Tru-Beam Flat
Wall
The Tru-Beam
has been used on a variety of projects such as deep
foundations, high-rise buildings, tunnels, shafts,
retaining walls, sewage treatment plants, reservoir,
water treatment plants and many others.
The basic components of this system are 2 ¼" x 7 ¼"
laminated wood beams engineered for a safe working
load of 1200 P.L.F. on a six foot span.
Backing these beams with 8" double steel channel
wales spaced six feet on center and facing the form
with at least ¾" Struc I plywood, allows ties (taper
ties or she bolts) to be spaced up to six feet
vertically and horizontally. With Tru-beams spaced
12" center to center, the resulting form has a safe
working load of 1200 P.S.F. or an eight foot liquid
head of concrete.
Forming Concepts believes this design pressure is a
good balance between form weight and cost and
concrete placing costs. The typical flat Tru-beam
gang will weigh about 15# P.S.F. To design a form
for a greater safe working load would cost more and
add to the weight, which we felt was not necessary
for most jobs.
However, when necessary with a change in the spacing
of the Tru-beams, wales and ties, a form can be
designed for a safe working load of 2000 P.S.F. or
more.
Many projects such as wastewater treatment plants
call for walls with haunches at the top or bottom or
both. Specifically designed channel wales can be
fabricated to accommodate those shapes.
Various types of plywood, M.D.O., H.D.O. or Finn
form can be used to face a Tru-beam gang depending
on the number of uses and the concrete finish
required. With careful fabrication, and a minimum of
ties required, a walk-away finish on the concrete
can be achieved with a minimum of labor.
The other advantage of the wide tie spacing is the
reduction in labor to set and strip Tru-beam gangs.
Studies have shown (see Concrete Construction
Magazine January 1986) that as much as 38% of the
cost of a concrete structure is related to form
labor. With almost 40% of that attributed to tie
labor needed to handle, set, strip and patch ties.
All in all the Tru-beam gang form system is one of
the most cost efficient systems available today.
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Tru-Beam
Circular Wall
One of
the more difficult concrete structures to form is a
round tank such as found on wastewater treatment
plants.
Forming Concepts has tried a number of different
approaches to this problem using Tru-beam gangs.
Based on results a reported from various
superintendents and foreman, using vertical Tru-beams
backed with double steel channel wales and shaped
with wood packing wales, turned out to be the most
cost effective method.
What most contractors prefer is to have the forms
fabricated in gangs the full height of the tank
walls in widths from 8' to 12'. The small additional
cost to strip gangs of this size is more than offset
by the savings in job site labor when these gangs
can just be unloaded from a truck and set in place.
If a job has wall heights that are fairly close but
different radii, the packing wales can be changed to
accommodate them.
Sometimes tanks on a treatment plant will have
troughs projecting out from the walls. Forming
Concepts has designed several methods to take care
of this situation with a minimum of labor. |
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