May 20, 2011
Better Buildings For Extreme Climates Will Be Focus Of Researcher’s Talk
NJIT expert speaks to construction industry in Montreal
Rima Taher, an expert in the design of low-rise buildings for extreme winds and hurricanes, will speak next week at the Annual Conference of Construction Specifications Canada (Devis de Construction Canada) in Montreal. Taher, a university lecturer in NJIT's College of Architecture and Design, is a civil and structural engineer, http://www.njit.edu/news/experts/taher.php. Construction Specifications Canada (http://csc-dcc.ca) is a national, non-profit association with chapters across Canada. Its mission is to deliver and develop quality educational programs, publications and services for the construction industry.Certain home shapes and roof types can make a big difference," is a common refrain in all her work.
Taher's key recommendations include the following.
Design buildings with square, hexagonal or even octagonal floor plans with roofs of multiple slopes such as a four-sloped hip roof. These roofs perform better under wind forces than the gable roofs with two slopes. Gable roofs are common only because they are cheaper to build. Research and testing demonstrate that a 30-degree roof slope will have the best results.
Wind forces on a roof tend to uplift it. "This explains why roofs blow off during extreme wind events," Taher said. To combat uplift, she advises connecting roofs to walls strongly with nails, not staples and hurricane clips. Stapled roofs were banned in Florida after Hurricane Andrew. The use of hurricane clips is recommended. The choice of roofing is important. Roofing systems perform differently under hurricane conditions. In tile roofs, loose tiles often become wind-borne debris threatening other structures.
Aim for strong connections between the structure and foundation. Structural failure-- one structural element triggering the collapse of another"”can be progressive.
Hurricane shutters can protect glazing from wind-borne debris. Various designs are available.
Roof overhangs are subject to wind uplift forces which could trigger a roof failure. In the design of the hurricane-resistant home, the length of these overhangs should be limited to about 20 inches.
Last October, Taher spoke at an educational conference in Santiago, Chile on strengthening schools and educational facilities against the risks of hurricanes and earthquakes. The event was sponsored by the Ministry of Education of Chile and the Inter-American Development Bank, Washington, DC http://www.iadb.org.
In the aftermath of the January earthquake in Haiti, Taher prepared a document for Architecture for Humanity about best building practices for hurricane and earthquake-prone areas. It was posted for many months on a reconstruction website in Haiti and still circulates there.
Taher has cooperated with wind researchers at Tokyo Polytechnic University, Japan, to help develop and translate into French a brochure for UNESCO to help Haitians prepare for hurricanes.
In 2007 Taher's article about the design of low-rise buildings for extreme wind events appeared in the Journal of Architectural Engineering of the American Society of Civil Engineers. Another article on improved building practices for hurricanes appeared in Caribbean Construction Magazine in July of 2009.
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