Under what condition is it acceptable to set member properties like E, A, and I to one in a structural analysis?
Explanation
For statically determinate structures, the internal forces and reactions can be found through equilibrium alone, independent of member stiffness. For some indeterminate structures, only the relative stiffness between members matters for force distribution. In these cases, setting E, A, and I to one (or any constant) is a valid simplification for finding forces, but it will not yield correct displacement values.
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