ASCE Load combination
ASCE Load combination
(OP)
Hi ,
Do i need to combine friction load with temperature load on steel structure or not in design of pipe rack. If yes or no whatever may be the answer kindly explain briefly.
Do i need to combine friction load with temperature load on steel structure or not in design of pipe rack. If yes or no whatever may be the answer kindly explain briefly.






RE: ASCE Load combination
If the friction load is a result of the temperature movement, yes, they have to be combined. The explanation is, they might (and likely will) occur at the smae time, so we combine them.
Where I used to work, we designed large hot gas ducts in coal power plants. We used to combine temperature due to the hot gasses (~400 degrees F) with snow on the duct. I asked why we did that and they said there might be an instant during start up where the duct is hot, but the snow hasn't melted yet. So you always want to combine loads in a conservative fashion. If there's any chance they might happen at the same time, combine them.
Now you might want to reduce the multipliers (LL=1.6 to 1.2?) based on the likelihood of loads occuring at the same time, but unless the ASCE has determined not to add them, be conservative.
RE: ASCE Load combination
However, I may point out that the load combinations in ASCE 7 do not necessarily address every single load or every combination of loads that need to be considered. You may need to add or modify terms to fit a particular case not clearly covered by the standard.