Force Vectors
Equilibrium of Forces
Moments from Forces (I)
Moments from Forces (II)
Illustrations for Forces and Moments
Force Couples
Transmissibility of Forces
Force/Moment Resultants
Equivalent Loading (I)
Equivalent Loading (II)
Practical Examples
Typical 2-D Supports (I)
Typical 2-D Supports (II)
Free Body Diagram (I)
Free Body Diagram (II)
Free Body Diagram (III)
Free Body Diagram (IV)
Two/Three Force Members
When a member is subject to no couple moments and the applied forces can be combined to be resultants at only two points, the member is called a Two-Force Member.
If a member is subject to three forces, then it is necessary for them to be either concurrent or parallel when this member is in equilibrium. Such a member is called a Three-Force Member.
Application of Two/Three Force Members
Redundant Constraints
Statically Indeterminate Structure
Ax = 0, Ay + Cy = 500 N --------- (2)
Cy * 5 m + MA = 500 N * 4 m ----------- (3)
Ay * 5 m - MA = 500 N * (5 - 4) m ----- (4)
5 m
4 m
{(3) + (4) (2)
Cannot solve for all unknowns !!!
Tricky Problems
Truss Structures
Truss Analysis
Joint Method (I)
Joint Method (II)
Zero-Force Members
(a)
(b)
(a)
(b)
Exercise Example
Internal Forces/Moments
Section Method (I)
Section Method (II)