Chapter 4 – Virtual work and energy methods

The concept of work is discussed and the principle of virtual work established for, initially, a particle, then a rigid body and, finally, for a deformable body. Expressions for the work done by internal force systems comprising axial and shear forces, bending moments and torsion are derived. Hinges are defined and the sign of internal virtual work is discussed. Expressions for the virtual work produced by external force systems are derived. Virtual force systems are considered and the principle of virtual work applied to the analysis of a variety of statically determinate structures.