Reference peak ground acceleration

[sonyablade2010]

Dear All,

I'd like to hear from collegues what numerical value they take as reference peak ground acceleration for A ground type? Theoritically this should be max gravity 9.81m/s2 but the value you may choose may depend on seismographical data if you have in hand, but I'm still a bit dubious about. Does anybody can shed light on that ?

Regards,

[t.sautierr]

BEWARE ... for example in france it is only for Guadeloupe, Martinique etc ... that you get this kind of value (max is 3.00 m.s-2)  .... and I doubt you can have a agr that is 9.81m.s-2.

It would mean that your building is about to take of ... or to roll.

However pga is given by local regulation. see attached for France.

Hope this helps.

[sonyablade2010]

Thank you Dear t.sautier,

As you can see, in your paper the design response spectrum reaches up to the 7 m/s2 shown at the bottom, which is not small value. Since I didn't translated that portion of nomenclature I don't even know whether it is intended for design or just for sampling.

 But the thing that I'm more curious about is that : choosing soil type and response spectrum type (Type 1  where M  > 5.5 and Type2 where M <5.5  ) should be enough for RSA to calculate the quake forces, if so then for what is that peak ground acceleration? I want to make sure and clearly understand that I'm not underestimating or overestimating something unnecesarily with setting that value. 

Other countries peak acceleration value and guidance will be appreciated,

Regards,

[t.sautierr]

In France, soil parmeter and peak ground accelereration is set by governement rules.

In other countries, I assume the same happens provided your situation can be considered classical.

In order to see precisely what is the pga -> refer to Eurocode 8 :

ag = agr (peak ground acceleration) * S (related to soil)* gammaI (related to building importance)

this value ag, is the one at the horinzontal branch (top of the spectrum).

[sonyablade2010]

Thank you for commenting,

It seems that I understood it to some extend but I'll summarize it once again to make sure that I'm on a right path and I'm not misinterpreting something, please confirm!

Since each graph ordinate shown in EC8(Figure 3.1 generic , Figure 3.2 for Type 1 and Figure 3.3 for Type 2 response spectrum) is in that form Se/ag then I have to provide that value in order to get the correct value of Se. right ?

Where Se is elastic response spectrum;

For example, in your case(Franece) you will use the agr given in your article,  to obtain ag which in turn will be used to obtain the Se.

Regards,

[t.sautierr]

Since each graph ordinate shown in EC8(Figure 3.1 generic , Figure 3.2 for Type 1 and Figure 3.3 for Type 2 response spectrum) is in that form Se/ag then I have to provide that value in order to get the correct value of Se. right ?

Correct and to complete : ag = agr * gi (parameters given by regulation)

For example, in your case(Franece) you will use the agr given in your article,  to obtain ag which in turn will be used to obtain the Se.

Correct and to complete : ag = agr * gi (parameters given by regulation)

You will see then that the acceleration (either vert or hor) CAN be beyond 9.81 ms-2 but it in the most severe region, and for most severe projects.