Lasers used in unprecedented application

Columbus, OH—In 1994 the state of California passed legislation requiring all hospital buildings at risk of collapsing during a strong earthquake to be rebuilt, retrofitted or closed by 2008.

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Columbus, OH—In 1994 the state of California passed legislation requiring all hospital buildings at risk of collapsing during a strong earthquake to be rebuilt, retrofitted or closed by 2008. In reaction to this legislation, hospitals have been searching out new ways to meet the state's seismic-safety requirements. Loma Linda University Medical Center (LLUMC) of San Bernadino, California, decided to look for new cost-effective methods for retrofitting.

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Beam from a high-power Nd:YAG laser cuts through reinforced concrete.
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Most hospital structures are made of reinforced concrete, commonly processed during retrofitting with cutting tools and jackhammers. The disruptions caused by these conventional methods can bring daily hospital activities to a standstill, making it impossible to continue patient care in buildings being retrofitted.

In 1997, LLUMC conceived of a laser-based process that can accomplish cutting, drilling and surface preparation of concrete in these sensitive environments. Initial testing of the process was funded by LLUMC and later led to a major federal grant through the Federal Emergency Management Agency in 1999.

In conjunction with the Edison Welding Institute, Battelle Memorial Institute and Trumpf Laser Technology Center, LLUMC has developed a laser prototype system using a Trumpf 4kW, Nd:YAG laser for cutting and processing concrete in the retrofitting of existing structures.

Laser technology has never been used to make deep cuts in concrete. Most importantly, this technology has never existed in a form that would make it useful for structural retrofitting of a reinforced concrete building. The new process, which will virtually eliminate the typical noise, vibration, dust and contamination problems associated with current concrete removal methods, offers hospitals an option that allows them to continue the delivery of quality healthcare while accomplishing the seismic strengthening required for the future.

Last December, LLUMC conducted a live demonstration of the laser cutting through concrete on a section of the actual hospital. The process is currently under further development and testing before it will be ready for use. The next demonstration is planned for this month.

Contact Heidi Wilson at the Edison Welding Institute at Tel. (614) 688-5000 or e-mail heidi_wilson@.ewi.org.

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