Question on load combinations
Question on load combinations
(OP)
I am using a structural design program and I was surprised to find out that the program generated load combinations
1. have load cases considering live load = 0. for example, if using UBC97 eq. 12-5, there are load combinatios 1.2D+1.0E
2. When using eq 12-6 in UBC97, have load combinations like 0.7D+Rho*Eh.
Can these be right?
1. have load cases considering live load = 0. for example, if using UBC97 eq. 12-5, there are load combinatios 1.2D+1.0E
2. When using eq 12-6 in UBC97, have load combinations like 0.7D+Rho*Eh.
Can these be right?





RE: Question on load combinations
RE: Question on load combinations
I have a different equation for 12-6 than you list. Perhaps we have different versions or updates. Check the section again and be sure you caught everything.
RE: Question on load combinations
but the problem is how to add the "E" in this combination ... there are 16 quadratic combinations to add.
and what is meant by 1.1(0.9DL+-1.0E) the + and - in this combination for what ???
thank you
RE: Question on load combinations
RE: Question on load combinations
the E term in the combination " 1.2DL+ 0.5LL + E " IS FOUND TO be added linearly ??
Is it a linear combination , if yes this would cause a zero result in some cases for example moment on columns
-40-10+50= 0
plz answer
RE: Question on load combinations
take for example Moment around y-axis "My" @ top of the column . we observe that the dead load gives a positive moment and the seismic gives a -ve moment thus when w add the combination 1.2DL+0.55LL+E it won't give the worst case infact it will reduce the moment and all other forces.
the ubc load combinations are not purely linear they are conditionally linear ...
Am I right ?????
thanks
RE: Question on load combinations
This is where the + or - comes in. If you use -E instead of +E, you will get -40-10-50=-100, not 0.
RE: Question on load combinations
This is where the + or - comes in. If you use -E instead of +E, you will get -40-10-50=-100, not 0."
but the combination is only +E: 1.2DL +fLL +E
there is no -E in this load combination
????
RE: Question on load combinations
RE: Question on load combinations
where the code presented the + or - condition and on the otherhand the combination 1.2DL + fLL + E presents only the +E condition???
StructuralEIT i really appreciate your posts
thanks
RE: Question on load combinations