loadcase

can someone advise me about what is the differences between these load cases + wind load if I interchange there sign
please share your opinions
1st
1a.)CASE 11 (OPE) W+D1+T1+P1+H+U1-U2+U3+WIN1
CASE 12 (OPE) W+D1+T1+P1+H+U1-U2-U3+WIN2
CASE 13 (OPE) W+D1+T1+P1+H-U1-U2-U3+WIN3
CASE 14 (OPE) W+D1+T1+P1+H-U1-U2+U3+WIN4

1b.)CASE 11 (OPE) W+D1+T1+P1+H+U1-U2+U3+WIN1
CASE 12 (OPE) W+D1+T1+P1+H+U1-U2-U3+WIN3
CASE 13 (OPE) W+D1+T1+P1+H-U1-U2-U3+WIN2
CASE 14 (OPE) W+D1+T1+P1+H-U1-U2+U3+WIN4

2nd
2a.)CASE 11 (OPE) W+D1+T1+P1+H+U1-U2+U3+WIN1
CASE 12 (OPE) W+D1+T1+P1+H-U1-U2+U3+WIN2
CASE 13 (OPE) W+D1+T1+P1+H-U1-U2-U3+WIN3
CASE 14 (OPE) W+D1+T1+P1+H+U1-U2-U3+WIN4

2b.)CASE 11 (OPE) W+D1+T1+P1+H+U1-U2+U3+WIN1
CASE 12 (OPE) W+D1+T1+P1+H+U1-U2-U3+WIN2
CASE 13 (OPE) W+D1+T1+P1+H-U1-U2+U3+WIN3
CASE 14 (OPE) W+D1+T1+P1+H-U1-U2-U3+WIN4

well I run the analysis and find out that there output are different..
what step should I follow regarding the signs of the seismic/acceleration load?
does it have a standard to be followed regarding the signs?

Do we both consider Seismic and wind load in occasional load case?
Maybe you're in offshore area.

Anyhow, unless your Load cases is exactly same, your result will not be same. For example, compare the loadcase 2nd 2a), 2b) case 13. Sign of U3 is opposite, so the result will be different.

You can find information in Userguide, and some of the webinars.

and yeah I know the result will differ if those signs will interchange...

I want to know if what is the sequence to follow regarding those signs,,
bec. we can just manipulate those signs in any sequence,

pls share your opinions

and for 1st:
it's the same in 2nd
1a.)
CASE 11 (OPE) W+D1+T1+P1+H+U1-U2+U3+WIN1
CASE 12 (OPE) W+D1+T1+P1+H+U1-U2-U3+WIN2
CASE 13 (OPE) W+D1+T1+P1+H-U1-U2-U3+WIN3
CASE 14 (OPE) W+D1+T1+P1+H-U1-U2+U3+WIN4
change to
1b.)
CASE 11 (OPE) W+D1+T1+P1+H-U1-U2+U3+WIN1
CASE 12 (OPE) W+D1+T1+P1+H+U1-U2-U3+WIN2
CASE 13 (OPE) W+D1+T1+P1+H-U1-U2-U3+WIN3
CASE 14 (OPE) W+D1+T1+P1+H+U1-U2+U3+WIN4

Does it have a pattern to used for the arrangement of signs?

need your opinions, thoughts and advice

thanks

DanJon,

Like you did, changing sign of U1 is not a problem, but are Win1 and Win4 has same value and direction(Check the direction cosine and parameters)? Changing sign is not a problem.

Load cases are equations to get the results you want.
You can make your pattern simply adjust load cases.

You can compromise its order, but it does have to make sense.
Assume simple load cases below
eg)
L1:W+P1+T1
L2:W+T1
L3:L1-L2

from above, you can get displ, and loads at the SUS, OPE cases from L1, L2 and EXP stress range from L3, but if we change the order like below,

L1:W+P1+T1
L2:L1-L3
L3:W+T1

you'll get the wrong values(Or not even able to precede), because c2 not yet calculate the L3.

Well, I only use B31.1 and it syas we don't consider seismic and wind occured at the same time, so I'm not familiar with your load case above. But I guess the logic is same.