shows a spatial truss loaded by two external forces F at the joints IV and V. Compute the forces in the members 1-6.

  shows a spatial truss loaded by two external forces F at the joints IV and V. Compute the forces in the members 1-6.

Figure. 2

Solution:

We free the joints V and IV by passing imaginary cuts through the bars, and we assume that the members 1-6 are in tension. The vector equations of equilibrium for these joints are given by

The initially unknown unit vectors can be determined from the vectors connecting adjacent joints, e.g., for e_(V/VI) we obtain

Similarly, the other unit vectors are

Introducing these into the two vector equations we get the six scalar equations

Their solution yields the forces