gibbothegreat Posted July 22, 2013 Share Posted July 22, 2013 Be interesting to find and log all these anomalies but there must be dozens like MPG while we sell petrol in litres.PAR numbers (It's eigths of an inch, i.e. 8 inches for a PAR64) Link to comment Share on other sites More sharing options...
adamharman Posted July 22, 2013 Share Posted July 22, 2013 This is getting a bit off topic, but..... The figures of 7.5kn/m2 for distributed load and 4.5kn for concentrated load come from: BS6399 Part 1: Code of practice for dead and imposed loads - Table 1. Minimum imposed floor loads. They're for stages in public assembly areas which may be susceptible to overcrowding. I only have the 1996 revision, but doubt they've been changed for a while. This part is interesting though: 5.1.3 Concentrated loads When used for calculation of local effects such as crushing or punching, the concentrated loads should be assumed to act at a position and over an area of appliction appropriate to their cause. Where this cannot be foreseen, a square contact area with a 50mm side should be assumed. In a venue which could potantially take visiting shows, and therefore you don't know what to expect, can the concentrated load reasonably be assumed to be applied over an area as large as 300x300?Edit to add: I suppose you can get round that by specifying that the load must be spread over that area. Link to comment Share on other sites More sharing options...
Giles Favell Posted July 23, 2013 Share Posted July 23, 2013 All this should be taken with caution..... Too many assumptions are being made.First of all, it is only theatres with 'large' stages e.g. Reps etc..... That are built to 7.5kN/m2 - Assuming they have been built to BS!Smaller theatres and educational will have been built to 5kN/m2 unless specifically otherwise specified - again, assuming they were built to code......The BS does define a concentrated load as 50 x 50 etc.., whereas the Yellow Book defines it as 300 x 300.MEWPs can be extremely heavy, and their point-load can be extremely high. Therefore one can only make judgements based on the exact model of machine, and full knowledge of the floor. Rest assured, these machines will find any weaknesses.One should always be aware of potential weaknesses such as traps, dip-traps, carpet traps and any alterations that may have been made to a stage floor that may have weakened it.It is not un-heard of to design a stage to 10kN/m2 in order to accomodate powered access. Link to comment Share on other sites More sharing options...
gibbothegreat Posted July 23, 2013 Share Posted July 23, 2013 All this should be taken with caution..... Too many assumptions are being made. Which was kind of my point all along - get the data, make the calculations, and you can find out whether or not it's a problem, rather than going on a hunchFirst of all, it is only theatres with 'large' stages e.g. Reps etc..... That are built to 7.5kN/m2 - Assuming they have been built to BS!Smaller theatres and educational will have been built to 5kN/m2 unless specifically otherwise specified - again, assuming they were built to code......Possibly an assumption right there: my venue is 300 seats, 6m x 9m stage, hardly large at all. Arups told me that they have used the higher figure for distributed load as their de facto standard since quite a while before that BS came into force. Generally, I'm of the mind that no-one ever got hurt by assuming a worse-than-actual case, but if, as seems possible in this case, it's being used to prevent a safer method of working being adopted, then it could actually be detrimental to do that.The BS does define a concentrated load as 50 x 50 etc.., whereas the Yellow Book defines it as 300 x 300.MEWPs can be extremely heavy, and their point-load can be extremely high. Therefore one can only make judgements based on the exact model of machine, and full knowledge of the floor. Rest assured, these machines will find any weaknesses.One should always be aware of potential weaknesses such as traps, dip-traps, carpet traps and any alterations that may have been made to a stage floor that may have weakened it.It is not un-heard of to design a stage to 10kN/m2 in order to accomodate powered access.Yep, agree with this big style - you need to do a thorough risk assessment of every possible point of weakness - but then again, you should have that for tallescopes too. Link to comment Share on other sites More sharing options...
Brian Posted July 23, 2013 Share Posted July 23, 2013 Too many assumptions are being made... Especially as the OP already said... 200-seat college venue ...and as his location is 'Cambridge' this could be a building with a floor constructed something before the last ice-age. Link to comment Share on other sites More sharing options...
Jevans Posted July 23, 2013 Share Posted July 23, 2013 Too many assumptions are being made... Especially as the OP already said... 200-seat college venue ...and as his location is 'Cambridge' this could be a building with a floor constructed something before the last ice-age. Going from OP's profile this is the Fitzpatrick Hall, Queen's College, which was built in 1989. Link to comment Share on other sites More sharing options...
Jivemaster Posted July 24, 2013 Share Posted July 24, 2013 The original problem was access to lights over the stage, (FOH seem to have fixed access) Installing suffecient carefully focussed lanterns onto the grid and having sufficient patching, access could be reduced dramatically so that the properly used Tallescope was suitable. HSE's guidance always suggests reducing the hazard, reducing the risk and repeating this, then and only after everything is minimised does PPE come into play. Link to comment Share on other sites More sharing options...
Brian Posted July 24, 2013 Share Posted July 24, 2013 I wonder what the price difference between a small MEWP and a tallescope is? That money could probably buy an awful lot of lanterns to put in a saturated rig over the stage. Link to comment Share on other sites More sharing options...
gibbothegreat Posted July 24, 2013 Share Posted July 24, 2013 I wonder what the price difference between a small MEWP and a tallescope is? That money could probably buy an awful lot of lanterns to put in a saturated rig over the stage. Five years ago we paid slightly less for a refubished Genie than Flint's list price for a new Tallescope... Link to comment Share on other sites More sharing options...
gyro_gearloose Posted July 25, 2013 Share Posted July 25, 2013 Five years ago we paid slightly less for a refubished Genie than Flint's list price for a new Tallescope.But what are the maintenance costs of a Genie vs. a Tallescope? No point buying a cheap Genie if it costs the earth to maintain. Link to comment Share on other sites More sharing options...
gibbothegreat Posted July 25, 2013 Share Posted July 25, 2013 Five years ago we paid slightly less for a refubished Genie than Flint's list price for a new Tallescope.But what are the maintenance costs of a Genie vs. a Tallescope? No point buying a cheap Genie if it costs the earth to maintain. Six monthly LOLER inspection is all that has been required to date, the firm that does this for us include small items like topping up hydraulic fliud if required. Refurbished is to 'as new' standard, I certainly wouldn't have known it wasn't a new machine if I hadn't seen the paperwork. Link to comment Share on other sites More sharing options...
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