1. WELCOME TO MY
PRESENTATION

2. Prepared by
Sharif Ibne Ibrahim
Student ID No: 10.01.03.136
Year: 4th, Semester: 2nd, Sec: C

3. Presentation on
Couple

4. Definition
A couple is system of forces that consists of
two parallel forces that has equal magnitude,
oppositely directed and do not act in a straight
line but are separated by a perpendicular
distance.

5. Schematic Diagram of Couple

6. Expressions
The magnitude of the couple is
given by
F
C=Fd
d
Here, F are the two forces
and d is the perpendicular
distance between the forces
or is the moment arm.
F

7. Properties
 Couple does not produce any translational
movement but rotational.
 The resultant force of a couple is zero. but the
resultant moment is not zero.

8. Properties
 Couple is independent of the moment center.
d’
F
The moment of couple about
d
the point A,
M(A)
A
d’’
F
= +F*d” – F*d’
M(A)
= +F(d”-d’)
M(A)
= +Fd
**[Anti-clockwise= +ve]

9. Is Torque and Couple same thing?
 In engineering mechanics, torque is the resultant moment of
a couple.
 In general physics, it represents the moment of a force.
Expression: t or C= Force * perpendicular distance

10. Couple in Reinforced Concrete
 The concept of couple is consider in reinforced concrete
member.
 Here, reinforcement takes tension and concrete takes the
compression so the two materials form a resisting couple
against the external moment
acting on the member.

11. Couple in Pre-stressed Concrete
 One of the general principal of pre-stressed Concrete is
directly governed by the concept of Couple.
 In this type of member, by pre-stretching and anchoring
the steel in the bottom of concrete member, we produce
compressive stress in bottom fiber and tensile stress in top
fiber. So when a external load act on that member and try
deflect it downward, the internal resisting couple generated
by high-strength steel counter that force.