Design And Use Of Engineered Steel Trusses
Based on engineered wood truss designs, steel trusses also follow the common triangular chord and strut configuration as demonstrate d in Figure 1:
The top chords typically bear loads directly, and the resulting tension and compression load distribution through the struts to the bottom chord accounts for the greater overall load bearing capability s of the wood truss.
A commonly observed use of the triangular steel truss system is for electric grid power line distribution towers, for example.
In fact, any wood truss design can now be competitively manufactured using steel elements. The engineering benefits of doing so are lighter weight and better resistance to rot, insect damage, and splitting. A significant architectural advantage of steel over wood is the ability to cold form arches and curves as chord members, further increasing the design versatility as well as engineering stiffness. By incorporating parallel chords much larger spans can be achieved for lightweight coverings and vertical constructions. A parallel chord truss typically uses tubular steel elements and two or more parallel chords much longer that the webs, or struts, as shown in Figure 2:
Note that the parallel chords need not be straight but can be curvilinear, lending additional architectural variety to these structural elements. Knowing the expected live and dead loads, the bearing points, overhangs, and other structural factors, spans over 300’ can be engineered with these steel trusses.
Arches are particularly useful with this application, creating large enclosed or semi-enclosed structures such as aggregate storage facilities, barns, manufacturing enclosures, workshops, etc.