Truss Connection Details

[7202cdz]

I try to design a steel truss connection using gusset plate welded to truss chord. The diagonal tension member and vertical compression member will be welded to gusset plate. Please see attached sketch Detail Option 1. I am thinking to extend the vertical member to the face of chord and also weld vertical member flanges to the chord. Are these two details provided same gusset plate design? Does the detail option 2 make the connection stronger than the detail option 1? Thank you very much.

 

[JedClampett]

Detail 2 makes the connection marginally stronger. More weld, plus no chance of the gusset plate buckling between the vertical and the chord.
But if correctly designed, Option 1 will work just fine. And it will be much easier to build. The vertical doesn't have to be cut exactly to the right length or perfectly square. If you look at 100 trusses, something closer to Option 1 will be on 99 of them.

 

[slickdeals]

How long is the truss? Is it going to be field assembled or shop fabricated? I would avoid field welded connections in case this is going to be stick built in the field.

Why aren't the 2 Channels back to back being bolted? Why is the vertical member a wide flange and not a 2C's or 2WTs?

Depending on your true clearances, welding the web of the W4 on the side where you have the diagonal could be difficult.

 

[7202cdz]

Thanks you both. The truss is around 60-ft. it will be field welded (weld on job site and erected). W4 is stock material. Is it possible that the Detail 2 requires more weld between gusset plate and chord members than the detail 1(if use same size gusset plate and locate at smae location)? Since the W4 flange welded to chord will change the welding centriod location og gusset plate weld to chord. This centeriod change might produce additional moment on gusset plate, welding between gusset plate and chord.Thank you very much.

 

[BAretired]

No, it is not possible that Detail 2 requires more weld between gusset plate and chord, but Details 1 & 2 are both awkward connections requiring a slit cut in the web of the vertical member. Double angles, one each side of the gusset plate are a more typical configuration for web members.

Since the vertical member carries compression only, you could rotate the vertical 90 degrees and rely on direct bearing between webs of the vertical and chord (assuming the bearing area is adequate for the compressive load). Then the weld would be nominal unless there is a possibility of stress reversal.

BA

 

[7202cdz]

Thanks BA. It is a stange connection. I am unable to find one similar case after review a lot of availabe information. Thanks again.

 

[rb1957]

doesn't detail 2 add welds (along the base of the compression member) ?

does detail 1 look particularly "tender" for bending about the weak axis of the gusset ? is shoring during erection a reasonable assumption ?

detail 2 looks like it requires the compression member to be cut very carefully (presumably you'd use the same gusset at the other end).



Quando Omni Flunkus Moritati

 

[sandman21]

Option 2, why are you notching the Wx vert.? just run the into it and weld.

I would suggest in either option adding full height stiffeners

 

[UpNorthStruct]

I agree with BAretired. Rotate the vertical 90 degrees and weld it directly to the chord. The gusset plate will only be needed for the diagonal and should simplify the connection. The out of plane bending of the truss is largely controlled by the width of the truss and not the section properties of the verticals, so rotating the vertical should not be an issue.

 

[charliealphabravo]

The capacity of a truss compression webs is usually governed by lateral unbraced length. If you compare the lateral buckling failure mode with the connection failure modes you will know if increasing the connection capacity will contribute anything to the capacity of the system.