BUILDING SYSTEM GIVEN DUAL ROLE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP86-00244R000300020041-7
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 2
• Document Creation Date: December 12, 2016
• Document Release Date: March 28, 2002
• Sequence Number: 41
• Publication Date: December 4, 1969
• Content Type: MAGAZINE

Approved Rijw~ Release 2002/05/09 : CIA RDP86-OO R000300020041-7
HUGE precast members are assembled like a building block set.
CONCRETE structure nears its full 16-story height.
Building System Given Dual Role
A building system that has produced
2,000 dwelling units now is being used
in the construction of a 16-story office
building, the first of four towers that will
he erected using precast components.
The system is the Firnkas System of
Modular Construction. The building is'
One Brookhollow Plaza, a 130,000-sq-ft
structure consisting largely of precast
concrete members, including the walls
of the 56 x 30-ft core. The core floor at
each level, however, is a cast-in-place
concrete slab on metal deck supported
by structural steel framing.
In addition to being used on the
2,000 completed units, the system, de-
veloped by Boston consulting engineer
Sepp Firnkas, is being used in another
3,000 dwelling units either under way
or in design, in the U.S.
Firnkas had to turn his system
around, however, for use in the Brook-
hollow project. The system, as applied
to housing, employs the wall bearing
principle. But on the Brookhollow
project the bearing walls are replaced
by 8-ft-high column-supported spandrels
that support hollow core precast con-
crete planks.
The four buildings in the $20-million
project will range in height from nine to
22 stories. The four will be constructed
with the Firnkas system, but only the
building under way will have a precast
concrete core.
The size and weight of typical core
units, 25 ft long by 13 ft high by 12 in.
thick, and weighing 43,000 lb, proved
difficult to handle, thus slowing to some
extent work on the prApprlo dl'Fior
VmZ
OFFICE complex evolving from a building system was developed first for housing.
general contractor, Hayman-Bryant-
Andres, Inc., of Dallas, therefore sug-
gested that the core in the other three
buildings be cast in place.
? Building block set-The 237-ft-high
building, 75 x 158 ft in plan, consists
of 25 different precast elements per
floor, with a total of 3,000 precast com-
ponents. This led the owning company,
a subsidiary of Texas Industries Inc.
(TXl), of Dallas, to describe the build-
ing as the product of a giant building
block set.
Precast units for the $3.5-million
building were hauled 10 miles from the
plant of TXI, a cement, aggregates and
precast products producer, at`a,rate of
about 10 truckloads a day. The precast
the truck into position in the structure.
Stockpiling of components at the site
was kept to a minimum.
Erection was handled by two cranes;
one a 150-ton-capacity unit with a 213-
ft tower and a 110-ft jib boom, the
other a 100-ton rig with a 230-ft boom.
The building has no basement, the
foundations consisting only of piers
drilled 10 ft into rock, which underlays
65 ft of expansive clays and hard blue
shale. The soil beneath the ground floor
slab was stabilized by injecting lime to
a depth of 10 ft. In addition, the eleva-
tor pit 20 ft below grade is completely
surrounded by granular fill placed at a
45-deg angle.
The building has 20 post-tensioned,
load-bearing exterior columns, eight on
es VM2A5iQHteCAAeF iR1 &00244ROWWD92QA6A-3. 34)
(4,;)December 4, 1969 ? ENGINEERING NEWS-RECORD
 each of the long sides and two on each
end. Workers set the columns around
the perimeter on pier caps containing
anchors with threaded couplings linking
the post-tensioning rods in the column
sections.
The columns, 6 ft wide by 1 ft thick
on the long dimensions of the building,
and 7 x I ft at the ends, extend beyond
the building line with no grade beam
tying them together. Instead, Firnkas
and T. Y. Lin & Associates-Dallas,
called for a 3-ft-high pedestal to he cast
along two sides of each column. The
pedestals, 18 in. wide and 61/2 to 71/2 ft
long, depending on the adjoining
column size, permitted the pedestal re-
inforcing to enclose the base of the
columns.
Columns, typically 13 ft high, were
:cast with two sleeves to receive the
stressing tendons which were post-
tensioned to 81,000 lb, and then
grouted. The columns, and also the core
walls, have a full bearing surface of
grout when the bars are tensioned at
each elevation.
unusual feature of the
core is a cantilevered arm extending 6
ft from two end walls to carry a 55-ft
beam spanning the columns at one end
of the building. The beam on the op-
posite side of the building rests on the
wall. By employing the cantilevered
arm, the architects eliminated the need
for a column that would otherwise have
been located in a circulation area of
each office floor.
The arm is heavily reinforced, and in-
cludes nine No. 11 bars, four of them
bundled across the top and three bent
downward into a No. 6 looped stirrup
welded to the top flange of a structural
steel beam. This structural member, a
welded on each side and No. 8 stirrups
welded on the flange faces, extends the
full length of the arm and into the core
wall to transfer shear stresses from the..
notch into the main wall.
Core wall sections were cast with
hollow tubes to receive the steel ten-
dons, which were post-tensioned after
erection of the wall. Throughout the
building, components were connected
with bolts, dowels and grout, tying the
members together so that in concert
they perform as a reinforced concrete
structure. Each of the eight components
making up the core walls at each typical
floor has two vertical tendons, one at
each end.
Floors at each level in the core, which
will contain emergency stairs, four elc-
vators and rest rooms, are cast-in-place
slab on metal deck supported by struc-
tural steel framing. These floors and the
2-in. topping on the hollow core plank
deck in the office areas were the only
cast-in-place concrete operations above
grade.
? The flooring job-Holes, 4 in. in di-
ameter and 16 in. apart, were formed in
the 4-ft-wide hollow core floor planks so
that the topping concrete could be
pumped into the plank's void to form a
T-section with the plank's supporting
beam, which is of composite design.
Voids were stuffed with excelsior 2 ft
back from the top of each plank. When
the concrete was pumped in, it created
a 4-ft T. Shear steel emerging from the
top. of the beam completes the tie with
the concrete.
A 2-in, concrete topping for the pre-
cast hollow core planks was pumped
about two floors behind erection. Top-
ping reinforcement consisted of 4 x 4-in.
10/ 10 woven wire mesh with No. 4
reinforcing bars over beams to provide
negative reinforcing.
The contractor averaged seven work-
ing days per elevation, including grout-
ing, tensioning and placement of the
topping. Labor disputes and adverse
weather conditions added to delays, so
the original construction schedule of 13
months has not been met. Work started
in September 1968, with occupancy now
scheduled for next March.
All exterior,surfaces have an exposed
limestone aggregate finish tan in color.
Double-glazed insulating solar glass of
of bronze tone will complement the
exterior finish.
Architects for the project are Har-
wood K. Smith & Partners, of Dallas,
and Paul Rudolph, of New York. Her-
man Blum Consulting Engineers, of
Dallas, serve as mechanical and elec-
trical engineers. TXI was subcontractor
for the casting and erection of the com-
10 WF 45 beam with Aprp dNk@3fsRe X29 9'05/"1`."MI - 8Bi-cM241R606300020041-7
. 34 December 4, 1969 ? ENGINEERING NEWS-RECORD