Duration of artificial accelograms

02-Analytical capabilities
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Joined: 18 Mar 2014, 04:57

Duration of artificial accelograms

Post by zbadar »

Hello, are there any rules to specify the duration of artificial accelograms generated with method 2 or 3 in SeismoArtif? Thanks in advance!!
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Re: Duration of artificial accelograms

Post by ruipinho »

Hi zbadar,

This should depend on the seismic hazard of your site (e.g. what is the magnitude-distance pair of the "dominating" event, as obtained from disaggregation analysis?).

If you are not in possession of information such as the one above, perhaps the seismic design code that you are using provides some guidance?

If the above is also unavailable, I wonder if there are any publications in the literature that will contain information on past earthquakes in your region of interest?

All the above failing, then I guess a 20s duration would be a good pragmatic choice.


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Re: Duration of artificial accelograms

Post by huffte »

As rui says, zbadar, this is really up to the engineer/analyst to dig out of the specific criteria used on the project. It depends on many variables: magnitude, distance, fault type, subsurface conditions. In Kramer's Earthquake Engineering, the following table of "typical" values for bracketed duration (time between first and last occurrences of a threshold acceleration, 0.05 in this reference) is given for sites closer than 10 km epicentral distance:

M5.0 - bracketed duration = 4 sec (rock sites), 8 sec (soil sites)
M5.5 - bracketed duration = 6 sec (rock sites), 12 sec (soil sites)
M6.0 - bracketed duration = 8 sec (rock sites), 16 sec (soil sites)
M6.5 - bracketed duration = 11 sec (rock sites), 23 sec (soil sites)
M7.0 - bracketed duration = 16 sec (rock sites), 32 sec (soil sites)
M7.5 - bracketed duration = 22 sec (rock sites), 45 sec (soil sites)
M8.0 - bracketed duration = 31 sec (rock sites), 62 sec (soil sites)
M8.5 - bracketed duration = 43 sec (rock sites), 86 sec (soil sites)

Again, these are "typical", are bracketed (not total) durations, and should not override any requirements which might be found in your overall criteria.

Best of luck.
Tim Huff
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