ceecrb1 Posted March 10, 2011 Posted March 10, 2011 Ok background info:I dont know about truss.. I´m a video and sound tech... I´m on holiday right now so dont have ALL the info.Please, I dont want opinions posted, I need hard facts so I can try to convince this guy he is mental (if my suspicions are right). Ok so, on friday he wants me to rig a 6x4 mtr LED screen in an outside public area, it will be situated in the middle of the public during the countries largest open festival in the middle of the city.. imagine all those new years gigs you do.. but 20 days long. The screen with cables should reach somewhere between 1200 and 1500 kg... I need to check that properly when I get back to work.He wants me to rig the truss using the heavy duty truss we have... 52x1mtr ish truss (again this aint my area. but í´m sure you know which type I mean). Now the problem is that he wants me to use the horizontal spans as legs as well.. to create a "large surface area" for advertising.Problems? well if I understand correctly these spans cant take compression loads like he wants when using them as supports... there is no way to afix the horizontal to the vertical other than he wants me to build the two legs, crane the cross piece on top and use ratchet straps to hold it in place..He has apparently got some steel plates made up to be bases (dont know any more than this). I DONT want to do this. I have told them so. but I am getting the "do it or leave" treatment.Here in spain the boss/company takes all LEGAL responsibility but this thing makes me so damn nervous and I dont know so if people WHO KNOW can give me a little idea as to what may or happen here.. I´d be very appreciative. It may work out to be the bosses responsibility but I just dont want this kinda thing over my head (legally and physically).This really is a case of money (advertising) over safety.I have volunteered to rig it properly with the proper legs and motors etc that we have... then to the leg strap on alu poles to create the size needed for the advertising.. at my own time expense etc I´d rather be there all bloody night in the rain doing it properly than what they propose but got told no. Again. Please keep the typical forum opinions quiet till the weekend till after I rig on friday.. I need solid info before then, not 100 posts of how bad this is.. I know already.I cant just walk away from my job over this.. I have a 1yr old baby and there are ZERO job prospects in spain. thanks in advance p.s. on a final note. imagining he has some idea how to safely secure the structure and support it etc etc. ie in "best case scenario" would this truss take the load in this form. Ie if its a case of "might work" and I´m better of keeping my mouth shut and keeping my job..... or is it a case of the numbers just WONT work and it WILL fall because of "x" reason... that I´d like to know so I can try and get him to get it verified etc.
david.elsbury Posted March 10, 2011 Posted March 10, 2011 I think you should leave. I know that's not what you want to hear, but seriously, you keep on going on about how much trouble you are having with this employer/boss of yours, so surely enough is enough? Otherwise, I'd suggest there's no point in posting here, if you already know the "typical forum opinions". I honestly don't know how you can expect people to give you (what appears to be) complex rigging and structural advice over an internet forum, particularly when you (by your own admission) "don't know about truss" and this "isn't your area". Sorry if that isn't what you want to hear... but I don't know how we can say anything else! David Edit: You say you'd like to know if, and I quote, "the numbers just WONT work and it WILL fall because of "x" reason... that I´d like to know so I can try and get him to get it verified etc." If he won't take your word for it now, that it's a bad idea, why is he going to take your word for it when you say some strangers on an internet forum say it's a bad idea?
Wilflet Posted March 10, 2011 Posted March 10, 2011 at risk of being 'typical forum answer':Ask the manufacturer of the truss, if they say its fine then that gives you more confidence than any yes the forum can give you.If its no then you print off the email, show the boss, and if the manufacturer says it wont work and theyve seen this then it should be pretty hard for them to argue to still do it.
ceecrb1 Posted March 10, 2011 Author Posted March 10, 2011 Wilflet.. You might be on to a good idea there, thanks..
Simon Lewis Posted March 10, 2011 Posted March 10, 2011 I need solid info before then, not 100 posts of how bad this is.. That information can only come from the truss manufacturer and / or a structural engineer - but that's always the case with such structures...
trussmonkey Posted March 10, 2011 Posted March 10, 2011 The only types of truss you can use in a vertical plane have diagonal bracing on at least 3 sides (if not all sides). You CANNOT use normal truss for vertical loadings it has to be specific tower truss. Also if you are putting up anything outdoors you must factor in wind speed and wind loadings. Anything that blocks the winds path is in effect a sail. As such this will have a massive effect on your overturning moment and how much ballast you need to put on the bases. As soon as you start cladding the truss etc for branding the sail area increases as you are blocking the winds path through the truss. You really need to walk away from this. You need to speak to a specialist rigging company (I work for one you can PM me if you need to) who deals with these type of outdoor structure all the time. This is not even something for your normal jobbing rigger. It need understanding of a lot of different elements. You should also be talking to a structural engineer who can produce a report on the amount of ballast you need. sorry for the bad news but this if a situation where if it goes wrong it will go wrong in a massive way. trussmonkey xx
gareth Posted March 10, 2011 Posted March 10, 2011 I'm guessing you mean Plaza del Ayuntamiento in Valencia? I'll be in Valencia for a few days at the end of next week - think I'll make a mental note to stay out of the way of any large video screens that I see ...
trussmonkey Posted March 10, 2011 Posted March 10, 2011 "he wants me to build the two legs, crane the cross piece on top and use ratchet straps to hold it in place" didnt read this bit..... all I can say is oh my sweet jesus. No way never. walk away. You may say that you wont be able to find another job in Spain but I doubt your family will like you going to jail for incompetence and involuntary manslaughter when the structure fails and possibly kills people. This is really scary ###### if you dont know what your doing.. The structure will fail as you dont have the right expertise and kit to put it up safely. Sorry again I really feel for you.
ceecrb1 Posted March 10, 2011 Author Posted March 10, 2011 NO gareth not plaza de ayunytamiento.. But similar crowd numbers. Be there for the fireworks at 2 in the afternoon. Impossible to describe but unmissable.. Get there an hour early to get a good spot! Thanks all for the help.. At the moment I'm at work.. He has calmed down and is actually liestening to me for once.. But I'm still not happy about it.Just trying to do what I can to get the changes etc etc..
trussmonkey Posted March 10, 2011 Posted March 10, 2011 Cee you really need to source the correct type of truss and go to a rigging company. cheers
kerry davies Posted March 10, 2011 Posted March 10, 2011 This; In part led to this;http://shop.istructe.org/temporary-demountable-structures.html Maybe if you project it on the workshop wall and mutter stuff like, "Wonder what would have happened if it fell forward onto the crowds?"
LXbydesign Posted March 10, 2011 Posted March 10, 2011 This; In part led to this;http://shop.istructe.org/temporary-demountable-structures.html Maybe if you project it on the workshop wall and mutter stuff like, "Wonder what would have happened if it fell forward onto the crowds?" Bloody hell! Oh, but its ok, the public were not at risk as the screen was designed to tip towards backstage! Never mind the crew then :unsure:
trussmonkey Posted March 10, 2011 Posted March 10, 2011 er no screen or structure is DESIGNED to fall over backstage or other wise !!!
kerry davies Posted March 10, 2011 Posted March 10, 2011 Just in case the younger BR member does not understand how insane the very idea of big screens in the square is at Las Fallas, enjoy these nutters; Have a look at a few of the bonfires setting the tarmac ablaze and just imagine the firemens overtime, they loves it!
ceecrb1 Posted March 10, 2011 Author Posted March 10, 2011 yeah that video shows "la ofrenda" (the offering) the massive flower statue of the virgin mary, a job we do the lighing for.it shows the nightly fireworks el nit de foc (night of fire) which are MASSIVE, the last one every year makes a new world record for the weight in powder burned in one show.The daily fireworks called "la mascletta" (no translation) at 2pm where it is all about noise and rhythm... you FEEL them shaking your organs inside your body,, sounds horrible but its amazing gives such a natural high and adrenaline rush that you cant describe. Trully words cannot describe how great a mascletta is.. I REALLY recommend the trip over in the middle of march to anybody, just to see one of the 20 daily mascletas.. 250kg of "polvera" (powder) in under 5 minutes... and the barriers start at 20mtrs away from the cage. The finale every time is just a pure rumble... trully earth shaking for 10 seconds or so.. the bombs used in the finale are all class 4 fireworks.. and there are so many that you cant distinguish one explosion from another.... in my video.. notice all of them hung from strings (1:45)... ALL of those are let off in seconds. There is also the "crema" (burning) .. again a job I do for the tv coverage.Infact the 2 burnings you can see I did the one at 5.30 but the lights are turned off once the flames take over.. Valencia is the 2nd capital of fireworks in the world.. just behind china.. infact the valencians will argue that they invented it before china... I dont know. http://www.youtube.com/watch?v=FPIWTNkFYOs&feature=player_embedded another far better version of the last one from last year.. I was there.. :oCheck out from about 5 mins onwards.. to see the finale and just how much of the square it takes up in relation to the first 5 mins.http://www.youtube.com/watch?v=N9hQDDP3b-8&feature=related back to my problem. Well I called in a favor of my ex-head tech here.. he knows the boss, he knows the gear we have and knows a lot about truss.We´ve managed to get a decent balance between some kit changes... some advice on how to "beef up" what the boss wont let me change and some other areas which are fine.... feeling far more confident now.. The boss was actually far better than usual. he is extremely head strong but he does trust this ex head tech a lot so took his advice better than my uneducated worries.. Thanks all for the advice and the help.. sometimes when your in a panic ... you cant see the wood for the trees..... I have had one such day.
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