Saturday, November 17, 2012

Reinforced Concrete

By John Ranieri

In Nicaragua, NGOs like Bridges to Community work with rural communities to help build strong, safe, and reliable homes for Nicaraguan families. Homes are of critical importance as a source of collateral, shelter from the elements and protection from burglary. Most rural Nicaraguans live in shacks put together by scrap wood, tarp, garbage bags, and pieces of rusted corrugated metal sheets. These are very fragile, not resistant to much force, and are destroyed by minor hurricanes and earthquakes. Since lumber is very expensive in Nicaragua, most ‘permanent’ houses are made with concrete. When Bridges to Community builds houses, they reinforce the concrete with both horizontal and vertical rebar trusses.


Ultimate strength of concrete: 25 MPa
Ultimate strength of reinforced concrete: 413 MPa

413 MPa/ 25 Mpa = 16.5

Max strength = F/A

So, for the same unit area, reinforced concrete can withstand 16.5 times greater force than normal concrete can.

These houses will be well protected against strong hurricanes and earthquakes.

References:
http://etd.library.pitt.edu/ETD/available/etd-11142009-163350/unrestricted/Zeno-11-20-09.pdf
http://www.engineeringtoolbox.com/concrete-properties-d_1223.html

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