Stanford Medicine Newsletter Updates For the Local Community

 

Under pressure

Building stress tests check for safety and stability 

Components of the new Stanford Hospital were subjected to intense air and water pressure at special testing facilities.

   

Components of the new Stanford Hospital were subjected to intense air and water pressure at special testing facilities.  While bulldozers and backhoes change the landscape to make way for the new Stanford Hospital, parts of the building already have been constructed and put under intense scrutiny. Drenched by high-pressure water hoses, blown by powerful airplane propellers and shaken like a martini, important structural elements have undergone numerous tests to see how they will hold up to an earthquake or other natural catastrophe — long before the actual building goes up.

These in-depth processes revealed potential problems that have already been addressed, saving on construction costs and ensuring the well-being of patients and staff.

The new hospital will deliver advanced treatments and technologies in an environment that is modern, welcoming and easy to navigate. But designing the hospital is not just about appearances: Because Stanford Hospital & Clinics is a crucial community service that must be up and running in case of disaster, the new building’s structural components had to be tested, monitored and appraised for safety and stability.

Integrated approach

“Structural testing was fully integrated into the design process. The tests show us how the building components will react to a major earthquake and other stresses,” said Joseph Brogden, AIA, senior project manager for New Stanford Hospital construction. “We need to check the fit and finish, and see how things move, so we can fine-tune the details now to avoid issues in the case of a real event.”

A design team made up of architects, engineers and contractors drew detailed renderings of several key building components, from the exterior’s precast concrete shell to the silicone that holds the oversize glass windows in place. The team focused on potential architectural stress points in the new hospital, including a glassed corner of a patient room, the circulation corridor outside the operating rooms, a ceiling connection in the main atrium corridor and the inset windows in the intensive care unit.

   

“We wanted to test as many different systems as possible, so we picked elements with multiple components that had to fit together,” Brogden said.

Shake, rattle and roll

Full-size reproductions based on the team’s exact specifications were built at national testing sites. First the team did a series of static tests to check for normal circulation and weatherproofing. Then they did dynamic tests to assess how well the sections held up when subjected to intense air and water pressure powered by a full-size airplane engine, followed by seismic movements replicated by hydraulic jacks. 

One test reconstructed a corner of one of the pavilions, built to scale at 45 feet by 25 feet by 15 feet. Over three days, the engineers subjected it to a number of stress tests to measure its movement range, wind loads and seismic loads. The section was jerked up and down, and side to side, while sensors measured potential leaks and weak spots.

Some of the windows in the new hospital, for example, will be the first in the United States to have a pressurized cavity between double-paned glass with automated blinds inside. These windows use silicon rather than standard fasteners to hold them in place. Since current building codes have not yet caught up to this technology, the 13-by-8-foot windows were tested multiple times at a specialized site in Pennsylvania.

“We needed to make sure that the windows would not leak. After the first test we found some spots where water got through, so we made modifications and tested it again,” Brogden said. “If there’s an issue, we do not leave until we understand the cause or take things apart until the problem is addressed.”

Finally the tests tracked how well the building components could withstand the effects of two different earthquake scenarios: the magnitude the structure can take without developing leaks and the highest magnitude it can tolerate and remain stable.

“Based on the results, each system will be able to withstand an 8.0 earthquake and remain functional,” said Brogden.

Sneak previews

The stress test scenario helps the design team with some of the more pragmatic aspects of the design as well, he said. “We know that the glass will not fall out under stress, but we were also able to see that we could replace the window if the glass somehow got cracked. We checked door heights and hall layouts to see how we could get a replacement in place if the motorized shades broke in 20 years.”

The interior has undergone a similar level of scrutiny. In planning the layouts of the new patient rooms and operating suites, life-size mockups were constructed off-site and assessed by physicians, nurses, technicians and even patients. Their evaluations of the space logistics provided first-hand feedback to improve efficiencies and coordinated care. The layouts also helped the construction teams, who used the walkthroughs to analyze how to position pipes, electrical wiring and infrastructure.

“As the building goes up we will continue to test to ensure that we meet specific criteria,” Brogden said. “Testing is an ongoing procedure, from the initial design to the final stage.”

Learn more about the Medical Center Renewal Project at sumcrenewal.org

 

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