Structural Strengthening of RCC Members Using CFRP
Normally RCC buildings have an average life span life of about Fifty years under the normal conditions. In many situations we are facing structural issues due to various reasons which need to be addressed by structural strengthening of the structural members by retrofitting. This paper deals about the retrofitting of beam using Carbon Fiber Reinforced Polymer (CFRP) retrofitting system.
A beam has been tested before the retrofitting and the same has been tested with static loading test with sand bags staged for 72 hours on the slab and the deflection was observed due to the additional load. The deflection was found within allowable limits due to the additional design load after retrofitting.
Strengthening the available structural member is considered as an important technology to meet out the service requirements, safety, Time and cost saving by saving the huge expenditure arising due to the demolition and reconstruction. When there is a structural deficiency in a RCC beam is needed to be addressed, the available structural capacity of the section at site is calculated based on the available section, grade of concrete and available quantity of reinforcing steel to resist the flexural tension and Tensile Shear. Then the additional capacity of the RCC structural member needed to be provided by some procedure. In the previous years, in most of the cases structural strengthening was done using MS rolled sections as a supporting structure to the RCC beams.
When such rolled MS sections were used, the headroom of the lower floor was minimized and also was giving a poor aesthetic in the lower floor. Providing such MS section as a strengthening method was not practically possible in most of the occasion as the lower floor would be occupied by some other party. In such cases it will not be a onetime disturbance to the lower floor occupant but also will be a continuous problem due to periodical maintenance to keep the MS sections free from corrosion. To overcome such limitations, the structural deficiencies in beams have been overcome by retrofitting the compressive zone and tensile zones of the beam.
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NECESSITY FOR STRUCTURAL RETROFITTING
When structural deficiencies arise due to some reasons, it is becoming absolute necessary to retrofit the particular structural member or the particular floor or the structure as a whole, for the better and safe usage of the building. The following can be the causes for the structural deficiency in a structure.
- Wrong design
- Faulty execution
- Additional loading
- Change in usage of the building
- Codal revision
- Aging of the structure
- Fire accident
- Alteration in the building
- Seismic loads