Protecting Dali's art

August 2011 » Features » PERFORMING ARTS FACILITY
The new Salvador Dali Museum reflects the artist's work in its structure.
Scott D. Martin, P.E., LEED AP BD+C
Two free-form glass systems – called the "Enigma" and the smaller "Igloo" – are made up of more than 1,000 individual glass panels held in place by interior steel space frames connected to the concrete superstructure.
Moris Moreno
Once the entire steel frame is installed, the pipe connectors are fully welded to the receptor sleeves.
Walter P Moore

Salvador Dali is considered by many to be the most prominent ambassador of the surrealism movement of the 20th century. And most are surprised to hear that the largest collection of his art – outside of his hometown of Figueres, Spain – is not in Europe, New York, or Washington D.C., but in St. Petersburg, Fla. This collection of Dali's art – the largest private collection in the world accumulated over 40 years by A. Reynolds and Eleanor Morse – was donated to a small St. Petersburg museum in 1980, which opened as the original Salvador Dali Museum in 1982.

Salvador Dali Museum
Owner
Salvador Dali Museum, St. Petersburg, Fla.
Structural engineer
Walter P Moore, Tampa, Fla.
Design architect
HOK, Tampa, Fla.
Contractor and construction manager
Beck, Tampa, Fla.
Mechanical, electrical, plumbing, and security engineer
TLC Engineering for Architecture, Tampa, Fla.

As the museum grew in stature and patronage, more space was needed. It also became evident that the converted waterfront warehouse facility that housed the collection provided inadequate protection from flooding and hurricanes. As a result, the museum's board of directors set out to build a new iconic facility that would not only protect Dali's artwork in West Florida's storm-prone environment, but also would attract attention and visitors from all over the world. They hired internationally renowned architect Yann Weymouth with HOK's Tampa office to design the new museum, collaborating with the Tampa office of Walter P Moore as structural engineer.

Protecting the art
One of the primary purposes of the new building was to permanently protect the priceless collection. The old museum was not storm-proof, so the artwork was regularly moved to a more secure inshore facility whenever a major storm threatened the area – an expensive and risky undertaking.

The proposed location for the new museum was only 200 feet away from Tampa Bay and five feet above sea level. Seasonal hurricanes bring not only wind, but also a storm surge up to 25 feet. To keep the museum dry in all non-hurricane flood events, 4 feet of fill was added to the site to raise the building pad. However, this brought the first floor only 14 inches above the base flood elevation. The first floor and its contents could still suffer water damage should a large storm surge accompany a hurricane. To keep the art high and dry, the gallery spaces were placed on the 3rd floor, and the vault and rare book library were located on the 2nd.

With the artwork above the high water line, now the challenge was to keep the rain and wind out of the building. The local building code for this part of Florida requires all buildings to be designed for a 123 mph wind storm – typical for a building with a 50-year useful life. This new museum, however, was being designed to last more than 100 years. The museum board elected to have the structure designed to resist a 165 mph storm.

The shell
A conventional one-way cast-in-place concrete slab and beam system was selected for the base structural system. To economically create attractive exposed walls throughout the building, unfinished and architecturally exposed cast-in-place walls were used in lieu of architectural precast. Using exposed concrete as the load-bearing structure and the architectural finish created several challenges. To prevent water migration through the unpainted walls, Walter P Moore drew on previous experience with walls exposed to moisture and specified 18-inch-thick walls using a dense concrete mix. The mix featured a low water-cement ratio, relatively high minimum cementitious material content, and 20 percent fly-ash replacement in order to minimize permeability of the concrete. To eliminate water infiltration under prolonged exposure during Florida's rainy season, Penetron crystalline waterproofing admixture was added to the wall concrete mix. This water-activated admixture forms a crystalline structure in the pores in the concrete, so that if hairline cracks form throughout the life of the concrete, crystals will form to seal them and prevent water molecules from passing through. The admixture serves as a backup system that is particularly important in areas where the glazing abuts the outer wall surface; any water that seeps into the wall concrete could migrate around the glazing joint.

The walls were poured full height floor-to-floor in one lift and the floor and roof structures were connected to the inside face of the walls with mechanical dowels and a shallow 2-inch key.
Walter P Moore

The architect wanted to minimize pour joints and keep the exterior surface of the concrete as uniform and blemish-free as possible. The traditional method of pouring a multi-level concrete building where there are pour joints below and above each floor level was not desirable in the exposed walls. For this reason, the walls were poured full height floor-to-floor in one lift and the floor and roof structures were connected to the inside face of the walls with mechanical dowels and a shallow 2-inch key. Highly flowable "self-consolidating concrete" allowed the concrete to flow around door and window openings and minimize surface blemishes as it was poured in 14-foot-high lifts.

(above) The spiral staircase continues 28 feet above the third floor and tapers down to a point at the top.
(below) A helical central grand stair connects the ground floor to the galleries 30 feet above.
Photos: Moris Moreno

The museum is not a windowless bunker. Seven of Dali's masterworks are on display in the main gallery and are naturally lit by skylights and light-directing cannons in the main gallery. To ensure the integrity of these openings in a major storm event, impact-resistant glazing with movable aluminum covers that take the initial impact force from flying storm debris were used in the skylights. However, glass directly over the artwork was not the only source of potential holes in the concrete shell. The primary glazing system that encompasses the grand central atrium was designed to withstand the code minimum storm, but could not be designed to resist the 165-mph storm threshold and maintain its aesthetic quality. The design team had to proceed assuming the atrium was exposed to the elements in the worst of storms. For this reason, the interior walls, doors, and windows enclosing the gallery and vault spaces were designed for exterior exposure and 165-mph winds.

An iconic building
Visitors to the new museum first notice two distinctive free-form glass systems referred to as the "Enigma" and the smaller "Igloo." These glazing systems, engineered, fabricated, and installed by Novum Structures LLC, are made up of more than 1,000 individual glass panels held in place by interior steel space frames connected to the concrete superstructure. HOK worked closely with Novum to define the shapes of the Enigma and Igloo, and then Walter P Moore's engineers worked with Novum's engineers to develop attachment strategies and details. Novum's free-form system has been used successfully in Europe, but this was the first application where it would be fixed on all sides and serve as the primary weather barrier. The connections to the structural frame occur at node points along the perimeter where the space frame legs join. Novum's usual connection at each node point utilized steel pipes that are slipped into larger steel pipe receptor sleeves that are precisely located on embedded plates cast into the concrete superstructure. Once the entire steel frame is installed, the pipe connectors are fully welded to the receptor sleeves. The glass was then clamped to the frame at the edges before using sealant to fill all of the joints between glass panels. However, in this application, the welded connections along all sides of the frame, especially a frame with three dimensions and re-entrant corners, produced unmanageably large thermal stresses, which were controlling the design of the steel frame and the foundations. By releasing the axial restraint on the foundation nodes and not welding the pipe to the sleeve – allowing vertical movement of the frames at the base – the maximum design forces greatly decreased and uplift on the foundations was eliminated.

The helix
Inside the building, the most stunning architectural feature is a helical central grand stair connecting the ground floor to the galleries 30 feet above. The spiral shape continues 28 feet above the third floor and tapers down to a point at the top. Dali was fascinated by the DNA structure as well as the recurrence of the golden section in nature. Though a double-helix stair was considered, a more economical single helix ultimately was built. The primary load-carrying element for the stair is the 14-inches-wide by 77.5-inches-deep wall stringer. The treads and landings cantilever off of the stringer adding lateral stiffness to the structure, and help to prevent unwinding. During construction, the stair was unshored and reshored between concrete lifts before locking it into the 3rd-floor structure. This construction sequence minimized stresses in the stair, and allowed most of the natural deflection of the coiled shape to be built into the treads and risers as the stair was erected.

To eliminate water infiltration under prolonged exposure during Florida's rainy season, Penetron crystalline waterproofing admixture was added to the wall concrete mix.
By releasing the axial restraint on the foundation nodes and not welding the pipe to the sleeve – allowing vertical movement of the frames at the base – the maximum design forces greatly decreased and uplift on the foundations was eliminated.
Photos: Walter P Moore

The location of the building, at the southern tip of downtown St. Petersburg, places it at the end of the city's burgeoning arts district. The building sits atop a new outdoor plaza providing a terrific backdrop for summertime concerts, and is a natural gathering place for patrons spilling out of the adjacent Mahaffey Theater or race fans gathering at Turn 10 of the Honda Grand Prix of St. Petersburg Indy Car street race. The public areas on the first and third floors offer full water views of Tampa Bay, but the building is oriented so the glazing has minimal exposure to solar radiation from the south and west. Rooftop solar panels even take advantage of the Florida sunshine to supply hot water for the mechanical equipment. The new $30 million, 66,400-square-foot building truly is a crown jewel in the revitalization of St. Petersburg and the Tampa Bay area, and a fitting architectural tribute to the talents of Salvador Dali.

Q&A with the structural engineer
Walter P Moore's Scott D. Martin, P.E., LEED AP BD+C (SM), project manager for the structural engineering efforts and the structural engineer of record for the Salvador Dali Museum project, discussed the project with the editors of Structural Engineer magazine (SE).

SE: What was most interesting thing about this project that inspired you during the design process?

SM: Working with the Yann [Weymouth, architect of record] and the architects at HOK to develop a structure that achieved what they were looking for aesthetically without preconceived notions of what the structure was going to be – for the stair specifically. There was a lot of back and forth between what we could engineer, what could be constructed, and what fulfilled the architect's design intent.

SE: How was BIM used on this project to benefit the structural engineering team? The whole project team?

SM: All structural elements were modeled accurately and imported into the architectural model so conflicts were quickly noticed in HOK's building sections. Of critical importance was coordination of the Novum glazing system connections to the primary concrete structure. The Novum systems connect to the primary structure on two wall elevations, the roof, the first floor level, and the underside of the 2nd floor slab. Accurately locating all of the connection points and coordinating shifts when necessary as the design evolved would have been much more difficult without the 3D building models.

SE: What was the most challenging aspect of the structural design? How was it solved?

SM: Designing the interface between the Novum system and the rigid concrete structure. Early design forces from Novum were received during construction document preparation, but the forces were revised six times as Novum furthered their design. The final loads were issued as the 2nd floor walls were being poured and more than a few connections had to be revised in the field hours prior to pouring.

SE: What was the most unique problem to solve on the project? How was it solved?

SM: The design of the stair. Walter P Moore had done spiral stairs before, but usually they only involve 1/4 or half turns before being supported by a hidden column or beam element. This stair was a true spiral that rotated one and a half times (540 degrees) and rose 30 feet between supports. Understanding the stair's behavior and determining the best sequence for construction was definitely the most unique challenge.

Firm facts
Houston-based Walter P Moore was established in 1931 and practices in the structural engineering, structural diagnostics/forensics, secure design, seismic design, sustainable design, moveable structures, tall buildings, and BIM fields. The firm includes 340 employees in 13 offices nationwide and has ranked consistently among the top structural engineering firms for Structural Engineer's "Best Firms to Work For" competition.

Q&A with the architect
Yanln Weymouth, AIA, LEED AP (YW), design director and senior vice president at HOK signed and sealed the documents for the Salvador Dali Museum. He shared the following information about the project.

SE: What was most interesting thing about this project that inspired you during the design process?

YW: I love to design complex buildings with a public role, and try to make them look simple. The complexity is an intellectual challenge while the public aspect means that many people will experience, appreciate, and hopefully value the design. Museums are especially multifaceted functionally, but also are a place of intense personal visitor experiences as you engage the building and the art it exhibits; especially when the art is first-rate.

It is special for a designer when a museum is dedicated to the work of a single artist. You can understand the scale and the texture, colors, detail of the paintings and drawings. The Dali is the largest museum in North America dedicated to a single artist – a great one. It was an honor to win the competition and then to permit Dali's work to influence our design. We refrained from ever permitting ourselves to "theme" the architecture, and I really hope we have avoided the trite, but there is no doubt that the design makes obvious but abstract references to the surrealist movement and its exploration of the unconscious.

SE: What lessons did you learn from this project that you will apply toward future projects?

YW: There are several:

  • Concrete: In Florida, concrete is a local product, and among other things, it has a strong sustainability side to it. It is an honest, natural material that one can expose and use to aesthetic ends, whether as precast or poured in place. Recent technical advances we used in the Dali project in waterproofing and super-plasticized mixes will surely be used in many of our new projects.
  • BIM: All our new projects are already in Revit, and we will now ensure that every discipline involved, including and especially the mechanical, electrical, and plumbing fire-protection will also be full BIM. The world will see once the "Great Recession" finally ends for those of us in the built world will be very different from the old one. To design swiftly and in good control of cost and schedule management in this new era will be critical as we move toward integrated project delivery (IPD) on a range of project types. We are now sold on the use of all the design tools we can now exploit.

By the numbers
No. of square feet: 66,400
No. of stories: 4
Structural system types: One-way cast-in-place concrete slabs and beams on concrete columns and bearing walls
Foundation type: Shallow spread footings on soil improved by vibroreplacement

Unique project aspects

  • Impermeable architecturally exposed concrete walls
  • Structure designed for 165 mph winds
  • 60-foot-tall spiral CIP concrete grand stair
  • Depressed slabs in elevator and theater dip below flood plain and designed for buoyancy forces
  • Interior walls around gallery, vault, and library spaces designed for exterior exposure

Cubic yards of concrete: 7,000 in the building (2,300 of which is self-consolidating concrete in the walls)

Unique construction aspects

  • Largest embed plate to connect glazing to concrete was 49 inches by 16 inches by 2 inches thick with stiffeners to fully distribute load
  • Several embed plates connect through and grab the wall with plates on both sides and an HSS section connecting them
  • Concrete walls were poured floor-to-floor in 14-foot-high lifts with self-consolidating concrete to flow around and under window and door openings with minimal vibration

Project schedule
Timeframe for design completion: 24 months
Timeframe for construction completion: 23 months

Project costs
Overall cost: $30 million
Cost of structural elements (concrete, steel, CMU): $4.9 million

Key products

  • Self-consolidating concrete – Mix designed by Florida Rock and installed by Reinforced Structures, Inc.
  • Crystalline waterproofing admixture by Penetron
  • Primary glazing system by Novum Structures
  • Spiral stair modeling conducted in SAP 2000, software by CSI

Scott D. Martin, P.E., LEED AP BD+C, is a senior associate with Walter P Moore in its Tampa office and was the structural project manager for the Salvador Dali Museum. He can be reached at 813-221-2424 or smartin@walterpmoore.com.

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