In the case of a simple truss, we have the following condition for its proper rigidity (the truss will not collapse - is not a mechanism):
m= 2j-3
where m is the total number of truss members and j is the total number of joints.
Loads must be applied to the joints only, and not to the members themselves. In the analysis of the truss, the weights of bars are either omitted or, if required, they are applied to the joints (a half of the weight to each of the bar joints).
In medicine, a truss is a kind of surgical appliance, particularly one used for hernia patients.