Civil Engineering Reference
In-Depth Information
Jib
To w e r
F
IGURE
4.2
Overhead crane
structure
B
A
C
(a)
Collapse
(b)
F
IGURE
4.3
Basic unit of a truss
Further properties of a pin-jointed triangular structure are that the forces in the mem-
bers are purely axial and that it is statically determinate (see Section 4.4) so long as
the structure is loaded and supported at the joints. The forces in the members can
then be found using the equations of statical equilibrium (Eq. (2.10)). It follows that a
truss comprising pin-jointed triangular units is also statically determinate if the above
loading and support conditions are satisfied. In Section 4.4 we shall derive a simple
test for determining whether or not a pin-jointed truss is statically determinate; this
test, although applicable in most cases is not, as we shall see, foolproof.
The assumptions on which the analysis of trusses is based are as follows:
(1) The members of the truss are connected at their ends by frictionless pins or
hinges.
