Thoughts on the Engineering Industry

A blog covering engineering, technology and business topics

Archive for the month “December, 2013”

The New “Flying Carpet” Roof For the Courtyard at the Musée de Louvre

Hello everyone.  I hope your holidays have gone well so far if they started. If not, cram as much fun with your family into the next week.  Today I decided to not post a lengthy or detailed article.  I just wanted to share something cool I just read about today. The Musée de Louvre has recently completed construction on a roof over a courtyard area that literally looks like a flying carpet.

The concept of having a design like this is extremely impressive.  Not only that, there was a lot of coordination and change of work late in the process to insure the architect achieved the desired look.  This is the type of project I would love to work on…very challenging and technical with coordination and team work being a necessity.  In fact, it’s so technical I’m not going to even try to explain the details.  The basic design is a steel frame with various pieces of glass that vary in size and thickness so as to withstand the stress placed on the glass.  The glass is curved and tinted so that it literally looks like a flying carpet and is supported by slender pinned end supports placed such that lateral movements are resisted.  All of this required highly technical computer analysis and was very impressive to read about.  I definitely recommend finding the reference below or finding more information about it if you are a structural engineer.  Below are some photos I found that show new roof structure.

http://goo.gl/YYLSGk

http://goo.gl/x1MnlP

What are your thoughts on the roof?  If you were in Paris, would the Louvre be a place you had to visit to see this structure?  Please share if you find this article interesting and subscribe if you want to read more.  Thanks for your time and have a good week off. 🙂

Resources:

Bucci, Pierluigi, “Flying Carpet”, Civil Engineering Magazine, June 2013, pg 49

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Advancements in Resilient Timber Design

Hello everyone. I hope y’all are doing well.  I’m looking forward to Christmas and I hope you are too.  Just in case I decide to not do a post before Christmas I just want to wish y’all a Merry Christmas.  Today I want to talk about some advancements in timber design taking place in the multi-family residential building industry in California.

In California, residential structures can be vulnerable to seismic loads – especially if there is an open floor plan on the bottom.  Engineering professor John van de Lint from Colorado State University has been leading a team of researchers in that specific area of study as it pertains to first floor garages.  He has previously completed similar research with Simpson Strong Tie in 2009 in regards to natural disasters and it led to the consideration of timber for mid-rise structures with high seismic loads.  According to Lint, “Earthquakes are particularly damaging to buildings with open spaces at street level because they collapse – the first-floor parking makes the building structurally weak and soft…There are tens of thousands of these multi-family buildings throughout California and much of the U.S., making this a serious safety issue.”  The team has tested several concepts for earthquake retrofitting on structures designed to replicate common California architectural practices.

A common characteristic among all the models they tested is a timber frame structure with an open structure on the first floor and a purely timber structure on the upper floors.  Some of the retrofits followed the FEMA P-807 guideline because that is the current retrofit requirement in California.  This law requires that buildings with a soft story be retrofitted within the next several years.   One of the retrofits tested is cross laminated timber.  In this test, the shear walls are constructed with cross laminated timber and the floor diaphram is reinforced using plywood and attached to the shear walls using Simpson Strong Tie straps and clips.  The test was successful up to 50% Maximum Credible Earthquake (MCE).

The article also mentions some innovations for dealing with harsher environments.  In locations with more humidity and rain, protection from the elements can be a critical issue for timber frames.  Huber Engineered Woods has developed a material called ZIP System R Sheathing for the construction of walls where protecting the structure against the elements is critical.  This is currently the first product of it’s kind to be approved by the International Building Code.  This sheathing provides protection against bulk water, thermal, air and moisture resistance while being strong and durable.  The sheathing also provides increased energy efficiency for HVAC systems.  This system has advantages over regular plywood or oriented strand board in harsher climates because an additional layer of house wrap and hurricane clips is not required.

Both of these improvements may seem a bit generic at first.  In fact, the more I think about the descriptions above, the more I think of an advertisement pamphlet you might get from a timber supplier.  However, it is my opinion that these are significant advancements for the future of timber usage.  These two situations above are textbook reasons for the usage of a material other than timber for taller buildings in these seismic or weather critical locations.  With the proper implementation of these advancements in the future, the use of timber can be expanded to a larger variety of locations.  The only major drawbacks I see are the increased cost of using the materials and the necessity for contractors with experience implementing these designs.

Do you see these products changing the use of timber on a larger scale?  If so, how and why?  If not, what is the critical issue that has to be overcome?  Thanks for your time and have a good week!

Resources

Zweig, Christina, “Resiliant Wood: New Wood Products Help Cope with Nature’s Challenges”, Structural Engineer Magazine, November, 2013, http://goo.gl/NoJT9Z

The Application of “Bendable Concrete” to Increase Durability

Hello everyone, I hope your week went well.  Sorry about the delay in posting – the ice days in Fort Worth really decreased my general productivity.  However, I am here now and back on track.  Today, I would like to discuss the creation and use of a ductile concrete in regards to the durability of concrete structures.

Concrete is strongest in compression; as a result, tensile failure and cracking concerns are what control structural concrete failure overall.  Recent studies have shown that these recently created ductile concretes – referred to as strain harderning cementitious composites (SHCC) – increase the overall strength and failure load of concrete structures.  Furthermore, SHCC’s show a tensile stress-strain curve behavior similar to a ductile metal while still having the compressive strength of a normal to high strength concrete.  Even though it is more expensive, it has found its way into the Japanese markets and codes; it is here that it has earned it’s name of “Bendable Concrete” due to it’s ability to bend and withstand high flexural deformation without steel reinforcement.

The reference article mentions a couple applications in which it has been used:

The first one is a high rise construction project in Japan sponsored by Kajima Corporation in Japan.  The original seismic structure called for 2 pairs of columns ending at the top of the high rise and is connected to a 9 ft deep concrete beam using dampeners in a perpendicular shape.  The design was adequate overall, but using a crane to get the concrete beam up to the required height is difficult and it also requires difficult fabrication.  Instead, the seismic structure is now designed such that SHCC beams will connect the core walls on each floor so that the beams can deform as needed when subjected to a seismic load.

The second application is a solid bridge deck built by Michigan DOT.  The standard construction of the bridge would use normal concrete decks on steel girders with expansion joints in between the concrete decks to account for expansion and contraction.  In this case, a link of SHCC is used in place of the expansion joint.  The SHCC deck is 9 inches deep, measures 16.5 ft by 60.75 ft and is linked to a regular concrete deck.  The SHCC deck is intended to deform as the regular concrete expands and contracts and the combined deck rests on the steel girders.  As such, this requires a 2% tensile strain capacity and is something that only SHCC can achieve.

More applications such as the repair of the Mitaka Dam and Hida tunnel lining are mentioned as well, but not described in detail.  I would also like to add that all of these applications come from either Japan or Michigan DOT and I have noticed over the years that they are good about researching new structural engineering technology and implementing it well.

In my opinion, the is a very innovative and ground breaking improvement in the design of concrete.  In previous methods of concrete design, bridges have always needed to find ways to either add tensile strength or keep the concrete constantly in a state of compression.  And on top of that, this same strength in compression and weakness in tension has also forced engineers to come up with systems to limit cracking and allow for more ductility in the structure.  This innovation can solve both of these problems if applied well.  However, there are still currently some issues.  The main one I foresee is cost – it is more expensive than regular concrete and could limit it’s usage.  Along with that, there is the need of skills and knowledge in the construction of SHCC that might not be available on a nation wide scale yet.  However, this is a promising solution to one of the critical issues in concrete design.

What is your opinion on the usage of SHCC?  Are there any further applications you could see this being used for in the future?  Thanks for your time and have a good week! 🙂

Reference

Li, Victor C., “What if Concrete Can be Made Ductile?”, StructureMAG Online, December 2013, http://goo.gl/BtkmiK

The Overlap of the Architectural and Engineering Design Process

Hello everyone.  I hope you and your family had a good Thanksgiving.  My family in Texas got together for the first time since my Aunt Nana passed away, so it was good to have everyone back together again.  Today, I want to pose another question related to architecture.  I got to thinking about topics at the last minute and I was reading my previous weeks post.  It got me wondering if I could find some quotes that outline the overlap of engineering and architecture.  The format I’m going to go use is the following: bring in a quote, then interpret what I think it means and close by posing a question as to your thoughts on it.

The first quote I am going to have immediately came to mind when I thought about this topic.  It is a famous one and a classic amongst engineers:

“A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away.”

– Antoine de Saint-Exupery

Even though this doesn’t mention architects or engineers, I started with this because it outlines the main goal of an engineer.  Come up with the simplest and most effective system for building a safe structure.  Efficiency can take many forms (money, material, time, etc.); whatever we define efficient as, that is usually our goal.  And the interesting thing is that architecture has recently trended towards this same thing in modern city design.  And yet the classic concept of architecture is to make a structure pretty and artistic; efficiency was considered low on the list of concerns based on the buildings with a heavy architectural design influence over 100 years ago.  Where do you see the trend going and how has efficiency played into the design process for architects?

Another quote I found is interesting because it casts this efficiency in a negative perspective:

“I had a lot of trouble with engineers, because their whole background is learning from a functional point of view, and then learning how to perform that function.”

– Briano Eno

He is a famous musician and artist, and I would imagine that he is what we would call the classic creative personality – whimsical and artsy.  Engineering from this negative perspective alone would make one think that we just lead dull boring careers and do nothing interesting with the buildings we design.  Most engineers knows that this not always the case, but I could see some of our work falling into this category.  However, when combined with an architect who has a flair for the creative, it can allow us to apply the concept of learning a function and performing that function to a whole new level.  It can force us to design structures that use that function in unique way and exercise our problem solving creativity.  Have you ever had to use some creativity to solve a problem in your field? How often do you have to do so and how important is it?

Now I am going to bring in two quotes that combine to have an interesting message.

“We require from buildings two kinds of goodness: first, the doing their practical duty well: then that they be graceful and pleasing in doing it.”

– John Ruskini

“Architecture begins where engineering ends.”

-Walter Gropius

Both of these quotes have a combined message that architecture is critical in making a structure complete.  Not only do structures need to fulfill their purpose but they need to look good and be pleasing to the users.  And not only that, architects are the ones who do this.  That engineers are the boring ones who make it function and architects are responsible for the creativity.  I strongly disagree – there are many times I have listened to a engineers talk about a project and they talk about their input on the creative work they have done with the architects.  A lot of times it is in taking what an architect has drawn up and come up with a modification just as aesthetically appealing.  And sometimes, the engineers themselves play the dominant role, as shown with the recent trend of having landmark bridges in cities.  Who do you think is the most important person as far as creativity in the design is concerned? Why is that?

And finally I would like to end on a humorous yet enlightening quote.

“Engineers like to solve problems.  If there are no problems handily available, they will create their own problems”

– Scott Adams

For me, this outlines exactly the unique function engineers bring to any process.  We may seem narrow minded and boring, but for the most, we believe that there is always a better a way to design something.  The need for efficiency in regards to time, money, and material bring us to an end result.  However, this unique idea that there is always a problem to be solved drives a good engineer.  How often do you see yourself exhibiting this trait? Is it usually in a positive or negative aspect?

I hope you enjoyed the far less than technical post this week and didn’t find it too pedantic.  Please share this post if you find it interesting and follow me if you want to read more of my blog posts.  Thank you for your time and have a good week!

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