Column and Footing details for Architectural and Engineering students. What is a column. Parts of Columns. Types of Columns. Footings and footing details. Samples of different types of footings. Descriptions and Images.

2. ▐ A column is a vertical structural member designed to transfer a
compressive load. For example, a column might transfer loads from
a ceiling, floor or roof slab or from a beam, to the foundations.
▐ Columns are typically constructed from materials such as stone,
brick, block, concrete, timber, steel and so on.

3. Shape
Columns can be classified according to
their cross sectional shape. Common
column shapes include:

4. Elements of classical columns
The base is the lowest part or division of a
column.
The shaft is the portion of a column between
the base and the capital
The capital comprises the uppermost elements
of a column. While capitals differ according to
the classical order, they usually include the
following elements:

5. ▐ Footings are an
important part of
foundation construction.
They are typically made
of concrete with rebar
reinforcement. The
purpose of footings is to
support the foundation
and prevent settling.
Footings are especially
important in areas with
troublesome soils.

6. DIMINISHING SOIL PRESSUREAs the load under a footing spreads out,
pressure on the soil diminishes. Soil
directly under the footing takes the
greatest load, and therefore should be
thoroughly compacted.
Because the load spreads out, the
pressure on the soil is greatest right
beneath the footing. By the time we get
down below the footing a distance equal
to the footings width, the unit soil pressure
has dropped by about half. Go down the
same distance again, and the pressure
has dropped by two-thirds. So it's the soil
right under the footing that is the most
critical and also, typically, the most
abused.

7. WHAT ARE DIFFERENT
TYPES OF FOOTINGS?
Footings can be of the following types.

8. SPREAD FOOTING OR
ISOLATED OR PAD FOOTING
▐ It is circular, square or rectangular slab of uniform
thickness. Sometimes, it is stepped to spread the load over
a larger area. When footing is provided to support an
individual column, it is called “isolated footing”.

9. STRAP FOOTING
▐ It consists of two isolated footings connected with a structural
strap or a lever, as shown in figure below. The strap connects the
footing such that they behave as one unit. The strap simply acts
as a connecting beam. A strap footing is more economical than a
combined footing when the allowable soil pressure is relatively
high and distance between the columns is large.

10. COMBINED FOOTING
▐ It supports two columns. It is used when the two column are so close to
each other that their individual footings would overlap. A combined footing
is also provided when the property line is so close to one column that a
spread footing would be eccentrically loaded when kept entirely within the
property line. By combining it with that of an interior column, the load is
evenly distributed. A combine footing may be rectangular or trapezoidal in
plan.

11. STRIP FOOTING OR
CONTINUOUS FOOTING
▐ A strip footing is another
type of spread footing
which is provided for a load
bearing wall. A strip footing
can also be provided for a
row of columns which are
so closely spaced that their
spread footings overlap or
nearly touch each other.

12. MAT OR RAFT FOOTING
▐ It is a large slab supporting a
number of columns and walls
under entire structure or a large
part of the structure. A mat is
required when the allowable soil
pressure is low or where the
columns and walls are so close
that individual footings would
overlap or nearly touch each
other.

13. SAMPLES