Dan:
The potential problem that may occur is that you will laterally load
the basement wall due to the vertical load of the tower. This is
called surcharge horizontal earth pressure. It depends how deep your
basement is. In your case the surcharge vertical pressure starts at
the underside of the tower foundation. It will spread out (rule of
thumb not knowing your soils info) at a 45 degree angle from the edges
of the tower foundation, i.e., 1 foot out for 1 foot depth. If the
edge of the foundation is 2.5 feet from the outside of your basement
wall then the wall will not feel anything from the foundation vertical
load until 2.5 feet below or down 8.5 feet. If your basement is about
that deep or even say down to 10 feet you really will not be loading
the basement wall too much remember that the load is spreading out
both in the vertical and horizonatal directions at 45 degrees.
As far as lateral loads, assuming a guyed tower, I wouldn't worry too
much. Kinda the same idea if the primary load is lateral and not
vertical. Just make sure to do a good job compacting the backfill
around the tower foundation.
I is always better to move the load farther away but it may not be
practical in your installation. If really worried expand the
foundation of the tower to the basement wall and drill in rebar dowels
and pour the tower foundation up to the basement wall.
Hope this give you a feeling for this type of situation. Good luck and
good dx.
73
Hank Lonberg, P.E.
KR7X
______________________________ Reply Separator _________________________________
Subject: [TowerTalk] Tower bases near basement walls
Author: Dfmich@aol.com at ~INETMAIL
To: <towertalk@contesting.com>
Date: 8/29/98 11:24 PM
I am in the process of installing a tower requiring a base that is 48 in dia
and 6 feet deep. My current plan is to place it about 2.5 feet from my
basement wall. It suddenly occurs to me that this may not be a good idea
because of potential stress transferred to the wall when a big wind blows.
Anyone have thoughts or experiences to share on this issue?
Dan K9EA
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