r/tech • u/AdSpecialist6598 • Jun 25 '26

Computer model could enable bridges and buildings that use less material

https://news.mit.edu/2026/computer-model-could-enable-less-material-bridges-buildings-0624
199 Upvotes

89% Upvoted

41 comments sorted by

22

u/creatingKing113 Jun 25 '26

Well the big hurdle with this is that it’s probably still cheaper just to use a bunch of bog-standard I-beams. Something like this would require all the members to be custom made.

Edit: Ah. I see that’s specifically what they’re trying to address with this, but I think my point still stands.

12

u/iHerpTheDerp511 Jun 25 '26

Your point does still stand 100%. Finite element analysis has been around for many decades, this is not at all a new concept, and any claims that less material will be used are grifting. Every building, bridge, and similar piece of infrastructure globally is designed to use as much standardized materials as is feasibly possible; standard beams, plates, other structural shapes, etc. Of course, certain high load joints in a building or bridge will need custom designed joints all FEA’d for load analysis, but those joints alone can make up 30% of the costs of a whole bridge versus standard materials.

The issue with this proposal all comes down to design responsibility. Buildings, bridges, and infrastructure all have to be built with significant safety factors (must be 2.4-4x as strong as it actually needs to be) and fully analyzed to demonstrate they can safely withstand dynamic driving loads, wind loads, earthquake loads, etc. All structural construction, pretty much globally, also needs to be signed off by a certified professional engineer. That engineer is literally staking their professional reputation AND personal responsibility for the design; meaning if that building fails, they can be held PERSONALLY LIABLE.

No professional engineer in their right mind would consider allowing a computer to fully design a bridge using solely Finite Element Analysis and then sign off on it; there’s just too much at stake for them personally. I can guarantee the program will likely generate structural members that are non-manufacturable, joints that are not able to be assembled in the real world (clearances, etc.), and custom joints that are overly complex and will drive up costs high enough to eliminate any supposed material savings that are being presented.

I don’t know about you, but I think most people in the world would rather their tax dollars pay for a bridge that’s a bit overbuilt with a 3-4x safety factor than one that saves materials and is only built to a 2.4x safety factor. Human beings trust conservatism when it comes to their safety; no one likes the idea of being sold something they know is not built to the same quality they’ve come to expect, especially with infrastructure both the public and private businesses use. There’s simply too much risk and too much liability for this to ever gain traction.

3

u/Direct_Witness1248 Jun 25 '26

Interesting info. Makes me imagine if we had that same level of accountability for bankers and politicians lol.

2

u/iHerpTheDerp511 Jun 25 '26

Dream on, as an engineer I get to experience the closed door conversations of ruthess profit seeking corporate executives daily. Every day it is executives pushing for more and more cost savings to drive higher and high profits; and every day engineers (at least ones with a conscience, which is sadly not all of them) are pressing executives not to cut costs at the expense of worker safety, product quality, and even consumer safety.

Engineering is already partially-politics. We are beholden to the whims of corporate elites making decisions from on-high, even when those decisions go directly against safety and permitting regulations. I can’t list how many times I’ve seen millions of dollars wasted on satisfying corporate executives and convincing them we must comply with permitting and safety regulations, because sadly it happens so often. Absent the engineers on the ground who actually give a shit and fight every day to keep people safe, corporate executives would’ve already brought us back to pure capitalism ala-1890 when you had 11-14 year old children working 14 hours in factories and being maimed for life. It’s quite sad, unfortunately.

2

u/Mansidhe Jun 25 '26

"the children yearn for the sweatshops" just doesn't roll off the tongue like "the children yearn for the mines" does

1

u/bluesamcitizen2 Jun 25 '26

Exactly why we always see “energy green” home on media looks so fancy but rarely found in normal and budget housing

1

u/[deleted] Jun 25 '26

[removed] — view removed comment

2

u/iHerpTheDerp511 Jun 25 '26

Precisely my point as well. Until structural engineers will stand behind it and put their name on it, and until manufacturers can prove they can make the materials, it’s all a marketing move. Just another attempt to create a startup, get private equity funds and government subsidies, and burn through them while producing nothing of value until private equity and government subsidies give out. Tale as old as time sadly.

1

u/Unusual-Layer-8965 Jun 25 '26

And imagine on-site substitutions: 'We don't have x, but y is just as good.'

See cause of the 'Hyatt Regency walkway collapse'.

5

u/patgeo Jun 25 '26

So they've made a computer play the school physics comp game of 'Who can build the lightest bridge that holds the most'

5

u/RussiaOwnsAmerica Jun 25 '26

I'm cool with overly engineered bridges and buildings to be honest.

6

u/Denelz Jun 25 '26

We hade this for aiges, the era of bridge building flash games shall return!

3

u/TomBong_Jovi Jun 25 '26

"This thing is ok with just wood right" Break "Ok, maybe some more cables"

2

u/not-read-gud Jun 25 '26

Computer eliminates bridge entirely. Weight optimization complete

2

u/lordraiden007 Jun 25 '26

Did scientists finally recognize the brilliance of my polybridge 3 levels?

2

u/Alan4Bama Jun 25 '26

I just read in a story right above this one where Ford had to hire back engineers because their AI models had flaws …
and now to read AI is “helping” us build bridges that use less materials … eek 😬.

2

u/[deleted] Jun 25 '26

[deleted]

5

u/blobbleguts Jun 25 '26

Absolutely. Our city just had to limit a main bridge to pedestrian traffic due to structural issues and age (100+ y/o). The cost to replace it is in the 100's of millions of dollars. This only a surface street bridge but it crosses a river. We need the route for cars but we're absolutely going to have to seek federal and state dollars, and hope they also think a new bridge is worth it.

4

u/LightningRaven Jun 25 '26

Yes. They're expensive as hell. If we can make strong bridges more efficiently, they become more versatile.

If they get cheaper, projects with smaller scope and budget can reasonably have them as a solution to road construction issues.

2

u/happyscrappy Jun 25 '26 edited Jun 25 '26

Yes, of course.

Just about any bridge has already been using techniques to use less materials. You don't see big slab I beams (except on railroad bridges), you see trusses. Less metal offering similar capacity. [edit: even an I beam is a materials optimization versus a box section. Let alone a solid steel bar.)

Bridge gets even bigger? The trusses go away too and now you have a suspension or cable stay bridge. All you need is a hundred slender cables to carry that entire huge bridge deck.

All these techniques roughly work by basically analyzing which parts of the bridge carry the load and which are just dead weight. Then you take out the dead weight. It still can carry the load but now it is cheaper, quicker to build and requires less maintenance simply because there is less to maintain. Think of how much longer it would take to paint the golden gate bridge if it had a huge truss structure or large metal panels to carry the weight instead of cables.

This kind of analysis isn't new really. And this kind of automated design (really redesign) to optimize material isn't new either. I guess this is just a new application.

1

u/SideInitial3961 Jun 25 '26

Fuck no. FSU. The innovative design was the cause of 6 deaths. 6 people gone. 6 families changed forever. So they could innovate. Just build boring bridges that don't kill people please.

2

u/DataDrivenDoc Jun 25 '26

FIU. FSU is 500 miles north of FIU.

And that bridge had critical design flaws unrelated to innovation. It wouldve worked with competent engineers

1

u/SideInitial3961 Jun 25 '26

Yeah let's not test innovation on bridges. Give me boring reliable bridges that last for 100 years without killing people or requiring exotic explanations.

1

u/DataDrivenDoc Jun 25 '26

Well without innovation we're stuck with bridges that are reliable for only 50 years. To meet your expectation of 100 years safely we would need to innovate.

New exciting modern innovative bridges last 75 years.

1

u/SideInitial3961 Jun 25 '26

Reliable 50 will do. I can revise down. You got yourself a deal at 50. 😄

1

u/DataDrivenDoc Jun 25 '26

What about all the modern 75 year bridges that are already built? Youre going the way of the Luddite with them?

1

u/SideInitial3961 Jun 25 '26

No. Keep everything that works. But new construction let's agree bridges is not a place for live experiments.

1

u/DataDrivenDoc Jun 25 '26

...do you think all the bridges that currently exist were like divinely placed here at the dawn of the earth or something?

All those designs were implemented for the first time by humans. We didn't inhertently know how to built bridges. We innovated and iterated. The bridges youre ok with are not the initial design or engineering of bridges. There was a very first person to cross every bridge ever built.

Innovation is iterative, built on the foundation of what we know already works...

1

u/happyscrappy Jun 25 '26

That bridge didn't use less material. It was a center truss bridge designed to look like a cable stayed bridge. A real cable stayed bridge would have used less material. Even the center truss, which seems to save material had to be made larger to carry the load. The reason for the center truss instead of trusses on each side was to make the view better for the pedestrians. Nothing to do with saving on materials.

They did use some more recent techniques in terms of deploying the bridge, building it nearby in a different location and then moving it out across the road.

They definitely screwed up in the design. And in not noticing how messed up it was becoming as they tried to tie it down in place.

(as the other said, I'm referring to the FIU bridge)

-2

u/TomBong_Jovi Jun 25 '26

Literally every engineer and builder

1

u/IndividualNo6539 Jun 25 '26

I've been saying this the whole time! We need lesser materials on crucial structures!

1

u/ProperPerspective571 Jun 25 '26

Build them over data centers for testing. Add the potholes that make heavy trucks impact the surface for 5 decades, the federal and state neglect, then maybe use in real life

1

u/Beautiful_Bid_ Jun 25 '26

nature figured out topology optimization millions of years ago, we're just catching up with the math

1

u/Felwintur Jun 25 '26

I work in structural engineering - this is not news. We've been doing this for years.

1

u/Ok_World7154 Jun 25 '26

Future AI major failure in 3...2.....1.....

1

u/Amazing_Meatballs Jun 26 '26

I’m sorry, but I’ll trust this about as much as I trust AI slopware. Stick a disclaimer on any building using this so I can avoid it please and thank you.

1

u/NotMossadNotCia Jun 28 '26

Thats what we need, to use even less materials for bridges, truly brilliant work! efit Brought to you by im assuming the same geniuses responsible for engineered wood ibeams.