Lecture Presented on 06 February 1997
For more further information on this topic,
please see the laboratory
handout titled "Flexibility and Stiffness of a Portal Frame".
- The structure for this experiment is a simply supported
portal frame, shown in the figure below.
- The force-displacement relationship for three points of
the frame (center of the top, center of the roller
supported column, and base of the roller supported
column) need to be determined.
- The relationship to be constructed experimentally is:
here P1, P2,
P3 and D1,
are the forces and displacements of points 1, 2, and 3,
- Matrix [f] is the flexibility matrix.
- The flexibility matrix can be constructed by the unit
P1 = 1.0
P2 = P3
f11 = D1
f21 = D2
f31 = D3
- This procedure is repeated for:
P2 = 1.0
P1 = P3
P3 = 1.0
P1 = P2
These results can be used to construct the second and
third columns of the flexibility matrix.
- The stiffness matrix of the structure, [K], is
now defined as the inverse of [f], such that: