beam bracing

[structSU10]

I am trying to determine connection requirements to provide appropriate bracing of a wale beam. It is a double channel wall laid flat, resting on sheet piles with tie back anchors inset 2-3' from the wale beam ends. The argument was over the need for a positive attachment at support / bracing points, assuming friction along the compression flange would be adequate to brace the wale.

Where this argument falls apart is near the short cantilever where the compression flange is away from the sheeting. Even with stiffeners I find it hard to justify the stability without positive attachment. The wale has a bracket to rest on and would need to twist upward which would try to kink the tie back - is there some form of stability provided by the prestressed anchor?

 

[Bagman2524]

A sketch would help

All I know is P/A and Mc/I

 

[milkshakelake]

A sketch would be helpful. But in general, I don't consider the flange away from the sheet piling to be braced. It's very questionable to say that the stiffeners will brace it because it does reduce the rotation, but it doesn't brace it from rotation like a steel deck or other commonly accepted lateral brace. The anchor (generally I think they're post-stressed, but maybe I'm thinking of a different method) will also not laterally brace the waler from rotation like a steel deck would. Considering that the rotation restraint would come from tension in the tieback and be transferred through a hex nut or plate, how much rotational restraint does that really afford? It's not a moment connection.

If the double channel doesn't have enough bending strength, you can weld a plate to it top and bottom, making it like an I-beam. I try to avoid that, but it's necessary sometimes with highly loaded tiebacks.

Depending on how the flange closer to the sheet pile is connected, that COULD be considered laterally braced, like if it's welded. I don't know if friction alone is enough to consider lateral bracing, but adding a few small welds can guarantee it.

Another idea is to use high strength channels. I haven't tried that personally, and I'm not even sure it would be on the market, but it's an idea.

 

[KootK]

Where this argument falls apart is near the short cantilever where the compression flange is away from the sheeting.

At a cantilever, it actually the tension flange that one wants to brace, not the compression flange.

What I most want from a system like this is a tieback to whaler connection that provides rotational restraint to the whaler at that location.