Exciting architecture projects to look forward to in 2019

Table of Contents

Toggle

Exciting architecture projects to look forward to in 2019

2018 was an outstanding year for architecture, but 2019 is shaping up to be just as exciting too, and there are already several noteworthy projects on the horizon. From a supertall skyscraper to a massive airport terminal shaped like a starfish, here’s our pick of projects to look forward to this year.

Though issues arise and buildings sometimes get delayed at the last hurdle, we’ve focused on projects that are, as of writing, expected to be completed in 2019. Read on below to see our pick and you can also hit the gallery to see more of each project.

CopenHill – BIG

First unveiled all the way back in 2011, the Bjarke Ingels Group (BIG)-led CopenHill (aka Amager Bakke) is a power station in Copenhagen with a “smoke ring generator” that will expel a steam ring each time 250 kg (551 lb) of carbon dioxide is produced. It’s also topped by a ski slope for visitors and locals to enjoy.

This one’s a lot of fun and it’s hard to imagine a firm other than BIG coming up with the idea. The power station itself is already operational but the ski slope roof is currently being tested and is expected to be open in April.

Under – Snøhetta

The design for Europe’s first underwater restaurant was unveiled by Snøhetta back in 2017. The last time we checked in, the project was being built atop a barge and the engineers were preparing to submerge it and secure it onto the sea bed at Norway’s southernmost point.

Snøhetta likens Under to an oversized periscope and it will sport a large panoramic window offering diners a view of the seabed as they eat. The building will measure 600 sq m (6,458 sq ft) and sport 1 m (3.2 ft)-thick concrete walls to protect it from the crashing waves. Under is expected to be open for bookings in “Spring 2019” (northern hemisphere).

One Thousand Museum – Zaha Hadid Architects

The late Zaha Hadid’s One Thousand Museum sports an eye-catching glass-fiber reinforced white concrete exoskeleton that twists as it rises to a maximum height of 215 m (706 ft)-tall.

The residential project is aimed at the well-heeled and billed as a “Six Star” residence. It includes just 83 homes in all, with apartments measuring between 4,600 and 9,900 sq ft (427 – 919 sq m). Each will boast multiple balconies and the building overlooks Miami’s famous Biscayne Bay. One Thousand Museum is due to be completed sometime this year.

Vessel – Heatherwick Studio

Looking like a strange cross between a big pineapple and an M.C. Escher artwork, Vessel is the centerpiece of a massive development in Hudson Yards, New York City, the largest private real estate development in the history of the United States.

Costing US$150 million for what is essentially just a fancy viewing point, the structure will rise to a height of 150 ft (45 m) and comprise 54 interconnecting flights of stairs, 2,500 individual steps, and 80 landings – as well as an elevator for disabled access. It’s certainly something a little different and should be finished in the next few months.

Lakhta Center – Gorproject/RMJM

Rising 462 m (1,516 ft) over St. Petersburg, Russia, the bullet-shaped Lakhta Center is rated the 13th tallest building in the world and is Europe’s tallest tower.

Its construction has taken over six years and involved 20,000 people from 18 countries. The foundations required concrete to be poured continuously for 49 hours and its glazing measures 72,500 sq m (780,383 sq ft). It takes the form of a spire with five wings that twist a total of 90 degrees from top to bottom and has been pre-certified LEED Gold (a green building standard) for its energy-efficient design. The Lakhta Center is due to be officially completed soon.

Beijing Daxing International Airport terminal – Zaha Hadid Architects

Another project by ZHA, the Beijing Daxing International Airport terminal (aka Beijing New Airport) was promoted as the world’s largest airport terminal building when revealed and as far as we know this still stands. It’s expected to open for business in September, 2019.

The huge building was created in collaboration with ADP Ingeniérie and takes the form of a massive starfish, with a total floorspace of 700,000 sq m (over 7 million sq ft). It will eventually have a capacity of 100 million passengers annually and will apparently also boast sustainable technology, but we’ve still received very little information on it as of writing. No doubt we’ll learn more once it’s finished in late 2019.

Gardenhouse – MAD Architects

MAD Architects’ Gardenhouse was originally slated for completion in late 2018 but now expected sometime this year. It consists of a large podium envisioned as an artificial mountain, with 18 houses atop. The podium will be covered in native, drought-tolerant greenery and contain commercial spaces for rent on ground level.

There are some potential issues like noise and pollution, but it’ll be fascinating to see if the firm can meet its goal of bringing the feel of a mountain village to Beverly Hills, California.

Source: www.newatlas.com

What type of pavement is used for airports runway?

The materials used for airports is generally the same as what is used for roadways, however, the depths, or thicknesses are different, and the tolerances are much tighter at an airport. The material for runways usually needs to meet a much tighter spec.

A typical section for an airport can use asphalt or concrete. Below is a generic look at the structural section for either asphalt or concrete from an FAA Advisory Circular on Aiport Pavement Design and Evaluation.

You will notice that the materials in the middle are thicker and then taper to thinner. This is because the loads on the runway are primarily from the 2 landing wheels, which will be in the middle of the runway. The effective tire width is pictured below.

The surface must be smooth and well bonded, and resistant to the shear stresses of the airplane wheel loads. The non-skid surface must not cause undue wear on the airplane tires . The surface must be free of loose particles that could damage the airplane or people. In order to meet this requirement, there must be good control of the mix. This usually requires a central mixing plant be used for the hot mix asphalt.

The base course is integral to flexible pavement design such as asphalt. The loading in flexible pavements transfers downward and outward. For this reason, the base, subbase, if used, and subgrade contribute to the strength of the pavement section. For concrete pavement, the concrete provides the strength to the structural section.

The base course must be of sufficient quality that it won’t fail, or allow failure in the subgrade. It must be able to withstand the forces from the airplane wheel loading without consolidating which would cause the surface course to deform. The base course uses very select material with very hard and durable aggregate. The requirements for the base course are very strict.

What is Concrete Slab Moisture

WHAT is the Problem?

Concrete slab moisture can cause problems with the adhesion of floor-covering material, such as tile, sheet

flooring, or carpet and bond-related failures of non-breathable floor coatings. Many adhesives used for installation of floor coverings are more water-sensitive than in the past, due to restrictions on the use of volatile organic compounds (VOCs).

To warranty their products, manufacturers require that the moisture emission from the hardened concrete slab be less than some threshold value prior to installing floor coverings or coatings. Fast-track construction schedules exacerbate the problem when floor-surfacing material is installed before the concrete slab has dried to an acceptable level.

WHAT are the Sources of Concrete Slab Moisture ?

a. Ground water sources and when the floor slab is in contact with saturated ground, or if drainage is poor. Moisture moves to the slab surface by capillary action or wicking. Factors affecting this include depth of the water table and fineness of soil below the slab. Fine grained soil promotes moisture movements from considerable depths compared to coarser subgrade material.

b. Water vapor from damp soil will diffuse and condense on a concrete slab surface that is cooler and at a lower relative humidity due to a vapor pressure gradient.

c . Wetting of the fill course/blotter layer, if any, between the vapor retarder and the slab prior to placing the slab will trap moisture with the only possible escape route being through the slab. A blotter layer is not recommended for interior slabs on grade (CIP 29).

d. Residual moisture in the slab from the original concrete mixing water will move towards the surface. It may take anywhere from six weeks to one year or longer for a concrete slab to dry to an acceptable level under normal conditions.

Factors that affect the drying rate include the original water content of the concrete, type of curing, and the

relative humidity and temperature of the ambient air during the drying period. This is the only source of moisture in elevated slabs. Any wetting of the slab after final curing will elevate moisture levels within the slab and lengthen the drying period.

HOW do You Avoid Problems?

Avoiding problems associated with high moisture content in concrete can be accomplished by the following means:

• Protect against ingress of water under hydrostatic pressure by ensuring that proper drainage away from the slab is part of the design.

• Use a 6 to 8 inch [150 to 200 mm] layer of coarse gravel or crushed stone as a capillary break in locations with fine-grained soil subgrades.

• Use a vapor retarder membrane under the slab to prevent water from entering the slab. Ensure that the vapor retarder is installed correctly and not damaged during construction. Current recommendation of ACI Committee 302 is to place the concrete directly on a vapor retarder for interior slabs on grade (CIP 29).

• Use a concrete mixture with a moderately low water-cementitious material (w/cm) ratio (about 0.50). This reduces the amount of residual moisture in the slab, will require a shorter drying period, and result in a lower permeability to vapor transmission. Water reducing admixtures can be used to obtain adequate workability and maintain a low water content. The water tightness of concrete can be improved by using fly ash or slag in the concrete mixture.

• Curing is an important step in achieving excellent hardened concrete properties. However, moist curing will increase drying time. As a compromise, curing the concrete under plastic sheeting for 3 days is recommended and moist curing times greater than 7 days must be avoided. Avoid using curing compounds on floors where coverings or coatings will be installed.

• Allow sufficient time for the moisture in the slab to dry naturally while the floor is under a roof and protected from the elements. Avoid maintenance and cleaning operations that will wet the concrete floor. Use heat and dehumidifiers to accelerate drying. Since moisture transmission is affected by temperature and humidity, maintain the actual service conditions for a long enough period prior to installing the floor covering.

• Test the slab moisture condition prior to installing the floor covering. When concrete slab moisture cannot be controlled, consider using decorative concrete, less moisture-sensitive floor coverings, breathable floor coatings, or install moisture vapor suppression systems (topical coatings).

HOW is Concrete Slab Moisture Measured?

Various qualitative and quantitative methods of measuring concrete slab moisture are described in ASTM E 1907.

Test the moisture condition of the slab in the same temperature and humidity conditions as it will be in service.

In general, test at three random sample locations for areas up to 1000 sq. ft. [100 m2] and perform one additional test for each additional 1,000 sq ft. Ensure that the surface is dry and clean. Record the relative humidity and temperature at the time of testing. Some of the common tests are:

Polyethylene Sheet Test (ASTM D 4263)

– is a simple qualitative test, where an 18 by 18 inch [450 by 450 mm] square plastic sheet is taped tightly to the concrete and left in place for a at least 16 hours. The presence of moisture under the plastic sheet is a positive indication that excess moisture is likely present in the slab. However, a negative indication is not an assurance that the

slab is acceptably dry below the surface.

Mat Test

– where the adhesive intended for use is applied to a 24 by 24 inch [600 by 600 mm] area and a sheet vinyl flooring product is placed face down on the adhesive and sealed at the edges. A visual inspection of the condition of the adhesive is made after a 72-hour period. This test is no longer favored since it can produce false negative results.

Test Strip

– in which a test strip of the proposed primer or adhesive is evaluated for 24 hours to predict its behavior on the floor. This procedure is not very reliable.

Moisture meters

– Measure electrical resistance or impedance to indicate slab moisture. Electronic meters can be useful survey tools that provide comparative readings across a floor but should not be used to accept or reject a floor because they do not provide an absolute measure of moisture conditions within the slab.

Gravimetric

– This is a direct and accurate method of determining moisture content by weight in the concrete slab. Pieces of concrete are removed by chiseling or stitch-drilling and dried in an oven to constant weight. The moisture content is then calculated as a percentage of the dry sample weight. This is rarely recommended by floor covering manufacturers.

Nuclear Density and Radio Frequency

– This nondestructive test instrument is relatively expensive and can take a long time to properly correlate correction factors for each individual project. The instrument has a radioactive source and therefore requires licensed operators.

Anhydrous Calcium Chloride Test (ASTM F 1869)

– is specified by most floor covering manufacturers for pre installation testing. A measured amount of anhydrous calcium chloride is placed in a cup sealed under a plastic dome on the slab surface and the amount of moisture

absorbed by the salt in 60 to 72 hours is measured to calculate the moisture vapor emission rate (MVER).

Maximum limits of vapor transmission generally specified are 3 to 5 pounds of moisture per 1000 square feet per 24 hours. This test is relatively inexpensive, and yields a quantitative result. However, it has some major shortcomings: it determines only a portion of the free moisture at a shallow depth of concrete near the surface of the slab. The test is sensitive to the temperature and humidity in the building. It provides only a “snapshot in time” of current moisture conditions and does not predict if the sub-slab conditions will cause a moisture problem later in the life of the floor.

Relative Humidity Probe (ASTM F 2170)

This procedure involves measuring the relative humidity of concrete at a specific depth from the slab surface inside a

drilled or cast hole in a concrete slab. The relative humidity is measured after allowing 72 hours to achieve moisture equilibrium within the hole. Typically a relative humidity of 75% to 80% is targeted for installation of floor coverings. Relative humidity probes can determine the moisture profile from top to bottom in a slab, conditions below the slab,

and can monitor the drying of a slab over time, leading to predictions of future moisture conditions. These instruments have been used for many years in Europe and are becoming more popular in the

United States.

Lean Concrete vs Flowable Concrete

Table of Contents

Toggle

Lean Concrete vs Flowable Concrete

Lean concrete and flowable concrete are terms used to describe low-grade concrete slurry that is used in a variety of construction projects. In some ways the two terms are interchangeable, both describing concrete made with lesser ingredients, but there are some differences in how the two are used. Lean concrete tends to be more long-lasting than flowable concrete, which is often temporary.

Lean Concrete

Lean concrete is made with low cementitious material content. This means that it does not have many of the heavy, high-density rock and sand elements that normal concrete has. Instead, it can use a mixture of standard concrete materials, reclaimed and crushed concrete, discarded sand and recycled ash. This makes lean concrete very cheap in nature and simple to make and use.

Uses

Main function of the lean concrete is to provide the uniform surface to the foundation concrete and to prevent the direct contact of foundation concrete from the soil.
Lean concrete is used under the foundations.
It is good for providing a flat bottom in uneven or dirt terrain.
Lean concrete has a lower level of cement in it, which is why it’s mostly used for fillings or under the foundations, to keep it protected from the soil.
Lean concrete is used to provide a level surface , where main foundation (raft, isolated or any other type) can be placed.
Another purpose is protection of main foundation from soil below, as moisture or other chemicals in soil like sulphates may attack concrete and can weaken it.

Flowable Concrete

Flowable fill concrete is a self-compacting cementitious slurry consisting of a mixture of fine aggregate or filler, water, and cementitious material which is used as a fill or backfill in lieu of compacted-soil backfill. This mixture is capable of filling all voids in irregular excavations and hard to reach places (such as under undercuts of existing slabs), is self-leveling, and hardens in a matter of a few hours without the need for compaction in layers.

Flowable fill is sometimes referred to as controlled density fill (CDF), controlled low strength material (CLSM), lean concrete slurry, and unshrinkable fill.

Flowable fill materials will be used as only as a structural fill replacement on VA projects. Unless otherwise noted, flowable fill installed as a substitution for structural earth fill, shall not be designed to be removed by the use of hand tools.

The materials and mix design for the flowable fill should be designed to produce a comparable compressive strength to the surrounding soil after hardening, making excavation at a later time possible to produce the compressive strength indicated for the placed location, as determined by the Engineer.

Purposes

Like lean concrete, flowable concrete or flowable fill is used for sub-bases and subfooting as well as abandoned wells and cavities. But flowable concrete is more associated with backfill projects where the concrete will be removed in several months when projects are completed. Because it will be taken away, it may be made of cheaper and less durable materials than lean concrete.

Best sites for PMP, PMI-ACP and CAPM certification exams

There are lot of good blogs and sites are available in the internet for learning PMP certification exams.

Project Management Article from Whizlabs – This is one of the popular blog for Project Management courses. Whizlabs offers PMI-ACP, PMP, CAPM certification exam practice questions and self-study training materials in their blog.
www.rmcls.com/ – This site is maintained by Well known author and trainer Rite Mulcahy. It is very useful to know the latest update on PMP exams.
www.oliverlehmann.com/ – Oliver is one of the most popular PMP author and instructor for the PMP exam. You can find very useful information related to PMP exam in his site.
kavitasharma.net/blog-archive/ – Kavitha Sharma is one of the popular independent PMP trainer in India. She writes about latest updates in PMI and guides user to prepare effectively for the PMP certification exams.
www.pmbypm.com/ – This blog is maintained by PMP trainer Praveen Malik. He is a certified Project Management Professional (PMP®) with a rich 19 years of experience. He provides help for the PMP students by educating them on the PMP topics. You will find lot of useful information about PMP in his blog.
pmzilla.com/ -This is one of the most popular forum for preparing PMP certification exam. If you have any questions related to PMP, this forum is the right place to start with.
www.pmhangout.com – This is one of the good forum for discussing the PMP and CAPM certification exam.
www.stellman-greene.com/ – Stellman is the author for best seller Head First PMP book. He also releasing his latest book for CAPM exam. His site is very useful with tons of details about the PMP exams. It is good site.
preparepm.com/index.html – Edwel is an independent instructor who take training for PMP exams. There is lot of free questions for PMP in his site. The questions are based on the PMBOK 5th edition. Also you can find lot of information on his site Edwel.
www.pmstudy.com/ – This site offers more practice questions for the PMP exams. This site also a good for preparing PMP exams.
www.simplilearn.com/project-management/pmp-certification-training – SimpliLearn is one of the good site or training institute for taking the PMP courses. This site offer 200 free questions that would be very much helpful for the exam preparation. However, the question explanations are not so good compared to Whizlabs questions.
Master of Project Academy
www.justpmp.com/ – This site has no special information about the PMP exams. Normall training details for Project Managements Professional (PMP) exam information.
www.deepfriedbrainproject.com – This PMP site has lots of useful information and techniques to crack the PMP exams. It would be useful for your PMP, CAPM and PMI-ACP preparation.
www.examspm.com/blogs/ – This blog has good amount of articles about the PMP preparation. They also offer free training for the PMP courses.
http://www.pmexamsmartnotes.com/ – This blog has very good information about the PMP certification exam and have lot of free resources for preparing PMP certification exam.
pmstudycircle.com – This blog has 100 free questions. You can buy more practice questions from this blog.
Welcome to the CATALYSTS Project Management Blog
6th Edition Guide Release Date and Timeline
Project Management Blog
PMP Exam and CAPM Exam Blogs by Aileen
7 Lessons Learned from the PMP Exam (guest blog by Cornelius Fichtner)
The Best Resources for Free PMP Exam Sample Questions for 2015
PMP – Blogs
Bob Sutton
PMHut – Project Management Articles and Tips for Project Managers
www.girlsguidetopm.com – This site is very good and have lot of resources for learning PMP certification exam.
https://project-management.com/
Herding Cats
Blog – PMStudent
http://blog.globalknowledge.com/
edward-designer.com/web/pmp/ – Edward Chung shares his experience and resources on getting the PMP® Certification, PMI-ACP®, ITIL® v3 Foundation and Zend PHP.
www.efficientlearning.com/blog/pmp – Another good resources for PMP related topics.
vicranth.blogspot.com/2013/08/pmpcertificationtrainingtips.html – It’s very good link for exam preparation ideas.

Best PMP Training

Whizlabs.com – Whizlabs is one of the best online training provider for PMP exam. They are offering 1200 practice questions.
www.izenbridge.com/ – This site is dedicated for the PMP training programs. There is lot of good stuff in this site like PMP Eligibility Calculator can be used in their site.
www.project-management-prepcast.com/ – This is another site where complete PMP related courses are offered. You can find all the project management certification exams details are in the site.
www.techrepublic.com – 7 great IT certification exam simulators for project managers
www.brainbok.com – This site offers only PMP related training, but little expensive compared to other companies.

Free Practice Questions for PMP / PMI-ACP / CAPM

75 Sample Questions for the PMP Certification Exam
PMP® Free Test – Project Management Professional (PMP)® Certification
http://www.oliverlehmann.com/con…
free.pm-exam-simulator.com/
www.headfirstlabs.com/PMP/pmp_exam/v2/quiz.html
www.pmstudy.com/PMP-Exam-Resources/freeSimulatedTest.asp
www.examspm.com/free-pmp-exam-questions-2/ (200 Questions with detailed explanations for each questions)
www.certchamp.com/pmp-sample-questions.jsp – 200 Free Questions
certification.about.com/od/projectmanagement/a/pmp_test_whiz.htm – 20 Free Questions
www.slideshare.net/UHS-Computer-Survey/capm-time-150-question-final-keyapm – 150 Questions
www.tutorialspoint.com/pmp-exams/pmp_mock_exams.htm – 50 Questions
projectmanagementacademy.net/free-pmp-questions – 50 Questions
sites.google.com/site/pgmpguide/pmp-1-20 – Lots of questions on PMP
www.preparepm.com/mock1.html – 75 Questions

Best Commercial Training for PMP

www.whizlabs.com/project-management-professional-pmp/ – Whizlabs is pioneer in the PMP exam training materials. They have recently updated their content to meet the Jan 2016 PMI updates. Their sit has both, practice questions and self-study training materials.
www.greycampus.com/ – Grey Campus is one of the leading online training provider. You can get good training courses in their website.

These 6 phrases give hiring managers the eye-roll

Table of Contents

Toggle

These 6 phrases give hiring managers the eye-roll

When it comes to job interviews, first impressions are everything. You probably know to avoid certain faux pas–like being late, or saying something mean to the receptionist. But you also need to stay away from giving clichéd answers that will discourage your interviewer from advancing you to the next stage.

As a hiring manager (and the founder and CEO a staffing firm), here are some of the most common ones I hear:

“I’m an overachiever”

I’m a big believer in word choice and semantics–people meaning what they say, and saying what they mean. When I hear this, I believe you are an underachiever, or you’re a decent worker, but not a superstar.

Here’s what I mean: Being labeled an overachiever means that people underestimated you. If you overachieve, that means you did more than people thought you could. To me, this raises the question, why did they believe that you were limited in your abilities?

“I give 150 percent”

Whenever I hear this phrase, I always say, “I think you need to recalibrate.” I can only give you 100 percent. I can’t give you 150 percent of me, because there isn’t one and a half times of me. When you say something like this (especially without any specific examples to back it up), it makes you sound disingenuous, and you’ll probably end up over-promising, and under-delivering. This is not something that hiring managers want.

“I really love this company”

Really? Tell me, what do you know about the company? Is it more than the small bit you reviewed online? Any interviewer will assume you applied for the job because you like the company, so you don’t need to state the obvious. But you should know much as you can know without actually working there, which requires you to look beyond the company website. You need to understand what you can bring to the company, and how that ties it on their mission and overall objective.

Ask questions about why the people working there think it’s a great place. Find out where they believe the company can improve. Most importantly, think and ask questions to help you form opinions, not just for the sake of asking questions. As a hiring manager, I want you to tell me that you’ve done the research and talked to people because that’s the only way for you to understand what we’re building and creating.

“I’m hard working, I’m a team player, I’m committed”

You might think this is what the person on the other end wants to hear. I’m telling you that it’s not.

This is what I want to hear: “I will outwork and outproduce anyone else on this team. I will take on extra education to grow faster than my peers. I will put in time beyond standard business hours if and when necessary to achieve goals, and to cross-train in skills that other people have.”

But people won’t say those things because most people aren’t willing to execute them later on. To clarify, I’m not looking for people who want to work a million hours. I want people to be honest and for people to articulate what they bring to the table, and then deliver on it. In any relationship, if you lie about who you are and what you’re willing to do, it usually catches up to you. Always tell the truth.

“I’m extremely detail oriented”

If that’s a true statement, you better know the minute details of your job and your team. What happened last month, last quarter, and last year? Why were there problems and what was the cause of the successes?

As a hiring manager, I want to see concrete evidence of that. That means no typos in your resume and involvement in projects and deliverables that showed your attention to detail. As a candidate, the onus is on you to prove that to me.

“I feel like this is a place where I can learn and grow”

Okay. Now tell me what’s in it for us, the company? What are you going to contribute? We make money by growing revenue or cutting expenses; what are you going to do to move us in that direction, and how? This kind of answer to the question is focused on you, rather than on the company–and most interviewees tend to focus on themselves and what they want.

When you’re interviewing for a role, you should always focus on the company and what the company can gain by employing you. Yes, the advice seems obvious, but you’d be surprised how many people don’t follow this advice. Remember, you’re there to convince the company that you’re the best solution to their problem, that you’re the best person to fill their vacancy. Focus on that, and you’ll be surprised at how far you can go.

Source: www.fastcompany.com

5 proposed designs for O’Hare airport’s huge expansion

Some of the biggest architecture firms in the world are competing for the contract, which will transform one of North America’s air traffic hubs.

Chicago’s O’Hare airport is one of the busiest airport in the U.S., and it’s only growing. The city recently approved a $8.5 billion expansion, which will balloon the airport’s indoor footprint from 5.5 million to 8.9 million square feet and require over 60,000 full-time workers to complete by 2026.

Now, as part of a public review process, the city has shared the five new terminal concepts for the first time, developed by the architecture firms Fentress-EXP-Brook-Garza, Foster Epstein Moreno, Studio ORD, Skidmore, Owings & Merrill, and Santiago Calatrava.

The public proposals share many similarities: They are all buildings with sprawling footprints to connect across O’Hare’s terminals, with white bones, undulating ceilings, and windows covering every available surface. Their differences appear to be formal rather than functional, with few quibbles over the optimal flow of 200,000 human bodies trudging through body scanners daily.

But the designs are still fascinating to compare, and a few big differences definitely stand out.

The architects at Foster Epstein Moreno JV imagine the terminal as three straight tubes that lead to a single grand view of the runways, creating “a theater of aviation.” The giant, arched panorama would certainly be a sight to behold, but I suspect the inevitable influx of vendors could ruin sight lines to this scene throughout most of the terminal. I’m curious, could you ever actually take in that view all in at once?

Studio ORD, led by Chicago architect Jeanne Gang, shared a three-pronged design that Curbed points out is likely a nod to the city’s river system. It features the surprising use of wood beams across the entire ceiling–a material you don’t often find in airports or in buildings that range in the millions of square feet. Coupled with organically curved, branching interior columns, the effect seems to be that of standing beneath a calming canopy of trees rather than inside a stifling airport.

Meanwhile, Skidmore, Owings & Merrill LLP–the same firm that brought Chicago the Willis Tower and the Hancock Building–proposed a glass-encased orchard at the center of the building, seeming to tease onlookers who would really prefer to be outside, vaping in nature. The green space is actually intended to be public, but one frame does feature a single traveler, enclosed in a glass box, with their feet up in a single hammock–as hundreds of grumps walk by in what I can only assume is seething, jealous rage.

Santiago Calatrava, LLC–perhaps most famous for the Oculus in New York City–imagines a future hotel and shopping complex complete with an expansive network of outdoor walkways (ahem, Chicago has a lot of winter, architects), but for the core indoor terminal area, it leverages Calatrava’s very recognizable architectural signature: an arrowhead footprint and fishbone ceiling.

Fentress-EXP-Brook-Garza didn’t see Calatrava’s proposal in advance, of course, but its proposal almost seems to answer back to it: “I can do exactly what you did, but without all the symmetry.” This proposal creates a space that twists more like a river, with roof supports that fly overhead like contrails rather than fishbones.

At this point, knowing what we do about these ideas–which is to say, very little–all we can really do is critique their look and feel. And they look and feel largely the same.

The public was able to vote on its favorite designs, but it’s unclear how, if at all, their votes will affect the final winner (the runner-up will also create a few new buildings at O’Hare, too). In fact, as the Chicago Tribune points out, the Mayor’s office has been entirely unclear on who is making a final call on these designs, at all. In any case, Mayor Rahm Emanuel is supposed to announce a winner before he leaves office this May. And whatever is chosen, it’s probably a huge upgrade from the O’Hare we have today.

Source: www.fastcompany.com

Concrete vibration – The why and how of consolidating concrete

Table of Contents

Toggle

Concrete vibration – The why and how of consolidating concrete

What factor has a greater effect on concrete compressive strength than any other? Most engineers would say water-cement ratio … as water-cement ratio increases strength decreases. Duff Abrams showed this in 1919, and Abrams’ law is the principle behind most concreting proportioning methods used today. But Abrams ran his tests on fully consolidated concrete.

Unless concrete is properly consolidated, voids reduce strength regardless of the water-cement ratio. And, as shown in Figure1, the effect is significant.

Right after it’s placed, concrete contains as much as 20% entrapped air. The amount varies with mixtype and slump, form size and shape, the amount of reinforcing steel, and the concrete placement method. At a constant water-cement ratio, each percent of air decreases compressive strength by about 3% to 5%. Consolidating the concrete, usually by vibration, increases concrete strength by driving out entrapped air. It also improves bond strength and decreases concrete permeability.

Figure 1. Degree of consolidation can have as much effect on compressive strength as water cement ratio. Low-slump concrete may contain up to 20% entrapped air when placed.

Vibration is a two-part process

How does vibration consolidate concrete? Figure 2 shows it to be a two- part process. A vibrator creates pressure waves that separate aggregate particles, reducing friction between them. Piles of concrete flat-ten as the concrete flows around reinforcing steel and up to the form face. Large voids (honeycomb) disappear. But making the concrete flowable doesn’t finish the compaction proces s. Almost simultaneously, a second stage starts to occur as entrapped air bubbles rise to the surface.
This deaeration process continues after the concrete has flattened out. Until both vibration stages are complete, the concrete isn’t fully consolidated. If the vibrator is removed too soon, some of the smaller bubbles won’t have time to rise to the surface. Vibration must continue until most of the air entrapped during placement is removed. It’s usually not practical, though, to remove all the entrapped air with standard vibrating equipment.

Figure 2. A vibrator consolidates concrete in a two-part process. The first waves liquify the concrete so it flows better and the continuing waves knock out air bubbles.

Different vibrators for different jobs

The earliest form of equipment used as a vibrator was a rod stuck into the concrete, pushed down and pulled up. Rodding works for concretes with slumps greater than 3 inches, but it’s rarely used because of the costly labor required. Because rodding doesn’t put extra pressure on forms, howe ve r, it has helped more than one contractor complete a concrete pour when forms were bulging.
The most common vibrator used is the electric, flexible shaft type. Other types include electric motor-in- head, pneumatic, and hydraulic. Vibrator output, usually expressed as a frequency, is controlled in a different
way for each type of vibrator:

An electric vibrator uses voltage.
A pneumatic vibrator uses air pressure.
A hydraulic vibrator uses pressure and flow rate of hydraulic fluid.

On the jobsite the contractor can check the operating performance of his equipment by measuring frequency.
If it’s low he should check for voltage fluctuations, air pressure losses, or hydraulic pressure drops. The type of vibrator must match the requirements of the concrete and the jobsite (Figure 3). Frequency rates determine the amount of vibration time required to complete the two-stage consolidation process.
In the 1960s, vibration frequencies were much lower. To compact a 1⁄2-inch-slump concrete took 90 seconds at 4,000 vibrations per minute (vpm), 45 seconds at 5,000 vpm, and 25 seconds at 6,000 vpm. Today’s typical frequency of 15,000 vpm requires only 5 to 15 seconds of vibration
time.
Internal vibrators chosen for most jobs have a frequency of 12,000 to 17,000 vpm in air. The common flexible shaft-type vibrator reduces its frequency by about 20% when immersed in concrete. Motor-in- head types provide a constant frequency when in air or concrete.

Figure 3. The vibrator head must fit between the rebars and have a high enough frequency to quickly consolidate the concrete.

How to use an internal vibrator

Producing a dense concrete without segregation requires an experienced vibrator operator. Inexperienced operators tend to merely flatten the concrete because they don’t vibrate long enough to deaerate the concrete. Undervibration is more common than over vibration because of a worker’s effort to keep up with the concrete or to increase productivity. The operator can judge whether or not vibration is complete by watching the concrete surface.
When no more large air bubbles escape, consolidation is adequate. Skilled operators also listen to the pitch or tone of the vibrator motor. When an immersion vibrator is inserted in concrete, the frequency usually drops off, then increases, becoming constant when the concrete is free of entrapped air.
Never use a vibrator to move concrete laterally. Concrete should be carefully deposited in layers as close as possible to its final position in the form. As each layer is placed, insert the vibrator vertically. The distance between insertions should be about 11⁄2 times the radius of action (usually 12 to 24 inches). Radius of action is a distance from the vibrator head within which consolidation occurs. It varies with equipment and concrete mix.

Walls and columns

Special techniques are necessary to blend layers of concrete in walls and columns. Let the vibrator penetrate quickly to the bottom of the layer and at least 6 inches into the preceding layer. Then move the vibrator up and down, generally for 5 to 15 seconds, to blend the layers. Withdraw the vibrator gradually with a series of rapid up and down motions.

Elevated beams and slabs

Beams and joists placed monolithically with slabs should be vibrated separately before slab placement. Place the slab concrete after vibrating the beam, but before the beam concrete is set. Allow the vibrator to penetrate through the slab into the previously placed beam to blend the two structural elements.

Undervibration vs Overvibration

Undervibration is far more common than overvibration. Good quality normal- weight concrete is not readily susceptible to the problems caused by overvibration, so when in doubt, vibrate more.
The problems associated with undervibration include:

Honeycombing
Excessive entrapped air
Sand streaks
Cold joints
Subsidence cracking

The problems associated with overvibration include:

Segregation
Sand streaks
Loss of entrained air
Form deflection
Form damage or failure

Overvibrating, because it causes entrained air loss, might be expected to decrease freeze-thaw resistance. Research results don’t bear this out, however. In one study, overvibration of low- slump, air- entrained concrete had no effect on freeze-thaw resistance. Overvibration should not be a concern unless high- slump, improperly proportioned concrete is being placed.

Vibrating around congested reinforcement

To provide good concrete- to- steel bond, vibration is especially important in areas congested with rebar. Vibration alone doesn’t solve the problem. Other actions must be taken to help complete concrete consolidation, such as:

Using admixtures to increase flowability but limit segregation
Changing mix proportions or ingredients to increase flowability
Designing the reinforcing for ease of concrete placing

Figure 4. Vibration alone won’t consolidate concrete adequately when reinforcing is congested. To ensure adequate consolidation it may be necessary to use superplasticizers, reduce aggregate maximum size, or adjust rebar spacing.

To achieve proper consolidation by internal vibration in congested areas, the designer should provide obstruction-free vertical access of 4×6-inch minimum openings to insert the vibrator. Horizontal spacing of these openings should not exceed 24 inches or 11⁄2 times the vibrator’s radius of action. Engineers designing congested reinforcement should also design for proper consolidation, otherwise contractors can’t always guarantee adequate concrete to steel bond (Figure 4).

References

1. “Guide for Consolidation of Concrete,” ACI 309R-87, ACI Materials Journal, September-October 1987, American Concrete Institute, Box 19150, Detroit, Michigan 48219.
2. Whiting, D., G. W. Seegebrecht, and S. Tayabji, “Effect of Degree of Consolidation on Some Important Properties of Concrete,” SP-96, Consolidation of Concrete, American Concrete Institute.
3. Olsen, Mikael, “Energy Requirements for Consolidation of Concrete During Internal Vibration,” SP-96, Consolidation of Concrete, American Concrete Institute.
4. Troxell, Davis, & Kelly, Composition and Properties of Concrete, McGraw- Hill, New York, New York, 1968.

by Prof.Dr.Bruce A.Suprenant

Road Safety Audit Stages

Table of Contents

Toggle

Road Safety Audit Stages

Road safety audit is the formal examination of existing roads, future roads or various sorts of traffic projects by any independent group of trained expertise. They examine the deficiencies in road safety. There are various stages of road safety audits. Number of stages depends on the number of stages in a road project before completion.

Feasibility study phase
Preliminary design phase
Detailed design phase
Pre-opening phase
In service phase

Feasibility Study

In feasibility study phase, trained specialist study and evaluate the results of following questions;

What is the scope of this project?
How many choices of routes available?
What will be the impacts on the existing transportation system?
Which design should be selected as a design standard for that road?
How long this route could be continued?
Which location will be the best location of interchanges?
Number of lanes required for managing maximum average daily traffic?
Where to provide the route terminals?
What will be the effects on the environment?
Control access

Technical team works on these questions step by step and at the end gives the most feasible solution possible.

Preliminary Design Stage:

Preliminary design is the second stage of road safety audits. In this stage designs of roads are carried out. As preliminary phase, therefore designing is not carried out in a very detailed. Following are road designs that are done in this phase;

Alignment of horizontal and vertical curves
Width of land and shoulder
Layout of intersection
Provision of super elevation and side slopes with pavements
Provision of overtaking lanes
Provision of separate way for pedestrians and cyclists.
Safety arrangements during construction on site
Provision of sign boards.
Design of Link roads
Space management

Detailed Design Stage

After the completion of 2^nd stage, designs are carried out in detail. Following are the road designs that completes at the end of this stage;

Signals
Sign boards
Line marking
Lighting
Intersection details
Delineation
Provision of shoulders
Management of traffic during construction
Design of road drainage system
Provisions of way for road user groups. For example, pedestrians, cyclists, vans, trucks etc.
Provision of slopes.
Provision of road side objects

Pre-Opening Stage

In this phase technical audit team drive through the completed project. During drive, they observe the provision of safety level, quality, sign boards, road material and all other aspects that they took under consideration during the preliminary survey and detailed design phase. They came on the site during different weather conditions like during day time, night, etc… after the completion of survey they wrote a report on it and deliver it to the main authority.

In-service:

After the pre-opening examination, road is opened for public and during that still technical team remains active and they observe the working of safety features during heavy traffic.

Difference Between Flexible And Rigid Pavement

Flexible pavement differ from rigid pavement in terms of load distribution. In flexible pavements load distribution is primarily based on layered system. While, in case of rigid pavements most of the load carries by slab itself and slight load goes to the underlying strata.
Structural capacity of flexible pavement depends on the characteristics of every single layer. While, the structural capacity of rigid pavements is only dependent on the characteristics of concrete slab. This is so, because of low bearing soil capacity of underlying soil.
In flexible pavements, load intensity decreases with the increase in depth. Because of the spreading of loading in each single layer. While, in case of rigid pavement maximum intensity of load carries by concrete slab itself, because of the weak underlying layer.
In flexible pavement deflection basin is very deep, because of its dependency on the underlying layers. While in case of rigid pavement, deflection basin is shallow, this is because of independency of rigid pavement on the underlying layers.
Flexible pavement has very low modulus of elasticity (less strength). Modulus of elasticity of rigid pavement is very high, because of high strength concrete and more load bearing capacity of the pavement itself. Than compared to flexible pavements.
In flexible pavements, underlying layers play very important role. Therefore, more role are playing only underlying layers. In case of rigid pavements, slight function of underlying layers. Maximum role is playing by the top layer (that is slab) by itself. Therefore, minute part is taking by sub layers.