Forces working on dam:
Let a dam retaining water as illustrated in Figure (a). What are the forces working on it?
The forces working on dam are as follows:
1. Weight of the masonry working vertically downwards through the centroid of the cross-section, and
2. The horizontal water pressure that goes on enhancing in magnitude as the depth of water increases.
Therefore, the structure shown is subjected to a system of forces as mention in Figure.
Several systems of forces may be classified according to the arrangement of the lines of action of the component forces of the system. The forces can be classified as following :
1. coplanar or non-coplanar,
2. concurrent or non-concurrent, and
3. parallel or non-parallel.
All of these systems of forces have been described in subsequent paragraphs.