FOR RELEASE: May 7, 1997
Contact: Blaine P. Friedlander, Jr.
Office: (607) 255-3290
Internet: [email protected]
Compuserve: Larry Bernard 72650,565
http://www.news.cornell.edu
ITHACA, N.Y. -- For building engineers and climatologists, the memory of
the Blizzard of '96 refuses to melt away.
Well over a year since the heaviest snow of the century fell over the
Northeast, climatological studies now show that had it not been for
structures built "better-than-code," more roofs could have collapsed under
the weight, researchers say.
"In places where roofs should have collapsed, they didn't collapse," said
Arthur T. DeGaetano, a climatologist with the Northeast Regional Climate
Center at Cornell University. "It showed that most buildings exceeded the
minimum building code requirements."
The Blizzard of '96 (Jan. 8-10, 1996) was a whopper, but with snow resting
on rooftops, another smaller storm followed and contributed to even greater
snow weight on roofs. "It snowed, stayed cold, and we got more snow,"
DeGaetano said. "It was the accumulation of snow from the two storms that
posed the snow weight problem."
Enough snow fell throughout the 1995-96 season, that Boston, New York City,
Philadelphia, Baltimore, and the greater Washington area smashed their
snowfall records.
But, during the Blizzard of '96, news reports of roof failures throughout
the Northeast corridor -- Boston to Washington -- prompted DeGaetano;
Thomas W. Schmidlin, associate professor of geography, Kent State
University; and Daniel S. Wilks, Cornell associate professor of
meteorology, to author a peer-reviewed paper, "Evaluation of East Coast
Snow Loads Following the January 1996 Storms," in the Journal of
Performance of Constructed Facilities (May 1997), a publication of the
American Society of Civil Engineers, New York City. The study was funded
by the National Oceanic and Atmospheric Administration.
DeGaetano and the other scientists examined the weight of snow during the
period Jan. 6-15, 1996. Once the snow weights were determined based on
water content within the snow, they corroborated the climatological
information with minimum building codes for given areas. For example, some
of the hardest hit areas were northern and central New Jersey.
For northern New Jersey, building-code minimums generally require roofs to
withstand snow weights of 21 pounds per square foot -- the equivalent of a
storm that occurs once every 50 years. More infrequent storms bring snow
weights of 26 pounds-per-square-foot in 100-year events, and 31
pounds-per-square-foot for 200-year values. The Blizzard of '96 and the
subsequent storm amounted to the equivalent snow weight of a 125-year
snowstorm.
Coastal Maine has different code requirements, as their 50-year snow weight
level is 62 pounds-per-square-foot, their 100-year snow-weight level is 72
pounds-per-square-foot, and their 200-year mark is 83
pounds-per-square-foot. Snow weights here did not exceed the code.
In areas south of Boston, the researchers found that snow weights exceeded
the minimum building requirements.
The Philadelphia building inspector's office reported 55 collapses, mainly
from porches and rowhouse roofs. In Camden, N.J., there were 16 reported
porch and rowhouse roof collapses. These types of structures, however, are
often not covered by building code requirements, or pre-date the
establishment of these standards.
Staggered news reports during the Blizzard of '96 and the subsequent snow
storms provided the scientists with anecdotal information as well, lending
insight to the type of structures and geographic locations to pay attention
to. For example, a barn collapsed in Woodsboro, Md., killing 150 cows
inside; a supermarket roof collapsed in Massapequa, N.Y., injuring 10
people; a 2,500-square-foot section of shopping mall collapsed in
Tewksbury, Mass.; a building that housed a printing company in Bethesda,
Md., completely collapsed; and a lawn and garden shop in Berks County, Pa.,
collapsed under the snow weight, killing one person.
"Climatology affects a lot of different fields, someone has to show how
much snow can fall and what an engineered-structure can handle," DeGaetano
said. "You have to ask what's the maximum snow weight that a roof can
hold, what's the frost depth for underground utility lines, what's the max
winds in an area so that roofs can withstand the winds, what's the maximum
rainfall for an area, so that sewers can handle rainfall. That's what
climatology is all about."
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