Category: Construction

• Sloping columns and columns in tension

  

  I had an interesting meeting today talking about the structural approach behind this OMA-designed project in Brooklyn (pictured above).

  I have always found structural engineering fascinating. Structures, along with physics, were some of my favorite classes from high school all the way to grad school. So even though I don’t think my personality is ideally suited to engineering, if I were ever to become an engineer, I’m fairly certain that I would need to be a structural one.

  For this project the big structural challenge was the large cantilevers that you see above in the tower on the left. As I understand it, there a number of ways to deal with this. One way would be to just design large transfer slabs and/or beams. But given the size of this tower, these would end up being very deep, and so you’d be really compromising the spaces where these structural transfers occur.

  How they actually dealt with it is through sloping columns (which you can see in the above photo if you look closely). What these columns do is gradually transfer the loads across multiple floors in the building, until they reach structure that runs all the way down the tower.

  At the same time, the spaces underneath the sloping columns are essentially “hung” from above. Meaning the columns are in tension, instead of being in compression, which is typically how columns work. The result is that you get some sloping columns in the suites. But I think that’s kind of cool. If you’re nerdy enough to care, it tells you how the structure of the building is working.

  Obvious disclaimer: I am not a structural engineer. You probably want to consult one if you’re looking to do a cantilevered tower with sloping columns.

  Photo: Elevated Angles via Highbury Concrete

  2023.07.26

• Retractable balcony glazing system — what do you think?

  This morning I toured a site/project that is using a balcony glazing system from a company called Lumon. The product looks like this from the outside:

  

  Like this from the inside (from on the balcony):

  

  And it retracts/opens up like this (the glass panels stack neatly to one side when you want to create a traditional balcony and guard condition):

  

  Obviously the idea here is to create outdoor spaces that can be enjoyed for more months of the year. In the summer it opens up so you get a typical balcony condition. And then in the cooler months or on a windy or rainy day, you get a solarium. Maybe it even works in the winter with the right sun exposure.

  But obviously there is a cost to adding something like this to new projects. So my development question to all of you today is: Would you be willing to pay a premium for a balcony glazing system like the one shown here? And if so, how important would you rank a feature like this for multifamily buildings?

  If you have a few minutes, please let me know in the comment section below.

  2023.06.13

• Pill-shaped prototypes

  Back in 2020/2021 when we were getting ready to launch sales for One Delisle, the team came up with the idea of pill-shaped kitchen islands for our residences. 

  What that means is we wanted to use perfect semi-circles on both ends. We didn’t want oval islands. We didn’t want distorted semi-circles. We wanted islands shaped like pills!

  We felt these opened up the kitchens and also looked really unique. So with Studio Gang and the rest of the team, we proceeded to design a few different types.

  We needed ones that would work for smaller suites, we needed ones that would work for larger suites, and we needed to accommodate breakfast bars/seating.

  When we approached Scavolini Toronto about this idea their first response was, “we’ve never done this before. It would be a first.”

  However, their second response was, “but we’ll figure it out with you.” And based on this response, we built (by hand) a pill-shaped island for our condominium sales gallery, and then included them as part of One Delisle.

  Fast forward to 2023 and we are now in the “let’s figure it out phase”. This week we reviewed the very first production prototypes in Scavolini’s factory in Pesaro.

  

  

  

  

  They are everything we could have hoped for, and we are thrilled that Scavolini was a willing partner in this endeavor.

  It’s not easy doing new things in construction. The smallest things can (usually?) end up being a lot more work. But it all feels worth it when you get to see the results.

  2023.05.26

• Scavolini’s pasta sauce test

  Today I learned that one of the most important quality assurance tests you can run on a kitchen is this one here:

  

  It is the “pasta sauce test”. And it involves repeatedly boiling a cauldron of water underneath some cupboard doors for at least several hours.

  It is an important test because the combination of heat and humidity is particularly tough on certain kinds of finishes.

  So if you happen to be in the market for a new kitchen, make sure you ask them about the pasta sauce test.

  P.S. Scavolini is supplying the kitchens for both Junction House and One Delisle.

  2023.05.25

• Timing matters in development

  Early on in my career, I worked on a new office development where the decision was made to start construction having only pre-leased 25% of the building. (It may have actually been closer to 22% if my memory serves me correctly.)

  Our big constraint at the time was that this first tenant had to be out of their current space by a certain date, and the only way we could meet their deadline was to immediately start construction. Otherwise, we knew we would lose them to another development or to an existing building.

  To convince ourselves that this was a reasonable thing to do, we looked at all of the upcoming lease expiries in the market, and then came to the conclusion that there would be enough demand in the coming years to fill the rest of the building.

  Still, we were taking a leap of faith, even if it was an informed one. And it meant running the project entirely on equity until we could secure a construction loan. Thankfully, in this particular instance, our hypothesis proved true. The lease expiries did end up creating the demand we were hoping for and so we were able to fill the rest of the building.

  The project was a success.

  But that was then. And in hindsight, this move feels scary. What would have happened had we made this exact same decision at the end of 2019? Things would have been very different. Not because of a fundamentally different decision on our part, but because of a black swan event that was truly impossible to predict. Our timing would have been bad.

  This is just one example of the many risks associated with the building of buildings. Development never happens in a vacuum. You’re always solving for a long list of constraints. And sometimes you need to solve for things that you don’t even know exist yet.

  2023.04.28

• Skyscraper construction speed by city

  Brian Potter, of Construction Physics, recently tried to determine which cities build skyscrapers the fastest.

  Here’s how he went about that:

  • He started by looking up the 50 largest cities in the world on Wikipedia
  • He then pulled data from the Council on Tall Buildings and Urban Habitat to get a list of every skyscraper completed between 2000-2020 that was over 100 meters, had a start and completion date, and had a gross floor area
  • The result was a list of 986 skyscrapers completed in 39 cities, most of which (~740) were completed in the US, China, Japan, and Canada
  • Finally, he calculated completed square feet per year and made some charts

  Here are the results:

  

  

  And here’s one thing he had to say about them:

  Interestingly enough, the huge outlier in slow construction isn’t the US, but Canada, with an average skyscraper construction speed of half that of the US’s.

  For a lot more information on this topic, click here.

  2023.03.24

• One Delisle has started the big hole part

  

  The most boring part of constructing a high-rise, like One Delisle, has got to be installing the shoring piles. Sure there are big rigs moving about on site but, for the most part, there’s almost no visible progress. That is, until you start excavating. Then you get to see said piles and you also end up with a big hole, which is something.

  Thankfully shoring works are now complete at One Delisle and we have started on the big hole part (see above photo from our rooftop cam). The next major milestone will be our “bottoming out,” and that’s when the tower crane will go up and our massive raft slab foundation will get poured. Visible progress is certainly more fun.

  2023.03.23

• More on soft story buildings — a Q&A with structural engineer James Cranford

  As I mentioned yesterday, I am not a structural engineer. However, my friend James Cranford is. He is Principal at Stephenson Engineering and he was nice enough to answer a few of my questions about soft story buildings (storey if you’re Canadian).

  BD: What is a soft (or weak) storey building? And why is it such an important design challenge, even in a very un-seismic city like Toronto?

  JC: A soft storey refers to any level in a building that has LESS capacity than the level above. This means it has both less strength to resist loads and less stiffness so that it will move more than the levels above. Soft stories are one of the most significant challenges that many modern building designers face because they are one of the most likely ways that a building can fail catastrophically if not properly designed. A soft storey failure occurs when the building hinges above the weak level and the columns below can no longer support the load of the building above as they become overstressed and loaded in ways they were never meant to act. This leads to a sudden, often pancake type collapse that is likely to bring down the entire building.

  

  We see potential soft storey issues most commonly in mid to high-rise residential buildings that have either amenity or retail spaces at the ground floor. These are spaces that by nature are large and as open as possible. During design, the structural engineer needs to recognize this and compensate for the lost capacity in other ways. This is usually done through a combination of increasing the capacity of the remaining walls and adding new walls at the weak level that fit with the building layouts.

  BD: What does the Ontario Building Code mandate in terms of soft storeys?

  JC: The OBC generally does not permit soft stories in any form for buildings where people are likely to live, work or play. In critical infrastructure like hospitals which must remain fully functional in the event of a major earthquake, the OBC goes further and does not permit any ‘lateral force resisting elements’ like shear walls or steel frames to be discontinuous below. This means that if you have a wall on the 5th floor of a hospital, that wall must exist with equal or greater capacity on EVERY level below, without exception.

  BD: How much more stringent is British Columbia, where there is greater seismic risk?

  JC: The requirements in the British Columbia Building Code (BCBC) are almost identical to those in Ontario in this case. However, the seismic design forces will be much higher based on the potential for much larger earthquakes, so while buildings will generally be designed for a higher seismic capacity, they must be proportioned similarly to prevent soft stories.

  BD: Speaking generally, what is usually required structurally in order to retrofit an existing soft storey building so that it can properly withstand things like earthquakes?

  JC: The most common way to retrofit a soft-storey is to increase the capacity of the weak level. In smaller buildings this can usually be achieved by adding new ‘lateral-force-resisting elements’ like shear walls or moment/braced frames until the overall storey capacity matches or exceeds the capacity of the levels above. On larger buildings this becomes more complex, as the loads are much higher and simply adding capacity may not be either feasible or practical. Therefore a full structural analysis is usually required to find a solution that can be tailored to the unique structural and architectural conditions. This often involves a combination of increased capacity and the introduction of ductile detailing which will allow the building to dissipate seismic energy. This can be roughly thought of as a ‘bend but don’t break’ approach to surviving an earthquake.

  In some jurisdictions, the extreme risk caused by (many) homes built with soft stories has prompted local governments to intervene. The City of San Francisco (as well as many other municipalities in California) have enacted ordinances requiring home owners to assess and upgrade their properties, including single family home with garages a the lowest level, to reduce the risk of soft-storey failure in an earthquake.

  BD: Thanks for this, James.

  I don’t usually do Q&As on this blog, so let me know in the comment section below if you found this one valuable and if you’d like to see more of them.

  2023.03.07

• Soft story collapses

  I am not a structural engineer (or an architect for that matter). But one of the things that has come to greater light as a result of the devastating earthquake that hit Turkey & Syria last month is the number of “soft story buildings” throughout these countries.

  Technically, a “soft story building” is exactly what the name suggests. It is a building where one floor is less than 70% as stiff as the floor above it, or less than 80% as stiff as the average of the three floors above it (source).

  The typical application of this is a ground floor that has less structure (missing shear walls for example) and is more open. And it is usually done to accommodate things like parking and retail uses, and to, of course, build more cheaply.

  However, there is a massive problem in that they are often structurally suboptimal! (Again, not a structural engineer.) This is why we saw so many of the buildings in Turkey “pancake” during its earthquake. The ground floor failed and then it brought down the rest of the building.

  I can appreciate that retrofitting older buildings is both difficult and expensive; but it is inexcusable to not work toward that and it is certainly inexcusable to not mandate that every new building meet whatever building codes are required to save lives.

  2023.03.06

• Why construction productivity lags other sectors of the economy

  Construction is an essential sector of the economy, responsible for building and maintaining the physical infrastructure that underpins our society. However, it’s no secret that construction productivity lags behind other sectors of the economy, such as manufacturing and information technology. So why is this the case?

  One of the main reasons for the productivity gap is the unique nature of the construction industry. Unlike other sectors, construction projects are often one-off, bespoke endeavors, making it challenging to achieve the economies of scale that are typical of manufacturing or technology. Each project requires a different set of skills, tools, and materials, which can be costly and time-consuming to source and manage. This leads to a lack of standardization and efficiency, which can hinder productivity.

  Another factor that contributes to low productivity in construction is the reliance on manual labor. Despite the increasing use of technology and automation, much of the work in construction still relies on physical labor, which is subject to human limitations and the potential for errors. This can result in delays, rework, and additional costs, all of which impact productivity.

  Moreover, the construction industry faces challenges in terms of supply chain management and workforce development. The industry relies heavily on a complex network of suppliers, subcontractors, and laborers, all of whom must be coordinated and managed effectively. This can be difficult, particularly in light of the current labor shortage and skills gap in the industry.

  To address these challenges, the construction industry needs to embrace innovation and new technologies to improve efficiency, standardize processes, and reduce waste. There is also a need to invest in workforce development and training to upskill the existing workforce and attract new talent to the industry.

  In conclusion, the construction industry faces unique challenges that make it challenging to achieve the productivity gains that are typical of other sectors. However, with the right investments in technology, training, and process improvement, the industry can overcome these challenges and continue to build the infrastructure that our society relies on.

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  Maybe you didn’t notice. But if the above doesn’t sound like me and my writing, it’s because today’s blog post is brought to you by ChatGPT (AI). The prompt I used was, “write a short blog post about why construction productivity lags other sectors of the economy.”

  On some level, it’s unsettling that AI can now, almost instantaneously, spit out a blog post like this. It would now be pretty easy to set up a daily blog, like this one here, and use ChatGPT to populate it each day.

  But of course, while that might be interesting initially, it would quickly become a banal baseline. Anyone and everyone could copy what you’re doing. AI is going to change a lot. But our jobs remain the same: find new ways to create value and be remarkable.

  2023.02.18