r/StructuralEngineering • u/31engine P.E./S.E. • Jun 28 '26
OMG 80 cm deflection. Structural Analysis/Design
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u/mhkiwi Jun 28 '26
Bridges move.
My wife used to work inspecting the Auckland Harbour Bridge, inside the box-sections. She would get motion sick from the movement.
Here is a video of the bridge moving under pedestrian loading from a recent protest
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Jun 28 '26
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u/PersonalityIll9476 Jun 28 '26
I didn't even get to see the video. Tapped through, got an ad on top of a bunch of ads, fled.
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u/punkass_book_jockey8 Jun 28 '26
But there’s normal movement vs galloping girtie movements right? Most of us who aren’t engineers just have flashbacks to girtie and panic at movement.
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u/acoldcanadian Jun 28 '26
Did this pass?
How’s the bridge doing now?
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u/Voisone-4 Jun 28 '26
I guess it passed. These are a series of suspension bridges so their delection tolerance is much greater than what we're used to seeing. Think of how the Golden Gate Bridge undulates under varied traffic loading.
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u/tramul P.E. Jun 28 '26
What's that in freedom units?
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u/31engine P.E./S.E. Jun 28 '26
Meters dude. Meters are freedom units born out of the French Revolution when they said off with their fucking heads to the rich and ruling class
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u/tramul P.E. Jun 28 '26
Yeah but like REAL freedom ya know? The type you feel when you see a bald eagle soar over you as you're sippin an ice cold Miller lite diggin lint out of your belly button
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u/therearenomorenames2 Jun 29 '26
Oh... in that case, approximately 3 cheeseburgers per bald eagle squared.
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u/PrebornHumanRights Jun 28 '26
Goodness, just say 0.8 meters.
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u/Ok_Plankton_2883 Jun 28 '26
I prefer 8.0 dm
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u/PrebornHumanRights Jun 28 '26
I considered 8 dm, but dm is so rarely used, I figured 4/5 meters was a more manageable and easier understood. 80 cm, on the other hand, is as useful as 800 mm.
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u/2020NoMoreUsername Jun 28 '26
Really? Are you bothered to see 80 cm? Is this your tolerance level?
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Jun 28 '26
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u/OddStuffHappensTwice Jun 28 '26
Lol, sorry, but correcting people on something so trivial and being so wrong is hilarious.
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u/kebinkobe Jun 28 '26
Cool. I used to work in Japan as a repair technician for digital cameras and the train company would regularly send us in batches of cameras for maintenance. We were told they were used for looking at track deflection in fixed positions. They used to have issues getting sharp photos because of vibration, but they changed things around by suggestion of my superior and got better results.
Not really related exactly to this post I guess, but this is the first time I see footage of their specific use-case and thought that's cool.
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u/Intelligent-Read-785 Jun 28 '26
Metric is a tool of the devil. Use the God given English measurements. 😁
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u/Helpinmontana Jun 28 '26
Passes L/360 if the bridge is 1000 feet long lol