Truss Top Chord Lateral Support 1

[hoshang]

Hi all,
For a Pratt truss, lateral support is provided by a transverse U-frame consisting of the floor beam and truss verticals. What about a Warren truss? It doesn't have verticals.

 

[hoshang]

BAretired said:
The cross braced members would be considered tension only as they appear slender enough to buckle under a compression load.

Can cross brace members be ignored in gravity load analysis if they were to be considered as tension only? If so, the support structure in the foreground would seem like the attached image, isn't it?

 

[BAretired]

X-brace members have zero stress under gravity load, but they cannot be ignored because they are required for stability of the structure (actually only one member is required for stability, but it would have to be capable of resisting both tension and compression).

Under wind load from the left, the solid red member would be in tension. The dashed red member would be in tension for wind from the right.

 

[hoshang]

BA,
appreciate your valuable insights. Please find the attached image:

the truss is supported by the inclined member (blue) via bottom chord (green). Why is the horizontal member (red) is there? Can't floor beams (yellow) between the blue lines take the same role as the red one (i.e., make yellow and red as one member? Why the red line is lower than the yellow one? is it to make a room for welding? The inclined member (blue) isn't in the plane of the truss, how the joint connecting green, blue, truss diagonal can be analyzed and designed?