ABSTRACT
External forces: External forces act on the surfaces of bodies and may be considered to be distributed and applied over contact areas. When the contact areas are very small in comparison with the area of the surface, the distributed forces can be idealised as single concentrated forces acting at points on the surface of the body. A typical example of an external force which is distributed over a surface is wind load acting on the walls of a building. Concentrated external forces may be considered to be applied to a bridge deck by a vehicle whose weight is transmitted to the deck through its wheels which have small contact areas relative to the area of the deck.
