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Thread ID: 141816	2016-03-04 21:14:00	Darwin Rules !	Terry Porritt (14)	PC World Chat

Post ID	Timestamp	Content	User
1416887	2016-03-05 21:22:00	I too think it's a bit heartless laughing at the students for their ignorance. It's like blaming a child who electrocutes themselves by poking a finger somewhere they shouldn't. I think that is a very accurate point comparing University Students with young children. :D	B.M. (505)
1416888	2016-03-05 21:43:00	Certainly not drunken students. "Thinking" is just not in the party tool chest. absolutely ! there is a risk here that this incident will be swept under the carpet without ever being looked at. everyone will blame the students, council is already ducking for cover and no one will actually go in and work out exactly why it failed.	tweak'e (69)
1416889	2016-03-06 04:17:00	absolutely ! there is a risk here that this incident will be swept under the carpet without ever being looked at. everyone will blame the students, council is already ducking for cover and no one will actually go in and work out exactly why it failed. They are blaming the students for jumping up and down on a balcony which they did. No one else is to blame. When I was in the air force doing f****** route marches around Woodbourne we were told get out of step going over a bridge. Now jumping on a deck in time with the music is guaranteed to bring down a balcony. This is so Darwin's law if he hadn't gone to the Galapagos and worked out the theory with finches on different islands he could have used University students in Dunedin and come up with the same reasoning.	prefect (6291)
1416890	2016-03-06 05:03:00	They, (the students) even probably thought it was great fun, even a thrill, getting the balcony to bounce up and down, and maybe that's why they didn't stop when told to do so by the police. It wouldn't be too difficult to estimate the fundamental natural frequency of the balcony with 20 average weight people on it. I'd do it myself if I was more enthusiastic about it, and compare with typical pop beat of 120 per minute, multiples or fractions thereof. Knowing the damping factor for 6x2 radiata pine could give an estimate of amplitude and an estimate of when the wood fibres would begin to fail. I expect this will be part of the post mortem. The static load capacity must have been OK, otherwise it would have fallen earlier, and as tweake said it would have been rated to carry a capacity crowd. A preliminary look by someone from the council (I think) on TV said there were no obvious visual faults like rot.	Terry Porritt (14)
1416891	2016-03-06 05:22:00	I don't think it's so complicated as hitting the resonant frequency or any such thing. It's Simply that Jumping up and down increase the instantaneous force on the deck massively. You can easily double your weight with a small hop if you land straight legged. The deck might hold 30 people ok, but jumping up and down it could be equal to close to the weight of 60 or even more. Add to that if enough of them are at the railing then the leverage of the extra distance magnifies it even more. If you are trying to break a piece of wood by standing on it and it won't break what to you do? Jump up and down on the far end of it. As we get older and do a few stupid things and hurt ourselves a few times even the slowest learners amongst us generally get a bit more cautious, young people are of course on the other end of that experience and also tend to egg each other on. The police knew better, some of the onlookers knew better, it's probable some of the culprits even knew better, but it happened anyway essentially because young people do stupid things. This is how some of them learn :)	dugimodo (138)
1416892	2016-03-06 05:56:00	Even if the resonant frequency was different to the jumping frequency, the deck was still subjected to a forced vibration which would need to be analysed properly, and the maximum deflections and bending moments determined. Your crude jumping analogy does yield any useful quantitative information.	Terry Porritt (14)
1416893	2016-03-06 06:22:00	I meant doesn't yield any useful quantitative information	Terry Porritt (14)
1416894	2016-03-06 06:25:00	They are blaming the students for jumping up and down on a balcony which they did. No one else is to blame. When I was in the air force doing f****** route marches around Woodbourne we were told get out of step going over a bridge. Now jumping on a deck in time with the music is guaranteed to bring down a balcony. This is so Darwin's law if he hadn't gone to the Galapagos and worked out the theory with finches on different islands he could have used University students in Dunedin and come up with the same reasoning. We were told the reason for breaking step on bridges when I was a Girl Guide. That was around 100 or so years ago now! The same principle applies to a group jumping up and down on something such as a balcony. Don't be too hard on them, some of them will live with that for the rest of their lives. They're kids and it was probably not much different to some of the brainless things we did (if we are all honest about it) when we were around their age or maybe a little younger and were lucky to get off unscathed. We thought there was no tomorrow and were bulletproof. About the only thing different is that, with a few exceptions, we were never even thought of as being mature until well over their age. We had neither the money nor the freedom a lot have now. They've learned a hard and painful lesson. Let the blame game commence.	Marnie (4574)
1416895	2016-03-06 06:37:00	looks like they are going to investigate which is good. i would like to see exactly why it happened rather than just wild guesses and blaming the students before knowing what exactly occurred. maybe something good might come out of such a bad incident.	tweak'e (69)
1416896	2016-03-06 07:03:00	looks like they are going to investigate which is good. i would like to see exactly why it happened rather than just wild guesses and blaming the students before knowing what exactly occurred. maybe something good might come out of such a bad incident. So you want the building code to double the safe working load of decks and balconies to take into account jumping up and down simultaneously? If you can not blame people for jumping on a balcony then our Western democracy is buggered.	prefect (6291)
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