PROVIDENCE CANCER CENTER Portland Medical Center Expansion

PROJECT OVERVIEWOWNER: Providence Health & ServicesLOCATION: Portland, ORCOMPLETED: August 2008SIZE: 486,000 square feetARCHITECT: ZGF Architects

Received a 2009 Grand Award for Engineering Excellence from the American Council Of Engineering Companies Of Oregon

The 11-story world-class facility on the Providence Portland campus posed several thought-provoking problems. Adjacent facilities and a freeway bound the site, and an existing boiler building located within the new facility’s footprint complicated construction. Unable to interrupt the hospital’s 24/7 operations, the team decided to erect a portion of the new 486,000 square-foot center directly over the functioning boiler. Easement issues mandated that the support system span lengthwise over the existing rectangular building.

115-foot span transfer trusses up to 14-feet deep were required to carry the load of nine floors above. The large high-strength structural shapes required for the trusses arrived by ship from overseas. The welded truss sections weighing 40-tons each were trucked to the project site and field assembled.

A diverse building program also created complexities. Traditional lateral systems were ruled out due to layout conflicts and/or schedule concerns. Engineers ultimately selected steel plate shear walls (SPSW) as the best approach for both space planning and performance reasons for this essential facility. While strategic positioning of the SPSWs left continuous programmed spaces within, the system was not yet codified when design began in the spring of 2004. The system had to be approved by the Structural Advisory Board before the City of Portland would allow the 160-foot tall structure to be built to the SPSW maximum height limit.Although challenged by the project’s accelerated construction schedule, KPFF devised inspired solutions that allowed this nationally regarded center to become a place that blends innovation and practical application – in its healing programs and its construction.

INNOVATIVE DESIGN

The Providence Portland Medical Center is an extremely constrained site in an established residential neighborhood adjacent to an interstate freeway. The cancer center was part of a larger campus expansion that demanded creative staging to accommodate a new 900-car parking garage, a three-story Child Center addition that included an employee child care center and a central utility plant. Phasing coordination and communication were paramount as construction was split between two contractors. The engineers also had to deftly work around existing conditions. The boiler room that served the campus sat inside the new facility’s footprint, and its continuous operation to serve the campus’s 24/7 hospital functions was imperative. With nowhere else to locate the new facility, the team performed an intricate operation and erected the new 11-story center over and around the intact 1940s boiler room. Massive trusses up to one-story deep and 115-feet long straddle the boiler room to support the load of nine floors towering above the structure into the sky.

Although the current code now provides guidelines for SPSW systems, the Providence Cancer Center is a preeminent case study that takes the system to its engineering limits.

Built at the maximum allowable height in a seismic design category D area, the essential facility shows how SPSWs can achieve multiple program requirements and meet an owner’s fixed schedule. The project’s success also points the way for engineers to push beyond conventional thought and strive for the acceptance of new solutions.

The Providence Cancer Center characterizes the best of the structural engineering profession to the public. Today’s technology has made the public become accustomed to continual advances in speed, convenience, safety and health. The enormous trusses and SPSWs offered speed in steel erection, the convenience of maintaining diverse floor plans, protection from seismic impacts, and allowed this important health center to be built without impacting life-saving services. The structural solutions are a prime example of invention and solid science, which allow the building’s program elements to shine through. Walking around the facility, the public is greeted by an elegant and tranquil healing environment.

COMPLEXITY

Project staging on the restrictive site was like solving a Rubik’s cube – each critical component had to be in place before another could be removed. With financing tied to the project schedule, the work of accommodating new utilities had to proceed before the scope was finalized. A 10-foot space lay between the boiler room and a parking garage, but it had an easement which meant that no MEP equipment, columns, or foundations could be placed in the space. The team had to incorporate a new central plant within the garage and seismically upgrade the structure to an essential facility without disturbing the easement. In addition, the team had to dig down below the garage’s footings to install two 20,000-gallon fuel tanks.

Finding a way to vault nine stories of the essential facility over a working boiler room required creative expertise. The easement mandated that the support system span lengthwise over the rectangular building, and the transfer trusses needed to carry the load of nine floors above were 115-feet long and one story deep. Manufacturers in the United States could not provide the enormous high-strength rolled steel shapes, so they had to be obtained from Europe and fabricated in Canada. In addition to supporting the load, the trusses had to prevent vibrations from affecting delicate surgical operations and sensitive research equipment. An aggressive building program created diverse floor plans within the single building and the project had a rigorous schedule. In addition, the floor-to-floor heights of the new building had to align with the existing hospital to

accommodate above ground walkways and city code had placed a height restriction on the new facility. It quickly became clear that traditional lateral bracing systems would not meet all the criteria or would add months to the construction schedule. KPFF selected a SPSW system although this facility would be built in a seismic design category D to the maximum height allowed, and the system had not yet been codified.

Faced with demonstrating the shear walls would perform properly under earthquake conditions and with little information available on design and detailing, the engineers turned to professors and an ETABS computer model for answers. Each plate was broken down into 10 diagonal strips to model plate tension field action. Holes from duct work and windows would compromise the integrity of the system, so the plates had to carefully interface with the design. Strategic plate positioning and clear calculations earned the approval of the City of Portland’s Structural Advisory Board to proceed with the project. Meticulous pre-planning was required for erection in the field. Nearly 7,500 shop drawings had to be reviewed in 18 weeks to meet the fabrication schedule. To support the lateral system, engineers designed large mat footings between 6-and 8-feet deep. The building’s overturning forces were handled by massive SPSW columns weighing more than 700 pounds per foot. Anchorage of these columns to the foundation required anchor rods as large as 4 inches in diameter with embedments of 8 feet.

THE STRUCTURAL TEAM

Anne takes a highly collaborative approach to design. She strives to find holistic solutions that combine the owner’s goals with the building architecture, designed systems, and construction techniques. Anne’s deep commitment to sustainability motivates her to create structures that respect both the project location, site, and future generations they will serve. Her hope is to design building structures that withstand the test of time yet remain flexible for future adaptations. She finds medical facilites especially gratifying for the critical role they serve in their communities, but also for the team challenge they pose in design and construction working on 24/7 campus environments.

Anne Monnier, PE, SEPrinicpal | Project Manager

A wealth of experience in numerous project types positions Brad as an excellent design engineer and skilled manager. Brad perceives buildings as living objects that interact with people and serve many generations. He finds education and medical projects particularly gratifying as they benefit students and offer a critical service to society. For the award-winning Providence Cancer Center, Brad guided highly progressive structural solutions and encouraged inventive technologies. With KPFF Portland since its inception in 1974, Brad’s judgment and insight supports his role on the board of the National Council of Structural Engineers Associations.

Brad Moyes, PE, SEPrincipal | Structural Engineer