A RC slab undergoing a considerably large deflection, it can easily be noted visually. The slab is a rectangular in shape resting on walls from the four sides. This large deflection is due to inappropriate design (low concrete grade and low reinforcement) and overloading. How can this slab be rehabilitated ?
By strengthening with steel or FRP plates, or Introducing RC or Steel beam within the top or bottom face of the slab.
Thank you Dr. Qasim M. Shakir , but the large deflection indicates that the steel is most probably reaches the yield limit. Do I need to jack upward first and then apply the FRP plate?
You are right Mr. Abubakr E. S. Musa,
The CFRP sheets can be applied after jacking the slab upward and the design of the rehabilitation is based on the carrying capacity of CFRP if the steel is already yielded.
TRY TO REDUCE SPAN OF SLAB, REMOVE ANY ADDITIONAL LOADS ABOVE SLAB. STOP USING SUCH SLABS BECAUSE ACCIDENT MAY HAPPEN ANY TIME. EXCESSIVE DEFLECTION IS GIVING WARNING OF COLLAPSE. BETTER REMOVE SLAB AND CONSTRUCT NEW.
Yes, it is recommended to stop utilizing the building till rehabilitation took place. Removal of the slab is costly. Isn't it?
Although it may cost for you
But the numerical model presented on this site is similar to your Project:
https://numericalarchive.com/shop?olsPage=products%2Ffinite-element-analysis-of-reinforced-concrete-slab-using-abaqus
I hope to help you
Abubakr E. S. Musa ,Surely you need to restore the original shape of slab by jacking after reducing loading as possible.Then, you can do the required repairing.
Abubakr E. S. Musa , As others have recommended, I will suggest conducting a load rating for the slab by back calculating the maximum load the slab can support for an allowable deflection. The newly determined load should be the maximum load the slab would be subjected to. While calculating the load, since the reinforcement has yielded, the stiffness (Ie) to be used should be modified to account for concrete cracking and creep as recommended in ACI318. However, if the load cannot be reduced because of usage, it will be better to introduce an intermediate beam to reduce the span of the slab. Special attention would be paid on connection of the existing slab to the newly introduce beam to make the structure act as a single unit.
- Badges
- Science topic