August 22, 2013

Children's addition built to be safe after an earthquake

By TERRY LUNDEEN Coughlin Porter Lundeen

During an earthquake, if the primary structural elements of a hospital remain generally intact and the occupants unharmed, the building can still be left inoperable by damage to interiors and systems.

A single triggered sprinkler system can flood multiple floors and require evacuation of patients. A broken light boom or a severed gas line in an operating room would leave it unusable during that critical window immediately following the seismic event.

For most buildings, modern seismic design codes are focused on protecting the occupants from harm. The ability to occupy the building immediately after a seismic event is ideal, but is not mandated.

But for essential facilities like those operated by Seattle Children's, the needs are different. In providing Level 1 trauma rehabilitation and critical care for four states, the Seattle Children's mission mandated that their new facility, Building Hope, would continue to serve the Northwest regardless of local seismic events.

A new approach

Since the 1970s, the level of analysis and design for hospitals has progressively advanced beyond standard building code, with the recognition that these essential facilities must continue serving the community immediately following an earthquake. What is only now starting to be addressed is how to reliably secure all of the other building systems and contents to ensure the building will be not only safe, but useful.

During the early planning stages for Building Hope, Coughlin Porter Lundeen recognized a more comprehensive approach to managing seismic risk would require two major changes: a shift in funding allocation and an agreed-upon process to ensure the design and installation specifications are precisely executed during construction.

Setting design goals

Collaborating with ZGF Architects, our earliest priority was to work with the Seattle Children's leadership team to determine their performance goals for the building so risk-management funding could be allocated. As California discovered after passing SB 1953, a hospital seismic safety law, replacing a non-compliant hospital is often more cost-effective than attempting to upgrade it to immediate occupancy standards, so well-informed initial investment decisions are crucial.

We examined hospitals damaged by past earthquakes in Chile, California and elsewhere to determine what might require more emphasis during design.

Photos by Steve Savage [enlarge]

Pneumatic tubes whisk lab results and prescriptions throughout the hospital. The seismic design focused on keeping such essential systems up and running after an earthquake.

Current seismic core design standards for health care facilities have been successful in keeping the buildings standing -- even after an extreme quake. However, many of the facilities were out of operation for prolonged periods due to damage to contents. This suggested that an emphasis on additional structural strengthening may not be as beneficial as securing building contents.

We presented the Building Hope leadership team with a series of scenarios and straightforward options, clearly demonstrating relationships between post-earthquake building performance and upfront capital investment costs.

Seattle Children's selected an enhanced seismic design that best met the organization's performance goals of immediate occupancy, post-event. These goals included a greater focus on securing building contents than has likely been the case with any health care facility in Washington state.

Performance-based design

Our initial task was to perform advanced site and structure-specific analysis. These analyses generated definitive seismic goals for both the building structure and its interaction with the building's contents during an event. The design team then began the task of integrating this analysis into specifications for every wall, pipe, conduit and manufactured piece of equipment that would eventually compose a major hospital.

In collaborating with Seattle Children's on smaller past projects such as the construction of their data center, Coughlin Porter Lundeen used performance-based design with success for similar purposes. Performance-based design, first used in the 1990s to address seismic retrofits, is a process that identifies what is needed for the building to function and integrates those needs into the building's overall design.

Building Hope was Seattle Children's first opportunity to apply performance-based design at a programmatic level and on a project of this magnitude and regional importance. To achieve this, each building system was examined through the lens of a possible major seismic event, and design specifications were modified to reflect the goal of remaining operational.

Lessons from California

During an earthquake, seismic design accommodates building movements in gradations. The greater the movement, the greater the potential damage to the building. But structural damage doesn't necessarily cause the building to be vacated after the event.

Experience shows securing building contents is more critical, which means that in addition to designing to an enhanced level, the specification, construction, commissioning and installation of all contents must be rigorously scrutinized. For example, even broken glass from incorrectly installed windows would require patient evacuation.

As a practical matter, building design and construction typically accommodate a margin of error. The need for absolute compliance raised concerns about the ability to source project components, such as emergency generators, that would offer consistently high quality.

Another concern with this approach for Seattle Children's and general contractor Sellen Construction, was ensuring that the need for this enhanced level of compliance did not impact the eventual occupancy date.

To respond to both issues, the design team turned again to lessons learned in California.

California's health care facility construction is governed by the Office of Statewide Health Planning and Development (OSHPD). Among the most advanced in the U.S., the requirements are effective in providing the needed quality, but the process is notoriously slow.

For Building Hope, selective use of OSHPD performance metrics, specifications, and pre-approved components was key to keeping the project on schedule while still maintaining the necessary quality. With no seismic oversight agency in Washington state, the project team was able to use the most successful aspects of the OSHPD framework within a streamlined private-sector process.

Nine months prior to construction, design specifications were distributed to all subcontractors to provide early notice of the enhanced requirements. A dramatic shift from traditional construction, all subcontractors were required to submit extremely detailed drawings for pre-approval showing installation details so the design team could evaluate compliance.

However, for many items, subcontractors were able to utilize pre-approved OSHPD design details and equipment for elements such as elevators, pump systems, and mechanical vibration controls. The ability to use these pre-approved details and equipment maintained quality while reducing the level of effort and coordination for each building system.

Our firm provided design specifications and oversaw Mayes Engineering, who hired Washington state's first OSHPD-certified inspector for the duration of the project. Sellen successfully provided the extensive coordination required to educate and administrate full compliance among the numerous subcontractors.

Building Hope successfully opened in April, fully compliant to the enhanced seismic design specifications, and with no impact to the overall schedule. Thanks to the vision of the Children's Hospital leadership team, Building Hope can expect minimal disruption after a seismic event.

Coughlin Porter Lundeen Principal Terry Lundeen has more than 30 years of experience on health care facilities, high-tech office buildings and public structures.

 

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