SESIMIC & WIND LOADS

Dear Analysers...

I had a problem with my system while considering Wind & Sesimic.
My system is not converging unless if i consider Y restraints on the existing pipe rack. The pipe is running nearly 450M long run having only one expansion loop(lug is 4.5M & Width is 20M)of 700M total length.

Any have i made it run with +Y restraints. But the problem is, the code stress ratio is getting more(nearly 8lakhs) and lifting is more than 800mm. The i/p's are everything clear. I am getting this much deflections only in Wind and Sesimic.

The Forces(Fy) in Design & Operating condition is acting towards downside. And i dont know how the lifting is coming too high. And the loads at the anchor points on both side of the loop is more than 6tons. Can any1 plz assist me to get out of this issue. From last one week am fighting againest this issue.

And ill send my model if any1 is interested.

Thanks in advance.

It must be the way you construct the load cases.


Regards

Hi, if you want you can send your model and i will look at it.

Regards,
Rk

hi friend
i think u should go and check user defined wind data
like press. Vs ele. carefully may columns of that got
interchanged.Otherwise that much of temendious stresses
are imposible.As fsr as support lifting phenomenon
u can find it in supports on loop.It is bcoz of bend at the
start and at the end of loop is going downwords in ope
therefore the loop get lifting tendancy.

thanks and regards

Danb,

Thanks for the sujjestion.
I got the solution finally.
Now i am able to run the cases using +Y restraints.

The load cases which i made previous is the normal practise we are doing for wind and seismic.

I really got astonished by seeing that much change in OCC loads after changing load cases.

Previous i have not included wind and seismic along with OPE cases. Now i added OCC along with OPE cases, where it got worked out. But the cases which i used earlier is also recomended. Can you plz define the diff in load cases which i made earlier and the current cases.

I know the difference between the cases but i want exactly...what is the factor that lift the pipe while we cosider OCC cases straight away.

Current cases defined:

CASE 1 (HYD) WW+HP
CASE 2 (OPE) W+T1+P1
CASE 3 (OPE) W+T2+P1
CASE 4 (OPE) W+T3+P1
CASE 5 (OPE) W+T4+P1
CASE 6 (SUS) W+P1
CASE 7 (OPE) W+T1+P1+U1
CASE 8 (OPE) W+T1+P1+U2
CASE 9 (OPE) W+T1+P1+U3
CASE 10 (OPE) W+T1+P1-U1
CASE 11 (OPE) W+T1+P1-U2
CASE 12 (OPE) W+T1+P1-U3
CASE 13 (OPE) W+T1+P1+WIN1
CASE 14 (OPE) W+T1+P1+WIN2
CASE 15 (OPE) W+T1+P1+WIN3
CASE 16 (OPE) W+T1+P1+WIN4
Then OCC & EXP continues....

Previous load cases

CASE 1 (OPE) W+D1+T1+P1
CASE 2 (SUS) W+P1+F1
CASE 3 (OCC) WIN1
CASE 4 (OCC) WIN2
CASE 5 (OCC) WIN3
CASE 6 (OCC) WIN4
CASE 7 (OCC) U1
CASE 8 (OCC) U2
CASE 9 (OCC) U3
Then OCC & EXP continues....


Thanks
pratap kollapaneni

keduchem,

Every input i had given is very clear...
I considered wind in both X & Z directions(+ & - as well).

Thanks and regards

I'm glad I was of some help.

The difference is that everything is in presence of the weight. If you apply let say U2 vertical up over the pipe without weight ( U2 alone is exactly what it does) only the anchors will restrict the move.

Regards,

Danb,

Happy to see a prompt responce from you...Your explanation is right..that i know...
But what about the cases starting from case L17: L7-L2 (OCC) & so on...

They are just sesimic and wind loads without weight of pipe. How you can justify this...

And one more thing i want to ask you is...am getting high loads in ANCHOR points 200 Kpa in axial direction(U3,Zdirection). How can i eliminate this load without distributing this loads to someother supports. There is no anchor bays in existing pipe rack and it is not allowed to accomadate more than 80 Kpa on a single support at anchoring. Can any one have the answer for this without using any special supports(like Bracings).

And client is not interested in giving another loop where it increase the cost of the project[4extra 3D elbos(24") reqd for one line(tot 8lines)]...so give me the alternate solution. The below is the related post where i couldnt find the answer.

http://65.57.255.42/ubbthreads/ubbthread...=true#Post35701

Expecting expert opinions plz...

Regards
kollapaneni

Regarding the load cases L7-L2, it is a net seism effect but in the presence of weight (because was applied when weight was present) So is the real one. And this is why I believe is a parallelism with the T load case from lift off. It can not be applied alone .

Regarding the load on the limit stop, well it is about the (weight x U).

This is the length therefore this is the load.

You can place another limit stop in the mid of the loop, or you can ask for snubbers (very unfriendly devices).

Regards,

Hello RK,

Thanks for the curiosity...and sorry for the late reply.
Actually i can send the model,but some variations in layout.
Ill finish the model by tomorrow and ill send it with updation.

And one more thing is am getting more loads on to the pig nozzle.
Plz verify the model and give your valuable sujjestion to decrease the loads coming on to nozzle.
ill comme to you soon along with model.....thanks once again.

Regards
Kollapaneni

Danb,

Thank you so much..,
ill come to you soon,

regards
KOLLAPANENI

RK,

Please send your mail address.
Ill send my model...awaiting for your reply.

Kollapaneni