What indicates a diaphragm discontinuity irregularity?

A diaphragm discontinuity irregularity is indicated by changes in the effective diaphragm stiffness of more than 50%. This substantial variation signifies that the diaphragm’s structural capacity to resist lateral forces is compromised and may lead to uneven load distribution or potential failure under lateral loads, such as those experienced during an earthquake.

Uniform stiffness throughout a diaphragm would suggest a well-designed and consistent structural behavior, which is desirable for stability. Similarly, discontinuities that are less than 50% do not typically signify critical irregularities, as they might not significantly affect the performance of the diaphragm. The option stating that all diaphragms are continuous does not take into account the varying conditions and configurations encountered in real-world applications, as some diaphragms can indeed have discontinuities that affect their structural integrity. Thus, the choice that highlights a significant change in effective stiffness directly points to potential weaknesses in that diaphragm.