A pitched roof is a roof comprising a sloping surface or surfaces with an angle of usually over 20 degrees. It is a bi-fold, bi-planer roof with a ridge at its highest point. To be more specific – a pitched roof requires a pitch of more than 10 degrees or a roof with two slopes that meet at a central ridge.
Zero Force Members
There are two rules to look for when identifying zero-force members.
Joints with three members where two of the members are parallel, and there is no external load. The third member will be zero-force.
Joins with two members and no external load. Both members are zero force.
The figure below has FIVE (5) zero-force members. Find them all, it's kind of fun.
beam bridges are