The equilibrium conditions of statics state that a body at rest remains at rest if the sum of all forces and moments acting on that body is zero. Determining the forces and moments is the basis for the design and dimensioning of structures and components.

In statics, the internal reactions show the counteraction of forces and moments within a component in response to the action of external forces. Free body diagrams are the main way in which the internal force states are represented in rods, beams and cables.

Various methods are presented for determining bar forces in plane trusses. Calculation method such as the method of joints and Ritter’s method of sections as well as a graphic method, the Cremona diagram.

Experimental equipment for investigating a suspension bridge, a Gerber beam and various arches.

Friction occurs in all solid bodies that are in mutual contact and that are moved against each other. The cause of the occurring forces is, among other things, the surface roughness which causes the surfaces to interlock.