HI,

I used to combine all my occasionnal load cases with the operating cases:
L1 = OPE+Wind
L2 = L1-OPE
Finaly L3 = L2+SUS

But in my new job, the senior piping engineer doesn't combine Wind with the operating load case :

L1 = WIND
L2 = L1+SUS

I don't know wich one is the correct combination. And i saw on the coade forum that we don't have to combine with operating if we have non linear bondary condition. But I don't know what is non linear bondary condition.

Can anyone help me?

Thanks

The way you used to do it (the 1st set of load cases above) is always correct.

The 2nd set of load cases above is correct IF the piping system has only linear restraints. As soon as you introduce non-linear restraints this 2nd set of load cases may be inaccurate.

I have also another question for the same type of load case.
He only considers Wind positively in plan WIN1(x) and WIN2(z). He don't consider WIN3 for (-x) and WIN4 (-z)(wind is define as a pressure f(elevation)). Can he do that?

And when he combines wind with the sustain loads, he considers as absolute (ABS)combination and not Scalar. And he don't consider the wind effects on the restrains because he don't combine it with the operation cases.

Is it correct?

Personaly i used to combine the wind with the sustain as scalar and first of all with the operating case. and if the restrains values of OPE+WIN are higher then OPE, I consider the OPE+WIN to modelise the suports.

Sorry my english is very bad.

Thanks

I have also another question for the same type of load case.
He only considers Wind positively in plan WIN1(x) and WIN2(z). He don't consider WIN3 for (-x) and WIN4 (-z)(wind is define as a pressure f(elevation)). Can he do that?

And when he combines wind with the sustain loads, he considers as absolute (ABS)combination and not Scalar. And he don't consider the wind effects on the restrains because he don't combine it with the operation cases.

Is it correct?

Personaly i used to combine the wind with the sustain as scalar and first of all with the operating case. and if the restrains values of OPE+WIN are higher then OPE, I consider the OPE+WIN to modelise the suports.

Sorry my english is very bad.

Thanks

I have also another question for the same type of load case.
He only considers Wind positively in plan WIN1(x) and WIN2(z). He don't consider WIN3 for (-x) and WIN4 (-z)(wind is define as a pressure f(elevation)). Can he do that?

And when he combines wind with the sustain loads, he considers as absolute (ABS)combination and not Scalar. And he don't consider the wind effects on the restrains because he don't combine it with the operation cases.

Is it correct?

Personaly i used to combine the wind with the sustain as scalar and first of all with the operating case. and if the restrains values of OPE+WIN are higher then OPE, I consider the OPE+WIN to modelise the suports.

Sorry my english is very bad.

Thanks

I have also another question for the same type of load case.
He only considers Wind positively in plan WIN1(x) and WIN2(z). He don't consider WIN3 for (-x) and WIN4 (-z)(wind is define as a pressure f(elevation)). Can he do that?

And when he combines wind with the sustain loads, he considers as absolute (ABS)combination and not Scalar. And he don't consider the wind effects on the restrains because he don't combine it with the operation cases.

Is it correct?

Personaly i used to combine the wind with the sustain as scalar and first of all with the operating case. and if the restrains values of OPE+WIN are higher then OPE, I consider the OPE+WIN to modelise the suports.

Sorry my english is very bad.

Thanks

I have also another question for the same type of load case.
He only considers Wind positively in plan WIN1(x) and WIN2(z). He don't consider WIN3 for (-x) and WIN4 (-z)(wind is define as a pressure f(elevation)). Can he do that?

And when he combines wind with the sustain loads, he considers as absolute (ABS)combination and not Scalar. And he don't consider the wind effects on the restrains because he don't combine it with the operation cases.

Is it correct?

Personaly i used to combine the wind with the sustain as scalar and first of all with the operating case. and if the restrains values of OPE+WIN are higher then OPE, I consider the OPE+WIN to modelise the suports.

Sorry my english is very bad.

Thanks

Wind can act in any direction. You want to consider the worst condition, and that could be either positive or negative (directions) depending on the orientation of the structure and the behavior of any non-linear restraints.

The Code wants a "scalar" combination.

Yes you want the worst restraint loads.

Thanks Richard for your answers.
i have a last question
I didnt find any combination rules in asme b31.3.
Do you Know wich code gives us The rules for load cases combination?
Thanks.

The code requires "scalar combination" as follows:

302.3.6 Limits of Calculated Stresses Due to Occasional
Loads
(a) Operation. The sum of the longitudinal stresses,
SL, due to sustained loads, such as pressure and weight,
and of the stresses produced by occasional loads, such
as wind or earthquake, may be as much as 1.33 times
the basic allowable stress given in Appendix A.

Now we do some magic and delete some words:

302.3.6 Limits of Calculated Stresses Due to Occasional
Loads
(a) ........... The sum of the ..... stresses,
...........,AND of the stresses.......

hence "scalar combination"

Best regards,

pls suggest me that the snubbers can be used for wind loads? if not y?

I heard that in USA they try to replace all the snubbers with classic guides and/or limit stops due to some malfunctions or concerns of malfunctions. It was another topic with the same question.

Regards,