Load combinations

[Usimo]

Considering the combinations from the IBC 2000 or 2003, particularly the 0.6D+0.7E for structural design, if we have an instrument, we consider the instrument selfweight as D load in addition to member weight, and the operating weight (weight of content at operating; OPERATING WEIGHT) as L load. But, when we calculate the E earthquake load, we use both instrument weight+OPERATING WEIGHT in addition to member weight as W.( E=CsxW). Then, How can we implement the load combination 0.6D+0.7E?

0.6( member weight+ instrument self weight+ OPERATING WEIGHT)+ 0.7xE?
(here actually OPERATING WEIGHT is live load)

OR

0.6(member weight+ instrument self weight)+ 0.7xE?
(here we neglected the OPERATING WEIGHT that considered in calculation of E)

Please your advice would be greatly appreciated.

 

[UcfSE]

In lieu of a definate answer that you are 100% sure about I would use which ever yields the worst case for design.

 

[MrStohler]

I would use a "dead" load that is consitent with the mass used to calculate the seismic loads.

 

[pmkPE]

When you speak of an "instrument" is this a permanent part of the building structure? If so than it would be dead load, otherwise it is live load such as furniture, book cases/shelves etc.