.Removal of walls or columns
12.Removal of slab sections for openings
13.Insufficient reinforcements
14.Insufficient structural depth
15.Fiber reinforced polymer(FRP) jacketing

2.Section enlargement or concrete jacketing

materials to be used:anchoring adhesvie

entire cross section of member is increased

additional structural reinforcement steel with shear stirrups

process involves surface preparation, additional reinforcement and concrete curing

advanced

Good reliability, improve bearing capacity, Rigidity range is relatively large

3.Bonded steel plate

materials to be used:steel plate bonding

in this method of strengthening steel plates or other steel member are glued to concrete surface by a two component epoxy adhesive. The method has the advantages of fast construction, little or no wet work on site, and has no significant effect on the appearance of the original structure.

4.Pre-stressed FRP system application

materials to be used:Prestressed CFRP laminate

1.Improve the bearing capacity of bridge structure, has incomparable advantages in large-span beam slab of flexural reinforcement. 
2.Significantly reduce deformation of the structure and improve the bearing capacity of structure, decrease the crack width and deflection deformation, and is suitable for large span beam slab of flexural reinforcement. 
3.Improve the stiffness of structure ,and make full use of the material performance ,save a lot of materials and engineering cost.

5.Steel jacketing:structural strengthening epoxy 

materials to be used:HM-120M structural strengthening epoxy 

is a two component epoxy product, a resin and a hardener, used to bond steel plate to the overstressed region of RC member. This epoxy with strong adhesion, room temperature curing. it has excellent anti-aging ,shock resistance propertied in self-adhesion and mutual adhesion of steel and concrete, with high shear rate, used for seismic strengthening of many building .