q
P
B
A
C
D
Figure F.1
(a) Loaded Portal Frame
1
BC
MC
BC
MB
BC
TB
BC
VC
BC
VB
AB
TB
CD
MC
AB
VB
BC
TC
CD
TC
CD
VC
AB
MB
F.1 (b)
AB
MA
AB
VA
AB
TA
CD
MD
CD
VD
CD
TD
2
The positive sign convention
consistent with beam theory is
shown in F.1(b). As seen from
F.1 (b), the positive sign
convention is (a) tension axial
force, (b) shear forces that
produce clockwise moments and
(c) bending moments that result
in tension stresses in the interior
frame fibers.
The sign convention of F.1(b) can
be seen to be equivalent to the
beam sign convention rotating
columns AB and CD to line up
with beam BC.
3
Example Deflection
Calculation – Mechanically
Loaded Truss Structure
EA = constant
Rocker
Calculate the vertical displacement at A.
4
Example Problem
Shear and Moment Diagrams
Calculate bending moment
equations and the rotation at D.
5