# Terzaghi's Equation with more than one column

I've been send to do a project about the construction of a building. Throughout the project I had a doubt I couldn't solve and wish you could help me with:

When we are working with foundations, we can apply Terzaghi's formulas to get the bearing capacity of the ground. However, in everything I've read they always use a single column. How can I apply the formulas having the weight of the building and a more than one column?

• Please only put one question in each post. Also, putting more information in your question will result in a better question and hopefully better answers. – hazzey Apr 12 '17 at 16:20

## 1 Answer

I would start by resolving the loads into a single load/moment system at the center of the foundation - in both the x and y directions. It will then be possible to use the Terzaghi equations to calculate the bearing capacity of the foundation, taking into account a reduced effective breadth and length calculated using the following equations.

$$B'=B-2e_B$$ $$L'=L-2e_L$$

It will also be necessary to check that the resultant loading lies within the middle third of the foundation.