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# RE: phi in both sides of formula 14-1

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: phi in both sides of formula 14-1
• From: "Roy Harrison" <ro35984(--nospam--at)bigpond.net.au>
• Date: Sat, 1 Apr 2006 11:43:06 +1030

```I have been quite intrigued by this on-going saga.

Whilst I do not have at hand the specific formula 14-1, I am familiar with
the concept.

Here "down under" we have similar expressions in the local standards/codes.

I believe this is a mathematically correct algebraic expression.

As Paul observed - taking phi from the LHS of the expression and placing on
the RHS we get a division.  As noted phi/phi becomes "1" and hence the
expression becomes Pnw = 1 x (whatever constitutes the expression for Pnw
this side) hence mathematically consistent

Or am I missing something ??

Roy Harrison

Roy Harrison & Associates
Consulting Structural Engineers

mailto:ro35984(--nospam--at)bigpond.net.au
http://users.senet.com.au/~tectonic/

-----Original Message-----

-----Original Message-----
From: Gary Hodgson & Associates [mailto:ghodgson(--nospam--at)bellnet.ca]
Sent: Friday, 31 March 2006 11:29 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: phi in both sides of formula 14-1

I have never liked that usage but since it does't
Here (where Wyoming looks balmy, David),the left hand
side of our equations uses M(Sub)r, V(Sub)r, etc,
indicating the resistance of the member.  I much prefer
ours but it really is a matter of what you are used to.
I could see someone like Eugenio making the assumption
that it is part of an algebraic equation, as that was
the same  assumption I made when I first saw a US code
with that content.
Gary

On 30 Mar 2006 at 13:43, Paul Feather wrote:

> Yes Dave, I will admit to the same off-beat comedic reaction.
>
> On the other hand, to answer the man's question:
>
> Eugenio,
>
> The design expression is not straight algebra the way you are thinking
> of it.  The phiPnw is the name of the variable you are trying to find, if
this makes sense.  The axial load strength, Pnw,  would be 14-1 without
"phi", the design axial load strength is "phi" times the axial load
strength.  Since phi is in the right side of the equation, the nomenclature
is phi-Pnw on the left so you know phi has been applied.  It would not
cancel out algebraically.
>
> Paul Feather PE, SE
> www.SE-Solutions.net
> pfeather(--nospam--at)SE-Solutions.net
>   ----- Original Message -----
>   From: David Maynard
>   To: seaint(--nospam--at)seaint.org
>   Sent: Thursday, March 30, 2006 12:08 PM
>   Subject: RE: phi in both sides of formula 14-1
>
>
>   Eugenio wrote:
>
>   "I am confused with the formula (14-1) "Design axial load strength"
which sowns a factor "phi" at the two sides of the formula.     In the 2001
California Building Code.
>
>   My recollection in algebra says that a value goes to the other side
> of the formula with the oppossite sign. If I follow the rule, "phi"
> multiplying goes dividing, means phi/phi=1.
>
>   Why in such Chapter 19, DIVII - 1914.5.1 even it gives a value of
> 0.70 to phi?.
>
>
>
> architect."
>
>
>
>   In response:
>
>   I think the last statement just about sums up the root of the
> problem right there.
>
>
>
>   *laugh*  Sorry, I couldn't resist.  *laugh*  Just havin' some fun.
> I'm in a goofy kinda mood today.
>
>
>
>   But come on. how many Engineers out there read that statement and
> thought the exact same thing.  I know you're out there.  You know who
> you are!!!
>
>
>
>   Comedy by:
>
>   Dave Maynard, PE
>
>   Gillette, Wyoming
>
>
>
>   P.S. The wind's blowing like crazy today.  I'm starting to get cabin
> fever.
>
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