Monthly Archives: March 2013

Fontainebleau Halle

David, our Hong Kong corespondent, sent a great link to J. C. Grosso’s post on a structure designed by Nicolas Esquillan.

The post is in French….using google translate on my iPad…

The back ribs suggests a structure beyond (ie, material, rhythm and geometry) is affirmed and qualified by the presence of glass blocks (circles). The presence of the ribs is crutiale rhythm, the pattern is not far from celuis of Romanesque architecture. In some sunshine, the projection of the shadow of the ribs should be visible and send a thickness (mass).

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The Fontainebleau Halle, designed by a major 20th century engineer/architect, Nicolas Esquillan, responsible notably for the CNIT in Paris, was supposed to be destroyed by Fontainebleau city hall which wishes to renovate the area. Initially, there were in fact two identical buildings, one of which was razed in 1969.
This decision was widely opposed but the Architecte des bâtiments de France having given his approval, the building was not protected and an appeal by local associations having been rejected by the courts, Fontainebleau city hall could thus proceed whenever it wanted to demolish it. Although it announced this would take place this summer, city officials decided to start immediately, taking everyone by surprise. The associations, spearheaded by the SPPEF, which seems to stand out for its energetic defense of heritage causes whenever needed, led the protest and several demonstrators even stood up against the bulldozers sent out to tear down the building.

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The economics of Accelerated Bridge Construction

Update: I figured out how to solve America’s infrastructure problem. If user costs (a benefit) = bridge cost ( a cost) then Free Bridge!

So we have to value user costs higher and maybe we can even make money on a project! Now I just have to figure how I collect user costs….

Cash flow diagram.

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Since I started teaching engineering economics I find I have more questions about projects than answers. One of the things I look for now is the bias in an economic report. How the person writing the economic analysis might inadvertently slant their findings.

Accelerated Bridge projects often use user costs as the reason to construct an ABC bridge over a more traditional structure. Since user are costs are subjective, you could promote a winner based on some faulty reasoning.

But let’s say that the initial cost and user costs of an ABC bridge are perfectly defined and the bridge is a lower cost solution than a traditional bridge. My question is, what about maintenance costs and lifespan costs?

Will an ABC bridge have the same maintenance costs as a regular bridge, things like deck overlays or repairs? Will an ABC bridge last as long as a conventional bridge? Will an ABC last 75 years or more?

Since ABC technology is fairly new, it is a tough question to answer. As an engineer, my feeling is the more joints, the less likely a bridge will last a long time, (Think driving salts and water) but I don’t know.

So if you add in lifespan costs alone you might find that traditional structures would typically win even in the most urban areas. So as engineers should we include maintenance and lifespan costs in an analysis?

From a recent article
Cracks emerge in Minnesota bridge construction

“I understand that all agencies are trying to minimize traffic disruptions, but at what cost?” said Matt Zeller, executive director of the Concrete Paving Association of Minnesota and a former MnDOT assistant concrete engineer.

Paul Rowekamp, a MnDOT bridge standards and research engineer, said the agency is enhancing concrete mixes as part of an effort to reduce cracking in the precast bridge decks.

The surface deck cracking doesn’t compromise the structural integrity of the bridges, but it results in higher maintenance costs over the life of the structures, according to Rowekamp.

“It’s all about long-term durability, which is important for our local partners,” Rowekamp said. “They want to build it once and not go back for a long, long time. We are not quite there yet.”

Zeller said it “seems like a good idea to minimize disruptions. But if they are looking at short spans, which would generally imply they would be in more rural locations, I’d think the amount of traffic disruptions would be minimal.”

Years ago, no one thought much about “user costs” such as traffic delays, according to Rowekamp. But as traffic volumes increase, more agencies are looking at ways to pick up the pace of construction, he said.

Best Engineering videos – 1

Help me out, I’m trying to become better at making instructional videos. If you find a good one can you point me to it? I would appreciate it.

I thought I would also start a list of good engineering videos. The one below is a good start, short, well filmed. If you find good engineering videos I would appreciate a heads up and I will post them.

They can be in any language and any facet of engineering. THANKS!

Civil Engineering from Green Lemon Pictures on Vimeo.

iPad videos! Shear and moment diagrams

Okay this is not my best effort but it is notable for one thing, it was completely made on an iPad, uploaded to YouTube from the iPad and blogged with the iPad.

Sure everybody is doing it and now I’m part of the in crowd! ( well maybe on the far fringes of the in crowd, behind the dumpster)

I used GarageBand, iMovie, Doceri and Artstudio. Tablet computing is getting there and plants vs. zombies is addicting!

Update: I watched the video and is definitely lousy but the apps on the iPad are getting better. iMovie on the iPad is pretty basic, you can’t fade music, making cuts is difficult but you can put something together. I used my phone to upload to YouTube since I didn’t have Internet access when I made the video.. I know your hearing excuses, sorry. I will say it is amazing what you can do now, I remember Netscape and dial up modems. My first “real” computer cost $2000 and it only had two floppy drives, no hard drive! Those were the days, monochrome monitors, and WordPerfect on disk. I miss lotus 123..

Engineers suck at PowerPoint

Engineers suck at PowerPoint but is it our fault?

Imagine your going to an annual meeting of bridge engineers and you are going to showcase your recent discovery of nano mites in concrete. You call them ce-mites (hey your name not mine) and you want the world to marvel at their secret world.

Of course the first thing you do is fire up a PowerPoint presentation to display your research. Since the ce-mites are too small to be seen all you have are mathematical calculations proving their existence. Now you have a PowerPoint presentation comprised of words and calculations. This should sound familiar to any engineer that has attended a conference….

Now here is the problem, go to any site that professes to be an expert in giving talks and their advice, use pictures and minimize the amount of words to the bare minimum. I have long struggled with giving effective PowerPoint presentations but how do you explain structural analysis or engineering economics in pictures? How do I show calculations in pictures?

So like most of you I suck at powerpoint. I’m scheduled to give three lectures on construction engineering and contracts in April. I have about 60 slides of bullet points, now that is going to be a fun lecture to attend….a real barnburner.

So what should I do to liven it up?

Lets start with Things that I hate:

Text that whizzes in and out – seriously, that is not going to keep us interested.
Sound effects – fail
Clip art – are you trying to start a fight?
Over three bullet points per slide – I compromised and allowed a few bullet points. We are engineers after all.
Abbreviations – have you ever gave a talk and forgot what the letters stood for, I have….

Things I like:

Pictures – obviously good pictures are fun to look at but please relate them to the talk.
Voice changes – try not to be a monotone speaker, snore.
Enthusiasm – speak like you enjoy the topic (hard to do on engineering economics)

One place I just found was a blog called “Presentation Zen”, that has some interesting articles. (Yes I am late to the party)

So do you have any good advice for giving engineering presentations? I for one, could really use the help.

Presentation Zen link about Star Wars and PowerPoint

Great paper here by Jay Lehr – “Let there be Stoning”.

The Engineer as storyteller

I have been reading a great deal about the best ways to teach and give presentations. One nugget of advice that always bubbles to the surface is to tell a story. Now when you teach a class of a hundred, three times a week, this becomes difficult. (Which relates to the other top piece of advice, reduce class sizes.) Especially if the subject is somewhat dry like structural analysis.

But I think the idea of storytelling is a good one and something engineers have failed to do in their work. Architects are taught to have a “meaning” for their concepts, a reason or story that gives the public a way into their design. Artists are master storytellers, producing works that give life to a subject and fill the world with mysterious light.

Engineers on the other hand often see their work in terms of cost and buildability. We do a great job of actually getting things done but a poor one in terms of explaining our work. Take my latest video for example. (A few posts back.) I think it is a competent overview of how to draw shear and moment diagrams, with a bit of analysis in STAAD thrown in. But it is dead boring, something only an engineering student, under pressure to pass a course, would find helpful.

Thinking about it today, I could have made it a much more compelling story by adding a real life situation to the analysis. Imagine if instead of a line drawing with loads, I gave a brief background story to the problem. For example, the line drawing in the video represents the loads on a new beam designed to support a small mobile hospital building in Siberia. The hospital is being quickly assembled to treat locals affected by the recent asteroid. Will the beam hold the loads?

Now that story is certainly a stretch but even the thinnest yarn gives some background to the design. It becomes less of a boring problem and more of a reason to actually do the work.

Now we engineers do not have to make up stories about our projects but we should think about giving our projects the meaning they deserve. A bridge is not just a bridge, it is a gateway to new communities, a safe passage for those in trouble and something that unifies a city.

Buildings hold thousands of stories, families who are moving to a better life, romance, heartbreak, and the push to a better future. Think about the story for a project, it will make it more meaningful to you and the public.

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Bridge Engineers say they have less control over projects

This is from a year old article but I think it is still holds true. Engineers working on public infrastructure projects have always had to work with the political apparatus.  I am working on a project right now with non bridge engineers and it gets difficult to explain why or why not you can do something.

“One of the key issues for me is that I see the present (project) process being driven by vocal special interests,” he said. “I would not say a faulty structure is going up, but one that is driven by many demands.”

“Engineers need to better adapt to this process and be more proactive with the public to better communicate the technical requirements,”

Engineering failure – Sleipner A offshore oil platform

David sent me some great links to the Sleipner A offshore platform failure.

Link 1
Link 2
Link 3

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Sleipner A is a condeep gravity-based offshore oil and gas drilling platform. It taps into the Sleipner natural gas field, which is about midway between Scotland and Norway in the North Sea (Figure 1) and operated by Statoil. The original concrete support structure for Sleipner A sank in the Gandfjord near Stavanger, Norway on August 23, 1991 during a controlled ballast test.

The loss of the structure was due to design flaws that resulted from flawed analysis of a tricell joint. The loss resulted in a two-year delay of the exploitation of the Sleipner gas field. Sleipner A was intended to contribute 3 years of a planned 30 year period (1993 to 2023) in which 10% of western Europe’s gas demand will be met by natural gas fields in the North Sea (Jakobsen, 1994).

The financial loss from the Sleipner A failure has been reported variously (and in values that have not been inflation adjusted) as $180 million (Collins, 1997) and $700 million (Jakobsen, 1994).

There are two financial components to the cost. One was the physical loss of the structure itself (perhaps this can be figured at the lower $180 million mark). The second is the lost revenue due to the delay in setting the Sleipner gas field in operation (perhaps this accounts for the difference in the two reported figures).

Before the investigation was even concluded, construction of the second Sleipner condeep commenced. The second Sleipner was mated to its deck on April 29, 1993, 20 months behind schedule. Norwegian Contractors was found liable for the failure and dissolved as a company. In considering the dissolution of Norwegian Contractors, one should bear in mind the tremendous accomplishments of the twelve faultless condeeps they made besides Sleipner, of which are included some of the largest moving concrete structures in the world.

The amazing thing is the replacement was designed only with hand calculations. A good lesson about reliance on computers….

Probably the biggest lesson from this case study is the need never to treat computer analysis as a black box process.

Computer analysis is only as good as the user who inputs the model and interprets the results. Proper modeling and interpretation requires a strong understanding of the theoretical and practical workings of the programs and a thorough understanding of what the results mean.

Rational methods of checking results should always be employed and quality assurance processes should allow the time for proper attention to such details.