I'm looking for unconventional ideas for large weights. We've had issues several times with large events in locations where we cannot use concrete blocks (because a forklift can't be used), can't stake (pipes underground), and don't have readily available water supplies (for 55 gallon barrels or the 200+ gallon water "jugs"). I'm not kidding, one event used a combination of about 100 steel counterweights (from a nearby high school), dozens of sandbags, and several 800# heavy equipment tires. Obviously, while safe, this was a giant undertaking both logistically and crew time wise.
Large Weights
- Thread starterLavaASU
- Start date
Yes-- they didn't have enough ballast, what they did have shifted, and the guy wires snapped.
Len-- guessing you know this, but I'll post anyways for some of our less experienced members. DISCLAIMER: THIS IS A OVERSIMPLIFIED EXPLANATION FOR EDUCATIONAL PURPOSES ONLY. CONSULT AN ENGINEER OR EXPERIENCED GROUND SUPPORT RIGGER IF YOU NEED TO USE ANY OF THIS.
Unfortunately friction will always be a concern with ballast, just as the soil conditions are an issue with stakes. If the ground is slicker so-to-speak, you need more weight or a way to increase friction. The equation for friction (static) is:
Force to overcome friction= coefficient of static friction * mass of the weight
It would be nice to be able to put in engineered anchors at every place a roof is ever used, but also not very practical for small ones like we use. To be honest, the biggest structural threat to nearly any roof is sail-like objects (backdrop, roof tarp, banners) and pendulums (line arrays, video walls, hanging scenic elements). So we minimize those-- windmesh, quick releases and failsafes for sails and make sure the pendulums can either be dropped quickly or at least cannot swing freely (the forces from an object swinging is a lot higher than the wind load from the object).
Len-- guessing you know this, but I'll post anyways for some of our less experienced members. DISCLAIMER: THIS IS A OVERSIMPLIFIED EXPLANATION FOR EDUCATIONAL PURPOSES ONLY. CONSULT AN ENGINEER OR EXPERIENCED GROUND SUPPORT RIGGER IF YOU NEED TO USE ANY OF THIS.
Unfortunately friction will always be a concern with ballast, just as the soil conditions are an issue with stakes. If the ground is slicker so-to-speak, you need more weight or a way to increase friction. The equation for friction (static) is:
Force to overcome friction= coefficient of static friction * mass of the weight
It would be nice to be able to put in engineered anchors at every place a roof is ever used, but also not very practical for small ones like we use. To be honest, the biggest structural threat to nearly any roof is sail-like objects (backdrop, roof tarp, banners) and pendulums (line arrays, video walls, hanging scenic elements). So we minimize those-- windmesh, quick releases and failsafes for sails and make sure the pendulums can either be dropped quickly or at least cannot swing freely (the forces from an object swinging is a lot higher than the wind load from the object).
Actually, I didn't know much about that stuff (still don't) so I'm glad you have a handle on it. I just ask because I know some people read things and think "hmmm, a couple 25# sandbags ought to do it." It forces those of you who have a clue to give better explanation of the risks involved to those who think this stuff is a piece of cake.
MPowers
Well-Known Member
We have two different threads going here. The OP lavaASU asked about alternate sources for ballast weight. The thread has shifted to "is ballast weight the way to go?"..
We have used all the ballast methods the OP mentioned and more. Because one of our biggest clients, (20 + events a year), is Caterpillar Farm Equipment, no bands or such, but lots of high roofs, moving heads, 20x40 video walls, 150 x 200 foot tents, et al, one of the ballasts we have used is 5 to 10 ton farm equipment. The equipment is part of the display and as a secondary benefit, part of the ballast for the tent/truss/stage roof etc.
Back to the OP's question. Alternate weights and/or how to get them to the site. Worst case, you're stuck with a lot of small weights, sand bags, stage weights etc. Doesn't matter what the weight is, there is a logistics problem, requiring lots of time and manpower. For smaller weights, sand bags etc. we have relied on ATV's and golf carts. Other times we have used water ballasts and military type "water buffalos" and very long delivery hoses. FWIW water has proved to be our best choice of ballast. Even if you have to pay a premium to get it in, you don't have to do anything except pull-the-plug to get it out. Concrete, sand or iron have to be lugged out, same way used to get it in. Second cost.
Bottom line here is you need to get large amounts of weight to a site that has difficult access. Between us we have outlined the ways to do it. Lots of weight (any kind, doesn't matter) carried, golf carted, fork lifted, just weight to be used as ballast.
There's no magic weight or way to move it, just man-up and plan on X hours of time by Y workers to do the job. That's what it takes, charge the client accordingly. It is what it is.
Change the word "ballast" to anchor and you are correct. Ballast is a type of anchor but not every anchor is a ballast. Duckbills into the earth and pile driven stakes into tarmac are anchors but not ballasts.
We have used all the ballast methods the OP mentioned and more. Because one of our biggest clients, (20 + events a year), is Caterpillar Farm Equipment, no bands or such, but lots of high roofs, moving heads, 20x40 video walls, 150 x 200 foot tents, et al, one of the ballasts we have used is 5 to 10 ton farm equipment. The equipment is part of the display and as a secondary benefit, part of the ballast for the tent/truss/stage roof etc.
Back to the OP's question. Alternate weights and/or how to get them to the site. Worst case, you're stuck with a lot of small weights, sand bags, stage weights etc. Doesn't matter what the weight is, there is a logistics problem, requiring lots of time and manpower. For smaller weights, sand bags etc. we have relied on ATV's and golf carts. Other times we have used water ballasts and military type "water buffalos" and very long delivery hoses. FWIW water has proved to be our best choice of ballast. Even if you have to pay a premium to get it in, you don't have to do anything except pull-the-plug to get it out. Concrete, sand or iron have to be lugged out, same way used to get it in. Second cost.
Bottom line here is you need to get large amounts of weight to a site that has difficult access. Between us we have outlined the ways to do it. Lots of weight (any kind, doesn't matter) carried, golf carted, fork lifted, just weight to be used as ballast.
There's no magic weight or way to move it, just man-up and plan on X hours of time by Y workers to do the job. That's what it takes, charge the client accordingly. It is what it is.
Haha-- no worries. Its honestly quite a complicated world I don't claim to be an expert (though I am qualified to safely build the structures we regularly use). I think I learned more about it in my mechanical engineering class than anything else (understanding the forces and dynamics involved, not how to actually build it). That said at some point I'd love to learn more about the larger roofs, so if anyone that does those is looking for an intern or assistant let me know.
Oh and funny story about the sandbags. Had a client email me saying they were "just" going to switch the water barrels (55gal, ~450#) for 2 sandbags (25# each) because those are really heavy and they want to be safe. Major face-palm moment.
Yeah-- sorry should've clarified that. None of the venues we regularly do shows in allow rigging stakes of any type (some allow tent stakes, but thats not very useful!), so in our case we have to use ballast as the anchor.
Thats awesome. Just make sure the tractor doesn't drive away before you remove the lines... that could be bad.
What are water buffalos? Are those the giant water bags? I'd love to find a collapsible water ballast (to make transport easier).
Haha. Unfortunately being a university group that usually boils down to "Hey guys, our 8am call just became 6am" or "hey has anyone been caught drinking in the dorms lately that has community service hours to work off". The later of those obviously being the preference.
FWIW, I can't imagine it costs that much to buy a load of water and have it delivered in one of those water trucks used in construction.
I agree with MPowers that however much it costs to erect the structure is however much it costs. Don't compromise the quality of assembly because the client doesn't want to foot the bill. If they cannot afford to have it done properly, they should not be doing it.
I work at consulting/contracting firm, and nobody in our office would take a job they think they couldn't do properly within the constraints of the project's budget. The first conversation that happens when those things come up is one with the client telling them:
+ that their budget isn't large enough for what they want
+ what it would actually cost for what they want
+ what their options are that fit within their price range.
At the end of the day, if something isn't possible under the constraints of the project, then you either have to find a way to alter your constraints, alter the project, or walk away from the job.
I agree with MPowers that however much it costs to erect the structure is however much it costs. Don't compromise the quality of assembly because the client doesn't want to foot the bill. If they cannot afford to have it done properly, they should not be doing it.
I work at consulting/contracting firm, and nobody in our office would take a job they think they couldn't do properly within the constraints of the project's budget. The first conversation that happens when those things come up is one with the client telling them:
+ that their budget isn't large enough for what they want
+ what it would actually cost for what they want
+ what their options are that fit within their price range.
At the end of the day, if something isn't possible under the constraints of the project, then you either have to find a way to alter your constraints, alter the project, or walk away from the job.
MPowers
Well-Known Member
lavaASU wrote:
A water Buffalo is a trailer that is basically a 200 to 500 gallon tank. It can be pulled by most any vehicle with a hitch. The term is also frequently used for a deuce and half tank truck. The term is from the military.
http://www.bing.com/images/search?q...AB9D759F94C3EA908C6DC341E28EF673C&FORM=IQFRBA
A water Buffalo is a trailer that is basically a 200 to 500 gallon tank. It can be pulled by most any vehicle with a hitch. The term is also frequently used for a deuce and half tank truck. The term is from the military.
http://www.bing.com/images/search?q...AB9D759F94C3EA908C6DC341E28EF673C&FORM=IQFRBA
Last edited by a moderator:
The biggest concern that I would have with alternative ballast would be the attachment point. How do you properly secure something that is heavy but no connection point? That would be horrible to see you have the proper weight in ballast, but the point you were forced to use cannot support the load.
We are having to use certified weight to test stage lifts (Gala) these are 1000 pound chunks of weight that are moved with a 2 wheel cart with and "eye" on the weight. We have moved these up and down house aisle so they are not that bad to move and the eye is rated to carry its own weight of 1000 pounds so that get you the tie off point. We get ours from truck scale people, they are in most major city's, elevator people have weight also. Just a thought.
