Non-Diaphragm Building

[lutein]

We are designing a non-diaphragm building, i.e. steel skeleton building with no diphragm. Would appreciate if you could share your experience and shed some lights into:
1. for gratings clipped on steel beams, do you typically use grating as beam top flange bracing for LTB?
2. What do you usually do for lateral load transfer? What kind of horizontal bracing scheme do you typically use?
3. Any good recommendation on books for this type of structure?

Thanks in advance. Any input would be very much appreciated.

 

[jike]

I do not count on grating providing resistance to LTB.

 

[civilperson]

If there is no grating, there is no live load to cause LTB.

 

[lutein]

The main loads are actually from heavy machines bearing on beams, we are trying to use the grating to brace LTB of the beam. is that something that you all use?

 

[civilperson]

Use diagonal braces in the horizontal plane below the level of the grating connected to the supporting beams.

 

[JAE]

Keep in mind that grating (typical bar grating) has very little in plane shear stiffness and thus isn't very good at providing a "diaphragm" type system to brace your beams. If the grating is tied to a continuous rigid element such as a stiff wall, then the bars could conceivably laterally brace your beam. But as a diaphragm type system, I'd not count on it.

 

[steve1]

I have engineered a number of heavy equipment supports that amount to the equilivant of 4 to 6 storey buildings. In a number of instances we were prohibited from providing any horizontal bracing back to the vertical lateral load resisting system due to equipment. piping, and conduit interfearances or required removal areas. In those conditions I have used the weak axis bending strength of my main members to carry the lateral loads out to the braced frames. I don't count on grating to provide for LTB bracing. Quite often I used column shapes (such as a W8x31) as my beams as these have much better resistance to LTB than a typical beam section (such as W12x22).

 

[hokie66]

You use diagonal bracing in the form of X-braces, K-braces, V-braces, or Chevron braces in the vertical planes. Same in the horizontal planes. Just follow the forces. And no, don't rely on clamped grating for beam bracing. The grating in industrial structures can disappear overnight.