Page T1.2 . 14 May 2008                     
ArchitectureWeek - Tools Department
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Super Seismic Medical Center


In contrast, as Tiscornia describes, "With the base-isolated design, the building is going to be more of a tight box that moves on top of the bearings. Once you get inside the building, it is not much different from any other non-base-isolated building."

The Mills-Peninsula facility comprises a six-story, 450,000-square-foot (41,800-square-meter), 311-bed acute-care hospital, with a connected 150,000-square-foot (13,900-square-meter) medical office building.

The building is a rigid, brace-frame structure on top of pendulum bearings, resting inside what appears to be a huge bathtub.

Where the columns come down and normally would go into the ground, in this design they stop and sit on the friction pendulum bearings, each of which has a steel puck at its center.

The concavity of the bearings absorbs the movement. So the building will move in an earthquake, but as it moves in any direction of the X-Y plane, it will also move upward.

"The weight of the building will slow it down and absorb the force of the event," says Tiscornia.

"They've been doing this in hospitals in southern California," he continues, "but we're using a new technology which uses a triple-concave system which has not yet been used in the U.S." The company that manufactures the systems, Earthquake Protection Systems, is located in the Bay Area, but their biggest clients are in Japan.

In addition to the friction pendulum bearing system, there are fluid viscous dampers — basically giant shock absorbers spread out underneath the building. They are designed to absorb the impact of energy released in an earthquake.

The "bathtub" is actually a moat 30 inches (76 centimeters) wide that runs along the perimeter of the building to enable its movement. In the event of an earthquake, the moat covers will pop open; once the building settles, they will close again.

The utilities that are tied into the city grid come up through the ground and need to span via a flexible joint into the building above ground.

"The greatest complexity here was getting the utilities from the fixed base up into our building and setting them up so they are moveable in any direction, up or down, during the event, and won't fail," says Tiscornia. "There are a lot of seismic joints, ball joints, and flexible connections underneath the building to accommodate this."

Benefits of BIM

Starting early on, a design-assist process involving the general contractor and the major subcontractors was used to reduce "deferred approvals" and to identify potential clashes between the building's physical systems.

"As we got into the project, we recognized there are lots of advantages to three-dimensional coordination, which we never thought of when we started," says Tiscornia, who has ten years of experience using ArchiCAD BIM for the design and construction administration of healthcare projects.

"The seismic clearance zones, for example — we knew the building was going to move, but once everyone saw it on the big screen, we recognized that we needed to carefully coordinate how the systems move independently of each other... so that during a seismic event, all of these systems that are hanging off the building don't get knocked off and effectively shut down the building."

The structural engineer on the project, Rutherford & Chekene, modeled its components, and the subcontractors modeled their respective pieces, including mechanical, electrical, plumbing, and fire protection systems.

Tiscornia says that the majority of the modeling took only a few months. "However," he adds, "getting everybody up to speed — on not just analyzing the coordination, but on dealing with the complexity of resolving issues that came forth — is still going on today."

Navigating Complexity

The original construction drawings for the hospital building were completed in 2D AutoCAD®, and the 3D BIM model in ArchiCAD. Rutherford & Chekene uses Autodesk Revit® Structure.

Anshen + Allen has since completed construction documents for the office building using ArchiCAD to take advantage of BIM. The construction documents are extracted right out of the BIM model.

The construction company, Turner Construction, then uses NavisWorks® JetStream to bring in all the different model file formats and run the collision software reports.

Major challenges on the project have included the file size and the complexity of the model — specifically, what information needs to go in the model and what doesn't.

Tiscornia relates that the team started with a single BIM model, but the file became unwieldy due to an excess of detail.

"We were modeling things like flutes in the precast concrete," says Tiscornia, "and it was getting cumbersome. So we broke it down into individual stories, which became seven models, and that had its own pitfalls."

There was no way to create a single consolidated model that would be useful to the construction team. So there are two files for each story of the building, and each file is a consolidated model. Consequently, there are 14 models, each of them a separate wing and separate story. Back in their native software, they are all connected.

Tiscornia maintains a copy of the full model, but when he uploads to a contractor's FTP site, for example, he only publishes what they need for coordination.

"We're trying to work closer with our consultants, particularly our structural engineer, to be able integrate our models internally as opposed to in NavisWorks in the contractors' world," says Tiscornia.

"We want to be able to look at our systems and their systems together, so we've been working with IFC formats [Industry Foundation Classes object-oriented file format] to translate this information and utilize the structural engineering information in our design process."

Tiscornia admits to having experienced some difficulties. "I really would've liked our systems to work a lot better together," he says, "but we needed to move on, so we didn't have the time to sit down and solve a lot of these problems. We just worked around them and kept moving."

Designed for Healing

Special considerations went into making the hospital family-friendly and an asset to the surrounding neighborhood. Features include single-occupancy patient rooms and sleeping accommodations for patients' families. High-performance glazing, solar shading and floor-to-ceiling glass bring natural light into interior areas, including patient rooms and public areas. Rooftop and ground-level gardens allow patients to spend time outside and enjoy views.

Architecturally exposed steel, curtain wall, and precast concrete present an appealing exterior.

The design also includes low-VOC materials and finishes, cool roofs, advanced mechanical systems with ventilation systems that use 100-percent outdoor air, and a fanwall system instead of one giant fan. Interior areas will house furnishings built from recycled materials. Tiscornia credits the client for seeking out sustainable design.

Systemwide Approach

Mills-Peninsula Health Services is an affiliate of Sutter Health, a major healthcare organization based in northern California. Sutter is currently in the process of rebuilding or retrofitting almost all of its hospitals.

At the end of 2006, it was decided that all of the new projects in the Sutter network were going to be designed with BIM. Even though the design and documentation of Mills-Peninsula was substantially complete prior to this initiative, "they still felt there was value in moving forward with this process," according to Tiscornia.

"We're taking advantage of Sutter's investment in project delivery methods," he remarks, "and one of those methods has been building information modeling, a component of their integrated project delivery approach."

Although Mills-Peninsula is the first hospital in the San Francisco Bay Area to employ base-isolated design, other buildings in the region have already used it: San Francisco International Airport's new terminal, the de Young Museum, City Hall, and some bridges.

A year into the construction phase, it's still too early to crow about how the Mills-Peninsula project is progressing. Tiscornia is positive when he says the steel is going up "pretty quickly."

"The shop-fabricated MEP systems are just recently beginning to show up on site and be installed according to the model," he says, "so we will know shortly if what we've been doing over the past year will contribute to the success of the project."

The project team was ultimately pleased with the BIM approach, according to Tiscornia.

"When we started, everyone had high hopes, and, I believe, underestimated the complexity of what we were doing," he says. "Once we got up to speed, everyone has embraced the concept and thinks it is a great tool."

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Susan Smith is the editor of AECCafe, an online news portal for the architecture, engineering, and construction industry, as well as GISCafe and GISWeekly, an online portal and weekly magazine for the geographic information systems industry. She has been writing about architecture and technology for over 15 years and resides in Santa Fe, New Mexico.



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Through its VirtualBuilding™ concept, ArchiCAD® allows 3D spatial modeling and rendering, as well as more technical building modeling and detailing.
Image: Anshen + Allen Extra Large Image

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Mills-Peninsula Medical Center axonometric section drawing.
Image: Anshen + Allen

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Mills-Peninsula Medical Center site plan drawing.
Image: Anshen + Allen Extra Large Image

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Anshen + Allen and the project team were able to model all the Mills-Peninsula building's services in detail.
Image: Anshen + Allen Extra Large Image

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The Mills-Peninsula building boiler room, as modeled in ArchiCAD.
Image: Anshen + Allen

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With ArchiCAD, construction documents can be created directly from the 3D BIM model.
Image: Anshen + Allen

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One of the structural dampers installed in the Mills-Peninsula Medical Center.
Image: Anshen + Allen Extra Large Image

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Mills-Peninsula Medical Center diagram drawing.
Image: Anshen + Allen


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