PERMFILE57905

• Permit No: C1994082
• IBM Index Class Name: Permit File
• Doc Date: 2/19/2002
• Doc Name: GROUND MOTION ATTENUATION STUDY
• Section_Exhibit Name: TAB 14 ATTACHMENT 14-3
• Media Type: D
• Archive: No

Chapter 5
•
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Frepuehcy
Sample Rate;Error
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•°~ "~ (1U24
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# '(4096 Hz)yg
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0- 30 Hz negligible negligible negligible
error ertor error
31 - 50 Hz up to S Hz up to 2.5 Hz negligible
eROt eROf [ROr
51 -70 Hz uptoBHz upto4Hz upto2Hz
ertor ertor ertor
71 - 90 Hz up to 18 Hz up to 9 Hz up to 4.5 Hz
ertor ertor ertor
91 - I50 Hz up to 50 Hz up to 25 Hz up to 12.5 Hz
error ertor ertor
The B]aztMate III does not calculate frequencies above 100 Hz because of the high error level at
1024 samples per second. The message ">]00 Hz" displays. At 2048 samples per second, the
message ">200 Hz" displays. When recording at 4096 samples per second, the message ">400 Hz"
• displays: Furthermore if a waveform is very complex, or if it contains a large offset value, the zero
crossings may lie outside an acceptable window. Whenever a frequency cannot be calculated the
message "<1 Hz" displays. The message N/A iridicates an entire waveform was not captured and
therefore no frequency could be calculated. More accurate analysis is available using the
B1aztWare III software.
c. Peak Acceleration
The BlaztMate III calculates peak acceleration, the rate of change of velocity, by dividing the
difference in velocity by the difference in time. To obtain the peak acceleration, the BlaztMate III
subtracts two velocity readings and divides the result by the elapsed time between them.
_ dV _ eV
a dT _ eT
where:
pt = a small interval
The BlaztMate III calculates the peak acceleration at each point along the entire waveform and
reports the peak value. Note that this is not necessarily at the peak velocity for an individual
waveform.
d. Peak Displacement
The HlastMate III calculates peak displacement, or particle distance traveled, by mul[iplying speed
by time. In the BlaztMate III [he interval velocity is multiplied by the time interval and the
resulting displacement segments are summed.
5= Jvac=~(vec)
• where:
V =the velocity in each interval
~ B1astMare III Operator Manual