Methode van Secties

Consider a truss structure. Forces F₁ and F₂ are acting at points B and D.

The method of sections is used to determine the forces acting on a few members of a truss. It is based on the principle that a truss in equilibrium has each of its segments in equilibrium.

A free-body diagram of the truss is considered to calculate the forces acting on the member EF, DC and DF.

The equilibrium equation for moments about point A can be used to calculate the support reaction at point E.

Now, a cut is made along a sectional plane intersecting a maximum of three members.

A free-body diagram of the section, assuming the unknown forces as tensile, is drawn.

Summing moments about D yields a solution for the force acting on EF.

The unknown inclined forces are resolved into the horizontal and vertical components.

The equilibrium condition for the forces applied along the horizontal and vertical directions results in two equations.

Solving the simultaneous equations, the force along DC and DF can be calculated.