Pratt Truss Roof Details

These are very economical form of roof trusses.

Pratt truss roof details.

Better yet build your own pratt and howe truss bridges and compare their strength on your own. Pratt truss this is one of the most popular steel roof truss types and it is quite economical. Pratt truss pratt truss is made of steel. Flat truss with cantilever pratt configuration top chord bearing flat truss pratt configuration fl att rus w e nc of ig s l op i ngp are ch ds h w f u t sloping top chord howe configuration floor truss system 42 modified warren configuration mono trusses scissors mono mono parts of a truss framed roof gable end valley set gi rde.

These can vary a lot. However with most model bridges you are just using wood. It offers a new alternative in prefabrication and field assembly methods without basic departures from established. Roof truss span tables alpine engineered products 15 top chord 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 bottom chord 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2 12 24 24 33 27 27 37 31 31 43 33 33 46 2 5 12 29 29 39 33 33 45 37 38 52 39 40 55 3 12 34 34 46 37 39 53 40 44 60 43 46 64 3 5 12 39 39 53 41 44 61 44 50 65 47 52 70.

Vertical members are tension and diagonal members are compression. A roof truss based on two pratt trusses and a bottom chord. In a conventional pratt truss diagonal members are in tension for gravity loads. There are many types of roof trusses as wall as many types of roofs more types than there are parts.

This particular type of truss offers some interesting features mainly thanks to the fact that the vertical members provide tension while the diagonal ones are bringing in compression. For further details on how the loads are calculated on a truss and other design details please read this. The roof truss structure and design is integral to roof structural integrity and shape. There are six main types of roof trusses as listed below.

Pratt trusses are commonly used in long span buildings ranging from 20 to 100 m in span. A way of making a larger truss out of pre fabricated elements of smaller trusses these roof trusses are simple in design but very effective and cheap to build. Fan truss it is made of steel. The truss framed system tfs is a new light frame wood construction concept that inte grates customary construction components roof trusses floor trusses and wall studs into unitized frames.

The roots of the pratt truss involved using iron not wood for the angled members. The ones in the photo above are in a heritage building of around the 1950 s fannie bay gaol darwin nt. It can be used for spans from 6 10m. I think this does give the pratt an advantage but read my best bridge design article more for information.