ASCE 中活荷载折减的问题

各位大神，最近在做美国的规范，发现ASCE荷载规范中4.7中对于活荷载的折减有一段话十分不明白，请教下各位大神是什么意思？
原文在4.7.2中的EXCEPTION中，对于楼面活荷载的折减系数L取值：
EXCEPTION: For structural members in oneand
two-family dwellings supporting more than one
fl oor load, the following fl oor live load reduction shall
be permitted as an alternative to Eq. 4.7-1:
L = 0.7 × (Lo1 + Lo2 + …)
Lo1, Lo2, … are the unreduced fl oor live loads applicable
to each of multiple supported story levels
regardless of tributary area. The reduced fl oor live
load effect, L, shall not be less than that produced by
the effect of the largest unreduced fl oor live load on a
given story level acting alone.

各位大神有没有做过美标，请问下这段话应该如何翻译才能准确呢，非常感谢！！！