Posts Tagged ‘Northridge Earthquake’

Creating Quake-Proof Hospitals

Thursday, February 11th, 2010

New technologies may help California to build quake-resistant hospitals.California hospitals are just 21 years away from a requirement that they must be able to operate without interruption, even after a significant earthquake.

In response to the January, 1994, Northridge earthquake, the California Legislature passed — in November of that same year — SB 1953, the Hospital Facilities Seismic Safety Act to assure that hospitals meet seismic requirements. After the Northridge earthquake, 23 hospitals were forced to suspend some or all of their services.  Hospitals sustained more than $3 billion in quake-related damages.

SB 1953 required hospitals to meet three deadlines.  By 2002, they had to brace major non-structural systems such as backup generators, exit lighting and other features.  By 2008, all general acute-care inpatient buildings at risk of collapsing during a strong earthquake must have been rebuilt, retrofitted or closed.  By 2030, all hospital buildings must be operational following a major earthquake.

In the years since the legislation was passed, there has been an explosion in the use of quake-resistant technologies in Japan following a massive 1995 earthquake – technology that could be employed by California hospitals to meet the 2030 deadline.  The first quake-resistant system, known as “rubber bearing,” was created in New Zealand in 1977.

Nagahide Kani, of the Japan Society of Seismic Isolation, says the technology has already been implemented in a New Zealand office building and a U.S. courthouse.  Rubber bearings are comprised of layered thin rubber and thin steel plates, and their installation under a structure lets the building move flexibly in a horizontal direction and is highly resistant to quakes.  Additionally, Kani says the steel plates prevent the bearings from buckling even under a heavy structure.

Rubber bearing technology has been installed in office blocks, housing, and the administrative buildings of Japan’s central government.  Technologies introduced after rubber bearings are less costly and suitable for lighter buildings, according to Kani.

About 10 years after the rubber bearings’ introduction came the development of a “sliding isolation system” or slider.  This is made up of a bearing pad atop a curved surface.  During a quake, the pad slides on the curved surface to absorb tremors and support the structure.  Another base isolation system employs ball bearings that slide on parallel rails.  According to Kani, the current emphasis is the application of such quake-resistant solutions to existing buildings, including aged edifices.  He notes that development of quake-related technologies will be a never-ending process.

Sadly, California’s law is an unfunded mandate, so no state or federal funds were allocated to help hospitals pay for the improvements.  Hospitals that cannot afford to comply with SB 1953 by the deadlines will be forced to close or reduce patient services.