WiLL Posted September 7, 2015 Share Posted September 7, 2015 I need to extend my balcony which runs across the rear of my space to accomodate a larger band. I have two pieces of 8'x4' steel deck and all appropriate bolts, legs etc. The decks would be going up on 8' legs to bring it flush with the balcony and then strapped to the pillars which hold up the building (I say strapped but it would more likely be affixed using rigid scaff bars and clamps to both the pillars and the balcony rail). The decks would be joined on their short ends to create a 16' x 4' extension to the balcony making it around 9' deep. Now I have no problem with retaining all the legs on the upstage edge but would love to be able to achieve a clear span on the downstage edge by removing the downstage middle pair of legs (one from each deck). My worry would be though the torsional strain on that bolt, I certainly wouldn't want to rely on just a single bolt to take any enthusiastic jumping by the conductor or musicians. So I was thinking I would run a 16' 48mm steel scaff pipe immediately under the steel frame of the deck just inside the DS edge, clamped to the legs at each end with a diagonal cross brace on each corner, this pipe would sit supporting the entire DS edge of the frame. So I guess my question is, does anyone have any experience of achieving a similar clear span like this? http://i631.photobucket.com/albums/uu40/WiLLF77/scaff%20supports_zpsdponzpge.png Link to comment Share on other sites More sharing options...
J Pearce Posted September 7, 2015 Share Posted September 7, 2015 I'd be looking at doing it with scaffold or layher system, but if you must do it with deck I would be looking at some sort of truss member (2 chord vertical, as there shouldn't be a significant horizontal load) or girder as the bridge, the steeldeck will have less flex than the 48mm pipe, so that will be taking a tiny portion of the load. Consider also the horizontal load imparted on the outside legs by any vertical flex at the centre. I have seen deck floated on truss before to make flown platforms - the rock and roll riggers should have more information on that. [disclaimer - I am not a structural engineer, these are just quick thoughts not reasoned advice backed up with calculations] Link to comment Share on other sites More sharing options...
kerry davies Posted September 7, 2015 Share Posted September 7, 2015 Just take note of page 5 of this. There are staging systems that could form a "bridge" and give one third of the space open below the finished platform but at eight feet high it gets tricksy. I cannot tell you what to do since I do not know the venue or context but I can say with a reasoned level of confidence DO NOT build it like this design and put living humans up on it. If you can't find a generous BR member willing to take a look for a " pie and a pint" then get hold of someone used to building performance staging. Your local builder's scaffies normally haven't got a clue. Link to comment Share on other sites More sharing options...
WiLL Posted September 7, 2015 Author Share Posted September 7, 2015 Yeah I'm aware of the need for cross bracing, I didn't include it on the sketch because I was asking about the open span and couldn't be bothered to draw in all the cross bracing around the back and sides. Having quizzed a staging mate of mine there are systems to allow this but I think I'll end up going for the cheaper option which would be to hire an additional piece of deck making the bridge even larger but allowing a central gap rather then having a join on the centreline. Add that to the fact that in my venue I'm fortunate enough to be able to anchor large pieces like this to the structural steel work of the venue and to coachbolt legs into the floor the structure should suit needs given a little rejigging to the aesthetic dressing. Link to comment Share on other sites More sharing options...
Stuart91 Posted September 7, 2015 Share Posted September 7, 2015 Add that to the fact that in my venue I'm fortunate enough to be able to anchor large pieces like this to the structural steel work of the venue Thinking laterally, could you have a vertical bar going up from the deck to fix to support above? Link to comment Share on other sites More sharing options...
WiLL Posted September 8, 2015 Author Share Posted September 8, 2015 Add that to the fact that in my venue I'm fortunate enough to be able to anchor large pieces like this to the structural steel work of the venue Thinking laterally, could you have a vertical bar going up from the deck to fix to support above? No all I have over head on that line are suspended bars Link to comment Share on other sites More sharing options...
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