a bridge too far~ctm
Lehigh University researchers’ novel approach combining climatology, hydrology, structural engineering, and risk assessment could help communities fortify bridges against scour caused by extreme weather
Lehigh University
Climate change will ultimately affect our bridges. But to what extent?
That is the essential question addressed by Lehigh University researchers David Yang and Dan M. Frangopol in a paper recently published in the ASCE Journal of Bridge Engineering.
“We know climate change will increase the frequency and intensity of natural hazards like hurricanes, heat waves, wildfires, and extreme rains,” says Yang, a postdoctoral research associate in civil and environmental engineering at the P.C. Rossin College of Engineering and Applied Science. “For this paper, we’re looking at increased temperature as well as increased precipitation and their impact on bridge safety. The challenge here was that we didn’t know how to quantify those impacts to predict scour risk.”
Scour is the primary source of bridge failure in the United States. It’s created when floodwaters erode the materials around a bridge’s foundation, creating scour holes that compromise the integrity of the structure.
For their paper, Yang and Frangopol, a professor of civil engineering and the Fazlur R. Khan Endowed Chair of Structural Engineering and Architecture, had to fill the gap between the climate data and the structural safety quantification. They did so by using hydrologic modeling to convert climate simulation data to flow discharge data in the Lehigh River. The Lehigh River is a 109-mile long tributary of the Delaware River that runs through the city of Bethlehem, Pennsylvania, where Lehigh University is located.
“We took a holistic approach,” says Yang. “It started with a global climate model that was downscaled to regional hydrology, then we used structural engineering to get the failure probability of a structure in a future flooding event. From that, we could assess, does this structure failure pose certain risks to a community? So our model included these four steps of climatology, hydrology, structural engineering, and risk assessment.”
It’s the first paper to date that has combined all four steps to quantitatively look at the effect of climate change on bridges, he says.
In developing their model, the pair considered different climate futures and global climate models provided by the Intergovernmental Panel on Climate Change. To estimate the foundation depth of older bridges spanning the Lehigh River–information that is often unavailable–they developed a method to back-calculate the depth based on condition ratings from the National Bridge Inventory. They also took a regional and life-cycle approach to their analysis.
Frangopol is world renowned for his pioneering work in life-cycle engineering, which uses computational analysis to determine the long-term value and risk associated with infrastructure investments. In 2019, he was awarded the George W. Housner Structural Control and Monitoring Medal in recognition of his groundbreaking work and leadership in the field. This is one of many awards and honors bestowed on Frangopol from several professional organizations. Indeed, Frangopol, as part of a research team consisting of his former and current PhD students, will receive the 2019 State of the Art of Civil Engineering Award during the upcoming annual convention of the American Society of Civil Engineers (October 10-13, 2019) in recognition of their paper, “Bridge Adaptation and Management under Climate Change Uncertainties: A Review.” It’s the third time Frangopol will receive this prestigious award.
Taking such a regional and life-cycle approach, says Yang, was a novelty for this paper. “Bridges have a lot of microenvironments, and if you only look at one bridge, it’s really hard to capture the trend and get the increased risk from climate change,” he says. “So we broadened this analytical horizon both spatially and temporally to capture long-term trends.”
Of the eight conclusions Yang and Frangopol reached with their model, the most surprising was the extent to which the frequency of flooding may change.
“We realized that a 20-year flood may now become a 13-year flood at the end of the century, so that frequency nearly doubled,” says Yang. “This is why climate change may induce an increased risk to infrastructure.”
Perhaps their most important conclusion involves the question of mitigation. Specifically, what engineering measures should be deployed to reduce risk, and in which bridges.
“The reality is that budgets are limited,” says Frangopol, who is also affiliated with Lehigh’s Institute for Data, Intelligent Systems, and Computation (I-DISC) and the Institute for Cyber Physical Infrastructure and Energy (I-CPIE). “So it’s important to be able to determine, what is the priority here? You need to know the location of the bridge. For some communities, the failure of a bridge could be disastrous. For others, a bridge may not be as critical. This model helps you make that kind of decisions because risk is not only based on safety but also on the consequences of failure. You might have two bridges at the same probability of failure, but the consequences of that failure could be very different.”
Focusing on bridges along the Lehigh River was an obvious choice given their location, but both Yang and Frangopol are eager to share this model, not only locally, but with all communities looking to assess their infrastructure.
“We were inspired to do this research in part because historically Bethlehem was hit by multiple floods since 1902, and they had a significant impact on the community, so flooding is a significant hazard throughout the Lehigh River watershed,” says Yang. “We wanted to devise something that the community can use to become adaptive to future climate change,” says Frangopol.
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The research reported in this paper was supported by the U.S. National Science Foundation Grant CMMI 1537926 “Life-Cycle Management of Civil Infrastructure Considering Risk and Sustainability,” (2015-2020) with Dr. Dan Frangopol as the sole Principal Investigator.
Related Links:
- Lehigh University Faculty Profile: Dan M. Frangopol
- ASCE Journal of Bridge Engineering: “Physics-Based Assessment of Climate Change Impact on Long-Term Regional Bridge Scour Risk Using Hydrologic Modeling: Application to Lehigh River Watershed”
- Rossin College News Center: “Frangopol awarded 2019 George W. Housner Structural Control and Monitoring Medal”
- NSF Award Abstract: “Life-cycle Management of Civil Infrastructure Considering Risk and Sustainability”
- 2019 ASCE Convention
- ASCE State-of-the-Art of Engineering Award
The primary reason the I 94 bridge in Mpls collapsed was its design did not include redundancy in support structures. One beam broke and the entire bridge collapsed.
I read this was typical of bridges built in the 60s and 70s. That collapse was a huge wake-up call.
I know some folks who narrowly missed that disaster.
Civil engineers got a “Medal” for “groundbreaking”.
Don’t they know that the threat is warming and drought?
No mention of the latter.
Flooding events have increased in intensity as a consequence of land use changes. Cleared land doesn’t retain or slow down the movement of rainwater downslope as much as the forest it replaces; large fields separated by fences don’t slow down the movement of rainwater as much as small fields separated by hedgerows. Paved land doesn’t slow down the movement of rainwater as much as grass-covered land.
And so on, and the result is that extreme rainfall events, which may not have increased in intensity or frequency as a consequence of real or imagined changes in climate, can lead to more intense and/or more frequent flooding events due to land-use changes.
Assessment of upstream land-use would be a proper component of study on new bridge design and re-appraisal of old bridges. Plus changes in river management like dredging channels, building levees etc. None of which is related to “climate change” predicted by models. But they are anthropogenic and hence by definition, they must be bad.
100% of bridges that glaciers over run will be destroyed.
Ok, so he got a nice research grant, slightly tweaked a hydrology model, and published the result as sexy “climate change” research. (If he had tagged it as “global warming” research, it would not be nearly as sexy.)
This is run-of-the-mill “publish or perish” academia at work.
Lehigh is really good at this kind of thing.
“We know climate change will increase the frequency and intensity of natural hazards like hurricanes, heat waves, wildfires, and extreme rains,”
It really is fascinating how quickly model outputs become accepted wisdom.
Even when the real world, for decades, fails to deliver up any confirming evidence.
That’s the problem. Mother Nature is a denier.
We took a holistic (advocacy) approach to get published and notoriety and it worked.
I was taught engineering by a rare but eminent knighted engineer who was a colleague of Barnes Wallis when they designed and built the privately funded R100 airship in the late 1920’s: the one that was successfully launched and flew across the Atlantic, but which was abandoned following the crash of the R101 airship – the one funded, designed and built under government supervision. He also served as the head of R&D at Farnborough, the UK’s central aeronautics during the war. He later became a leader in introducing probability theory into designs, notably structural steelwork design, and the theory and practice of safety factors.
In the last year of our course, he gave a lecture which started by his simply saying: “every day of your career as a professional engineer, whether you are designing, manufacturing or constructing, or even operating an engineering system you will be putting a price on a human life!” As you can imagine, that was a showstopper and gingerly looking around we all saw the same expressions of surprise and fear on our faces, and we probably all had the same thought, “what the hell are we getting into?”
What he then explained was that no engineering system could be absolutely safe! He explained that there was always an unforeseen combination of circumstances that the system was not designed to accommodate! Hence the use of probability theory!
He then gave an example of the UK’s Severn Bridge design in the early 60’s. At the time, this was planned to be one of the longest suspension bridges in the world. He was asked whether it would be necessary to design the bridge towers so that they could survive the impact of a jumbo jet; very larger passenger planes that were then being introduced. His conclusion was that accommodating such a rare risk was not economically viable!
I think of this whenever I hear again and again the precautionist principle being applied by the CAGW warmists. They just do not even begin to understand that, unfortunately, costs and cost-effectiveness will always be a major, if not even the major, consideration. Even such a massive disaster as the 9/11 Twin Towers disaster has cost us all massively less than the costs of strengthening all such buildings to resist such aircraft impacts!
I also often smile when I see media headlines following a disaster, stating that a failed installation was unsafe, well before the reason for the failure was known!
Stern and others have produced estimates of the likely present day costs of remedying, repairing and/or replacing future damage and disruption to infrastructure and other works and services that would be generated per tonne of CO2 emitted. Even if CAGW theory is established, I believe that even providing such a cost estimate within an intended new works’ total cost comparisons between available base load Power Generation system, would identify that existing base load power generation mixes including Renewable Energy systems such as WT’s, SP’s, hydro-electric, other “storage” facilities, and nuclear would still be far more expensive than stand alone CCGT’ Plants and are thus unsupportable!
The World Trade Center towers did easily resist the impact of 767’s flown into them at 350 knots. Both towers absorbed and survived their respective impact at different heights quite well.
It was the subsequent fire from thousands of gallons of burning Jet Fuel that pushed the insulated structural steel columns past 723℃. That heating took about 45 minutes the heat the steel to failure since the water delivery lines for fire suppression were also severed in the areas around the impacts.
So the towers did survive the impacts quite well. It was the unrelenting fire that brought them down.
You are simply confirming what my old professor taught me! The structures failed due to an unforeseen combination of circumstances and their effects. The structure failed initially locally because of the unforeseen plane impact, resulting in a massive fire accelerated by massive amounts of jet fuel. The very intense heat created then weakened the structural steel even more at the impact level and leading to a cascade failure of the structure and dynamic loading from falling debris with similar effects on lower levels.
Impossible, well known metallurgist and structural expert Rosie O’Donnell declared that fire can’t melt steel.
Apparently structural beams are mined out of the earth sized, shaped and drilled for fit.
Who said the steel melted? It’s common knowledge within the Metallurgy and Engineering professions that any structural steel subject to massive ongoing continuous heat has its strength/yield strength lowered.
Peter
A interesting article about the steel in the WTC
https://www.tms.org/pubs/journals/jom/0112/eagar/eagar-0112.html
How do you reconcile this need to consider any higher flood risks to such structures caused by CAGW with the UK’s policy, supported by CAGW believers, of not dredging rivers to protect wild life habitat.
The flooding risks also increase with the lack of dredging and other waterway maintenance and clearing work.
Records show such lack of dredging is a major cause of bridge damage – for the same flows. This is a result of the raised running water level approaching the bridge for the same flows, caused by the raised bed level and increased water/earth interface “friction”, together with the increased flooded structure cross section of flow of the bridge, i.e. more obstruction area and hence higher lateral hydraulic loadings
Marginally increased scour around the footings and casings is not the big problem facing bridges and overpasses in the North-East US. Corrosion from salted-water is the real threat these bridges/overpasses face.
I have a BS in Civil Engineering (accredited) and passed the Colorado EIT exam.
So I probably know just enough about structural engineering to be dangerous. That said, and having lived in New England for 9 years (eastern Massachusetts near Marlborough), I was a big-time trail runner in those years and also a kayaker on various New England Rivers and Lakes. I used to look up at the bridges and spans and examine the footings and structural problems as I went under them. Lots of rust. Sometimes alarmingly so.
I can tell you by FAR and Away he biggest threat to any of those bridge structures, whether they are steel, reinforced concrete, or both, is corrosion from the salt that the highway departments apply in copious amounts during the winter months to keep the roads open after an icing/snow fall/freezing weather. The salt concentration can get very high to melt the ice, essentially it is brine water.
The brine penetrates the concrete at cracks and where structural steel connects and causes huge corrosion problems. Internally for reinforced concrete, rusting rebar expands and further cracks the cement allowing more salted-water to keep penetrating further into the concrete, further accelerating the corrosion. With steel bridges the problems are the same, they are just more visible since the rusted connections are not hidden encased in concrete. Bridge inspectors have sophisticated tools for both X-ray and conductivity testing to find corrosion. There isn’t a single bridge in all of New England that doesn’t have significant corrosion after 20 years, of what normally should be a 40-60 year structural life span.
In some limited cases, on some bridges the highway crews use Urea to melt the ice instead of salt to try to forestall the corrosion problems. But the salt still arrives carried by cars and trucks dipping wet from earlier salted road sections.
So if we are to believe in the Climate Change Fairy, and she is going to warm the Earth and supposedly reduce winter snowfalls and freezing weather, this should be a blessing to reducing the amount of salt used and thus lessening the corrosion problems.
And it is rainfall events in the springtime that serve to wash away the winter’s applied salt. So more rainfall will help flush the salt away from the structures, downriver, and out to sea.
Science and engineering today are not what they have been yesterday. And there is no tomorrow 🙂
There is engineering that is practiced by actual working engineers who have to solve real problems, stay within budgets, and not kill anyone.
And then there is this Academic Ivory Tower engineering that is practiced by these two rent-seeking, virtue signaling Lehigh University professors and by Mark Z Jacobsen at Stanford U. Solving real-world problems, staying within construction budgets, and not killing anyone with their academic studies is not their concern.
The two are becoming increasingly separated as the climate change rent-seeking corrupts all that it touches.
Don’t forget about the FIU Diversity Bridge!
“A bridge too far.” An excellent analogy for some of the climate alarmism floating around (e.g. get rid of meat). Various bridges in and around Arnhem (which was too far) were destroyed or replaced during and after World War II. The Waalbrug bridge over the Waal River at Nijmegen still stands. A warmist could be referred to as a “Waalbrugger.” (Hope that translates into Dutch as something civil.)
Is David Yang a relative of this clown (see after 0:11) ?
That picture of the bridge collapsing, it’s the Tacoma Narrows Bridge. link Wiki describes the cause as ‘aerodynamic flutter’.
Bob. I thought the photo of the bridge was pertinent to CAGW in that the designers of that bridge made a huge mistake by not understanding the effect of wind on the structure. Alarmist are making similar mistake by not understanding some very important science and by not understanding they are going to cause a collapse of our society.
Yes, an unforeseen dynamic lateral wind loading on bridge deck, not allowed for in the design codes of the time. They probably only had to design for “static” wind loadings based on those drawn up in the UK in the mid/late 1800’s following the investigation of the Tay Railway Bridge collapse in Scotland which only then identified such lateral wind loadings.
We have relatively recently had a failure of a group of Cooling Water Towers at a Power Station in Yorkshire U.K. where the Group effect was shown to have magnified the dynamic wind forces on these structure in the air flows between the closely grouped towers.
That’s engineering development for you, and always will be. Comet aircraft square window failures, Yarra Bridge failure of Box Girder failure in Australia and elsewhere, Ronan Point pre-cast concrete panel structural failure in London due to a minor gas explosion in one apartment – creating a cascade failure due to dynamic impact loads of floor and wall concrete panels at one corner of the tower structure.
While the engineering analysis of bridge scour is indeed a reputable line of research, this entire paper is nothing more than derivative bullshit.
When you start by saying “We know that …” and followed by stuff that we know is NOT true (warming causes more extreme weather, which is the exact opposite of fact, and truth, and we know this from geologic history that is extremely well documented that it is warm periods that have always been the most stable and benign of environments, and that it is cold eras that cause instability and vast disruptions of everything on the planet, from geology to the biosphere to the weather) .. then you have utter bullshit.
All the Climate Hysterics keep repeating bullshit that we all know isn’t true, and they always preface it by saying “We know that …”.
Bullshit in, bullshit out.
Take the George Washington Bridge. Please. It opened in 1931, and the lower deck was built some 30 years later. Before the addition of the lower deck, the bridge was known to sway as much as 30″ in high winds. Yikes.
More fantasy models based upon unicorns and fairy tales.
Odd that. Lehigh University is located in Bethlehem Pennsylvania along the Lehigh River.
“Historical Floods: Lehigh River at Bethlehem, Pennsylvania”
Which really only covers modern era floods, i.e. floods of the 20th and 21st Century.
Even with modern era floods, the most severe Lehigh River floods in Bethlehem Pennsylvania are 1942, 1902, and 1955.
Engineers design what is necessary to fulfill the purpose using history and modern materials. Fantasy models are impractical under the cold glare of fulfilling engineering requirements for service and safety.
^Latest red meat diet nutrition guidelines uses best science instead of best guesses,^ by Nina Techolz, LA Times, 10/9/19, at https://www.latimes.com/opinion/story/2019-10-09/red-meat-diet-nutrition-guidelines
Reckon the “inspiration” for this research came from the grant money.
This is no more than standard engineering practice with climate catastrophe tagged on to get the grant.
Bridges get designed to a 50-year or 100-year event. Climate change would cause the precipitation to increase and, like they say, a 20-year event would become 13-year event. This would throw out the hydrology on most bridges and the biggest issue would be scour. Since the design flow rates are so rare, the only impact on bridge structures would be the extremes, which still wouldn’t happen very often (even a 20-year event turning into a 13-year event doesn’t really make for a noticeable change to the average person except for in government bridge funding).
I think that it would not be very difficult nor expensive to increase scour protection under bridges. The odd one will wash out under an extreme weather event that didn’t happen before, but the bridge engineering field will adapt with any new bridge designs.
It is only a matter of time before the Boeing 737-Max problems will be blamed on climate change.
Analysis and policy fail miserably when they are based on inane, superstitious nonsense.
“We know climate change will increase the frequency and intensity of natural hazards like hurricanes, heat waves, wildfires, and extreme rains,” says Yang”
HOW do WE know this?????
What is “climate change” supposed to be, anyhow? Is there something closer to reality that we should worry about? Like “what is Santa Claus feeding those reindeer on that makes the bastards fly?”
Climate Change and bridge safety? I’ll go out on a limb here and say that any bridge covered by a mile of ice is probably not safe.
There was a man called Yang
Who’s theories collapsed with a heck of a bang.
“The climate, the climate” he wittered unending,
Until he heard of a disaster by Morendi
The Genoese got it right with no scam!