ETC Blog Articles
It is too early to tell what might have failed and caused this bridge to collapse and it will probably be many months before the investigation is complete. The bridge was designed to consist of post-tensioned concrete segments supported by steel cables. It was to have been built in two sections and only the first section was in place when the collapse occurred. The first section of the bridge had only been in place for five days before it fell, so it is not likely a case of being grossly under-designed or inadequate concrete strength. One report indicated that the post-tension tendons had loosened and were being retightened when it fell.
Institutional and government projects like this have many levels of design review and material testing involved to help ensure public safety and that the 100-year design life is achieved. This bridge was far from complete as there was a central support pier (pylon) for the steel cables that still needed to be installed. This pier and the cables would have provided additional support to the failed section of the bridge. Partially constructed structures can be very dangerous.
This catastrophic failure reminds us of the inherent hazards of all construction work, not just those involved with demolishing and rehabilitating portions of existing structures. Our prayers go out to all those involved in this tragedy.
When evaluating asphalt pavement, including asphalt-paved parking decks, ETC recommends core sampling as part of our investigative service. Extracting a core sample of the pavement can be beneficial in telling the history of the pavement construction as well as the conditions of the sub-base profile beneath the asphalt.
The cores can also tell the story of past pavement work, including structural repairs, pavement membrane (fabric) installation, and multiple repaved layers of asphalt, which can help minimize change orders during the work. This information assists us in developing specifications necessary to address the pavement rehabilitation needs.
Typically, pavement deterioration can be traced back to the sub-base design (the materials below the pavement) and their manner of installation and compaction. What we commonly look for is a stone aggregate material in thicknesses that exceed the pavement profile. In many instances, our sampling will also reveal the condition of the sub-base (or soils) below the pavement as well. Soils with high clay content can affect our recommendations for the type of rehabilitation work.
If these conditions are not defined before scope preparation and implementation, the pavement rehabilitation work may not adequately address the needed issues. This can lead to a reduced pavement life and more costly, long term repairs.
Don’t hesitate to contact us for all your pavement questions and concerns. We can have a member of our pavement consulting and inspection staff visit your property to provide a pavement evaluation proposal, free of charge.
The ETC team will be attending the Washington Metro Chapter of CAI Conference & Expo on Saturday March 10th. We would be so pleased if you stopped by to say hello.
Our team of experts will be there to answer any questions you may have about upcoming projects and/or building concerns. It’s a great time to gather some FREE advice! Show details can be found on our website at: http://www.etc-web.com/press/upcoming-events/
All property managers, owners and board members that visits our booth will have the chance to win a Yeti cooler! Hope YOU are the winner!!
Unfortunately, there isn’t a quick fix for addressing footprints in your sidewalk. Your best bet is to remove and repour the affected panel (section between control joints). There are other options out there including filling the footprint in with a repair material (e.g. sand filled epoxy), patching the area, or grinding down the area, but these repairs will be noticeable and/or may require follow-up repairs down the road.
An all too common building problem involves the formation of condensation (water) on the interior surfaces of windows. This can be caused by a variety of factors including deficiencies with the windows, the use of heavy window treatments that prevent air circulation on window surfaces, and excess moisture in building interiors. Sometimes, when too much condensation is present, water may even drip down the wall into the wall cavity or onto the floor to cause water damage, growth of mold and mildew, staining, and other problems.
Normal human activities (such as respiration, bathing, laundering, cleaning, cooking, pets, houseplants, aquariums, etc.) produce water vapor that must be accounted for in the design of the mechanical (heating, ventilation, and air conditioning or HVAC) systems for the building. In today’s air-tight buildings, window condensation can result from insufficient fresh air. Unless fresh air is introduced into conditioned space, humidity can accumulate until, in cold weather, the temperature of the interior window surfaces becomes so low that the air at the surfaces become saturated, causing water, or even ice, to form.
Why does fresh air help to reduce humidity? In a cold weather scenario, the outside air is dry and by introducing sufficient fresh air (increased ventilation) into the building, the humidity is diluted and reduced. However, too much fresh air may not always be a good thing during the heating season. In addition to high energy cost, too much fresh air may also render the space too dry for a comfortable environment.
Sometimes the issue may not be as simple as it looks. Improperly designed or installed HVAC systems can fail to remove the moisture and cause elevated indoor humidity. Undersized systems could produce inadequate air movement to remove water vapor. Oversized systems could prematurely satisfy heating and cooling demands, resulting in short-cycling, and reduced air movement. It is important to conduct a thorough investigation to identify the real cause of condensation issues in order to develop a successful and cost-effective solution.
ETC has first-hand experience with these problems and the methods to successfully correct them. Our mechanical engineering staff has the ability to identify and correct ventilation issues involving condensation or other concerns
Imagine a winter without the need for ice melt. Researchers at Drexel, Purdue and Oregon State University are working with concrete admixtures to hopefully make this a reality. Their research includes the addition of phase changing materials such as paraffin, coconut, or palm oils into the concrete mix and has proven to melt snow in certain conditions. The phase change materials release thermal energy as they solidify, meaning as the temperature drops, they release heat, which melts the snow. The inclusion of the phase changing materials in the concrete mix result in a one-time cost at construction rather than reoccurring costs, such as electricity, in cases where heating elements are embedded in concrete for snow melting. More information on the research can be found at the following link: http://drexel.edu/now/archive/2017/September/self-melting-concrete-roads/.
The Researchers state that this technology is ideal for the Mid-Atlantic region as the performance of the phase changing materials works best where the temperature frequently moves above and below freezing. There are many benefits to eliminating the use of deicing chemicals. Reduced operating costs and the reduced deterioration of concrete structures are the most beneficial to Building Owners. While to the environment, eliminating the use of traditional deicers will help keep the millions of tons of salt used in the region during a typical winter from entering the local waterways.
The new mix additives are expected to begin large scale testing in early 2018. While probably a few years away from widespread commercial implementation, it is nice to think that one day we may never need to clear our sidewalk of snow.
Parking garages in this region are attacked by road salts and water throughout much of the year. The cost to repair deteriorated concrete can be quite high and the project can cause significant inconvenience to garage users. So, as part of a parking garage restoration project, we recommend and our clients tend to include, application of a vehicular-traffic-bearing membrane on the structural slabs to help protect their investment and extend the service life of the garage.
There are two basic classes of products commonly used to protect garage slabs, one of which is penetrating sealers. Penetrating sealers include materials such as silanes and siloxanes, which are silicone-based water repellants. These compounds penetrate into the concrete and react with the silica to create a water repellant barrier that also retards chloride migration.
Penetrating sealers are breathable so they do not create a vapor barrier and are relatively inexpensive. However, they do not seal cracks and require frequent reapplication as their effectiveness decreases with wear and time. These materials usually need to be renewed on a three to five year schedule.
The other class is traffic-bearing membranes, which are liquid-applied materials in several layers of cementitious, epoxy, or urethane compounds. These systems are all relatively thick (up to about 90 mils) and are designed with the properties needed to withstand the destructive forces imposed by vehicles tires.
Incomplete combustion of wood in fireplaces creates a buildup of flammable oils (creosote) in chimney flues, which can contribute to chimney or building fires. Only dry, seasoned wood (preferably hardwood) should be burned in fireplaces. Green and/or water saturated wood burns at a lower temperature and less completely than dry, seasoned wood and poses a greater potential for creosote deposition. Coniferous woods (pine, fir, spruce, etc.) should not be used. They tend to be highly resinous and will deposit more material than hardwoods. Household trash or other items should never be burned in fireplaces.
Artificial logs should only be used in accordance with manufacturers’ instructions and limitations. Most such products are intended to be burned only one at a time. Artificial logs vary in composition from hardwood fibers (sawdust or other sawmill waste) combined with wax or other binders, to petroleum wax (paraffin) mixed with various recycled materials. As a general rule, artificial logs should not be used unless the composition and burning characteristics of a specific product are fully described and deemed acceptable. Plastics, unidentified composites, or other materials of questionable makeup should be avoided.
Fireboxes require occasional cleaning/removal of ashes. Ashes should only be removed when absolutely no embers are present. Because embers can remain undetected long after a fire is out, ashes should only be placed into fireproof, metal containers.
Chimneys should be periodically inspected and cleaned, the frequency of which depends on fireplace use. Annual inspection is recommended for fireplaces that are used regularly. Cleaning may not be necessary at every inspection interval. It should be noted that chemical cleaners (cleaning logs, fire additives, etc.) should not be considered equal to professional cleaning.
Some products incorporate catalytic chemicals that react with the creosote and cause it to soften, flake and debond; however, the dislodged material can accumulate on shelves or other chimney offsets. They also tend to react only with the outer layer of creosote and are only partly effective in the presence of heavy buildups. They also may have no appreciable effect on soot, or residue from artificial logs.
Some products (which employ copper or other metal salts) rely on the rapid expansion of gas created when the salts are burned to dislodge deposited material. The effectiveness of those products is questionable, particularly with respect to heavy accumulations.
Looking for that perfect employee gift this season? How about creating an enjoyable break room that will be used year-round.
Here is an example of space once confined by full height walls and only indoor lighting. Now, after adding frameless glass panels, it allows for natural daylight, as well as an open concept feel. A break room once used only for coffee cup refills, is now the center hub of the office.
Contact Shabbir Kazmi, AIA to discuss your break room needs.
Before any rope descent system (i.e., window washing boatswain chair) is used on a building, OSHA now requires that each anchor be identified, tested, certified, and maintained so it is capable of supporting at least 5,000 pounds in any direction.
Did all your anchors pass the test?
The OSHA set November 20, 2017 deadline for physical load testing of these anchors has passed. (29 CFR 1910.27(b)(1)(iii)).
Did you make the deadline?
We loaded anchors of many different configurations and found that not all anchors passed this stringent test. If you have any anchors that have not been subjected to this testing in the last 10 years, they must be load tested and certified by a qualified person before they are used. This regulation also seems to apply to new anchors that were installed after the November 20 deadline and not just older anchors.
Don’t postpone your scheduled winter or spring window washing work, get your anchors tested soon. Call us @ 410-312-4761 or 703-450-622o | firstname.lastname@example.org
On a recent project, we discovered a “scary” sight – an Exterior Insulation and Finish System (EIFS) that was not installed properly. The exposed wall revealed channelized white foam insulation, an inconsistently placed liquid waterproofing membrane applied on the sheathing, several different brands of materials, and incompatible asphaltic flashing to cover the building facade.
The manufacturer issued a warranty for a drainable system, but no weep holes were installed around the windows and doors to allow the water to drain. This cobbled together assembly is not only a problem for keeping the building watertight, but the warranty seems to be invalid.
This highlights the need for field inspections by Certified EIFS Inspectors (CEI) and installation by Certified EIFS Mechanics (CEM) and Contractors as designated by the AWCI (Association of the Wall and Ceiling Industry) to help ensure that the system is installed and performs as it was intended.
ETC and its employees are pleased to donate funds to Canine Companions for Independence throughout the year. This worthy organization provides assistance dogs free of charge to people with disabilities. We are proud to call CCI our designated charity. Learn more at cci.org.