Thoughts on the Engineering Industry

A blog covering engineering, technology and business topics

Archive for the category “Transportation”

Applications of Shape Memory Alloys in Concrete Infrastructure Rehabilation

Hello, I hope everyone is doing well.  I’ve been busy with the holidays but I’m finally going to get back to my blogging and will hopefully maintain my weekly posting schedule this time around.  Today, I would like to talk about some research on applications of shape memory alloy (SMA) in concrete infrastructure rehabilitation being done at University of Houston and Qatar University.

SMA’s are metal alloys that can be deformed and then return back to their original shape when re-heated.  In this case, researchers are testing the usage of SMA’s in a rod that would be wrapped around concrete beams or columns.  Their ability to deform, then return to their original shape, would apply an active confinement pressure.  The design/usage of SMA’s would perform the function of current fiber-reinforced polymers (FRP’s); however, FRP’s only apply a reactive confinement pressure.  The confinement pressure provided by the SMA’s would, in theory, further reduce long-term deterioration and degradation.

The researchers will focus on determining the best available material for concrete columns and beams.  There are three types of metal alloys being tested.  The alloys that are most commonly available are the nickel/titanium alloys, referred to as binary alloys.  Ternary alloys include a third metal in addition to the binary alloy metals.  A third option are the iron- and copper-based alloys, which are generally less expensive.  Since binary alloys require constant heating to have continuous active confinement pressure, the scientist are focusing their studies on a Ternary alloy using Niobium and Iron/Copper alloys.

I believe the application of SMA’s in this application could improve infrastructure rehabilitation.  However, there are some concerns I have.  I think we need to see definitive proof with testing that, by adding the active confinement pressure, we effectively improve the serviceablity life of the infrastructure. The other concern is that we don’t know how much the rods will expand due to creep – especially since the rods will be continuously loaded with an outward force and have already been deformed to a previously outward deformed shape.

What is your opinion on this application for shape memory alloys?  Do you think it will be effective and practical for concrete infrastructure rehabilitation?  If you enjoyed reading, like the post and share it with your friends.  Thanks for your time and have a good week!

Source 

“Shape Memory Alloys Could Bring Stabilizing Force To Concrete Infrastructure”, David Hill, Civil Engineering Magazine, June 2014

Image Source

“Shape Memory and Palladium Iron Alloys”, taboodada.wordpress.com/2011/03/31/41/, March 31, 2011

Application of 3-D Printing and Modular Design to Construction

Hello everyone, I hope you guys had a good weekend.  Today I would like to discuss a couple innovations which apply 3-D printing and modular design innovations to construction practice.  These are applications that were more common in manufacturing and prototyping initially but can be applied to construction as well according to the article by Business Review Weekly.

The first innovation is the application of 3-D printing to the creation of moulds for precast concrete.  Traditionally, other materials such as wood, foam or rubber have been use, and constructing these moulds could take months to construct.  The Laing O’Rourke Company has developed a method that 3-D prints a large scale wax substrate mould at a rate of 150 kg/hr using a robots.  They have applied this to common projects such as stormwater pipes and have achieved cost savings of 50% to 90%.  Additionally, this solves the waste problem because the wax mould is lifted off or melted away in a water bath after the concrete is cured.  The wax can then be filtered and recycled.

The second innovation is the use of modular components in hospital construction.  Hospitals are one of the most expensive areas of infrastructure because they are individually designed.  Hickory Group has developed a modular panel for use in reception and administrative areas.  These areas use what is referred to as “accommodation components” which constitutes up to 40% of the construction cost of a hospital.  By using the modular panel, construction time can be cut by 40%.  Furthermore, the panels are easily replaceable.  If a panel is damaged, the hospital  can simply order a replacement and have their maintenance worker install the new panel.

Both of these are very good innovations in my opinion.  They are taking methods that have been proven effective in several previously tested applications and expanded their usage.  Furthermore, a reduction in time of construction and cost of maintenance/construction has been achieved.  I would be interested in seeing a more detailed account of the numbers and statistics.   However, based on the information provided, these are great examples of low risk/high reward solutions that can greatly improve construction practices.

What is your opinion on these innovations?  Do you think they’ll be effective?  If you enjoyed reading, like the post and share it with your friends.  Thanks for your time and have a good week!

Sources

Michael Bleby, “BRW Most Innovative Companies 2014: Why Construction Companies Are Thinking Like Manufacturers”, Business Review Weekly, October 9, 2014, http://goo.gl/O0oD6E

Image Source

Anne-Mette Manelius, “Concrete After Dark – Is There An Afterlife for Concrete?”, Concretely, October 17, 2014, http://goo.gl/IYI6q2

Benefits and Constraints of “Self Repairing” Asphalt

Hello everyone, I hope your week went well.  Today I would like to talk about current research in designing “self repairing” asphalt.  Erik Schlangen, a civil engineer from Deft University in the Netherlands, is doing research with the goal of creating asphalt that can repair itself.  Schlangen has started testing an asphalt mixture made of basic asphalt with strands of steel wool mixed in.  His research shows that the asphalt when heated with microwave radiation will melt the asphalt so that the cracks will be smoothed out.  Schlangen has invented a vehicle which uses induction coils to heat the road and melt the asphalt/smooth out the cracks.  To properly maintain the asphalt roads, repairs would need to be performed every 4 years.

There are a some benefits I see with this:

Maintenance Cost

Currently, one of the biggest costs in the infrastructure industry is maintanence and repair.  If this is truly as effective as it seems, it could save a lot of money and free up some room in the budget for other projects.

Maintenance Schedule Requirements

The other big issue when considering maintenance and repair of infrastructure is time.  Living in Dallas, I am currently experiencing this issue right now.  If repair or maintenance takes a long time, it can make traffic conditions worse long before it improves them.  With this technology, repairs can be done quicker and will reduce the poor traffic conditions as a result.

That being said, there are some potential issues that aren’t addressed in the article:

Durability

The obvious issue in durability is the asphalt.  Since the asphalt can melt when heated theoretically, will it also be stiff enough to withstand the loads.  There are a lot of heavy trucks that travel over a highway on a daily basis and this adds to maintenance issues as it is.  Furthermore, at what point does the damage become too much to repair?  If this asphalt system is not durable enough, the technology becomes ineffective.

Scaleability

When and where can this be used? On most the of the highways in D/FW, traditional concrete topping is used.  If this asphalt system cannot be applied on a larger scale, the increased equipment and training cost for the maintenance itself will be greater than the cost savings of the technology.

I look forward to seeing research on this product.  If this is effective, this could improve the maintenance of our infrastructure a lot.  What are your opinions on this research?  Do you see any other potential benefits and/or issues?  If you enjoyed the article, feel free to like it and share it with your friends.  Thanks for your time and have a good week!

Source

Jason Fell, “Self Healing Phones? Try Roads That Fix Themselves”, Enterpreneur, September 16, 2014, http://goo.gl/a6uk5z

US Depart of Transportation, Federal Highway Administration, “What Can Be Done to Enhance HVUT Revenues?”, 2006, http://goo.gl/sG9VlF

Image Source

Karissa Rosenfield, “Erik Schlangen Demonstrates the Potential of ‘Self Healing Asphalt'”, archdaily, July 12, 2013, http://goo.gl/794P6

5 Critical Assessment Questions for Design Safety

Hello, I hope everyone is doing well.  Work has slowed down for me a bit, but I did go on a site visit recently where our firm inspected a floor structure collapse.  The collapse reminded me of the responsibility engineers have in regards to occupant/pedestrian safety and I would like to discuss some of my thoughts about that.  In this post, I will share the 5 questions that addressed to ensure a safe design.

  

1) Would you would feel safe?
The floor collapse first reminded me of a quote (written by Michael Armstrong) that I read a long time ago.  “The ancient Romans had a tradition: whenever one of their engineers constructed an arch, as the capstone was hoisted into place, the engineer assumed accountability for his work in the most profound way possible: he stood under the arch.”  When you design something, the safety of the occupants and other pedestrians is critical; if you don’t believe that you did everything possible to safely design the structure, then it shouldn’t be considered safe for other people to use either.
 
2) Are you qualified to make the decision?
In designing a structure, it is critical to have the necessary qualifications.  This ensures that you have practiced enough engineering and gotten enough experience in the design process.  Knowledge is important; however, just knowing how to do something does not mean you can adequately design the structure and all the parties involved can stand behind your decision from a legal perspective.  The best engineers have extensive practice and repeatedly executed the design process so that they know how to analyze the design instinctively. 
 
3) Do you have enough knowledge to make the decision?

This is similar to the previous point, but this gap in knowledge can also happen to an experienced engineer.  A design can start out being in one area of focus, but shift to another very quickly.  Or the scope of the design could not be very focused at all, and as time goes on the focus gets far more detailed which requires special education.  When this happens, it is critical that you as engineer obtain this knowledge and/or get some consultation from some one who as this knowledge.  If you don’t, it leaves doubts as to whether the design will perform as desired.
 
4) Are there unique circumstances that might make this situation different?
A design could also fail due to unique circumstances that were overlooked.  For example, you may be designing a structure that has been done a million times before but is constructed differently.  Or the structure and/or area around it could be different.  Whatever it is, these unique circumstances could change what is required for a safe design.  If these unique circumstances are overlooked, a critical check in the design process could be missed.
 
5) What is at stake if you are wrong?
Different buildings are used for different purposes.  Depending on the purpose, the cost of failure could change drastically; either in terms of pedestrian safety or the usage of the building.  To ensure that the design is safe and the community is not drastically impacted by it’s failure, the consequences of being wrong needs to be considered.
 
In my opinion, these are the 5 critical questions that need to be addressed for design safety.  What questions do you think are important for design safety?  Are there any critical questions I missed?  Thanks for your time and have a good week!
 
Image Source

Benefits of Reusing Composite Shingles in Asphalt Roadway Construction

Hello everyone! I hope y’all have been doing well.  Today, I want to talk about an interesting innovation I read about the construction of O’Hare Airport. (http://goo.gl/WjI8Ek)  They collected used composite asphalt shingles and used them as part of the asphalt binder in the runway and various road type structures for the facility.  In this post, I will outline the process and the benefits.

 
The process:
Old Shingles Are Collected:
First, shingles are collected for reuse in the system.  At first, there weren’t any incentives added to motivate people to recycle used shingles.  However, some incentives have been created through different programs in various locations – all them outlined in the article.  One of them is a ban on sending large amounts of shingles to the landfill.  Another concept is an increased charge for disposing of shingles as compared to providing them for reuse.  The only exception is shingles that incorporate asbestos in their production and various limitations are discussed for reducing that risk.  Overall, the incentives seemed effective in my opinion.
 
Shingles are mixed into a pure asphalt binder:
The next step is that shingles are ground up and melted.  Once melted, this product can be added to the pure asphalt binder to increase the volume of this asphalt binder product.  At O’Hare airport, the shingles made up a 3% percent portion.  This didn’t make a huge dent in the budget but depending on the project it could reduce costs more.  Statistics and comparisons are provided in the article.
 
Asphalt is Laid Like Normal:
The asphalt binder and resulting asphalt is used like before.  As long as any differences in material properties are accounted for, the design and construction remains the same.  This results in an easy implementation on the construction and design side of the process.
 
The Benefits:
Reduced Use of Oil:
Oil is a precious commodity; anytime it’s usage is reduced, I consider it a good thing.  Along with that, it is easier to get a hold of used shingles than oil.  For both of these reasons, I consider the reduced oil usage a considerable benefit.
 
Reduced Cost:
The cost of using reused shingles is lower than using a pure asphalt binder.  Unless the scale is large, it is a minimal cost difference.  However, considering the scale of infrastructure cost these days and the amount of repairs needed, the scale is large enough that it would make a difference.
 
Reduced Waste:
These shingles, if not used in this capacity, would most likely be going to a landfill.  The lack of landfill space and shear quantity of human waste going to landfills is a current issue and reducing the amount from the housing would be a large contribution towards reducing that waste.
 
What is your opinion on the usage of this mixed asphalt binder?  Does it provide enough benefits to outweigh the cost and effort of changing the process?  Are there any noteworthy drawbacks or additional benefits not mentioned?  Thanks for your time and have a good week!
 
Sources:
Jon Hilkevitch, “Getting Around: Old Shingles Get New Life on O’Hare Runway”, Chicago Tribune News, June 30, 2014, http://goo.gl/WjI8Ek
 
Image Source:
“Why Homeowners Should Choose Asphalt Roofing Shingles Recycling”, Asphalt Roofing Shingles Recycling, October 18, 2012, http://goo.gl/u9l7cD

The Balance of Public Private Partnership and Government Funding in the Infrastructure Industry

 

     Hello everyone, sorry about being away for a bit.  I had an exam and had to focus in on school work, but I feel like I did good on the exam and can get back to a normal rhythm.  Today I would like to pose an interesting question.  What is best for the infrastructure industry – public private partnerships or government funded projects?

     I read a good letter-to-the-editor piece in CE Magazine recently that was critical of politicians who only wanted to pursue the infrastructure investment bank option for increasing investment.  In the author’s opinion, it is the job of the government to do whatever it takes to provide the infrastructure systems for this country.  I don’t see it as one dimensional as the author does, but this brought an interesting point to my attention.  A lot of people involved with the infrastructure industry like the public private partnership type projects as a way to bring more investment to the infrastructure construction and maintenance process.  Since increased funding in this area is needed ASAP, I have no problem with them pushing for this option if people are willing to do this.  However, issues in the infrastructure industry that can’t be addressed through a public private partnership system are largely over looked.

    Public Private Partnerships can help relieve a lot of the issues that drag our infrastructure down right now.  For example, a private company could charge tolls for a road and use that to maintain the road as part of a business plan.  This is a great system once you solve the oversight and standards issues.  Another area that this could be beneficial for is management of projects and procuring construction manpower and equipment.  As people have discovered with the government projects, having to maintain a large bureaucracy in managing these large projects is expensive.  Off loading those expenses to companies willing to do the work would allow for increased efficiency in the infrastructure construction process.

    However, there are some parts of the infrastructure industry where government investment is required to some degree.  The main one I see is the initial investment stage of these large scale projects.  Any private company will need some help (or at least an incentive) to take on the large amount of initial investment required.  Private businesses in general prefer projects that have large profits and the lowest possible expenses.  Government can provide a lot of aid to the infrastructure industry by allowing private companies to apply their preferred model for business.  The other area I see the government being essential are the parts of infrastructure where for profit motives aren’t the bottom line.  A great example of this is public transportation.  Overall, it is a largely inefficient industry in regards to cost and maintenance.  However, it doesn’t mean that it is something that shouldn’t be promoted as a part of our infrastructure improvement plan.  I’m not saying that we should take a loss in these projects, but it is something that should be offered without an eye towards massively cutting cost or increasing profits.  Since a company will not see the same high margin of profits they might find in a large highway construction project, they are more like to not take the project or to maintain an inadequate system due to their goals of minimizing inefficiencies and increasing profits.

    To sum it up, a balance needs to found between the application of public private partnerships and government funded projects in the infrastructure industry.  Some of the ways I think we can find a good balance are listed above.  What is your opinion about the balance of the infrastructure industry?  Is there anything you think we need to do to improve it?  Thanks for your time and have a good week!

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

Start Up Plans and Revisions for the Hyperloop Design

Hello everyone! I hope y’all are doing well.  It’s the same old stuff for me.  Looking forward to Halloween though– it’s always my favorite holiday.  And I want to go to a haunted house since I haven’t been to one in a long time.  Today, I want to talk about updates on the hyperloop concept since Elon Musk has made the proposal.

JumpStartFund has recruited two people, Marco Villa (former director of operations missions at SpaceX) and Patricia Galloway (first female president of ASCE) to coordinate the month long fund raising process.  Dirk Ahlborn, CEO and co-founder of JumpStartFund, has said “a lot of people talk about why this project will never work and how difficult it is to realize,…We are honored to have Dr. Villa and Dr. Galloway on board to lead our community, and their involvement goes a long way to proving that our platform’s processes, along with our community, can actually bring mega projects to life, such as Hyperloop.”  This fundraising is unique in that JumpStartFund will apply concepts of crowd space design used in the design of open-source software.  Galloway is interested in the project because it offers some unique challenges.  According to her, the challenge in this stage of the project is to verify its viability and prove that it can be practically designed and constructed.  They will have to bring people into the project that can not only bring in useful expertise but some much needed equity as well.  Galloway said “I believe this project will revolutionize how transportation will be viewed for future travel to and from major cities similar to the way the Concorde almost changed air travel,…What is different today is the opportunities that crowdsourcing and crowdfunding offers in getting dreams and innovations off the ground to allow the Concordes of the future become reality today.”

The Technology Futurist of AutoDesk, Jordan Brandt, has also added some significant input as well.  He says “Elon Musk put a lot of this energy into designing the pod capsule, and the power requirements, and things like that,…but not so much into the infrastructure, which by the way is the most expensive aspect of the project.”  Using 3-D modeling software, Brandt has redesigned the tubes such that they are stacked in a vertical figure 8 design.  According to his calculations, this should reduce land area requirements and the quantity of pylons needed to support the tubes.  Along with other engineers at AutoDesk, he also devised a system, called a mobile braiding system, which would use carbon nanofibers to create the tubes as it moves along the planned route.  With a refinement in the carbon nanofiber manufacturing process the material could be cheaper and the transportation for the construction costs could be greatly reduced as well.  In his final estimate, he believes this will save billions of dollars on the project.

In my opinion, these are the types of innovations I was hoping would be made on the design.  In my previous blog post (http://goo.gl/X1UgIK, second to last paragraph), I cited construction costs as one of the critical issues to address and this is an innovative idea.  I worry that the refinements in manufacturing the carbon nanofiber might not be as effective as thought and I also worry about the need to create yet another untested machine to complete the project.  However, these are the types of creative ideas that I think are needed in transportation design going forward.

What are your thoughts on these new developments?  Do they help or hurt the viability and the implementation of the project?  Thanks for your time and have a good week!

Sources:

Rogowski, Mark, “With Engineers On Board, A Startup Is Driving The Hyperloop Idea Forward”, Forbes Online, 9/26/2013, http://goo.gl/uMjgGH

Jessica Leber, “What Will It Take to Actually Build the Hyperloop?”, Co.exist, 10/10/2013, http://goo.gl/j3ESai

Basic Overview of the Hyperloop

Hello everyone, I hope y’all are doing well.  I’ve taken a bit of a vacation, both literally for a weekend, and then for longer in regards to my blog.  I feel guilty but it just felt like the right time to do something like this.  Nothing else new has really been going on with me – still just looking for work as an engineer and keeping my resume up to date.  I have taken the time to really learn Revit which should help me and my next big to do list in regards to personal learning is getting sharp on AutoCAD again.  One fun thing is that I’m also working harder on getting my Spanish to a conversational level, it would really be nice if I could put that on my resume too although not as important.  I will also start working as a substitute teacher again and I hope that won’t cut into my job hunt and personal job training right now.  We’ll see how that goes.  Anyways, that’s about all as far as updates go – today, I want to talk about the recent Hyperloop Alpha Proposal published by Elon Musk (founder of Paypal, SpaceX and Tesla Motors).  It has created quite the stir in the engineering community and I thought it would be a good topic to come back on. For this blog post, I am going to reference Elon Musk’s Hyperloop Alpha Proposal (http://bit.ly/16LCXwt).  However, this is a complex enough idea with enough attention that I might do some more detailed analysis in another blog post.

The hyperloop is a combination of a maglev and vacuum tube system.  Similar concepts have been proposed by Rand Corporation and ET3.  The main difference is that the previous designs involve using a hard or near hard vacuum in the tube; however, the Hyperloop uses a low pressure system.  The low pressure system is supposed to be much easier to maintain using standard pumps and maintenance than a hard vacuum.  The propulsion system involves a combination of air pumps and magnetic levitation.  An air pump will be put in the front of the train and will pump air below and behind the train.  This will accomplish several things: reduce air pressure in front of the train, create a buffer of air below the train, and reduce drag behind the train.  A pump will also be used directly below the train to reinforce the buffer of air as needed.  The maglev system will propel the train forward and will be powered by a battery similar to the battery found in the Tesla Model S.  There are two options for the size and purpose of the train: one is a smaller passenger train and one that is a larger passenger train that can also carry several vehicles.  The Hyperloop is theoretically designed to travel at 700 mph according to the proposal.  However, the critical part of this design not the propulsion system but the tube system.  The proposal suggests a tube system that is supported above ground using precast reinforced concrete columns that would take up no more room than a power line pole would require.  The track would follow the I-5 Highway and only deviate from the highway when necessary.  Also, due to changes in elevation, it is estimated that the tube would occasionally have to be placed at or below grade.  The track would be stabilized using dampers and minor adjustments would be allowed for to account for foundation settlement.  The different sections track would be connected using expansion and contraction joints that would help account for lateral loads due to earthquakes and other lateral vibrations.  The rest of the report is numbers and calculations used for estimation and comparison in regards to other systems.  The specific numbers and calculations read like a rough estimate and aren’t worth discussing in this post in my opinion; however, I would recommend quickly browsing the numbers and calculations just to get a quick idea about the comparisons to other modes of transportation.  Elon Musk in closing goes on to list the critical issues that need to be considered to implement the idea:

“The authors recognize the need for additional work, including but not limited to:

1. More expansion on the control mechanism for Hyperloop capsules, including attitude thruster or control moment gyros.

2. Detailed station designs with loading and unloading of both passenger and passenger plus vehicle versions of the Hyperloop capsules.

3. Trades comparing the costs and benefits of Hyperloop with more conventional magnetic levitation systems.

4. Sub-scale testing based on a further optimized design to demonstrate the physics of Hyperloop.

Engineering News Record wrote an article (http://bit.ly/1a7MWQQ) recently sharing some professional critiques.  The first one is a quote from an unnamed source:

“Many media sources offer commentary from professors about the impossibility of the hyperloop. One of those same sources told ENR off the record that “the idea of building a $68-billion rail line that takes 25 to 30 years to complete is just as absurd.””

They go on to say that Elon Musk has addressed the issue that testing and further research is required, but that some blow back has come his way for that.

“Other media critique Musk for being only an idea man who is hiding behind his massive business responsibilities and not moving toward implementation of the hyperloop. Musk admits as much in his proposal and, noting that the hyperloop idea is not complete, asks for help from “all members of the community.””

The article then goes on to share some thoughts Ted Zoli of HNTB, National Chief Bridge Engineer.

““Just the substructure costs alone for elevated structure over the entire length of the alignment is enormous,” says Ted Zoli, national bridge chief engineer at HNTB. The hyperloop’s proposed design requires elevated piers every 100 ft. Zoli says if the structure was built instead at grade, the construction costs could be “sharply reduced.” He adds that it conceivably could be built at grade for much of the route, “particularly if it is in the median of I-5,” which is where Musk envisions much of the transit tube being placed.

Zoli suggested that, given the hyperloop’s 88-in.-dia passenger pipe, any necessary tunneling could be done with horizontal directional drilling (HDD), “an inexpensive pipe installation technique.” Zoli adds that the largest HDD done now is 56 in. in dia, but he thinks custom HDD equipment readily could be developed, given the size of the hyperloop project.””

In closing, a final addition to the list of concerns is added in reference to another comment by Ted Zoli.

“5. A closer look at expansion joints.

“The expansion joints have not been figured in, in any meaningful way, and would be required much more often than at the terminal stations [as the current proposal outlines]. I would expect something on the order of every mile or thereabouts, even with a telescoping connection. Bearings would also have to accommodate relatively large relative movements for this distance between expansion joints,” says Zoli.”

In my opinion, there will be several critical issues if this is pursued.  The main one is the tube system in regards to column supports or on grade and expansion and contraction joints.  Given the high portion of the budget it involves, the high maintenance cost, even if it is designed well, could make it infeasible.  That combined with the earthquake and dynamics issues make that the most critical issue.  Another possible issue is testing – this is a system that has never been used on this scale before and would need significantly more testing and research to make a final decision, both of which cost money and won’t magically happen overnight.  And the final issue I see that has not been mentioned in the article at all is the reticence of the government to use unproven systems.  Take a look at how long it has taken to get high speed rail going in California and that is a system that has been proven to work for a couple decades in other countries.

Well this post got longer than I expected for my first post back in a while but thanks for reading if you got to this point.  What are your thoughts on the Hyperloop?  Do you have any concerns about the hyperloop?  Do you think this system can realistically be designed and implemented?  Thanks for your time and have a good week.

New Landmark Bridge for Downtown Fort Worth

Hello everyone, I hope y’all are doing well.  Not much has changed with me…still looking for work and I am also making a solid effort to brush up on some structural engineering programs like Revit, SAP, and AutoCAD.  Today I want to share my opinion on a new bridge that is going up in my hometown of Fort Worth, TX.  Part of it is for selfish reasons –  it is my hometown and I am glad we are getting a fancy new bridge for an up and coming area of town.  However, it also uses a unique combination of bridge design concepts I would like to discuss.

The design of the bridge is a combination of two common bridge design concepts – a network-arch bridge and a precast concrete bridge.  The city wanted a network-arch bridge to add aesthetic appeal to the design.  However, they wanted minimal disruption in regards to traffic – hence application of precast concrete principals.  The article gives the following specifications for the bridge: “The bridge is a series of 12 post-tensioned concrete arches, six on each side, which are the main structural elements. Each arch is 163 feet long and over 23 feet tall. While the new bridge will remain with four traffic lanes, it will be much wider to incorporate lanes outside the arches for pedestrians and cyclists.”  The goal was to reduce the on site construction site down to 150 days.

To do this, the arches were cast on their side for efficiency.  Post tensioning was applied in three stages.  The arch was cast sideways and post tensioning was applied, the the arch tilted up right and another round of post tensioning was done.  Then the arch was moved into storage and a final round of post tensioning was done.  The casting process took between 3 to 6 weeks; while this was being done, the foundation and columns were constructed on site.  Transport and installation of the arches started in July and will finish by October.

Personally speaking, I like the bridge design and location.  The bridge will connect the up and coming West 7th District with downtown Fort Worth which should guarantee good visibility.  Along with that, the creative design process and improved construction time is also impressive.  This should make the bridge a good icon that can be advertised for the Fort Worth area.  The only drawback I could see is that the new combination of design concepts may not work as well as expected.  I trust that it can initially handle the dead loads and traffic live loads adequately so safety isn’t a major concern for me.  However, the lifetime demands like fatigue, deflection over time, etc. are more difficult to predict and can’t be tested as accurately – especially with uncommon designs like this.

What are your thoughts on the bridge?  Do you think the design will be effective?  And on a personal note, if you have been to downtown Fort Worth or West 7th Street district, do you think the bridge will be a good addition to the area?  Thanks for your time and have a good weekend.

Source:

Nancy S. Giges, “World’s First Precast Network-Arch Bridge”, www.asme.org, http://tinyurl.com/n7wblwa

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