Sentence 4.1.8.15.(6)

Intent 1:

To limit the probability that the lower system will be designed for lower forces than the upper system, which could lead to a weaker lower level, which could lead to yielding in the less ductile lower level, which could lead to structural failure, which could lead to harm to persons.

Intent 2:

To direct Code users to Sentence 4.1.8.9.(4), which addresses the values of R_dR_o.