The demand-to-capacity ratio (D/C) is the primary check for structural adequacy. A ratio above 1.0 means the applied demand exceeds the factored resistance — the section is overstressed. Code typically requires D/C ≤ 1.0 for all applicable limit states.

When D/C is between 0.9 and 1.0, consider increasing the section or reducing the load to provide a safety margin beyond code minimums.