Rectangular and Circular underground water tank comparison. Brief comparison of properties of rectangular and circular underground water tank. Mechanical, economical and ease of construction comparison.

1. COMPARING RECTANGULAR (CUBIC) AND CIRCULAR
(CYLINDRICAL) UNDERGROUNDWATERTANK
Underground water tank: Reinforced concrete water tanks are constructed for storing
water. The design depends on the location of tanks, i.e. overhead, on ground or
underground water tanks.
Underground water tank can be divided into rectangular or circular in shape.
Properties Rectangular Underground Water
Tank
Circular Underground Water Tank
When to construct? When capacity of liquid to be stored
is small
Capacity of liquid to be
comparatively large
Maximum Principal
Stress
The rectangular and circular water
tanks of the same capacities may
have stress results less than circular
tanks.
e.g. for a capacity for both types,
the maximum stress calculated for
rectangular water tank was
5.32N/mm2
Greater than rectangular tanks
e.g. For circular water tank,
7.1N/mm
Resistance to
pressure
Less In case of resistance to all
pressure exerted in the tank
circular is better.
Area of steel Area of reinforcement of circular
tank is greater
Less

2. Formwork Formwork in rectangular tank is
greater than the circular water tank.
Formwork required is less.
The formwork would be
significantly more challenged in
the construction of the circular
tanks
Amount of Concrete Less Amount of concrete in circular
tank is greater than that of
rectangular tank
Reinforcement Less Amount of reinforcement tonnage
in circular tanks is greater than
that of rectangular tank.
Surface Area Greater surface area A cylindrical water tank has the
least possible ratio of
circumference to area i.e. less
surface area than a box-shaped
water tank that holds the same
amount of water
Economical
comparison
For smaller capacities rectangular
shape tank is economical and for
large capacities circular shape tank
are economical.
Due to less surface area, a
spherical water tank requires less
building material than its box-
shaped equivalent and is
consequently more economical to
build
Structural strength Less in terms of structural strength A round structure is the strongest
geometrical structure and is
stronger than box-like
alternatives. Therefore, a round
structure will more successfully
withstand the outward-directed
force of the water stored within
and the force of wind and rain
that have an effect upon the
structure from without.

3. Constant Heat Level Less resistant to heat and cold Round structures minimize
surface area through which heat
can radiate, they keep the
enclosed water at a more
constant temperature than box-
like structures.
As a result, the water is less
affected by ambient temperature
fluctuations and also loses less
heat in winter and gains less heat
during the summer
Cleaning and Hygiene Cubic tanks have corners and it’s
difficult to keep the corners clean,
also, corners are known to harbour
microbes
Round tanks are much easier to
keep clean than those with
corners
Pictures

4. Terms:
Maximumprinciple stress:This theory or normal stress theory says that, yielding
occurs at a point in a body, when principle stress (maximumnormal stress) in a
biaxial systemreaches limiting yield value of that material under simple tension
test.
According to strength of materials brittle one strong in shear, weak in tension or
compression. That's why this theory preferred for brittle materials.