Health Partners Ramp
A healthcare provider signed a lease extension with its landlord for its corporate headquarters in Bloomington, MN. The headquarters is part of the Bloomington Central Station (“BCS”), a master-planned, mixed-use development in the city’s South Loop District. The lease extension enabled the contractor to make significant upgrades, including a new 8-level, 1,650-stall parking structure.
Significant time was dedicated to maximizing both the flexibility for future growth opportunities for the healthcare provider as well as preserving opportunities for future phases of development at BCS.
Consolidating the parking in the new parking structure reduced the distance and time the 2,500 healthcare provider employees need to walk to the building, eliminated the need for acres of impervious surface parking, and freed up former surface parking for future development of four or five new buildings on the northwest portion of the site, north of the light rail station and tracks.
KIND OF A BIG DEAL
This new eight-story (1 story below grade, 7 stories above grade) total precast parking ramp structure has 1,666 parking stalls to serve the office tower it neighbors, and facilitates future development within the complex. The parking ramp also has the ability to be expanded southward for a total of 2,700 parking stalls through a future phase of construction.
Precast very quickly emerged as the material of choice for this project. Precast was able to meet the cost, erection time, durability and expandability goals.
FORM IN CONJUNCTION WITH FUNCTION
From the early stages of design, the team of fabricator, contractor, architect, structural engineer, and parking planners worked together to fashion a design that efficiently met the performance and design goals for the project.
The efficiency of a simple box was embraced in conceptual design, and the team found opportunity for variation and relief in the detailing of the panels. Sandblast, acid etch, and honed finishes provided color and texture; simple framed relief in the casting beds provided reveals for shadows. Arranging panels of different finishes within the facades lends a tight rigor and purposefulness to the design; this sort of sophisticated and controlled expression was the goal for the design: to mesh with the overall campus development and play the role of a significant but ultimately background building. Though standing on its own now, the parking structure design anticipates future building developments on adjacent lots and does not want to overshadow those future expressions.
“Beyond the box, however, the design team also identified a major structural element to inject some dynamic spirit: the light wall. The light wall component was seized upon as a signature design element, providing a vertical expression to the overall horizontal expression of the parking levels. It was colored white to further highlight its contrast with the shades of grey in the horizontal panels. These vertical elements also cover the sloping ramp floors, simplifying the exterior into a play of vertical and horizontal only. The important functional purpose of the light wall is to ease the future expansion of the ramp to the south. Haunches are provided so that the wall can stay in place and accommodate bearing any future additional structures. The light wall was repeated on the north side for visual balance and interest.” Mark Baumhover AIA, LEED AP – BWBR
“The design advantages of a Wells Concrete precast parking structure ultimately drove our development decision: the ramp can be efficiently expanded if more office is developed on the site, the ramp was quickly constructed allowing us to accommodate the ongoing parking demand, the interior structural light walls maximize light and safety for ramp users, and the white exterior light walls give the ramp great character.” Mark Fabel, Executive Vice President Development – McGough
“A unique design element was the “fin wall” at the stair/elevator tower. This was an architectural wall that projected out beyond the corner of the stair shaft, and had both faces exposed with architectural finish. We went with back to back panels so that both faces had a consistent form finish.” Tim Morey – ERA
“The project was a success, finishing on-time and under budget.” Andy McIntosh – McGough
This open-air ramp needs to withstand the challenging Minnesota environment, including salt and dirt. Precast achieves this both for cars and foot traffic; the stairs are also done in precast.
Quite a challenge to make a structure this size be pedestrian-friendly. The solution was to maximize variation within the precast surfaces for visual interest, and coordinate the piece sizes to create pattern in the façade. The team coordinated the structural design to provide end load bearing spandrels with 20-foot cantilevers to avoid additional pieces that would have formed joints interrupting the continuous horizontal pattern.
The site is under significant height restrictions from the nearby MSP airport. A construction sequence was worked out to utilize two erection cranes so that the heights during construction were not violated and the erection process met budget and schedule.
The design team seized upon the nature of precast and the fabrication process for details and design interest. They had a desire to move away from the standard horizontal look of a parking structure and instead incorporate a vertical look to match the surrounding office buildings. The solution was to take the interior load-bearing light walls and replicate it to the exterior. Further accentuating the aesthetics by using a white design mix and a unique corbel feature to accommodate future expansion.
Structural details were worked out that incorporated reinforced concrete haunches to both sides of the light wall for double-T bearing and future double-T bearing so that exposed bearing plates could be avoided. This was particularly important because the light wall is white, thus more susceptible to discoloration had there been exposed metal weathering on its face.
The elevator tower needed to be functionally enclosed and tempered, while maintaining visual and material consistency with the rest of the open-air ramp. The solution was to utilize insulated precast sandwich panels.
Expressive use of structure as part of the building aesthetic was a unique design aspect; the contrast of dark horizontal precast with the white vertical precast on north and south sides. The location of these expressive panels also facilitates future expansion of the parking structure.
The parking structure location allows for future building development and shared use of the structure, fostering pedestrian friendly community.
Clear expression of vehicle entry from within the site and from the public road.
Stair tower with access to natural light to encourage the use of the stair – healthy.
A total of 553,687 sq. ft. or 2,004 members of precast concrete was manufactured and erected for this project. No rating systems were used. Components included:
- 3,579 ln. ft. of beams (145 pcs)
- 2,225 ln. ft. of columns (62 pcs)
- 435,661 sq. ft. of 29” x 12’-0” pre-topped double tees (622 pcs)
- 10,434 sq. ft. of 12” insulated walls (35 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- 1,335 sq. ft. of 12” solid foundation walls (8 pcs)
- 2,023 sq. ft. of 8” solid stair walls (8 pcs)
- 4,005 sq. ft. of 12” x 12’-0” shear walls (12 pcs)
- 19,187 sq. ft. of 10” interior light walls (64 pcs)
- 16,520 sq. ft. of 10” exterior light walls (60 pcs) w/ sandblast exterior finish (white arch. ext.)
- 677 ln. ft. of 10” x 3’-11” grade spandrels (18 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- 2,333 ln. ft. of 10” x 7’-3” spandrels (55 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- 204 ln. ft. of 12” x 3’-11” grade spandrels (7 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- 767 ln. ft. of 12” x 7’-3” spandrels (29 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- 159 ln. ft. of 12” infill spandrels (12 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- 821 ln. ft. of 10” infill spandrels (36 pcs) w/ sandblast / acid etch ext. finish (charcoal arch. ext.)
- Precast stairs (28 pcs) at both the main stair and egress stair.
- 1,643 sq. ft. of 8” solid slabs at stair / elevator cores (14 pcs)
- 5,598 sq. ft. of 12” solid slabs at stair / elevator cores (21 pcs)
Precast very quickly emerged as the material of choice for this project. Precast was able to meet the cost, erection time, durability and expandability goals. Earlier on, the contractor did an analysis of cast-in-place and total precast and found precast was the more economical choice. The contractor wanted to do a precast concrete ramp initially, but brought in parking consultant as required by the city, ultimately the team determined, precast was the best solution.