ASME B31e Seismic Design

[KevinNZ]

I have read some other posts on B31e and there have been questions on why B31e allows much higher stress over the B31.x codes.

The devil is in the detail. The design EQ action used in B31e is more that you would used in B31.x

B31e requires you to calculate the design action (ground acceleration factored by equipment ductility consideration) based on ASCE 7 where a_p is 2.5 and R_p <3.5.

But in ASCE 7 piping to B31.x has more ductility and the values of a_p and R_p are different.

For example pipe designed to B31e may have a acceleration of 0.8g while B31.X is 0.4g.

Also you should need to be careful how you pass the seismic support loads onto the support and foundation designers. They need to know how they are calculated as they need to consider the ductility differently than the piping.

Cheers
Kevin

 

[BigInch]

Not sure why you say that the acceleration factors would be different ( 0.8 vs 0.4). Is that factor not a property of the site, rather than specified by 31e.

you must get smarter than the software you're using.

 

[KevinNZ]

The ground acceleration does not change but the factors you the apply for the code stress check do, depending the weather you are using B31.x or B31e.

 

[DSB123]

Do you really mean "Whether you are using B31.x or B31E" ?

 

[KevinNZ]

B31.x means B31.1 , B31.3 etc. B31E is the EQ code for piping.