Reusing HUB structure saves money and history

Friday, September 14, 2012
Friday
HUSKY UNION BUILDING RENOVATION
Reusing HUB structure
saves money and history
 3-D structural modeling enabled team
members to streamline their coordination of
complex tasks and limit change orders.
By CORY HITZEMANN
Coughlin Porter Lundeen
At the outset of design for the University of Washington’s
Husky Union Building modernization project, a number of
schemes were evaluated that would save all, some or none
of the existing building structure.
After carefully studying the options,
the team decided the right choice would
be to keep the majority of the structure
to retain the building’s historic character,
control costs and preserve its embodied
energy in alignment with the project’s
sustainability goals.
The structure would be demolished
or rebuilt only where it compromised
the layout of the new spaces or where
renovations proved to be cost prohibitive.
Saving the building would be no simple
task, though, due to very tight floor-tofloor heights and close column spacing
Hitzemann
in much of the building.
The existing structure was composed of a variety of
concrete and steel framing systems built over a number
of phases from 1949 through 2001. While the building was
in good condition, it had never received a comprehensive
seismic upgrade over the course of these many additions.
As part of this project, the team was tasked with bringing the building up to today’s life-safety standards. Seismic
upgrade work included new concrete shear walls at select
locations, shotcrete strengthening of other existing walls,
and new steel drag struts where necessary to tie the various
components together.
The key was finding creative ways to minimize the use
of new shear walls while also allowing removal of some
existing walls, so the final interior layout would be open
and flexible.
Light-filled space
A major goal of the project was to design a new multistory
circulation spine and atrium space through the center of
the building to create an inviting sense of place.
Several floors were partially removed to make way for a
central atrium. Steel framing was added to support walkways, bridges, skylights and a stairway.
Photos courtesy of Coughlin Porter Lundeen
Article reprinted by permission of the Seattle Daily Journal of Commerce (www.djc.com)
This was accomplished first with precise, surgical
removal of a significant swath of the second, third and
roof levels, right through the center of the building.
Steel framing was then added back to create walkways,
bridges, skylights and highly customized circulation
stairs that connect the multilevel atrium. The result
is a dramatic light-filled space carved into the heart
of the building.
Another significant project goal was to relocate one
of the two main ballrooms to the opposite corner of
the second floor to improve the functionality of the
spaces.
Needless to say, moving a 150,000-cubic-foot room
within the building cannot be done without some
significant impacts to the structure. A portion of the
existing third floor and roof were demolished and the
second floor was expanded to accommodate the new
two-story south ballroom.
Next, after careful analysis, it was determined the
existing structure could support the weight of a new
third floor inserted into the vacated ballroom space to
capture additional usable area, albeit with a pretty low
ceiling due to the depth of the original roof trusses
that remained.
In the end over 400 tons of structural steel were added
to the building for seismic strengthening, floor infills,
reframing of areas that could not be preserved, and
other miscellaneous improvements.
Simplified seismic system
Early in the design phase it had been assumed that
the shell of the original auditorium space at the south
end of the building would be retained, and the raised
sloped seating floor structure would be removed.
It became apparent that retaining this shell was not
ideal due to significant seismic irregularities and other
constraints. An alternative was designed that replaced
this area with a light-framed custom steel-and-timber
structure.
This system allowed us to also simplify the building’s
seismic system significantly in adjacent areas, resulting in the construction of a new light-filled custom
space at an actual net savings of $1 million.
Jewel boxes
The two new glass-enclosed, three-story “jewel box”
entries were an inspirational design element to add to
the project.
The entries are framed primarily with sculpted
glu-lam members supporting the glass wall, roof and
entry canopy panels. The elliptical-shaped columns
and tapered brace and canopy beam elements required
precision construction.
The glu-lams were fabricated in British Columbia
through the use of North America’s largest five-axis
computer-controlled milling machine.
Lean principles
The UW Capital Project Office has been pursuing
ways to incorporate lean design and construction
principles within the limitations of the general contractor/construction manager delivery model.
For the HUB renovation it was recognized that routing entirely new mechanical and electrical systems
through the existing building would be very challenging given the low 11- to 12-foot floor-to-floor heights.
Due to the complexity of the various structural
systems in the building, Coughlin Porter Lundeen produced a detailed 3-D building-information model of the
structure. The model was then turned over to Skanska,
the GC/CM, for their coordination with mechanical
and electrical subcontractors, who produced detailed
3-D models of their systems prior to fabrication and
installation.
In addition, a mechanical detailer was hired to model
key areas where extreme congestion was identified during the design phase, and these models incorporated
into the bid documents. Skanska believes the early
modeling efforts turned out to be very successful in
streamlining coordination and construction efforts in
these key areas and limiting potential change orders.
On future projects UW would like to build on these lessons and find ways to further the use of lean principles
to streamline construction efforts.
The design and construction work on the HUB modernization has stretched over the past five-plus years.
While it has been a very challenging and intense project, the reward is seeing the finished product and the
university community’s reaction to their impressive
new facility. The building was in dire need of a makeover, both to improve its functionality and to address
seismic concerns.
The new, revitalized HUB will now be much better
suited to serve its purpose as the student nerve center
for this world-class university.
Cory Hitzemann is an associate principal at Coughlin
Porter Lundeen.
Article reprinted by permission of the Seattle Daily Journal of Commerce (www.djc.com)