Is there an acceptable length of standard 12" truss (let's say Light Duty Tomcat Box with Plates) that can be extended past a point, assuming there is nothing hung on the truss past the point? I realize there's potentially a few other variables here, but figured there must be someone with some guidance, who would start asking questions beyond, say 8ft. Last time I looked at a truss spec sheet I remember seeing distributed load totals but nothing about cantilevered truss.
12" Truss Cantilever- Acceptable Overhang?
- Thread starterjstroming
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Cantilevers are kind of weird. Depending on how they are loaded they can actually make the entire system carry more weight and deflect less. It all comes down to how they are loaded and what that is doing to the point itself and the system as a whole. I wouldn't want to see a cantilever past the center point of a stick, but that is more of a gut thing that I have no backup for.
I attached Delbert Hall's truss rigging calculator. There you can easily see how changing the cantilever affects the whole system. Don't take that calculator as gospel though, you need to do some reading before what all it can do makes sense. There is a lot of math that goes into this and there is no hard and fast rule. All truss makers will tell you that they design their truss so it does not matter how many sticks of truss you have. When correctly attached together they form one system that can be looked at as one beam, not many bolted together.
I attached Delbert Hall's truss rigging calculator. There you can easily see how changing the cantilever affects the whole system. Don't take that calculator as gospel though, you need to do some reading before what all it can do makes sense. There is a lot of math that goes into this and there is no hard and fast rule. All truss makers will tell you that they design their truss so it does not matter how many sticks of truss you have. When correctly attached together they form one system that can be looked at as one beam, not many bolted together.
There are a few things to consider with cantilevers. First, can the truss itself support the load at a given length. Second, are the loads balanced so that the truss stays stationary and doesn't become a teeter totter. Third, do the suspensions have enough strength to support the increased load created by he cantilever.
The calculator Footer shared will help with the second two items. For the first there is a rule of thumb you can use for determining if the truss itself can withstand the forces. The maximum cantilever load is equal to the center point load of a span 4 times the length of he cantilever. So for a 10' cantilever you would look up the CPL of a 40' span.
Again, this is only one part of determining if a cantilever is possible for a given situation. You still need to make sure the suspensions can handle the loads, and that the system is balanced to prevent movement.
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The calculator Footer shared will help with the second two items. For the first there is a rule of thumb you can use for determining if the truss itself can withstand the forces. The maximum cantilever load is equal to the center point load of a span 4 times the length of he cantilever. So for a 10' cantilever you would look up the CPL of a 40' span.
Again, this is only one part of determining if a cantilever is possible for a given situation. You still need to make sure the suspensions can handle the loads, and that the system is balanced to prevent movement.
Sent from my iPhone using Tapatalk
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