Pratt Truss Roof Design

In this fashion they form a pattern of interconnected ns.

Pratt truss roof design.

The pratt truss structure we will be working with a design called the pratt truss originally designed by thomas and caleb pratt in 1844. I have used it often for my model bridges including balsa basswood and popsicle sticks. 6b roof truss. This chord runs from the top of one chord down to the bottom of the other chord.

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. Here is how it looks. Design of industrial roof truss 1. An alternative pratt truss is shown below right where the diagonal members are in tension for uplift loads.

The pratt steel roof truss design is one of the most common designs. Sppu pune page 1 unit no. Sres sanjivani college of engineering kopargaon. Pratt trusses are commonly used in long span buildings ranging from 20 to 100 m in span.

This type of truss is used where gravity loads are predominant see below left. It is easy to construct and is a solid choice for a model bridge design. 2 0 load analysis span of roof truss 7 2m spacing of the truss 3 0m nodal spacing of the trusses 1 2m. 6 6a design of gantry girder.

The pratt truss design as pictured above is one of my favorites. Structural design i steel structures prof. In a conventional pratt truss diagonal members are in tension for gravity loads. From above analysis and design of pratt truss following limit state method is more reliable and economical than the working stress method for designing roof trusses for the same configuration of truss total percentage saving in weight of steel is by limit state method is 23 as compare to working stress method.

Often seen in bridges it features several vertical chords that are connected by a diagonal chord. This particular 6 section structure has 21 truss members and 12 joints. The consumption of steel is less in lsm with respect to wsm. Pratt truss this is one of the most popular steel roof truss types and it is quite economical.