steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
(OP)
Hi
I was wondering why do we always cut the angle sections by truss connections straight?
When we would cut it parallel to the main bottom and top members then we could reduce the gusset plate size by a significant amount.
This would also lead to shorter "gaps" between the members fixing points which should be also better for the load transfer, or?
Am I overseeing something?
By wooden trusses this is usually done this way, so why not by steel?
See attached images




I was wondering why do we always cut the angle sections by truss connections straight?
When we would cut it parallel to the main bottom and top members then we could reduce the gusset plate size by a significant amount.
This would also lead to shorter "gaps" between the members fixing points which should be also better for the load transfer, or?
Am I overseeing something?
By wooden trusses this is usually done this way, so why not by steel?
See attached images










RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
Well...one issue could be....it is easier to cut the diagonal member perpendicular
probably much cheaper in production
best regards
Klaus
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
once in the design office...somebody need to draw all the different angels
angle on one side may be different to the other side
then it is easy to make errors, because how do you measure now the length of the diagonal ??
Same thing in the workshop.... need to change the cutting machine for each member
and also easy to make errors
so all these things makes it expensive ..
best regards
Klaus
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
Reagrds
lolobau
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
In a single joist there could be a ton of different angles based on different member sizings. The design cost, and setting a machine up to cut each one differently would be far more than a little extra steel on the gusset plate. Also considering that you may find that plates come in standard sizes as well, and if your design calls for a minimum of 4.5" plate, 6" might be what's in the shop. They are going to leave that extra steel on because it's cheaper than cutting it to 4.5" and that 1.5" would just become scrap needing to be disposed of.
Keep in mind, for engineers optimization always has to come back to cost, not material. In some industries, like Aerospace and Automotive those are tied together in the overall lifetime of the vehicles, fuel saving will be cheaper in a lighter vehicle, in fields like Civil Engineering, usually minimizing construction labor is more important than a little material, not always, but usually.
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
Why am I seeing always the gusset plates outside of the member? Why don't we weld it inside? The center of gravity lines would then even line up much better
see attached image is version B and C not the best solution? and most ecconomic?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
Do designers actually look into best lining up of center of gravity lines?
see image below
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
dimensions of gusset plates? or is it going to much into detail?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
There are a couple more things about why B, not C as Jayrod indicated cost of the weld for one. On top of that, you can get more weld length in B on the gusset and along multiple faces which is good for redundancy, though that's sort of a tertiary benefit. The last thing would be that in B, the leg of the channel and the gusset stiffen each other more than occurs in detail C, which overall makes the joint stiffer.
Lastly, yes there is care taken in lining up centerlines, ideally all coming together at a point on the joist, in practice due to space at the connection it rarely happens.
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
Depending on the member sizes I doubt that C would really benefit you significantly in lining up the centrelines of each member. The slight eccentricity introduced in A and B likely shouldn't change the design significantly.
RE: steel trusses (angle sections) - gusset plate connection optimized with skew angle cut?
Steel trusses on the other hand transfer the loads, both compression and tension, through the connection plates. In extreme cases, if the web members are too short and the connection plates too thin, localized buckling can occur when subjected to compression. It is the old kl/r trick.
Best regards - Al