Exercise 4 - roof systems

Reinforced concrete

 

http://www.skyscrapercity.com/showthread.php?p=13583399

Structural Steel

 

http://www.wgmetal.com/portfolio/1130-01.html

Space frame

http://www.dpmfabricstructures.com/Space_Frame.html

Steel joist

http://www.quincyjoist.com/products/steel-girders/default.asp