Pratt Truss Roof Design

This type of truss is used where gravity loads are predominant see below left.

Pratt truss roof design.

Sppu pune page 1 unit no. I have used it often for my model bridges including balsa basswood and popsicle sticks. Design of industrial roof truss 1. Selection of gantry girder design of cross section check for moment capacity buckling resistance bi axial bending deflection at working load and fatigue strength.

What makes it so good and gives it an advantage over the howe truss is how it spreads out the forces when under load. It is easy to construct and is a solid choice for a model bridge design. Often seen in bridges it features several vertical chords that are connected by a diagonal chord. 6b roof truss.

The pratt truss design as pictured above is one of my favorites. An alternative pratt truss is shown below right where the diagonal members are in tension for uplift loads. Here is how it looks. Pratt trusses are commonly used in long span buildings ranging from 20 to 100 m in span.

Sres sanjivani college of engineering kopargaon. The consumption of steel is less in lsm with respect to wsm. This particular 6 section structure has 21 truss members and 12 joints. This chord runs from the top of one chord down to the bottom of the other chord.

In a conventional pratt truss diagonal members are in tension for gravity loads. The pratt steel roof truss design is one of the most common designs. 6 6a design of gantry girder. 2 0 load analysis span of roof truss 7 2m spacing of the truss 3 0m nodal spacing of the trusses 1 2m.

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. Pratt truss this is one of the most popular steel roof truss types and it is quite economical. The pratt truss structure we will be working with a design called the pratt truss originally designed by thomas and caleb pratt in 1844. Structural design i steel structures prof.