Architect: Morphosis, Culver City, CA
Structural Engineer: Datum Engineers, Dallas, TX John A. Martin & Associates, Inc. (JAMA), Los Angeles, CA
Contractor: Balfour Beatty, Dallas, TX
Total Project Cost: $185,000,000.00
Total Project Size: 180,000 sq ft
The new Perot Museum of Nature and Science is another beautiful structure that will be an icon for Dallas. Driving through Dallas on Woodall Rogers, one cannot miss the large concrete cube emerging from below the highway overpass. Its architecture is uniquely Thom Mayne and Morphosis. This unique and dramatic 6 story (170 foot tall) cast-in-place concrete museum has a very special precast concrete façade, an escalator on the exterior face of the building, a low, curving, and sloping green roof constructed of structural steel over the auditorium.
Morphosis is a group of highly creative and experienced architects who have lofty goals, but get their hands dirty to achieve the vision. Datum Engineers and John A. Martin Associates teamed together joining Morphosis to create this impressive museum structure. Working with such a crew with great talent, has made the Perot Museum a great success. The Morphosis vision of this new museum is “Designed to engage a broad audience, invigorate young minds, and inspire wonder and curiosity in the daily lives of its visitors, the Museum will cultivate a memorable experience that will persist in the minds of its visitors and that will ultimately broaden individuals’ and society’s understanding of nature and science… the new building itself becomes an active tool for science education. By integrating architecture, nature, and technology, the building demonstrates scientific principles and stimulates curiosity in our natural surroundings.” Morphosis, Datum and John A. Martin integrated steel reinforced concrete in innovative ways to accomplish this unique structure.
STRUCTURAL FRAMING SYSTEM
By maintaining a LEED Gold Certification, the structure incorporates energy, water and material sustainability concepts throughout. This building is unique in many ways. The design and construction of many different techniques can be seen throughout this structure. Remarkable pre-cast concrete planks create the cube superstructure and exposed concrete structure was intended to be the “canvas” for exciting exhibits for children and adults alike. The concrete frame is a simple pan and joist system stabilized with a cast-in-place concrete wall system at the core of the building. The core sits on a 4-foot thick mat slab supported on 64″ diameter concrete drilled piers. The reinforced concrete drilled piers extended 60 feet down to the limestone bearing stratum.
But, that’s where the “standard construction” stops and the creativity of the Datum/JAMA TEAM begins. The team created several physical models to study and understand the complex geometry of the building. In the initial stages of design, these models helped the structural team visualize and create solutions to difficult three-dimensional problems. As the design process matured, the physical models were replaced with three dimensional computer models using Revit and a Building Information Model (BIM). On the first level, sloping concrete columns create more open spaces, supporting an eight-foot tall perimeter concrete transfer girder. Morphosis envisioned an open atrium, encompassed with curving precast and large glass expanses. Long space stairways crisscross through the atrium, connecting floors and mezzanines. Post tensioned cantilevering concrete beams where used periodically to achieve the architect’s vision in some places. The tall glass curtain wall at the entry lobby is laterally stabilized with post-tensioned cable in lieu of standard mullions creating an extremely clear glass opening in the face of the building. Each of these cables are tensioned from 42,000 lbs to 75,000 lbs, pulling up on the first level and pull down on the second level with a great accumulative force.
UNIQUE STRUCTURAL AND/OR ARCHITECTURAL DESIGN FEATURES
The first and second floors were carefully designed to accommodate these special imposed loads in addition to the typical museum loads anticipated. There are massive cantilevering and buttressed retaining walls throughout the project and beautiful concrete lightwells on the north side of the museum allowing light in to the children’s study areas. The “Y-columns” support a large 8-foot deep transfer girder on the second floor supporting the above superstructure. The concrete girder is conventionally reinforced using strut and tie design over the “Y”. Reinforcement congestion was studied very closely working with the detailer in a 3D environment. Then, working with the contractor, a full scale Y-column mock-up was created to study installation of the reinforcement, formwork installation and final finishing results. This was a very successful and well-managed operation.
The building design allows a collection of storm water run-off into two underground, on-site cisterns. The water is treated and reused for various purposes. The water recycling strategy meets 100% of the sites irrigation needs. There are unique post tensioned concrete Vierendeel trusses, one story tall, between the 5th and 6th floor to create a relatively column free space on the 4th floor. It’s a 64-foot long, 15-foot tall concrete truss designed to be hidden through the fifth floor office space. The vertical elements are seen as columns. This mezzanine is hung from the Vierendeel concrete truss above, leaving a columnless space below. A full height concrete Vierendeel Truss between the 5th and 6th floors was also designed. This creative solution eliminated three columns creating a Grand Space for the Dinosaur Exhibit on the 4th floor. Mezzanines constructed between the concrete floor systems were constructed of structural steel to allow the concrete frame to be constructed without delay and the mezzanines were built later.
REASONS FOR CHOOSING REINFORCED CONCRETE
Concrete construction is commonly used in the Dallas area and was a natural method to incorporate. Much of the concrete structure is exposed and contributes to the goal of education and stimulating curiosity. We incorporated sloping columns, pan joist, cantilevered reinforced and post tensioned elements, and two-way flat slab design. Additionally, 51% high volume fly-ash/slag content was incorporated in the concrete elements to meet LEEDS requirements. The floors were painstakingly grinded and polished showing a beautiful assortment of exposed aggregate.
Not only is the building an impressive concrete structure, areas outside the perimeter of the building used reinforced concrete. A 35-foot tall concrete, buttressed retaining walls hide the museum dock area in a way that is integral with the overall design. Area retaining walls, walkways, light wells and underground cisterns were also designed and constructed.
“It is so compelling to hear how many great researchers, scientists, engineers, doctors and educators first became interested in their chosen fields as a result of visiting a great museum of science and natural history. It is our hope that this museum can be an inspiration to the next generation of pioneers, discoverers and visionaries.” – Nancy Perot Mulford.
“The Perot Museum was constructed using many reinforced concrete techniques to accomplish the architects Vision. Much of the concrete structure is exposed and contributes to the goal of education and stimulating curiosity. We incorporated sloping columns, pan joist, cantilevered reinforced and post tensioned elements, and two-way flat slab design. Very few buildings are designed using such a wide variety of reinforced concrete techniques.” – Jeffrey S. Koke, P.E., Datum, Structural Engineer.