Truck Drove Into Bridge Near My Job

[Daedalus]

Well, it was all but an ordinary day for me at the office. I'm the Sr. Software Engineer at Factor, and we are located on the 15th floor of one of the towers on the N.W. side of Oklahoma City. Just a few hours before it was time to leave, everyone started gathering near windows on the East side of the office because a semi-truck with some kind of heavy machinery loaded on its trailer tried to drive under a bridge that wasn't tall enough. So, I took the opportunity to take a few pics that actually made it on the news. As you can see, it collapsed the N.E. side of the bridge.

 

 

 

Unfortunately, I'll have to take a different route to Guitar Center and Best Buy when I take my lunches. Luckily, no one was hurt.

 

Here's a pic someone else took from the other side showing how badly the bridge is damaged. The building in the center of the image (maroon with tinted glass) is where my office is located.

 

Edited May 19, 2016 by Daedalus

[pzkpfw]

Wow. I've had that happen near my work, too. It was just the crane on a medium sized truck that hit a pedestrian bridge, but as my desk was right near the end of the bridge the noise was a good shock.

 

Look out the window and there's a truck that's swerved off into the roadside bushes, and a sad looking crane leaking hydraulic fluid all over the road. No damage other than a road sign on the side of the bridge that got dented.

 

I wondered how it would have been for a pedestrian near the impact.

 

 

Did no cars on your bridge get in "trouble"?

[MigL]

They don't build bridges like they used to.

[Daedalus]

Did no cars on your bridge get in "trouble"?

 

Luckily, no one was actually on the bridge.

[Sirona]

I was very surprised when I visited US cities, there are so many overpasses, lanes and bridges. I don't remember seeing many roundabouts, if any at all. I was very anxious driving there and the least of all because you drive on the wrong side of the road!

[iNow]

That's nuts. I've driven through that exact spot lots of times while visiting clients in OKC.

 

Part of me wonders if the structural integrity of the bridge had been previously compromised by the increasing frequency of earthquakes from injection of fracking wastewaters thus making it more likely than it might have otherwise been to collapse on impact.

Edited May 21, 2016 by iNow

[studiot]

It's not clear from you pictures if the brige is constructed from steel I beams or concrete beams?

 

If it was constructed from prestressed concrete beams unlucky impact could sever the prestressing, leading to sudden and catastrophic collapse.

This is the same reason why you should never drill into the prestressed zone at the (bottom) of a prestressed concrete lintel for fixings at home.

 

I see also that the truck struck the leading edge of the bridge, but only the outer beam or beams were displaced.

This would suggest that the truck profile tapered up from the front so there was a wedge action lifting the leading beams off their bearings to cause the partial collapse.

The deck appears to comprise four simply supported spans (you can just see the shadow of the joints over the piers) with no moment continuity at the supports.

So no, I do not think there was any preexisting weakness.

Edited May 21, 2016 by studiot

[Daedalus]

I was very surprised when I visited US cities, there are so many overpasses, lanes and bridges. I don't remember seeing many roundabouts, if any at all. I was very anxious driving there and the least of all because you drive on the wrong side of the road!

Yeah, we don't have many roundabouts, but we do have a few. For some reason, Americans love building bridges and overpasses and, yes, we drive on the wrong side of the road.

 

Part of me wonders if the structural integrity of the bridge had been previously compromised by the increasing frequency of earthquakes from injection of fracking wastewaters thus making it more likely than it might have otherwise been to collapse on impact.

Actually, this bridge was hit before back in the 90's but on the other side. So yes, the structural integrity of the bridge had been previously compromised, and I'm fairly sure that our earthquakes are at least partially responsible for the degradation of our infrastructure. I remember as a kid, we never felt the earthquakes. Most people that live here didn't even know that Oklahoma was seismically active. I experienced my first earthquake, where the building actually shifted, about 5 years ago. Before that, I never had experienced the effects of an earthquake. So, that should tell you something about the increased frequency and strength of Oklahoma's earthquakes.

 

It's not clear from you pictures if the brige is constructed from steel I beams or concrete beams?

I think that bridge uses concrete beams, but I'm not sure. Here's a better pic of the damage.

 

 

Sirona and iNow (really any of my friends here at SFN), if you happen to make your way to Oklahoma City, send me a PM. I'll be more than happy to show you around and treat you to dinner. If you like hibachi, then we can eat at Musashi's (Japanese steak house). Hmmmmm.... I love hibachi

Edited May 21, 2016 by Daedalus

[studiot]

Thank you for the extra picture.

 

It looks more like a steel beam than a concrete one. Steel is more malleable; concrete would be less likely to twist like that although it is still not clear.

 

I still see no evidence of preexisting weakness, the supports appear still sound.

 

14' 4" headroom clearly marked.

What is the US/Oaklahoma standard?

 

The damage remains consistent with my hypothesis of the edge beam being lifted off and dropped, at one end.

It is still capable of supporting itself for the full span (albeit diagnal now) even though a bit twisted.

So it did not fail in bending.

A plastic failure hinge would have formed midspan in that case.

Edited May 21, 2016 by studiot

[Daedalus]

What is the US/Oaklahoma standard?

I'm not sure what the standard is, but we do seem to have a problem with trucks hitting our bridges. I can't seem to find the pic, but a few years back we had a truck get stuck under the bridge because the trailer wouldn't fit.

 

Here's one that happened in Tulsa, OK: http://www.newson6.com/story/18992207/truck-gets-stuck-under-railroad-bridge-near-downtown-tulsa

 

Here's another one that happened in OKC: http://www.news9.com/story/29546329/semi-stuck-under-railroad-bridge-near-downtown-okc

 

I found the one that I was talking about: http://okcfox.com/archive/semis-continue-to-get-stuck-under-worst-overpass-in-the-city

 

This happens more than it should...

Edited May 21, 2016 by Daedalus

[studiot]

In the UK there is no minimum standard headroom, although new bridges will normally be designed to 16' 6".

Ensuring that the vehicle will fit under the bridge is entirely the rsponsibilty of the vehicle operator and bridges are

"at the height you find them"

 

The UK 'Construction and Use regualtions state

 

" the Construction and Use Regulations require any vehicle over 3m (9' 8") to have the height clearly labelled in the driver's cab. They still hit bridges, though"

Sometimes the load is not secured properly and springs up, without the driver realising.

Edited May 21, 2016 by studiot

[Sirona]

Yeah, we don't have many roundabouts, but we do have a few. For some reason, Americans love building bridges and overpasses and, yes, we drive on the wrong side of the road.

 

I think that bridge uses concrete beams, but I'm not sure. Here's a better pic of the damage.

 

BridgeCollapse.jpg

 

Sirona and iNow (really any of my friends here at SFN), if you happen to make your way to Oklahoma City, send me a PM. I'll be more than happy to show you around and treat you to dinner. If you like hibachi, then we can eat at Musashi's (Japanese steak house). Hmmmmm.... I love hibachi

Roundabouts are great, until you enter a massive multi-lane one and you forget about indicating because you're freaking out about being in the wrong lane. If you're me, you have a panic attack and slam on the breaks. Road etiquette was so different in the US, I learned that when you indicate to change lanes, people will automatically let you in but you must do so swiftly. In Australia, you're lucky if the third or fourth car lets you in and if you try to push in, you'll experience authentic Australian road rage.

 

That's nice of you! The last time I was in the US all I ate was American Mexican food (gringo?), I'm really showing my ignorance here. Mexican food is just not the same in Australia, it's all so light an healthy here. I had chilli con carne with cornbread for the first time and it was possibly the best thing I've eaten.

 

Edited May 21, 2016 by Sirona

[arc]

Thank you for the extra picture.

 

It looks more like a steel beam than a concrete one. Steel is more malleable; concrete would be less likely to twist like that although it is still not clear.

 

I still see no evidence of preexisting weakness, the supports appear still sound.

 

14' 4" headroom clearly marked.

What is the US/Oaklahoma standard?

 

The damage remains consistent with my hypothesis of the edge beam being lifted off and dropped, at one end.

It is still capable of supporting itself for the full span (albeit diagnal now) even though a bit twisted.

So it did not fail in bending.

A plastic failure hinge would have formed midspan in that case.

 

Here is some images I took today in Portland Oregon. This seems to be a nationally standard design from the 1950's or very early 60's:

 

 

This overpass was seismically up-graded in the past 15 years or so, you can see the cement blocking (A) that was added between the steel beams:

 

I believe the cement was pumped into the formed section, I am looking into the exact technique used.

 

 

The beam ends on the ledge were also boxed-in with cement:

 

 

And too also above the lintels:

 

 

This additional bracing does not appear to be present in the failed structure. Once those beams were rolled sideways, twisted by the heavy equipment passing underneath, the deck above would have little support.

 

 

The working platform of the construction equipment is lying under the outside beam, the force of the impact tore the equipment off the tractor-trailer that was hauling it. It appears there is some type of bracing between the first and second beam, that may have duplicated the sideload of the first beam to that of the second one. Without the boxed-in ends at the ledge there was probably little to hold them in place but a few bolts, so they were likely pulled off the ledge as they folded.

Edited May 22, 2016 by arc

[studiot]

I still await Daedalus confirmation of more detail but here is some more information on the type of bridge shown by arc.

 

Bridges constructed as a concrete deck slab in a longitudinal arrary of steel I section beams are usually monolithic construction.

The top and bottom flanges of the main I section girders are not usually of the same size because the top (compression) flange uses the deck slab as well (hence monolithic)

In order to transfer the horizontal shear from the steel flange into the deck shear connectors or studs are welded onto the top of the flange as in the picture of such a bridge under construction.

 

 

 

 

This means that the tops of the beams are pretty rigidly held in a very stiff matrix.

 

Wacking the bottom flange with a truck cause rotation at the bottom, but the top can't go anywhere.

So if you now prop one flange against the next etc as in your seismic stiffening you run the risk of the bottom flange shearing clean off rather than buckling/twisting sideways as daedalus' bridge upon impact.

 

In fact I'm not at all sure what would be achieved by those concrete props.

 

Tall steel girders have slended webs in substantial vertical shear, maximum over the supports.

As such they are prone to compression buckling at these points and are usually (should be) stiffened by perpendicular strips of stell welded in near the supports.

These are called web stiffeners.

Additional ones of these will help with vertical seismic activity.

Horizontal props just above the bottom flanges will not.

In fact , since the props are concrete, they cannot take tension and will loose any effect if there is any horizontal seismic movement or oscillation..

So I suspect they are of a political design, rather than an engineering one.

 

The diagonal bracing seen in my picture are there for stability, prior to the deck slab being cast, ie erection purposes, not structural stability during the service life of the bridge.

Edited May 22, 2016 by studiot

[Daedalus]

I still await Daedalus confirmation of more detail but here is some more information on the type of bridge shown by arc.

 

The bridge does use steel beams as can be clearly seen in the following image.

 

 

[studiot]

Thanks, looks pretty much as I suggested.

 

Only difference is that the deck seems to have taken the bearings with it on the collapsed span, pulling them right off the bearing shelf.

Perhaps they were seized or that was the fixed end.

The bearings can be seen as blocks under the main beams on the span still standing

[arc]

I believe this image is the most revealing of the lot.

 

 

Those beams defiantly took a hit, whether it was just the first one that was struck and then the bracing duplicated the forces to the adjacent beam or the lift contacted each beam in succession, is unclear. That bracing is lined up with the deformations rather nicely though. I believe the beam's final resting place, so far short of the ledge, suggests the beam's horizontal movement in addition to the shortening from the beam's deformation would be adequate to move the beam's end clear of its support.

 

Another thing that is interesting in that image above is the in-beds on top of the beams look as if their welds failed at every location, they don't appear to have even spalled the concrete anywhere. They also appear to be in much shorter quantity than in studiot's image, the ones that can be seen in the red stripe of oxide paint, pulled from the beam by the concrete, show spacing possibly +/- a meter. Theirs something fishy about that area where the beams contacted the deck above.

Edited May 23, 2016 by arc