Chapter 13 : Analysis of Perfect Frames (Analytical Method) 259
- The roof truss shown in Fig. 13.23 is supported at A and B and carries vertical loads at each of
the upper chord points.
Fig. 13.23.
Using the method of sections, determine the forces in the members CE and FG of truss, stating
whether they are in tension or compression.
[Ans. 38.5 kN (Compression); 24.2 kN (Tension)]13.15.CANTILEVER TRUSSES
A truss, which is connected to a wall or a column at one end, and free at the other is known as
a cantilever truss. In the previous examples, the determination of support reactions was absolutely
essential to start the work. But in the case of cantilever trusses, determination of support reaction is
not essential, as we can start the calculation work from the free end of the cantilever.
Example 13.6. A cantilever truss of 3 m span is loaded as shown in Fig 13.24.Fig. 13.24.
Find the forces in the various members of the framed truss, and tabulate the results.Solution. The example may be solved either by the method of joints or method of sections.
But we shall solve it by both the methods one by one.
Method of joints
First of all, consider the joint A, Let the directions of the forces PAB and PAD be assumed as
shown Fig 13.25 (a).