Prefabrication was employed at the following locations:
Stairs: Prefabricated
steel, field assembled. Railings,
treads and risers came in sections, concrete poured in treads and landings.
Precast terrazzo stair nosings in administration/library wing.
Elevators: Elevator
cars come prefabricated with rails and guides that have to be field assembled.
Windows: The
aluminum extrusions of the window frames and mullions were fabricated by Conair
in Salt Lake City according to engineering, shipped to the site, cut to size and
assembled, and then each opening was measured for the cutting of glass.
The gymnasium was converted into an assembly line to assemble the
windows.
HVAC ducts: Trunk
lines fabricated in and shipped in pieces.
Smaller ducts fabricated on site. Stainless
steel ducts used in natatorium to avoid corrosion due to evaporated pool
chemicals. Galvanized metal ducts
in gym.
Cabinet work: “The
look was important.” Accuracy important so also field measured.
Circulation desk and sculptural wood wall were intricate and in turn had
to be built by a local “artisan.” Book
shelves in Library are prefabricated.
Roof Trusses and other metal frames/members:
The steel in the building was imported from Asia, fabricated into trusses
by Rosco Steel in Billings, Montana, and then shipped to the site in multiple
pieces. The king post trusses in
the natatorium arrived in two pieces and the trusses over the gymnasium came in
three pieces each. Cafeteria-“bicycle wheel truss”-trusses rotated around a
king post.
After the foundations were poured,
the site was surveyed several times with laser levels. The measurements had to
be extremely precise, where each bolt to receive a base plate was measured for
elevation, pitch, yaw, and orientation (North-South).
A shop drawing process was conducted before fabrication and included full
three-dimensional modeling for review. Since
the steel has a tolerance of only one quarter of an inch, the concrete walls
were not even poured until after the steel arrived and a laser survey was
preformed by the installer to ensure an exact fit.
Having worked on many commercial
shopping centers and interest in the high-tech designers of England, designer Ed
Noland wanted to explore the implementation of king post trusses to make the
large spans over the gymnasium and natatorium, as well as at the student union
and library.
Concrete: Durability
was very important. The idea of
precast or tilt-up was only briefly entertained, however, they were ruled out
because they would have created a different finish that would not have matched
the existing buildings on campus. Board
formed concrete was employed at all the first floor spaces as a way of
connecting to existing buildings and as a matter of durability.
Exterior panels: Metal
panel skin has look of post WWII material aesthetic and easier to work with than
if building were concrete alone.
Prefabrication was employed for the following reasons:
§
Time:
Shortens construction period? Not
really. Was not a major concern
though since the school can work around schedule by using portable classrooms.
It is different from commercial developments where the client(s) are
really pushy about opening days.
§
Budget:
Did standardization/repetition to cut costs. What about difficulties in construction staging?
Staging/ location was difficult for trusses.
§
Quality:
Precision (the look), flexibility, technology? Precision and look were the most important factors since
building codes for schools require a well built structure and the architect
wanted something durable.
The possible disadvantages to and problems arising from
prefabrication:
§
Concrete was poured after the steel frame was erected, to
minimize the problem of the misalignment of prefabricated parts to site
fabricated parts. Steel installers
revised site measurements of steel structure twice before concrete was poured.
§
Shop drawings arrived in incremental packages.
Steel fabricator redrew the architect’s drawings for the entire
building rather than importing a computer file because of fear of mistakes/
inconsistencies. Steel fabricator
used computer modeling. RFI’s were really important to clarify shop drawings.
Dimensions had to be confirmed many times before fabrication could begin
since steel has only a ¼” Tolerance.
§
Shop drawings may be changed by fabricator to save money
which would explain some design changes. Some
things had to be redone that would normally be overlooked by contractor.
The prefabrication process ran into problems occasionally, especially at
the paneling. Since this was an
instance where the alignment of seams was noticeable, misalignment resulted in
prefabrication of certain parts.
§
The process of checking dimensions on shop drawings delayed
the process. 3-D computer modeling a hindrance in some ways since it is so
precise and required so much confirmation.
§
Since schools must follow more stringent codes, the
prefabricated structural parts had to be designed to these standards.
Precision is not as important in commercial projects where there are more on-site modifications. In addition to more stringent requirements, schools are more complicated since shopping centers use more repetition and timescale is much longer for a school since it has to be done right. Have used prefab steel trusses in commercial places but never as tight as this. But given scale of building, it had to be steel and concrete.