Introduction to shallow foundations- Classification

Question 1

Define pad footing foundation?

Answer 1

An individual foundation is designed to carry a single column load although there are occasions when a pad supports two or more columns.

Question 2

Define a strip footing foundation?

Answer 2

Also known as continuous footing has a length significantly greater than its width. It is generally used to support a series of columns or a wall.

Question 3

Define a raft foundation

Answer 3

Also called a mat foundation is adopted to cover big areas and usually is a large reinforced concrete basement supporting a high rise block.

Question 4

What does a pad foundation look like?

Answer 4

• It has an isoparametric plan (square or circular)0
• It has a rectangular shape when permanent eccentric loads are acting on the footing.

Question 5

When do we want strip footing?

Answer 5

A strip footing is adopted when the columns are aligned with a small distance between their axes and the soil mechanical properties are such that single pads would be very close.

Question 6

When do we want a raft foundation?

Answer 6

• It is dopted when the area covered by a net of strip foundations would exceed the 50-60% of the entire area covered by the building.
• It is also used to create an impermeable layer when the foundation level is below the groundwater table.