Thoughts on the Engineering Industry

A blog covering engineering, technology and business topics

Archive for the tag “structural”

Four Basic Steps to Determine if your Shingle Roof Has Been Damaged by a Hail Storm

Hello everyone, I hope your weekend went well.  I went to see the new Bond movie with my brother Friday and last night I went to a west coast swing dancing class and social event.  Other than that, I’ve been doing my usual stuff like working out and my job inspecting buildings.  Today, I’ve decided to write a blog post explaining four basic steps to determine whether a composition shingle roof has been damaged by a hail storm and quantify the extent of damages.  I’ve avoided this topic for two reasons: one is that there is a lot of information out there about this already, and the second is that it takes some prior experience to make an accurate assessment.  However, it is one major component of my job and I feel like I can provide some practical information that will help you should you need it.

1) Look for spatter marks on surrounding surfaces (http://goo.gl/COQH3i)

Spatter marks serve as a indicator of the size and direction of the recent hail.  The size of the spatter can be compared to the impact marks elsewhere to determine the extent of recent damage.  The directionality can be determined as well by figuring out which directional faces have or do not have spatter.  In addition, spatter will fade over time – this can differentiate between different ages of spatter marks within a recent time period in most cases.

2) Look for impact marks at susceptible surfaces (http://goo.gl/m15Wmc)

Impact marks can also be observed on some metal and wood surfaces.  Air-conditioning units are a good indicator due to the fact that they have 4 sides and metal/coil fins that are either soft or oxidized.  Spatter can be observed as mentioned before, as well as indentations.  Furthermore, the indentations can be examined to check for soiling, oxidation, or other forms of staining to determine the relative age of the older indentations.

3) Look at the general condition of the roof (http://goo.gl/7p5Yul)

The general condition of the roof will also affect the extent of hail damage.  Examples of other things that damage shingles aside from hail are general weathering, mechanical scrapes, blistered asphalt, and raised nails.  A roof with a worse general condition will be more susceptible to damage and could reduce the compensation should you involve the insurance company, similar in practice to automobile insurance compensation.

4) Look for hail impact marks and examine their condition/quantity (http://goo.gl/2nguV8)

The last step is to look for hail impact marks on the shingles.  Sometimes a relative age can be determined by checking for weathering of the reinforcement or asphalt within the exposed asphalt/shingle reinforcement.  To quantify the extent of damage, you can count the number of recent and/or old hail impact marks, as well as other general conditions if desired, withing a 10′ x 10′ square.  This is referred to as a test square by engineers and inspectors in the roofing business and is helpful information when estimating the cost of various types of repairs.

These 4 steps are the basic process I use to determine the extent of damage to a shingle roof.  Does anyone else have experience in roof inspections?  If so, what would you add to this list as a basic procedure?  For homeowners, have you had to deal with an issue like this before and how was the experience?  If you enjoyed my post, hit the like button, follow my blog for updates and share this post with your friends.  Thanks for reading and have a good week!

Image source

http://goo.gl/1MbnTT

Development of Transparent Concrete

litracon 1 Concrete Innovation Part 3: Design transparent inflatable Concrete Cement

Hello everyone! I hope the last couple of weeks has gone well.  I was preoccupied with a small vacation, school stuff, and having to get a new vehicle since my car was totaled.  However, I hope to get back on schedule after this.  Today, I would like to talk about a new development in concrete technology: concrete designed to be transparent.

According to the article by Giatec Scientific, the concrete mixture is modified such that 4 to 15 percent of the mix is fiber optics materials.  Ideas for transparent concrete since 1935; however, serious development had not been pursued until 2001 by Áron Losonczi for use in his architectural designs.  In 2004, production was started for other commercial usage as a type of concrete called “Litracon.”  Since then, other competitors have developed similar designs.  These products have been used with back-lighting or natural light.

I think the concept is very interesting.  It’s something I would probably enjoy working with or using in a design.  The aesthetics would be amazing to see and I like the idea that it could be used in circumstances where you need more stiffness than a big window could provide.  The situation would be similar to structures that use the glass masonry units.  There are however some issues I can see. One is when and where can it be used safely.  The article mentioned examples where it’s used in floors and floors can see a lot of loading in certain types of situations, i.e. stadiums or concert halls.  The other issue I see is behavior of over time.  Will the bonding of the cement hold up in a mixture with that much of a potential void ratio?  Even if it holds up in regards to it’s initial bonding, will the mechanical strength related properties such as creep and general durability such as cracking be reduced?  Along with that, I would imagine the aesthetics have to hold up as well.

What are your thoughts on the idea of transparent concrete?  Is it something that is practical to use in building design?  If you enjoyed the blog post, feel free to like it and share it with your friends.  Thanks for your time and have a good week!

References

Giatec Scientific, “Concrete Innovation Part 3: Design”, http://goo.gl/Ee7VBo

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

Design Issues for an Affordable DIY Tornado Shelter

Hello everyone. I hope y’all are doing well.  I’ve been taking some time to plan my move to the new job and be as ready as possible for the new job.  Today, I would like discuss the design of affordable DIY tornado shelters.  For reference, I will use a rough description of a study performed by Research Engineer Bob Falk of Forest Products Laboratory in Madison, WI. (http://goo.gl/qRM87t)

Tornadoes have always been a risk for people living in the midwest; and as a result, the design of wind and debri resistant structures has always been part of the house construction conversation.  There have been more technical and more resource intensive design/construction ideas discussed before.  However, the reason I chose to do a blog post using this source is because the goal is a design that can resist 250 mph winds and debri using only affordable wood and construction methods.  Additionally, the construction process is to be something that uses only basic construction skills.  I really like this concept not because this is the perfect solution, but because this is good starting point for people to be reasonably safe.  The design is constructed using interlocking timber with plywood overlay and the wood structure is connected to a concrete foundation using bolts.  The door is still designed using steel; however, Falk is researching a way to use a wood door.  The structure is currently undergoing testing using 2 x 4’s shot at 250 mph.

I believe that this would be a good design/construction process once the following issues have been addressed:

A repeatable design plan:

Whatever this design may entail, there needs to be an empirical, repeatable process that can be easily designed and built.  A good plan should include the following at minimum: door frame requirements, bolt spacing requirements along the wall, nail spacing requirements along the plywood and interlocking timber sections, timber grading requirements, concrete foundation requirements, and roof connection requirements.

Design Study of the Door and Frame:

As far as wind is concerned, one critical issue is the door and the frame around the door.  And especially after reading this article, it came to my attention because nothing is mentioned about the study of the frame.  The design uses a steel door, so the door shouldn’t be the issue in that case.  However, if the frame can’t resist the winds in the the hinge and bolt system and the wall/frame connection around the door the door system, it will fail to resist the loads.  Some basic wind tunnel testing should be a good starting point.

Bolt Connection to the Foundation:

The walls shouldn’t be the critical part of the wall if this is constructed as it says.  Yes, would splinters and could be dangerous; however, if the testing is occurring as described and enough strength is provided based on these studies the walls shouldn’t splinter.  However, there will be some very high shear and moment loads on the bolts.  If not adequately tested and designed, the wall could break of along the foundation.  I would argue that this even more critical as well since it would affect a whole section of wall, so I believe details need to be examined here.

Roof Connection and Design:

With the increased wind, the uplift forces on this structure will be very high.  Furthermore, I believe this has to be designed as an independent structure as well as a structure that is part of a larger building.  With this in mind, uplift forces applied to the whole structure of the second floor or roof needs to be considered as well.  Connections at the top of the wall need to be able to resist that full load or design needs to allow for relief of those forces if the house breaks around the shelter.  Either way, study and wind tunnel tests are required for a safe design.

What is your opinion on the shelter mentioned in the article?  Do you agree my assessment of the design?  Is there anything I missed?  Please share this post if you enjoyed it and have a good week!

An Innovative Technology for Concrete Roofing in Remote Areas

     Hello everyone! I hope y’all are doing well.  I’m almost done with grad school and looking forward to that.  Other than that, nothing much has happened.  Today, I would like to discuss a recent development in concrete roofing for remote areas.

     Scott Hamel, a faculty member of UAA (University of Alaska Anchorage), has developed a concrete roofing tile that can be used in place of cast in place concrete roofs.   While working with Habitat for Humanity in Port-au-Prince, Haiti, Hamel noticed that the prefered method of roofing is a cast in place concrete slab because it can double as a second floor if needed and was more resistant to the wind and elements.  However, these roofs weren’t adequately designed in regards to seismic issues and this caused a lot of trouble in the Haiti earthquake of 2010.  Additionally, the usual method for constructing these roofs is to carry up the concrete manually to fill the form work for the roof which is highly labor intensive.  These two combined issues lead him to create an innovative new system for creating concrete roofing.  It is concept that was widely used when making clay roofing tiles up until the 1950’s when improved techniques become more common.  He created a “thin shell, latex modified concrete barrel roof unit” – curved concrete roofing tile in which latex from old paint is added to create to increase flexibility.  To build the concrete shell unit, a mold was designed and the modified concrete is poured in to the mold with mesh metal reinforcement located in the center of the cross section.  Testing is being conducted to determine the optimal shape in regards to stresses and construction applications.

     There are several benefits to using this type of roofing system.  The main one is ease of construction in my opinion.  The roof tiles can be made on site on the ground or off site and easily be taken up a ladder to be put together on the roof.  Another benefit is the cost; according the article the tile will cost $2 – $3 per a square foot versus $6 – $10 per a square foot for cast in place concrete.   The other benefit I find very useful that isn’t mentioned in the article is that it is easily repeatable.  Someone with very little experience can build a safe roof and when there is a crisis like a natural disaster a large quantity of these concrete tiles can be built very efficiently on a larger scale as well.

     Do you think this would be a good roofing system for a remote area?  What if any issues do you foresee?  Are there any other applications this could be useful for as well?  Thanks for your time and have a good week!

Source

Kathleen, McCoy, “Hometown U: A Smarter, Stronger Roof Design for Haiti and Beyond”, Hometown U, March 1st, 2014, http://goo.gl/xk4k23

Concrete Eating Robots: A More Efficient Method of Breaking Down Concrete?

 

     Hello everyone.  I hope everything is going well.  I had a good Easter weekend with my family and I’m feeling rested after a busy week.  Today, I would like to talk about an innovation I read about a few weeks ago which is called a “Concrete Eating Robot” as described in a blog post by Peloton Land Solutions.

     The Concrete Eating Robot is a system which uses a high pressure water jet to break down concrete rather than using a wrecking ball or something else to crush concrete.  The water/concrete slurry is then collected to reclaim the reusable materials.  The clean aggregate can be used in other concrete mixes.  The water is reused by the system so that a large of amount of water isn’t wasted in the process.  And the clean and reusable rebar beneath the concrete can be pulled apart for use in other structures.  The only waste that I could find according to the article by Peloton Land Solutions is the cement mixture that can’t be reused.

     This invention has some very good benefits in that the rebar and aggregate can be reused in a very efficient manner.  However, cement is the least sustainable product required for concrete construction.  And in this case, I didn’t see a method for recycling cement which could make this a critical issue.  Depending on the situation, this could negate some of the benefits to the point that this invention might not be worth the investment.  For example, if this is a case where a high amount of cement is required and aggregate can be easily procured locally for any new construction, the cost benefit ratio might tilt back towards a more traditional method.  If this is a low to zero cement usage concrete in an area where the required aggregate isn’t easily obtainable, this would be a better situation for something like this.

   Here is a more detailed article on the device: http://goo.gl/SWDwN2

   What is your opinion on this invention? Do you see it being used regularly in the future?  Thanks for your time and have a good week!

Resources:

Peloton Land Solutions, “Concrete Eating Robots?”, March 3rd, 2014, http://goo.gl/Y920hK

CoExist Blog, “This Concrete Eating Robot Can Recycle an Entire Building on the Spot”, April 16th, 2014, http://goo.gl/SWDwN2

Visual Project Management for Construction Managers Using Google Glass?

Hello everyone – sorry about the long break.  I’ve been in the process of moving the last few weeks and I didn’t get internet until about a week ago.  Now that I am almost back to full productivity I should be doing regular posts again.  And now I can look forward to writing some of these posts on my back porch which will be nice too.  Today I want to talk about an application in development for Google Glass which would allow a construction manager to see a visual of future building elements to aid in the construction process. (Article: http://goo.gl/G6audi)

This application has a few benefits that I can foresee.  The main one is that the user can visualize what needs to be done and what it should look like.  I could also see how it would take a complicated construction drawing and help clear up any confusion as to what the specifications should look like.

However, I also see a lot of drawbacks.  The first one is location issues.  If there is any trouble in determining the user’s location, the visual provided will be inaccurate and that is worse than using less convenient methods.  Additionally, creating the model and making sure the users on site are familiar with the tech would be difficult as well.  And finally, I would think that if the application isn’t designed well, information overload and application management could be a hindrance that slows down the work to the point that it out weighs the benefits of having this visual representation.

The benefits gained by having the application aren’t worth the added issues in my opinion.  Combine this with the fact that construction managers should already be able to visualize and build the specifications from construction drawings cause this application to be more trouble than it is worth.  This is not to say that I think technology is not useful on construction sites.  I believe that being able to have a synced database for construction drawings and models would be very useful for a tablet application in a lot of situations.  However, there is only one time I see the Google Glass application being useful and that is for people inexperienced in construction/engineering such as owners to walk around an incomplete project.

What is your opinion on this application?  Are there some different applications for construction managers that would be good for Google Glass?  Thanks for your time and have a good week!

Reference

“Google Glass for Construction?”, ConstruTech, March 18, 2014, http://goo.gl/G6audi

Image

Orson, Parmy, “Why You’ll See Google-Glass Competitors In Construction Zones Before Starbucks”, Forbes Magazine, March 11, 2013, http://goo.gl/TYBuv

Benefits of BIM Modeling in Project Pricing for Head Contractors and Subcontractors

     Hello.  How is everyone doing?  Today I would like to discuss the statistical breakdown of the benefits in project pricing BIM modeling can provide for the head contractors and subcontractors involved in the design process.  BIM modeling is something that is collectively touted by most innovators in the building and infrastructure design/build field.  However, it would be helpful to understand who has the most motivation to implement improved BIM modeling.  As stated by David Mitchell, “For different types of projects the people you need to engage, changes. We need to acknowledge that the savings arising out of a building project differs significantly to those of a civil or resource project.  There also needs to be an appreciation of when a construction contract or subcontract is formed as well as the type of construction contract that has been entered into.”  Therefore, the issue is approached in regards to those factors.

For a commercial scale building project, the indirect cost such as design and overhead management amounts to 17% as compared to 83% for the construction costs.  In addition, the ratio of margins between subcontractors and contractors is 7 to 1.  Therefore, it benefits the subcontractors the most to apply the BIM modeling.  However, when a civil project is considered, the head contractor sees most of the benefits because subcontractors only control 17% of the costs.  The resource sector has some interesting statistics as well.  First of all, for a pipeline, the indirect cost is far greater at 45% of the cost going to head contractors.  In addition, the head contractor owns the material production plant/labor and the resulting cost accounts for 83% percent of the other 55% which amounts to an additional 46% of the direct cost and 91% of the overall cost.  Therefore, in this case, the head contractor holds a large portion of the cost control.  However, when building a refinement plant there are some critical differences.  There is a similar level of indirect cost cost at 45%, but the subcontractor sees 88% of the direct cost in this case.  The result is the subcontractor seeing 48% of the cost of the project as compared to 9% in the previous example.

The above statistics are interesting for several reasons.  The first one, as stated in the article, is the fact that BIM modeling is implemented by head contractor and other associated designers; yet in some cases, the subcontractors see the benefits.  Seeing as changes in pricing are based on estimation based on previous projects, pricing benefits aren’t planned for in the budget as efficiently, and, depending on the project and head contractor, a subcontractor could see large and consistent benefits.  This means that the benefits of using BIM might not be maximized aside from time and documentation for the head contractor in that situation.  And if it is a case where head contractors see a large amount of the cost savings, they can more readily pass along the cost saving of BIM modeling. But the subcontractors may not be motivated to help improve the BIM modeling because it doesn’t help their bottom line.  For both of these reason, it makes sense why it is most common for head contractors and designers to push for improvements and BIM modeling.  However, an often overlooked requirement is that the subcontractor needs to work with the head contractor in implementing the improvements and have proper motivation to pass along the savings the see the full benefit for everyone involved with the project.

What is your opinion on BIM model implementation in regards to subcontractors and head contractors?  Are there any ways to promote a shared interest in BIM modeling?  Thanks for your time and have a good week!

The Application of Biologically Grown Materials to Building Design

Hello everyone, I hope y’all had good weekend.  Today, I want to talk about some new building materials being researched that are biological produced in a replicable process.  One of the common characteristics is that these materials will involve bacteria or something else derived from organisms.  The fact that these materials don’t require significant carbon output is one major benefit.  Another benefit for most of these materials is that they are actively reproduced over time once they are installed as well.  The building materials are described below with some insight on possible benefits and issues.

bioMason Brickshttp://goo.gl/PY68HQ

The bioMason brick is a brick of sand and cementitious material in which the cementitious material is created using a bacteria.  The brick mixture is created and over the course of 5 days the bacteria solidifies into a coral type material with the strength of a normal brick.  The major benefit for this innovation is that it doesn’t require the heat and raw materials used in creating normal bricks; this reduces the cost of the brick by 40%.  They are currently conducting experiments to research bacteria creation using the following materials: urea, salt and yeast extracts, and seawater.

I see this having one major benefit – it would not significantly change the design and build process for masonry.  Masonry strength is mostly determined by the strength of the mortar as long as the masonry unit strength doesn’t change significantly.  The benefits of the bioMason bricks combined with the low technology change requirement makes this much more effective.

Mushroom Insulation Materialhttp://goo.gl/SZcfA

This is a stiff insulation material using plant stalks and husks combined with Mycelium.  There are two forms of application being tested currently: growth inside the wall and spray on insulation.  The insulation is fire resistant and fully compostable.  Additionally, it does not contain formaldehyde or any other harmful organic materials.  This same material can also be used as compostable packaging material.

There are several benefits to this material.  Like before there is no significant change to the other building processes related to it.  It also has great applications outside of this usage alone and is completely compostable once it is not needed anymore.  The only drawback I can potentially see is there being an organic material harmful to humans that is unknown as of yet – similar to what happened with Asbestos. It has great potential overall though – it is my recommendation that more health testing be done before large scale usage.

Self Repairing Concrete:

Research is being conducted on a bacteria that can be used to repair concrete as it ages.  Bacteria engineered to thrive in dry climates is being created to be placed in the concrete mixture.  The bacteria would release Calcium Carbonate as part of the waste process which would fill the holes and cracks over time.

There is one possible major benefit I see – the reduction in maintenance required for the concrete designed this way.  However, more research would be required to determine it’s efficiency.  Additionally, nothing is mentioned about resources and energy required to produce this bacteria; if it requires a high amount of energy and time/raw material resources, it may become impractical to use.  I might also add that the issue of infection might come up here as well; but if the claim is true that it is bacteria that thrives in dry climates, the danger to living organisms would be greatly reduced.

What is your opinion on these possible advancements?  Can you see them being used in the future?  Thank you for your time and have a good week!

Reference:

Wollenhaupt, Gary,”Self-Repairing Concrete Could be the Future of Green Building”, Forbes Online, January 6, 2014, http://goo.gl/IRyzHi

High Performance Energy Saving Design for the Karuna House – Window/Door Design

Passive House Green Home Building Tips: Karuna House Windows & Doors

Hello everyone! Today I would like to go back to my series of posts outlining the design and construction of the Karuna House.  The topic for this post will be the selection and resulting benefits of the improved windows and doors.  Windows and doors are the biggest holes in the building envelope above ground.  These innovations are what allow the HVAC systems to reach their maximum efficiency.  Additionally, windows and doors are also a major aesthetic concern and these aesthetic factors play a big role in the decision process.

The Karuna House uses triple glazed, high solar heat gain, R-8 windows with a very thin frame.  This type of window has an increased level of heat gain, but significantly improves the building envelope by allowing additional insulation to be placed around the frame.  The triple glazed window also has a well documented performance history because it has been in use since the 70’s in Scandinavia.  For the exterior doors, the Karuna House uses Optiwin doors.  These doors are thick with insulation in the middle and airtight with multi-locking mechanisms to ensure a tight seal.  To help with the heat gain issue for the windows, a shading system that can be lowered over the windows was installed.  This has an additional benefit of being modern and aesthetically appealing.  The triple glazing also provides a very clear view through the glass which adds to the modern, aesthetic appeal.  To further improve indoor conditions, these windows and doors increase comfort by reducing the draft found near the window and door openings.  All of the benefits above combine to reduce the impact on the mechanical systems which allows for a simpler, more efficient system to be used.

Overall these systems are simple and nothing too complex.  However, these systems apply the same philosophy that is applied to the building envelope in general – simple and efficient solutions to problems.  Furthermore, the philosophy applied to the building envelope, windows, and doors altogether should reap a lot of benefits for the mechanical systems and the energy usage correlated to that.  The take away here is very similar to the previous post on the Karuna House – a little a effort put into finding cost efficient improvements to small elements of the house can improve the overall efficiency a lot.

What do you think about the window and door improvements on the Karuna House?  Are there any issues that need to be addressed or  improvements that can be made?  Thanks for your time and have a good week!

Resource:

Hammer & Hand,”Karuna House: Windows and Doors”, http://goo.gl/j7zAAy

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