7.1 WHAT ARE TRUSSES?
À
p
Trusses are at the heart of many engineering projects. We can see one of these in the bridge across the grand river.
Basically, a truss is a collection of beams joined together to carry simple and complex loads.
We can see trusses use in cranes,
Trusses are typically made from beams that are joined with gusset plates.
Other times obvious pin joints are used. Consider the pin joint on the end of the tension member below,
With these types of problems the tension or compression of the beams/members should be clearly indicated. Materials and structures will not fail at the same load when in tension (necking then fracture), than in compression (buckling).
We can see a tension member in a bridge with turnbuckles for tensioning,
The basic assumptions used in most truss and frame problems are,
1. the joints have pinned ends, so the forces exerted by the beam has a direction that is along the line between pins.
2. Forces are exerted at pins, but no moments.
Types of trusses are shown below,
Picture of other types of trusses can be seen below,
Many of the methods in this section can also be extended to the analysis of trusses in 3D.
7.1.1 References
(|
Beer, F.P., Johnson, E.R., Statics & Mechanics of Materials, McGraw-Hill, 1992.
Hibbeler, R.C., Engineering Mechanics: Statics and Dynamics, 6th edition, MacMillan Publishing Co., New York, USA, 1992.
