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Re: Diaphragm Calculations

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Thanks Mike, 
This is the first response that I can truely understand and makes sense. Now 
why couldn't this be explained in the earlier response from Doug?

Now, how about the first term in the equation? This still comes out in Feet. 
Am I expected to apply a conversion factor of 1 in/ft to this part of the 
equation or is the equation incorrect?


In a message dated 7/8/99 1:45:30 PM Pacific Daylight Time, mtv(--nospam--at) 

<< Dennis:
 The implied units on the coefficient 0.188 are 1/ft.  This is one of 
 those cases where the equation results are only valid if appropriate 
 units are used.  As both a structural design engineer and a Mathcad 
 user, I also run into this type of difficulty.  The source of the 
 trouble is that many of our design "equations" are not derived 
 mathematically but are instead simply the result of curve fitting 
 applied to empirical data.  Consider for instance the ACI truism that 
 the square root of something in psi units is also in psi units; 
 Mathcad doesn't "understand" this.  The reality (call it unfortunate 
 if you want) is that everyone who uses such a "data-fit" equation 
 must confirm whether the equation is units consistent (can be used in 
 Mathcad directly) or units dependent (requires creative conversion).
 -Mike >>