of the 1.2 million-square-foot Denver Convention Center Hotel is well
underway, with completion slated for the end of December 2005. The new
hotel rises 438 feet and is the first high-rise building to be constructed
in the downtown Denver area in many years.
The 1100-room, five-star hotel building is composed of two towers joined
at the elevator cores standing above a 5-story “podium” whose
footprint fills an entire city block. One guestroom tower rises to 37
stories above the street level and is capped off with a 3-story, glass-enclosed
beacon illuminated from within at night. The other guestroom tower extends
to 27 stories above the street and is finished with a lounge on top that
features northwest views of the city and mountains. The podium contains
the hotel services, lobby, guest drop-off, and back-of-house functions.
Underlying the building are 3 levels of underground parking along with
mechanical rooms and the hotel laundry. Underground storm water detention
vaults were also constructed as part of the parking garage.
The typical tower floor slab is a 7½-inch post-tensioned flat
slab supported on rectangular concrete columns. The column sizes were
varied, with the largest column having dimensions of 40 x 40 inches at
the base. The stacking of different uses such as guestrooms, hotel services,
and parking created many challenges necessitating the strategic location
and transferring of columns.
lateral-load-resisting system consists of concrete shear walls. The shear
walls sit on a 73 x 73 x 6-foot-thick concrete mat supported by fifty-eight
42-inch-diameter concrete drilled piers. The building shearwalls that
surround the guest elevators and brace the building against wind and seismic
loads are located at the extreme end of the upper guestroom floor plates.
During preliminary design, it was discovered that this eccentricity produced
an undesirable twist of the building during high wind loading. An additional
shearwall at the far end of the floor plate combined with stiffening of
the core using high-strength concrete (8,000 psi) reduced the movement
to acceptable levels.
With specified concrete strengths from 4,000 to 10,000 psi, this unique
and complex project afforded many opportunities for innovation and for
the use of specialized concrete admixtures. The concrete specifications
were performance based to ensure the durability of the below-grade, post-tensioned
parking garage floors. The concrete supplier developed a mix design to
limit the expected shrinkage to 0.05%. Through a collaborative effort
with the contractor, slab support details were modified and improved to
allow the slab to shorten with minimal restraint. As a result, the garage
floors (which measure 400 feet in length by 200 feet in width without
an expansion joint) are crack free and expected to perform without maintenance
for many years.
The current pace of this fast-track construction schedule has the contractor
forming, pouring, and stripping one floor level every four days.
The building will be an 1,100-room, five-star hotel with facilities to
complement the new convention center located across the street from the
hotel. Amenities include grand and junior ballrooms, meeting rooms, a
full-service restaurant featuring a display kitchen, a convention bar,
and a business center for guest use. Additional features include a health
club with a lap pool, a whirlpool, and outdoor terraces on the fifth floor.
The first floor beam-and-slab structure had to be designed to support
a truck dock and a porte cochere / guest drop-off. The truck dock and
porte cochere areas consist of a sloped concrete topping slab over a drainage
mat and waterproofing membrane over an 8-inch- thick, one-way concrete
floor slab supported on concrete beams.
This unique and complex project afforded many opportunities for innovation
and the use of specialized concrete admixtures. Specified concrete strengths
ranged from 4,000 to 10,000 psi. Boral Micron3, a highly reactive pozzolan,
was used to reduce permeability of concrete and corrosion of rebar for
the underground post-tensioned slab parking garage. Agilia was used for
self-consolidation and to improve flowability for the 8,000-psi and 10,000-psi
The enormous amount of concrete required to construct the hotel superstructure
spurred efforts to minimize ready-mix costs without sacrificing performance.
To accomplish this, the ready-mix supplier was allowed to develop concrete
mixes free from the usual prescriptive constraints of the project specifications.
Performance-based concrete mix specifications were developed that allowed
the mix supplier freedom to create mixes that best suited the conditions
of the project.
Performance criteria were specified for strength, durability, and shrinkage.
It was left to the mix supplier (in collaboration with the contractor)
to develop the appropriate water/cement ratios, slumps, cement contents,
aggregate gradation, and addition of admixtures to satisfy all performance
criteria as well as the contractor’s requirements for pumping, placement,
Performance requirements limiting concrete shrinkage were especially
important to ensure the proper performance and durability of the below-grade,
post-tensioned parking garage floors. To minimize cracking of the slab
due to concrete shrinkage, the mix supplier developed a concrete mix that
limited the expected shrinkage to 0.05%. Cracking of concrete can also
occur in post-tensioned slabs as a result of restraint stresses due to
shortening caused by prestressing. Through a collaborative effort with
the contractor, slab support details were modified and improved to allow
the slab to shorten with minimal restraint. As a result, the garage floors
(which measure 400 feet in length by 200 feet in width without an expansion
joint) are crack free and expected to perform without maintenance for
Convention Center Hotel Authority, Denver, Colorado
Hotel Operator: Hyatt
Architect (Joint Venture):
Klipp Colussy Jenks Dubois Architects, P.C., Denver, Colorado;
Brennan Beer Gorman Architects, LLP, New York, NY; Harold
Massop Associates Architects, P.C., Denver, Colorado; The
Roybal Corporation, Architects, Denver, Colorado
Structural Engineer: S. A. Miro, Inc., Denver,
General Contractor: Hensel-Phelps
Project Manager: Faulkner USA
Concrete Supplier: Lafarge Construction Materials,