The Concept of a Load Path
For a structure to be successful it must carry the applied loads through to the support along a load path, maintaining equilibrium at every point along the way. One of the skills you should work at is recognizing the load path in a structure.
Consider your current situation sitting in a chair.
- The load (your weight) acts on the seat of the chair
- The seat carries the load to the chair legs
- The legs push down on the floor which transfers the load to the walls
- The walls carry the load to the footings
- The footings carry the load to the earth
So the load path is seat-legs-floor-walls-footing-earth. If any part of this load path is not present, then the structure will fail to carry the load (it will collapse).
For any situation you must be able to trace the load path from the point of application of the load, to the ultimate reaction (usually the earth). It may be useful to think of a structure as a tree. A bird lands in a tree. The load goes through the leaf to the twig to the branch to the trunk to the earth. This is an analogy for a structure.