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ASCE 7-02 Time period in Metric

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It appears that the reason for the discrepancy is that the factors for
metric are wrong in ASCE 7-02. Note that for ASCE 7-05 they have been
changed. For "All other structural systems" the metric equivalent is
0.0488 (instead of 0.055). It is also interesting to note that in ASCE
7-98 the metric equivalent was 0.0488, so for some reason they changed
the metric equivalent in ASCE 7-02 (erroneously), and then changed it
back for ASCE 7-05.

Using the correct coefficient:
   Ta = 0.048 (14.6)^0.75 = 0.364 s
which is the same as is given using the US Imperial units coefficients
and values.
I recommend using the ASCE 7-05 value since it is consistent.
Allen



Allen Adams, S.E.
Chief Structural Engineer
RAM International
(800) 726-7789 x113
Allen.Adams(--nospam--at)bentley.com 


From: "Anantha Narayan C.K." <anant_27(--nospam--at)yahoo.com>
Subject: ASCE 7-02 Time period in Metric
To: seaint(--nospam--at)seaint.org

Greetings,
   
  This might be the dumbest question on the forum, but could anyone
please let me know what I am doing incorrectly.
  
Reference : ASCE 7-02 Eq 9.5.5.3.2-1
   
  Ta = Cu * hn ^ x
   
  where for "All other structural systems" Cu = 0.02 (0.055 in metric)
and x = 0.75 [TABLE 9.5.5.3.2]
   
  For a building that is 14.6 m high (= 47.88' )
   
  Using English Units, Ta = 0.02 (47.88)^0.75 = 0.36 s
   
  Using Metric Units, Ta = 0.055 (14.6)^0.75 = 0.41 s
   
  Could anyone please tell me as to why there is a discrepancy between
the results?
   
  Thanks
  Anantha

 
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  ANANTHA NARAYAN, E.I.
  Structural Engineer
  Bliss and Nyitray Inc.
  Miami, FL - 33134



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