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Re: What a Structural Engineer Should Memorize

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For Concrete, the span expressed in inches should be the depth of the beam ie 15' span means 15" beam
 
Similarly to avoid slenderness forces in columns the least dimension of column in inches should be equal to the height in feet, i.e. 12' floor height should have at least as 12'x12' concrete column.
 
Cantilever retaining wall's foundation width should generally be at least half of the cantilevered retaining height.
 
The base moment in cantilever retaining wall for active earth pressure in SI units (meter & kilonewtons) is simply h^3.
 
The tension reinforcement required in concrete beam/slab is approx M/3d, where M is limit state moment & d is the effective depth.
 
Pankaj Gupta
Structures Online
India
 
----- Original Message -----
Sent: Wednesday, August 24, 2005 10:09 PM
Subject: RE: What a Structural Engineer Should Memorize

How about for concrete?

 


From: Stuart, Matthew [mailto:mstuart(--nospam--at)schoordepalma.com]
Sent: Wednesday, August 24, 2005 12:33 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: What a Structural Engineer Should Memorize

 

Half the span (expressed in inches) is the likely required depth for a steel beam (i.e. 24-feet span = W12)

 

Matthew Stuart

Structural Dept. - Manalapan

732-577-9889 x1283

 

 

-----Original Message-----
From: Dave Adams [mailto:davea(--nospam--at)laneengineers.com]
Sent: Wednesday, August 24, 2005 12:12 PM
To: seaint(--nospam--at)seaint.org
Subject: What a Structural Engineer Should Memorize

 

Hello list,

 

I've been compiling a list of facts & tidbits that I believe structural engineers should commit to memory in an effort to bolster an ability to think on their feet when confronted in the field or receiving that emergency phonecall.  Things that give a good "global" picture of what solutions might be practical for a given situation before actually running numbers.  These bits of information are never intended as the means & ends, but basically a starting point for discussing possible solutions to a problem.

 

Some of the things that I've got on my list include:

 

1.  The basic allowable shear value of ONE 16d common nail in Doug Fir is about 140 lbs.

2.  The basic allowable withdrawal value of ONE 16d common nail in Doug Fir is about 40 lbs/inch of penetration.

3.  The basic allowable single-shear value for ONE 5/8" diameter A307 machine bolt for a steel-to-steel connection is about 3 kips.

4.  The total wind pressure for a single-story building design in 70 mph/Exp. C is about 20 psf.

5.  The total seismic design load in UBC Zone 3 for a wood-framed building will be about 0.30*W.

 

Obviously there are other considerations, such as the fact that toe-nails and end nails must have their allowable values reduced, but the purpose of the list is just to give us a BASIC starting point for thinking through s solution to a field issue.  The final numbers are rounded off and I felt that the lateral loading figures should be bumped up a little when thinking a solution through.  There are certainly many more bits of info that are helpful to commit to "quick-recall" memory and I'd like to hear if anyone else would like to contribute to the list.

 

 

Dave K. Adams, S.E.

Lane Engineers, Inc.

Tulare, CA

E-mail:  davea(--nospam--at)laneengineers.com