Prolyte Campus blog: Stick to the nodes – Part 1
Nodes are those points in truss structures where the diagonals meet the triangular patterns that give us weight effective load bearing structures. Such structures are relatively easy to calculate for a structural engineer (and maybe harder to produce to some manufactures). There is a little bit of 'room' to play, as we are allowed to take that 'node definition'.
However, it's a good thing to realize that the group of the center between two nodes is the weakest point of that when applying loads. We have alternating strong and weak points in the chords. Truss failure will always initiate a weak point, in that case the strong points do not really matter any more. Just like the weak link in a chain.
The most important thing is that the supports must be in or very close to the nodes.
You should realize that, when the truss and the electric chain hoists, the machine capacity can be close to - or over - the truss capacity.
All the individual forces within a truss, caused by the applied load, will come together in a support point.
A second important issue is high point loads, caused by live loads such as PA clusters or LED screens. Again these support points must be applied in / close to the nodes. Failure of just one member in the lattice structure is enough to initiate a fatal collapse.
Reassuringly, repeated small loads, called Uniformly Distributed Load are not directly bound to the node points. However, trusses loaded with only a UDL should be carefully rigged. Also here, all the forces will come together in the support points.
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