4. Understanding structure

‘Understanding structure’ considers the science of how structures work. How do structures resist all of the demands made on them by forces of self-weight, people moving about, or wind that may blow a hurricane? These forces have to ‘flow-though’ the components of the structure. Some simple structures are statically determinate so the internal forces can be calculated by just making sure all of the forces are in equilibrium. More complex structures have too many unknowns to be solved this way—they are statically indeterminate. The internal forces in these structures are found by satisfying the three conditions of equilibrium, constitutive relations, and compatibility of displacements when the total potential is a minimum.