Principle 4 - Structural Strengthening

Whenever there is a need for structural strengthening such as due to a change of the structures designation, or to an increase in the structural load bearing capacity, the appropriate analysis must be performed by a qualified structural engineer. Various methods are available to achieve the necessary strengthening and these include: adding external support or embedded reinforcement, by bonding external plates, or by increasing the dimensions of the structure.

The selection of the appropriate method is dependant on the different project parameters that include the type of structure, cost, site environment and conditions, plus access and maintenance possibilities and many more. The standard outlines seven methods to increase or restore structural load capacity:

4.1 Adding or replacing embedded or external reinforcing bars
4.2 Adding reinforcement anchored in pre-formed or drilled holes
4.3 Bonding plate reinforcement
4.4 Adding mortar or concrete
4.5 Injecting cracks, voids or interstices
4.6 Filling cracks, voids or interstices
4.7 Prestressing or Post tensioning

Methods 4.1 & 4.2

The selection of the appropriate size and configuration of reinforcement, plus the locations where it is to be fixed, must always be determined by the structural engineer. Komerco supply a broad range of cementitious, epoxy and mechanical anchors to meet these needs.

The points for anchorages into the concrete should be designed, produced and installed in accordance with EN 1504 Part 6 and the relevant European Technical Approval Guideline and Australian Standards where applicable. The surface cleanliness of the grooves or anchor holes cut in the concrete should be prepared to be in accordance with EN 1504 Part 10 Sections 7.2.2 and 7.2.3.

Methods 4.3 & 4.7

Komerco's suppliers such as Sika and MBS have pioneered the development of many new materials and techniques in the field of structural strengthening. This has included the development of steel plate bonding and epoxy structural adhesives to modern composite materials, such as pultruded carbon fibre plates. Since then, newer technologies have been developed this technology by using unidirectional fabrics based on several different fibre types (carbon, glass, etc.).

The introduction of prestressed composite reinforcement for strengthening has now brought this technology to another level. This uses high strength, lightweight carbon fibre reinforced plates, plus curing times are reduced and the application conditions can be extended through innovative electrical heating of the adhesive.

The application of these materials are highly technical and specialised. It is recommended that only trained and experienced applicators undertake this type of work and as such, please be in contact here to discuss structural strengthening products with a Komerco representative.

Method 4.4

These methods and Komerco's range are covered in Principle 3 Concrete restoration. To ensure the necessary performance, these products also have to fulfill the requirements of EN 1504-3, class 3 or 4. Including the following ranges:

Class R4

Class R3

Methods 4.5 & 4.6

Injecting and sealing cracks generally does not structurally strengthen a structure. However, for remedial work or when temporary overloading has occurred, the injection of low viscous epoxy resin based materials can restore the structure to its original structural condition.

Sikadur 52

MasterInject*

SikaInjection*

*High pressure crack injection with one and two-component resin systems is a highly technical and specialist activity. It is recommended that only trained and experienced applicators undertake this type of work and as such, please be in contact here to discuss injection products with a Komerco representative.