Spread Footing Design

Topics:

• Determine size of spread footing
• Determine depth of spread footing
• Design reinforcement for spread footing
• Design of square footing
• Design of rectangular footing
• Design of wall footing

Introduction

One of the most common ways to support the column is spreading the column load over a large footing area.  There two parts in spread footing design:

Service load design:

1. The footing area should be large enough so that soil pressure under the footing is not larger than allowable soil bearing pressure
2. The weight of footing should be able to out-weigh column uplift due to wind or seismic forces safely.

Reinforced concreter design:

3. The footing depth should be deep enough to resisting punching shear and direct shear transferred from column load
4. The reinforcement in the footing should be designed to resist bending moments.
5. The dowels at the column-footing interface should be sufficient to transfer column loads.