| Forum Home | ||||
| PC World Chat | ||||
| Thread ID: 141816 | 2016-03-04 21:14:00 | Darwin Rules ! | Terry Porritt (14) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 1416917 | 2016-04-06 11:52:00 | This "notching" of the joists would appear to be a bad feature though it has been widely done as far as I can see wherever balconies are built. It's to lower the deck below room floor level so that water does not get under the windows/doors. The notching is more or less at the point of maximum stress in the joists, and will be a stress raiser. The report recommends further research into this. notching is not done any more. i understand part of it is due to exposing the poorer treated part of the timber to water and in the worse way ie top of timber where water sits. also as you mention its at the max stress point, but that depends on the design. odds are i suspect its a fixed timber design, ie the joist is nailed securely to the floor joists. this doesn't allow the joist to flex and all forces are concentrated where it rests on the wall. notching just creates a perfect start for a fracture. not to sure why they need to research the notching. its common with other materials. under stress they almost always break where the grain is interrupted. i really do not understand why anyone would go to the extra work of notching it out rather than using a smaller bit of timber. a smaller bit of timber will not be weaker and is cheaper, easier and quicker. current design is to use a smaller timber (external joist size) but also free float. which i thought was unusual but it does make sense. by only fixing it at one end, it allows it to flex and doesn't put all the forces into the one spot where it meets the wall. clever, but only works if the joist is flexible. |
tweak'e (69) | ||
| 1416918 | 2016-04-07 07:13:00 | the thing that i see is there is holes in the walls for the 11 or so joists, but the balcony only has 2-3 joists sticking out like they broke under the floor. it will be interesting to find out the cause of it. I see the same issues. I suspect that they didn't have cantilevered joists because there were no signs of fractured joists, the wall was clean. I wouldn't mind betting that the balcony was attached to the face of the wall and the bolts or other fixing simply pulled out of the wall, just like the last episode of 'balcony collapse'. There really wasn't enough weight there to collapse a properly cantilvered and secured balcony so the fact that it 'fell off complete' with the floor structure largely in place suggests that it was just 'pinned' to the wall with bolts. Cheers Billy 8-{) |
Billy T (70) | ||
| 1416919 | 2016-04-07 07:58:00 | I see the same issues. I suspect that they didn't have cantilevered joists because there were no signs of fractured joists, the wall was clean. I wouldn't mind betting that the balcony was attached to the face of the wall and the bolts or other fixing simply pulled out of the wall, just like the last episode of 'balcony collapse'. There really wasn't enough weight there to collapse a properly cantilvered and secured balcony so the fact that it 'fell off complete' with the floor structure largely in place suggests that it was just 'pinned' to the wall with bolts. Cheers Billy 8-{) i did see a pic of it. most of the joists broke at the wall line ie the pivot point. from what i have seen all joists did go under the floor as they should. as its done under old specs it probably a fixed joist rather than a floating joist, hence the snap off at the wall rather than a 'green stick' type break. testing of the wood would be interesting. to see if that was a factor. especially old dried out timber that may have a lower breaking point than newer wood. especially with a fixed beam situation. sadly i bet this will all be quietly shoved under the carpet and ignored. nothing will be learnt from it. which is somewhat insulting to the people who got hurt. |
tweak'e (69) | ||
| 1416920 | 2016-04-07 08:21:00 | Well there you have it it collapsed due to the poor quality of the music the band play Hang on, - doesn't student party music drive people UP the wall ? ;) |
R2x1 (4628) | ||
| 1416921 | 2016-04-07 19:30:00 | Hang on, - doesn't student party music drive people UP the wall ? ;) Oh yeah I forgot about the Northern travel effect of dodgy student music. It could of been the beer they were all holding, if they had been made to leave that inside the house the deck wouldn't have been overloaded :devil |
gary67 (56) | ||
| 1416922 | 2016-04-14 11:54:00 | just reading through www.beehive.govt.nz and www.beehive.govt.nz llapse%20of%20a%20Balcony%20at%20598%20Castle%20St reet,%20Dunedin.pdf a couple of quirks in the report. "Inspection and testing of the joists that failed has not identified any concerns about the standard of timber used in the construction,” Dr Smith says." but the report says "Two timber samples and a series of photos were sent to SCION Research Institute to try and identify the grading and treatment properties of the timber joists from the recovered remains of the balcony. MBIE is awaiting the results of these tests." apart from the obvious we havn't got results yet, they are not even testing the timber for strength. its a fairly poor investigation if they don't bother to do any critical material testing. its not that hard to go put one of the joists in a rig and see what weight it can handle before it breaks. tho it is good to see that they will review the standards decks are built to, after all a deck is a deck. also testing of the effect of notching. tho i would be interested in the differences in the old design (fixed notched joists) and the current design (free float non-notched joists). |
tweak'e (69) | ||
| 1416923 | 2016-04-14 19:41:00 | The minimum spec for the timber used is SG8 for gauged timber or N1 for rough sawn. Anything lower is sub standard. | gary67 (56) | ||
| 1416924 | 2016-04-14 22:04:00 | There is no excuse for crass stupidity. Gross overloading will sink ships, crash planes and collapse balcony’s. Simple as that! |
B.M. (505) | ||
| 1416925 | 2016-04-14 23:06:00 | Thanks tweak'e I must look at that report and see how it compares with the first one. I propose a formula like the one attached for defining the IQ of a group, the herd mentality if you like, see attached. It is the average IQ of the group divided by a function of the numbers in the group, ie the bigger the group the dumber the group. It is yet to be established the approximate nature of the function, any ideas would be welcome :) |
Terry Porritt (14) | ||
| 1416926 | 2016-04-15 08:42:00 | Thanks tweak'e I must look at that report and see how it compares with the first one. I propose a formula like the one attached for defining the IQ of a group, the herd mentality if you like, see attached. It is the average IQ of the group divided by a function of the numbers in the group, ie the bigger the group the dumber the group. It is yet to be established the approximate nature of the function, any ideas would be welcome :) A notorious group with 120 members on current experimental evidence has the smallest mean IQ (extremely mean)and the greatest total expenditure per capita of any grouping so far assembled. :( |
R2x1 (4628) | ||
| 1 2 3 4 5 6 7 8 9 10 11 12 | |||||