Method of section:
Define the method of section? How can you solve the problems with the help of method of section?
Sol.: This method is powerful method for determining forces in the desired members directly, without determining forces in the previous members. Hence this method is quick. Both the method, that is method of joint and method of sections is applied for analysis of truss simultaneously. For the member near to supports is analyzed with the method of joints and for members remote from supports can be rapidly analyzed by the help of method of section.
In this method section line is passed through member, in which forces are determined in such a way that not more than 3 members are cut. Any cut part is then considered for equilibrium under the action of internal forces developed in the cut members and external forces on cut part of truss. The conditions of equilibrium are applied to cut part of truss under consideration. As the 3 equations are available, thus, the 3 unknown forces in the 3 members can be determined. The unknown forces in members can be supposed to act in any direction. If magnitude of the force comes out to be positive then the assumed direction is right. If magnitude of force is negative than reverse the direction of that force.