thin-brick panels add distinctive accent to all-precast ... · bnim/cdfm2 kansas city, missouri g....
TRANSCRIPT
COVER FEATURE
Thin-Brick Panels Add Distinctive Accent to All-Precast Concrete Office Building
20
Tom Nelson, FAIA Project Principal
BNIM/CDFM2
Kansas City, Missouri
G. Kelley Gipple, P.E. Senior Vice President Structural Engineering Associates Kansas City, Missouri
H. Cam Blazer Ill, P.E. Project Manager
CSR Qu inn Marshall, Missouri
Precast and prestressed concrete, together with architectura l precast concrete, were used innovatively to build the new $13 million, fivestory 333 West Eleventh Street office building in Kansas City, Missouri. Adjacent and beneath the building are two below-grade and three abovegrade levels for parking vehicles. The precast/ prestressed structural system provided an economical way for the designers to match the 60 ft (18.3 m) parking bays below to the overhead office spaces. The exterior of the building features curves, overhangs and roof details that are created imaginatively from a combination of wide glass expanses, curta in wall and thin-brick-set architectural precast panels. This article presents the design and construction challenges, architectural and structural features, design considerations as well as the production and erection highlights of the project.
The new 333 West Eleventh Street office building in Kansas City , Missouri, is an all-precast concrete five-story facility with several distinctive features .
Adjacent and underneath the building is a parking structure with two below-grade and three above-grade levels. The structural frame of the building comprises precast/prestressed concrete components while the exterior has wide glass expanses and a curtain wall accented by thin-brick-set architectural precast panels (see Fig. 1). The combined effect produced a building that met the functional, strength, durability , aesthetic and cost requirements of the owner.
PCI JOURNAL
Key among the needs of the owner, a rapidly expanding data-processing company, was the creation of about 100,000 sq ft (9290 m2) of office space plus parking for at least 400 cars. Creating these spaces on the restricted , L-shaped site proved quite challenging. The design was complicated further by the desire for a facade treatment that complemented the surrounding buildings , many of which were brick-faced (see Fig. 2). In addition, due to tenant and financing needs, the project faced a tight construction schedule.
This article presents the design and construction challenges, describes the architectural and structural features of the building, and discusses the production and erection highlights of the project.
The building program was designed to supply approximately 19,500 sq ft ( 1810 m2) of office space on each of five floors (see Fig. 3). Parking facili-
Fig. 1. The 333 W est 11th Street office building in Kansas City, Missouri, combines a precast structure, thin-brick-set precast architectural panels, precast accents and wide window expanses.
Fig. 2. Thin-brick architectural panels help the structure blend with nearby buildings.
September-October 1997 21
Fig. 3. Office levels required only four interior precast structural columns, providing flex ib ility in layouts.
ties were laid out to_offer SO_D_parking spaces on two ramped side-by-side parking decks that flank the building, including two below-grade and three above-grade levels with 60ft (18.3 m) long bays (see Fig. 4) .
The desire for clear-span bays in the parking structure led to the allprecast structural design for the office building as well. The challenge typically rests with matching the office column bays [usually 30 to 45 ft (9.1 to 13 .7 m)] with the desired garage column bays of 60ft (18.3 m). In thi s case, the design team de-
22
cided to use 60 ft (18.3 m) long double tees in the office building to avoid the parking penalty that would have resulted from adding additional columns to the parking levels below.
With that design element in mind, it soon became apparent that an all-precast concrete solution could be used for both the office building and parking structure. This concept was reinforced by the additional economies that would result from the speed with which the precast components could be produced and erected.
VALUE ENGINEERING USED
In achieving thi s final design , the design/construction team brought the precast producer into the planning stages early to allow the company's designers to provide value engineering for every design element. The precaster, CSR Quinn, had built several buildings for the client and was familiar with the company's needs and approaches. Allowing the precaster to review drawings as they were finished in the design formulation stage al-
PCI JOURNAL
• • • •
1.1£ Of lli.D6. AT LfVEL B2
• PARKING LEVEL 83
l N
Fig. 4. Shear walls in the underground parking levels were designed to allow for 60ft (18.3 m) bays, opening the space for better parking layouts.
lowed his staff to devise the best efficiencies and determjne how changes could lower the overall cost without affecting other aspects of the design.
This also perrilltted the precaster to get a jump start on producing the precas t co mponents and creating the piece drawings that would be needed. The precaster essentially entered into a negotiated contract with the owner that then was assigned to the general contractor as work passed out of the design phase. Drawings were shipped to the precaster at regular intervals to update their designers on where the
September-October 1997
design stood. Due to the complexjty of the facade and its details, 467 production drawings were needed to properly document the 722 precast components used to construct the office building (see Table 1). Another 440 precas t components were used in the parking structure (see Table 2).
A key element of the project came in planning the 60 ft (18.3 m) office bays. The structural engineer worked with the precaster to determine if the structure could handle 100 lb (45 kg) live loads needed to span the spaces being planned. The precaster in turn
deterrillned that the loads could be met and helped devise a design for 20,000 sq ft (1858 m2
) footprints that could be ac hieved with only four inte rior columns. This approach greatly enhanced space plannjng and added flexibility in changing interior spaces to meet future needs.
PARKING USES AVAILABLE SPACE
The parking facility was designed as a combination below- and abovegrade structure to take full advantage
23
of the tight site restrictions (see Fig. 5). Usually, the goal would be to make the parking independent of the building , but it was required that every square foot of available space be used, so below-grade space running beneath the office structure was needed. The above-grade parking facade features a combination of thin-brick-faced spandrels and metal spandrels to provide a complementary appearance to the adjacent office (see Figs. 6 and 7).
Table 1. Precast concrete components for office building section.
Type of component Number of components
The key to this type of combined development comes in ensuring the drainage works effectively . With a minimum overdig available, the goal was to drill through rock rather than
t N
Wall panels
Stair
Roof tee
L beam
Inverted tee
Floor tee
Flat panel
Column
Brick panel
Brick column
Architectural panel
Architectural column
Total
Note: I ft = 0.3048 m .
.,...,_
FIRST FLOOR OFFICE
Fig. 5. This ground-level diagram shows how the tight L-shaped space was used.
24
193
22
45
2
52
222
15
33
27
56
26
24
719
Thickness (ft)
12
10
32
24
I
3 1
32
8
24
I
16
47
84
I 24
I Width (ft) -
I lOto 14
4
10
I
2
-
10
10
2
13
5
7
3
PCI JOURNAL
Table 2. Precast concrete components for parking garage section.
Type of component Number of components Thickness (ft) Width (ft)
Column 21
Brick column 18
Stair 19
R-beam
Brick panel 38
Wall 28
Floor tee 144
Roof tee 46
Inverted tee 22
Lite wall 34
L-beam 5 Flat slab 12
Spandrel 21
Planter wall 19
Bollard 12
Tota l 440
Note: I ft = 0.3048 m.
dirt and direct the water away from the structure. Precast perimeter walls were installed below grade as an earthretention sys tem . This allowed the construction team to progress with the foundation quicker, as the precast
24 2
24 6
8 6
15
8 10
10 13
24 10
32 10
24 3
10 12
14 2
8 12
8 6 12 7
19 3 L
components cou ld be cast while the foundation was being dug.
The project's structural system consists of precast shear walls resting on drilled-pier foundations. Connections include 922 #11 grouted splice sleeves
to resist Zone 2A seismic forces. Splice sleeves were used to ensure the splices did not expand outside of the column itself as the columns got higher and thinner. The thin tops of the columns would have made them difficult to pick up at their full height, especially with the trapezoidal-shaped components, so the thinner sections were spjjced to the top.
An expansion joint was placed on the south side of the building. By doing so, the design team was able to take all of the horizontal shear for the structure through the shear walls in the core and then below grade take it into the perimeter walls. In this way, no additional shear walls were needed in the office structure, thus maintaining the open spaces.
ARCHITECTURAL PRECAST CONCRETE ADDS
AESTHETIC APPEAL The precast structural system for the
office allowed work to progress quickly, as it keyed off the already placed parking structure beneath. This
Fig. 6. The combination of brick and metal cladding on the parking garage (foreground) along with precast rooftop accents on the office help the structure blend in with the neighboring bui ldings.
September-October 1997 25
Fig. 7. Vertical accents in the parking structure's stair towers reflect the verticality of nearby taller buildings.
allowed the designers to take advantage of economies of scale in producing precast components, further reducing the budget. In addition, precast architectural panels became a key element in designing the facade , which combines large expanses of glass, curtain wall and brick. These worked in harmony to create a variety of visually attractive elements, including a curving center entry pavilion and precast detail at the roof that includes a large overhang.
The brick facade was created by applying thin brick pieces to precast panels, which reduced the cost, speeded up construction and met the owner's desire to blend in with the surrounding buildings. The neighborhood has an eclectic look, i ncl udi ng a precast building directly across the street that also was designed by the same architect and precaster. However, the designers agreed with the owner that the building should reflect the look of the older, richer structures in the area , which were brick-faced.
Grout joints were left gray to match standard mortar colors, while the acidetched white cement portions had to be separated carefully in production to avoid color infiltration between them. Designing with these thin-brick panels
26
JOINT TO MATCH JOINT BETWEEN BRICK
4" RECESS
1'-J 5%
Fig. 8. Section detail showi ng th in-br ick facing on precast panels.
PCI JOURNAL
was complicated by the designer ' s interest in adding complex details such as brick wraps at the corner, soffits and finishes on all sides in brick as well as an entry pavilion with radiussed surfaces (see Figs. 8, 9 and 10).
BRICK PIERS CHALLENGING A particular challenge arose in pro
ducing the brick piers that conclude at the fifth level of the building with precast and cast-stone capitals supporting an imposing precast overhanging cornice. The cornice, which projects out 6 ft (1.8 m) over the structure, gives the building a definitive termination and provides effective sun-shading. The 60 ft (18.3 m) long double tees had more camber than anticipated -as much as 2 in. (51 mm). This camber created fit-up challenges where the full height windows span between the camber floor and the cornice and where the windows met the cast stone capitals. This did not affect the structural integrity of the building, but it did affect the architectural detail and its true elevation.
The "hat" shape at the top of the entry consists of an L-shaped spandrel and eyebeam in one that forms the structure for the roof, providing both function and decoration (see Fig. 11). It produced structural and casting challenges that were met in design considerations and in the field to achieve the striking visual addition for the roofline that was desired.
The curved entry pavilion also presented challenges for achieving the proper radius (see Fig. 12). Although the design team had worked with curved precast structures previously, creating one with the brick finish meant paying strict attention to tolerances and making some connection adaptations in the field. As the structural engineer also served as the special inspector for the city, engineers were on site most construction days and were readily available to ensure erection went smoothly.
SEQUENCING WAS CRITICAL
All of this work had to be accomplished within the constraints of a building that was designed to be built right to the edges of the property. To
September-October 1997
~ ~
-T WOOD NAILERS AND 1/8" 1/8" EXP. BOLTS BY OTHERS
3/4"
,._ I
1-1 ci g;;
"' OJ ·..,.""""
I
h "' I
"' 1'-6" ,.,
I 1-1
~ ..., ,., :;:;. ::
!\~~ ... ,\ -f{-3/4"
7'-Cf'
Fig. 9. Connection detail between panel and tee.
1/t'± JT. 5' -11 5/8" 1/t'± JT.
1'-11 13/16" 1'-Cf' 1' -Cf' 1'-11 13/16"
3/4" JT. 1'-11 9/16" 2'-Cf'
3/4" JT. 1'-11 9/16"
END OF CORBEL 1 Cf' let' END OF CO BEL
6" 6"
FACE BRICK (2) BE-44 6"x1/4"x0'-6" MASTJCORO PAD w/ 1 5/16"f HOLE CTR'O.
Fig. 10. Connection detail for architectura l panel.
achieve the needed maneuvering room, a staging area was created five blocks away on an open lot.
The precast components were manufactured at CSR Quinn's plant in
Marshall, Missouri. They were delivered to the project site by truck trailer, a distance of about 90 miles (144 krn) .
The precaster delivered ten loads of precast components to the staging
27
Fig. 11. The distinctive roof overhang was created from an L-shaped spandrel that provides function and decoration.
area to prepare the components for erection. These were then taken to the site and lifted into place, with the truck then returning to prepare for another delivery. Each trip was escorted by police vehicles to facilitate moving through traffic and ensuring no
accidents occurred along this short path.
Work started away from the streets and worked toward them. As the structure neared completion and less space was available on the site, sequencing became critical to ensure
Fig. 12. Overview of construction showing erection of precast/prestressed elements.
28
each piece arrived exactly as needed. Work progressed until only two bays were left to be erected. At this stage, the street was shut down except for one lane, and the erection crane was positioned in the street to finish the project.
Erection of the precast components took place between July 1995 and March 1996 (see Fig. 12). The office building was completed in January 1996 and the parking structure was finished only 6 weeks later. The facility was opened for occupancy in July 1996. As expected, during the past year the facility has performed well and the building has become a distinctive landmark in downtown Kansas City (see Fig. 13).
The total cost of the building complex was $13 million. The precast work (production, delivery and erection) amounted to $3,443,000.
CONCLUDING REMARKS
The judges in the PCI Design A wards Program agreed that the building made a unique statement, as they honored it as a co-winner of the 1997 Award for Best Office Building. In bestowing the award, the judges said:
"This building makes extensive use of precast concrete in the structure and its cladding, but its distinctiveness does not stop there. The design solution is more than just a fully integrated approach to using precast concrete; it is in fact an aesthetically pleasing scheme that creates a very light, airy building due to the combination of a curtain wall and precast panels. The use of precast concrete in the roof eyebrows creates an unusual three-dimensional quality that most buildings of this scale have not attempted to work into their designs. And it is a thoroughly delightful, articulated building using a combination of precast concrete and brick."
Many challenges had to be met on this project to create the most effective structure, architectural design and erection logistics. The key to the solution came in the close coordination between the design and construction
PCI JOURNAL
Fig. 13 . Curved thin-brick-faced architectural panels add elegance to new 333 West Eleventh Street office building.
teams during the design and erection phases of the job. The project comprises a mosaic of precisely articulated textures as a result of the careful integration of metal curtain wall, brick, cast stone and architectural precast concrete components. The new facility takes its place comfortably in a downtown neighborhood of both old and new buildings.
September-October 1997
CREDITS Owner: Broadway Square Partners, Kansas City, Missouri
Architect: BNIM/CDFM2 Architects, Kansas City, Missouri
Engineer: Structural Engineering Associates, Kansas City, Missouri
Contractor: J.E. Dunn Construction Co., Kansas City, Missouri
Precast Prestressed Concrete Manufacturer: CSR Quinn, Marshall, Missouri
Office Precast Designer: Frontrange Design Group, Arvada, Colorado
Garage Precast Designer: Bob D. Campbell Engineers, Kansas City, Missouri
29