Corner Brace/Diagonal Strut Forces

[OUOY]

Hey everyone.

I've been working on a few projects recently and we've been wondering about designing corner struts and transferring forces properly. Everything I can find in literature, lectures, and design guides only talks about struts that are only in compressive forces with a wall directly across from it, nothing on diagonals.

Our understanding is that the corner struts will only transfer axial forces and will not develop shear or bending in them. Our connection is just fully welding (5/16" fillet) the strut (we'll call it a HP12x53) all around to the waler flange. This would be for a ring set waler with a strut in each corner.

The issue came when we saw that they used spliced beams (moment/shear plate) from our yard for the strut and we were wanting to ensure that the splices are sufficient if the struts were to develop bending moments. We're adding on moment plates regardless from the waler cutoffs that will be sufficient if there is any extra forces developed.

We also had a shoring memo recently on a public project we redesigned that suggested a waler-strut system and recommended designing the strut for bending as well due to possibly eccentricity as it would be field welded.

I'd love to hear any thoughts or help to understand how the forces actually transfer in corner/diagonal struts, thanks!

 

[PEinc]

I have always designed corner bracers for axial load and for bending due to brace weight, worker live load, and probable build-up of excavation spoils. Make sure that no one in the field uses the corner or cross braces to store materials or equipment (e.g., welding machines, dewatering pumps, etc.) unless the braces have been specifically designed for these added surcharge loads.

http://www.PeirceEngineering.com

 

[EireChch]

Out of curiosity, why would you not assume that there could be some moment loading? It seems very unrealistic. Self weight is the obvious one as PEinc stated. Accidental loading such as impact from an excavator is another that has a relatively high chance of occurring.

 

[GeoPaveTraffic]

I have always designed braces, corner and cross-lot, for axial plus shelf weight; nothing more. Conner braces tend to be fairly short and I usually use the same material as the wale, so the corner braces usually end up being way over designed. Cross-lot braces are a different matter. My preference is to use heavy pipes for cross-lot braces.

 

[OUOY]

I have always designed corner bracers for axial load and for bending due to brace weight, worker live load, and probable build-up of excavation spoils. Make sure that no one in the field uses the corner or cross braces to store materials or equipment (e.g., welding machines, dewatering pumps, etc.) unless the braces have been specifically designed for these added surcharge loads.

Gotcha, I probably have a little bit more forces to add in but as GeoPaveTraffic said below, they're usually pretty under stressed in the first place.

Out of curiosity, why would you not assume that there could be some moment loading?

That's what I am having a hard time understanding. I get the struts are in compression but at an angle, I can't understand how they wouldn't be developing a moment within them.