Fish 0 Posted September 21, 2020 Author Share Posted September 21, 2020 It is not my area of specialty but these steel structures have a finite life. Cyclic fatigue. Same as your mast or wire rigging in a way. Think of breaking a piece of wire by bending it constantly in the same spot. I believe the effect is a reduction in modulus and an increase in ductility, until it looses its strength. (could have my techo terms wrong there, but the stiff metal goes like a noodle) I am curious as to the state of the remaining structural components, and if the jolt to this one piece tickled up some other pieces. As for the pace of response, I'd be interested to see how agile NZTA can be with something like this. I wouldn't expect a peer review needed to be completed before they start fabricating a new span. If anything, they could get 2 or 3 spans underway in fabrication to different designs. What I am really interested in, is where the steel comes from? I assume the steel components aren't normally held in stock, but made to order for specific projects (spec of steel, size, shape, length etc). Anyone in the steel fabrication industry know what is involved in sourcing the materials to re-build this span? Or if there is standard construction grade girders (I beam) that can be whacked in as a temporary fix while they fabricate the longer term one? Quote Link to post Share on other sites
Steve Pope 255 Posted September 21, 2020 Share Posted September 21, 2020 In the photo of the damaged strut it showed that all the bolts on that particular plate had sheared, I would be very surprised if other bolt ups are not partially sheared as well. Not going to be a quick fix. Quote Link to post Share on other sites
Romany 163 Posted September 21, 2020 Share Posted September 21, 2020 2 hours ago, Dtwo said: Jeez why ask them when they could just get you guys to do the job. Personally I would prefer the job to be done properly I'm not sure what the problem is there Dtwo. I don't believe that anything in my reply indicated a sh*t job was acceptable, just that it seemed the engineering was already available and has been proven by father time. Quote Link to post Share on other sites
Fish 0 Posted September 21, 2020 Author Share Posted September 21, 2020 2 hours ago, Steve Pope said: In the photo of the damaged strut it showed that all the bolts on that particular plate had sheared, I would be very surprised if other bolt ups are not partially sheared as well. Not going to be a quick fix. Apparently they are design to fail, so that the rest of the structure is not damaged. But yeah, give something a big knock, chances of some damage elsewhere are not insignificant. Don't forget a possible outcome here is the bridge actually falling down. That would be a bit more than a few weeks inconvience ... Bridges do fall down fairly regularly. There was that key motorway bridge in Italy that came down, with cars and trucks on it, killing people. First world, developed country and all... The Morandi bridge tragedy killed 43 and left 600 homeless – but also dealt a hammer blow to Italy’s engineering legacy https://www.theguardian.com/cities/2019/feb/26/what-caused-the-genoa-morandi-bridge-collapse-and-the-end-of-an-italian-national-myth Quote Link to post Share on other sites
harrytom 698 Posted September 21, 2020 Share Posted September 21, 2020 When the Clip-on's under went their repair. Happened to meet the Swedish engineer at Robertson park mangere.(steam trains)He reckon the repairs would only last another 10/15 yrs,that was 2009 and the main span was made from inferior metal.his recommendation was not to think about a new crossing but rather to start. Quote Link to post Share on other sites
Ed 151 Posted September 21, 2020 Share Posted September 21, 2020 What complicates the matter is that strut is a stressed member. Fabricating a bit of steel is the easy bit, getting it in there is somewhat harder Imagine trying to replace a spreader, and you have to get the rig tension and mast bend back to where is should (must) be, without touching the turnbuckles or addind any significant weight aloft. Its certinaly not beyond the wit of man to complete, but considering the implications if it goes wrong the amount of planning, peer review and analysis that goes into this will be significant 3 Quote Link to post Share on other sites
Dtwo 157 Posted September 21, 2020 Share Posted September 21, 2020 9 hours ago, Romany said: I'm not sure what the problem is there Dtwo. I don't believe that anything in my reply indicated a sh*t job was acceptable, just that it seemed the engineering was already available and has been proven by father time. This. Not so much your comment but a stream of bollocks from others. Yawn. 'Yep, too much navel contemplating, and cuzzy consulting. Get it done, son. I'd think that one of the pollie parties would sieze on this as an election issue. Yes days on it would be good to think that the meetings and discussions have finished and that the fabrication to engineers drawings has commenced -it would have elsewhere in the world. Who do we ask that straight question to ?' Quote Link to post Share on other sites
Romany 163 Posted September 22, 2020 Share Posted September 22, 2020 I would be rude not to acknowledge that NZTA does seem to have pulled a rabbit out of the hat. Temp repairs underway tonight is a pretty good response. Who woulda thought that a 61 year old bridge was as technilogical as it sounds eh. I just thought it was a giant meccanno set Quote Link to post Share on other sites
vic008 17 Posted September 22, 2020 Share Posted September 22, 2020 Ed, you've got me thinking. As an old steel worker.Do you need to take into consideration that it is stressed? You wouldn't just measure and say fab to those measurements? Quote Link to post Share on other sites
Island Time 1,310 Posted September 22, 2020 Share Posted September 22, 2020 Nope. It’s apparently a stressed member, so needs those measurements once loaded. Steel is quite elastic. Not a simple replacement I would think. Quote Link to post Share on other sites
Ed 151 Posted September 22, 2020 Share Posted September 22, 2020 Just to preface this, I'm not a bridge, mechanical or structural engineer, so this is all best guess from heavily loaded snafus I've seen over the last 20 yrs IT, you're right Its a reasonably long slender member, so it will have a bit of stretch one loaded. However, I would guess though that the bridge structure itself has moved more that that. If Vic remade the piece to the original dimensions, when you went to install it you would probablly find it would appear to be to short ad the structure will mave likely moved away. The challenge is then to pull the structure back to the correct shape while still leaving space to install the new part and not overload anything else in the process Quote Link to post Share on other sites
vic008 17 Posted September 22, 2020 Share Posted September 22, 2020 Ed, would the new column then not be taking all the load? Quote Link to post Share on other sites
marinheiro 365 Posted September 22, 2020 Share Posted September 22, 2020 1 hour ago, Ed said: Just to preface this, I'm not a bridge, mechanical or structural engineer, so this is all best guess from heavily loaded snafus I've seen over the last 20 yrs IT, you're right Its a reasonably long slender member, so it will have a bit of stretch one loaded. However, I would guess though that the bridge structure itself has moved more that that. If Vic remade the piece to the original dimensions, when you went to install it you would probablly find it would appear to be to short ad the structure will mave likely moved away. The challenge is then to pull the structure back to the correct shape while still leaving space to install the new part and not overload anything else in the process from what I can make out this strut is in compression as part of the support truss so if this is the case stretch/elasticity would not be an issue Quote Link to post Share on other sites
Island Time 1,310 Posted September 22, 2020 Share Posted September 22, 2020 I trained as a mechanical engineer. But I've not seen design details of this bridge, so I cant make sensible comments. Uninformed comment is usually not worth the time it took to write it, or read it! 1 Quote Link to post Share on other sites
Romany 163 Posted September 23, 2020 Share Posted September 23, 2020 But whats your point IT 🤔? Not posting uninformed opinion would be the death of ZB and -dare I say it, forums like this. Quote Link to post Share on other sites
Ed 151 Posted September 23, 2020 Share Posted September 23, 2020 1 hour ago, Romany said: But whats your point IT 🤔? Not posting uninformed opinion would be the death of ZB and -dare I say it, forums like this. To be fair, this thread is in Marine talk, which is usually has quite well informed commentary. Small talk on the other hand.... 1 Quote Link to post Share on other sites
Fish 0 Posted September 23, 2020 Author Share Posted September 23, 2020 30 minutes ago, Ed said: To be fair, this thread is in Marine talk, which is usually has quite well informed commentary. Small talk on the other hand.... Are you saying small talk is a train wreck? or are you trying to demonstrate the ductility of railway tracks? I don't have a lot to do with steel, but I was involved in a project to install a new high pressure gas pipeline (technically I think it was medium pressure, ahem). Anyway, steel pipe will behave like a piece of spaghetti if you weld it together into a long enough string. Turns out you can drill it under and around all sorts of things. The main physical constraint is the ability to steer the drill head, which is largely to do with the geotechnical properties of the ground. Quote Link to post Share on other sites
harrytom 698 Posted September 23, 2020 Share Posted September 23, 2020 The Bridge is fixed,how engineers interpreted how it should of been built. Quote Link to post Share on other sites
Fish 0 Posted September 26, 2020 Author Share Posted September 26, 2020 NZTA now aware that cold fronts may bring high wind gusts... Lanes on the Auckland Harbour Bridge are being closed on Sunday morning ahead of a forecast wind shift that could see gusts of up to 90kmh. There are currently northerly wind gusts of up to 70kmh in Auckland, but the bridge is relatively sheltered. However, Metservice is forecasting a wind shift from the north to the west in the morning, which could bring winds of 80kmh to 90kmh. “The wind shift could bring a swift change in the strength of the gusts, so as a precaution we will close one southbound lane and two northbound lanes on the bridge until the wind settles,” said Waka Kotahi NZ Transport Agency senior journey manager Neil Walker. https://www.stuff.co.nz/auckland/300117484/auckland-harbour-bridge-lanes-close-as-winds-tipped-to-reach-110kmh Quote Link to post Share on other sites
marinheiro 365 Posted September 27, 2020 Share Posted September 27, 2020 they should have painted the temporary piece of pipe Harbour Bridge Gray, too many people slow down to look at the temporary repair Quote Link to post Share on other sites
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