Where's the engineer? - was string seating - was bridge caps

[jolly roger]

At 10:23 PM 4/13/01 +0200, you wrote:
>Hi Roger, bur surely your fence differs in that it doesnt have 20 tones of
>pressure bearing down on it?
>
>Brian Lawson, RPT

Hi Brian,
              Side bearing per pin is probably less than 10 Lbs. One post
suporting 8ft ft of fence in a 50m.p.h. wind will add up to tons of
pressure, dependent on suface area. Plus the rocking effect from varying
wind speed.  Way more pressure on that fence post than you may think.
You have to think in terms of the turning moments of force, and it's
resultant vectors.The string may have 175lbs tension, how ever the angle of
bearing will determine the actual pressure on the pin.
Typical ball park, 4-6 lbs down bearing, 8-12lbs side bearing. Just going
by fuzzy memory. This asuming no friction on the bridge cap.
The bridge pin may be more predictable than a fence post, knowing our
weather.  <G>
Regards roger