around Reo. bars in panel

[PowerRanger]

Hi Fellows

The builder required me to add a N12 bars around the 100mm panel with 80mm cover to the edge. What is the purpose for it? Is it used for crack control at the support? so why the bar required to go all around the panel, not just at the bottom? what principal should i use to design this bar?

Thank you for your time.

 

[apsix]

Presumably you are designing precast concrete panels, although 100mm sounds thin.
It is normal practice to provide perimeter bar/bars all the way around the perimeter. This should provide the strength required for any stress concentrations due to shrinkage, mis-handling, load concentrations etc. Two bars are used for the thicker panels and if there are edge lift points or ducts for locating dowels.
I'm not aware of any design principal to use.

 

[dbuzz]

From the Western Australian Code of Practice for Tilt-up and Precast Concrete Construction (

http://www.safetyline.wa.gov.au/pagebin/codewswa0234.htm).

For concrete panels additional reinforcement may be required...at edges and around openings in the panel to resist thermal and shrinkage stresses and to prevent cracking due to panel mishandling.