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Sites Not Defined By ASCE 7 Methods

Sites Not Defined By ASCE 7 Methods

Sites Not Defined By ASCE 7 Methods

Dear Engineers,
I will like to know if some of you have designed structures according ASCE 7 outside USA.
In this case is necessary to get the factors SD1, SD2, Ss ,etc for that country.
I found in API 650 2018 section EC-4.3 “ Sites not defined by ASCE7 methods” a vey simple an practical procedure that basically is to asume “Z” ( the maximun horizontal acceleration in rigid soil with 10% of probability of be exceeded in 50 years) equal to Ss of ASCE 7. And then all the othersr factors (Sd!,SD2,Fa,etc).
The engineering office of the client claims that this specification only apply to tank design and can not be applied to other structures.
I will like to know what is your opinión about this client claim.

RE: Sites Not Defined By ASCE 7 Methods

What country are you designing for? Most countries will have their own seismic codes.

RE: Sites Not Defined By ASCE 7 Methods

Double posting is frowned upon here.

RE: Sites Not Defined By ASCE 7 Methods

There is no Difference in calculation of seismic force for a geometric body. seismic force depends upon:
1)Mass of the Body.
2)Soil Type of that region.
3)Natural Frequency of the Body i.e. again depended on the mass and stiffness of the body.
4)Damping of soil i.e. depended on soil type.
5)Another factor most codes introduce is the importance of structure you design.

while coming to calculation of seismic load the only part which is deepened on
geometry is the stiffness of structure. So in it is quite reasonable and practical you can use it
for any other structure.

RE: Sites Not Defined By ASCE 7 Methods

In canada we sometimes use american codes when the local building code doesnt apply, vessels for example. Biggest difference i can remember is canadian ground excelerations are based on site class c whilst american are site class d. So an adjustment needs to made there. Ss is Sa(0.2) if memory serves me correct. I would have to refresh my american code to give any info on sd1 and sd2.

If you are considering usimg seismic values based on a different return period, mostly likely they need to be adjusted. To figure out how to do that I would find a good seismic book, maybe
"Elements of earthquake engineering and structural dynamics".

I just reread the last part of your question, tyically local building codes govern, foreign codes (american in this case) would only govern in specific cases where the local codes are not adequate. This is stated in the canadian code commentary.

RE: Sites Not Defined By ASCE 7 Methods

Thank you all
First, Mr. Oldestguy, I have not double-edited; I was surprised to see a message from Mr. Ramakrishna Das, with whom I totally agree. The seismic force calculated by the code does not depend on the type of structure that is being analyzed. It depends on whether of the 5 factors listed by Mr. Ramakrishna Das.
Mr. Liam Nesson, thank you for your comments.
Mr. KevinNZ, the design is for Peru where there is a proper standard; but the client is an American company and wants ASCE 7/2016 to apply; but considering the typical factors of the Peruvian seismic code.

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