Dear knrsa,
There are only two main considerations Flexure and Shear.
You just need to focus that the additional shear and flexure is catered by making sure that a perfect connection exists between old and new footing.
I have attached an image of detailing. Hope it helps as I dont have the calculations right now.
Moderator note:
Your image realy help. Try to learn how to post the uploaded image if you want someone see it without effort.
There are only two main considerations Flexure and Shear.
You just need to focus that the additional shear and flexure is catered by making sure that a perfect connection exists between old and new footing.
I have attached an image of detailing. Hope it helps as I dont have the calculations right now.
Moderator note:
Your image realy help. Try to learn how to post the uploaded image if you want someone see it without effort.
"Imagination is more important than Knowledge." Albert Einstein