Yesterday I sent out episode #14 of the reinforced concrete series. But this time with a different e-mail newsletter platform and e-mail address.

The open rate isn’t too bad. But some of you texted me that the e-mail was sent to the spam/junk folder.

Please check your spam folder, move the e-mail to your inbox, and add the e-mail: laurindominik97@gmail.com to your address book.

In Gmail, you simply click on my photo next to the email address and click on Add to contacts.

In Outlook, you can either add the e-mail from scratch:

1. From the new Outlook navigation pane, select People.

2. On the Home tab, select New contact.

3. Enter my name Laurin Ernst or Structural Basics and then select Save.

Or add my e-mail address from the e-mail itself:

1. In Mail, open the email “The strut & tie method to design corbels, pile caps and frame corners” in the reading pane, and then select my name / my e-mail address.

2. On the profile card that opens, at the bottom of the card, select Add to contacts.

3. Select Save.

I hope this will resolve the issue for those of you who want to continue to read my weekly newsletter. If it doesn’t help please check your spam folder next Wednesday again and respond to the email.

Thank you everyone and have a great weekend when you get there!

Cheers,

Laurin.

The first time I saw somebody use software to do hand calculations, I was blown away.

Everything was digital, it looked nice and every time you changed a value of a parameter like for example the width of your beam cross-section, the whole design calculation was updated within seconds.

With paper and pen, this takes at least a couple of minutes.

This aha-moment happened in the 1st week of my masters at DTU, and I haven’t done a design calculation with paper and pen since then. And if you have been following me for a while, you know that I am the biggest fan of digital hand calculations.

That’s why I am very happy and proud to share that Maplesoft reached out to me to sponsor the Structural Basics newsletter.

As a Structural Basics reader, you also get a special deal. You get a 1-month free trial, instead of 14 days, if you sign up with this link:

Download link for Maple Flow: For your extended-length trial, visit https://www.maplesoft.com/fulfillment/ and enter coupon code SBFLOWPRO (code valid up to JUN 1, 2025).

Special for students: If you are enrolled in a university and like the software, you can also get a Maple Flow standard license (lifetime – no expiry) for only 150 euro → here ←.

I am very happy about this partnership, because I truly believe that every structural engineer and student should be using a digital hand calculation software like Maple Flow. It speeds up your hand calculations, you make fewer mistakes, your colleagues actually understand your calcs because the formulas are not hidden like in Excel, and it’s much cleaner for your reports.

So, in this article, I’ll show you how to get started with Maple Flow and all the main features you need to create your first calculation report.

1. Installation of Maple Flow

When you sign up, you will get a download link and a license code in the email.

Once it is installed you can try out the Tutorials or, like me, if you wanted to get started straight away, click on New Canvas to get started.

2. The user interface

If this is the first time that you are using a hand calculation software, you might be overwhelmed. But trust me, it doesn’t take too long to get used to the user interface. It’s very intuitive.

In case you have used Mathcad or Smath before, you will notice that Maple Flow is very similar.

There are a couple of toolbars and palettes, as you can see from the picture below.

Main Toolbar

In the main toolbar you find features like Save, Save As, Undo the last operation, Turn the grid on, zoom in, zoom out, etc. Features you know from other software programs.

Palettes

In the palettes, you find all the tools you need for your calculations and documentation - Greek letters, units, matrices and more advanced mathematical expressions like integrals, sums, etc.

If you are more advanced, you know shortcuts for Greek letters and mathematical expressions, which speed up your workflow. I’ll show you how later in this article.

Context Toolbar

The context toolbar only appears if you click on text or an equation. It lets you change the font, font size, font colour, etc.

3. First equation

To “write” your first equation, simply click on the page/canvas so that you see a blue cross.

Then start typing. Let’s say we want to calculate 3 + 4 = 7.

Type in 3+4 and hit the “=” sign on your keyboard. You then should get your first result of 7.

4. Equations with variables

The power of digital hand calculation tools like Maple Flow is that you can use variables which can quickly be changed.

Define a variable: Type in a letter of choice and type in “:=” in your formula.

Next, type in a number of choice. This number is now stored in the variable.

To use the variable, we are calculating x + 6 = 8.

Type in “x + 6 =” and it will automatically calculate 2 + 6 = 8.

Now, change the value of x to 3 and the second equation will automatically update the result.

After you define a Variable, you can see a list of the values in the Variables Palette on the left – and this is updated for the location of the cursor, you won’t lose track of those you have already entered.

5. Units

Maple Flow can work with units. There are 2 ways to use units.

• You can insert a unit from the palette “Units”

• Or use the shortcut “Ctrl” + “Shift” + “u” + symbol of the unit (e.g. meter = m)

Let’s try to add 3 m with 4 m.

First, type in “3”, then select m from the length section of the Units palette.

Next, type in “+ 4” + “Ctrl” + “Shift” + “u” + “m” + “=” to use the shortcut. If you did it correctly, you should see the result of 7m.

With Maple Flow, it is very easy to manage a mixture of units. For example, my rebar spacing might be given in millimetre, but in my final result I want to show my lap length result in m.

I can change the result by clicking on the result unit, so it goes blue and overtype with the new unit “mm”. I can even use “mil” for thousandths of an inch!

6. Greek letters

In structural engineering, Greek letters are used all the time to define and store values.

So let’s have a look at how we do that in Maple Flow, and also how we can speed up things with shortcuts.

As always, first click somewhere on the page. Then we can pick a Greek letter of choice from the palette on the left side of the UI.

We are selecting α and typing further “:=30” → “Ctrl” + “Shift” + “u” → “degree”.

Now, we can calculate cos(α) by typing “cos(α)=”.

Shortcut for Greek letters

To speed up the process of calculating with Greek letters, there are shortcuts which we cover now.

By typing “a” → “Ctrl + g” Maple Flow automatically creates the letter α.

This works for all Greek letters. In general, those shortcuts work as

latin letter → “Ctrl + g”

(Control & g click at the same time)

7. Add text

Adding text is essential for improving the readability of a Maple Flow sheet. Especially if you use it in your structural documentation.

To add text you simply click on “Space” on your keyboard. Now you get a blue box (green means that it’s an equation) and you can add a description of the variable as an example.

8. Subscripted variable names

Subscripted Variable names are a must-have in engineering calculations and reports.

To write E_cm (Secant modulus of elasticity of concrete) in Maple Flow, type in

“E” → “Ctrl + Shift + _” → “cm” → “:=33” → “Ctrl + Shift + u” → “MPa”

Or you can use two underscores to enter a subscript like

“E” → “__” → “cm” → “:=33” → “Ctrl + Shift + u” → “MPa”

Try it out, what you like more. I personally like the two underscores more, as it’s faster.

9. If - else function

If else functions are very useful to automate your calculation sheets, because Eurocode often defines different formulas for different ranges.

As an example is the coefficient related to the bar diameter η₂ according to EN 1992-1-1 (8.2) which we calculated in the article about the anchorage length.

Let’s do this in Maple Flow. There are actually 2 ways to do an if-else function.

First, let’s define the parameter d_s.

In solution 1, we write ifelse(“condition 1”, outcome if true, outcome if condition 1 is false). In our example this looks like the following.

In solution 2 we use the piecewise function from the Expression palette.

10. Document header and footer

To make the document look professional, headers and footers can be implemented in Maple Flow.

To include a header, click on Insert → Header Footer…

I like to add the logo, date, name, revision number, etc.

Now, if you click on Print or Print Preview, you can see the header and footer.

11. Export as PDF

It’s possible to save the file in Maple Flow format (.flow files) to continue editing, and then when you have it in final state you can export it as a PDF.

To export your first structural design document in Maple Flow as a PDF, click on:

File → Export As...

Final words

Congrats, you have now created your first PDF document with Maple Flow, which you can now attach to your Structural Design report.

As I said in the introduction, I am a big fan of tools like Maple Flow. I used them for all of my hand calculations in my master’s. You find mistakes much quicker than in a tool like Excel because you type in each formula and can check the result of each calculation step.

It’s also much easier for others to understand your calculations.

In my job as a structural engineer I also use digital hand calculation softwares every time, I need to do a verification which is not covered by the structural design packages that we have in the office. I personally never use Excel to do calculations from scratch.

I hope this helped some of you getting started with digital hand calculations.

Thank you, Maplesoft, for sponsoring this episode of the Structural Basics newsletter.

See you next Wednesday.

Let’s design better structures together,

Laurin.

P.S.: In case you missed the Maple Flow trial link, here’s another chance to claim your 1-month free trial with coupon code SBFLOWPRO and get started with digital hand calculations today.

Today 3 years ago (02.01.2022) I published my first blog post on structuralbasics.com.

And man - have we come a long way. When I published this first article about different types of roof structures, I had never imagined having a newsletter with 10,000+ subscribers, a YouTube channel with 2,500+ subscribers and a homepage with 40,000+ visitors/month just 3 years later.

I could only build this because of you - Structural Basics members. Thank you very much for your feedback, your messages and questions.

I really appreciate you!

So to celebrate 3 years of Structural Basics content, I sat down and recapped what has happened, what we created and what we plan on building in 2025.

Hope, you’ll enjoy the video.

Structural Basics is here to help you understand structural engineering better.

I want to help as many people as possible. Therefore, please let me know what you want to see in the future.

There’s only so much I can cover in one newsletter or video. To understand the structural design of a whole building, we need longer guides. Therefore, I want to work on more paid products in 2025. What paid products / services do you want to see in the future?

If you want to see something else or if you think I missed something, feel free to text me by answering to this e-mail.

2024 was great, and I am super excited for 2025. Hope you are too.

Thanks for being on this journey with me.

Let’s build better structures together.

Laurin.

I’ve been shooting and editing videos in the last couple of days. Episode #3 of the structural basics series is out now, and a special video celebrating the 3rd birthday of Structural Basics is coming on the 2nd of January.

In the video, I talk about

• Story of the month: how my first 2 months in Munich and at the new job have been

• Structure tip of the month: different solutions to reinforce timber beams

• Update and growth stats of Structural Basics: newsletter, YouTube and structuralbasics.com

I hope you enjoy watching it. If you liked the video, I really appreciate a like and follow.

See on Wednesday (January 1st) for the next newsletter. We are not taking a week off. ;)

Laurin

P.S.: I hope you’ll have a great start into the new year.

I set out to a last challenge in 2024. On the 31st, I’ll participate in a 10k race, trying to beat my personal best of 45 minutes 04 seconds.

See you in 2025.

I just wanted to wish you and your family Merry Christmas.

I hope you get to relax, hang out with old friends and eat tasty food the next couple of days before working hard on your 2025 goals.

Btw there will be a Wednesday (25th of December) episode as always. The article is already scheduled.

See you there.

Cheers,

Laurin

Today we are not talking about reinforced concrete but instead about how we can understand static systems (cantilevers, continuous beams, shear walls, tension rods, etc.) better with physical models.

An amazing resource to build you own structural models is Mola. It’s kind of Lego for structural engineers.

I wanted to get a MOLA Kit for a long time, because it’s a great way to teach and understand the behaviour of static systems. But until now I never had the time to look into it. That’s why I am super happy to share that they reached out and send over one of their KIT’s.

In today’s newsletter, we’ll introduce all structural elements and connections of the Mola Structural Kit 2, model a cantilever beam, a continuous beam and a 3D system (which could be a building) to investigate stabilizing elements like diaphragms, tension rods and shear walls.

So let’s get into it..

1. Introduction to Mola’s structural elements and connections

There are many different components in Mola 2 which all represent a structural element or connection.

Mola structural kit 2 consists of the following structural elements and connection types:

• Base plate represents the soil

• Base connections represent pad footings

• Springs represent columns, beams and bars

• Plates are used as load bearing slabs and walls but also for stabilizing elements such as floor diaphragms and shear walls

• Diagonals are tension members used as tension rods / wind braces

• Hinge connections are used for all connections. In case we want to make a connection continuous or rigid, we add the respective component

• Rigid connections: When we add a rigid connection to a hinge connection, the connection becomes momentstiff

• Continuous connections: When we add a continuous connection between 2 horizontal springs/beams, the beam becomes continuous. Note that there is still a difference to the rigid connection, because the connection between column and continuous beam is still a hinge.

Now, let’s look at some models..

2. Modelling a cantilever beam (maybe a different name)

For everyone who needs to catch up on the characteristics of a cantilever beam you can check out → this article ←.

The static system of a cantilever beam is characterized by have a fixed support on one end and no support at the other end.

But there are only a couple of examples where the main structure is a cantilever (e.g. in-situ concrete cores of high-rise buildings, cranes traffic light posts, etc.).

In most cases, the cantilever beam is attached to other structures like balconies, overhangs of roofs, and even aeroplane wings.

The effects on the main structure, a cantilever beam is attached to can differ depending on how the fixed support/connection is executed. This is something we can visualize very well with Mola.

How do we model a cantilever with Mola?

Let’s look at cantilever beams that are connected to other structures like walls, slabs, beams and columns.

For that we model a 2d frame with 2 columns, 1 beam connected to each other by hinges and 2 rigid (=momentstiff) supports. To make the frame stable out-of-plane, we add 2 tension rods. This represents our primary structure. Let’s say we want to visualize a balcony connected to a building. In this case, the horizontal element is a slab and the vertical elements the walls.

Here’s the static system of this 2d frame:

Now, we add the balcony (=spring) to one of the corners. One of the great things about Mola is that we can quickly identify unstable systems. If we only add a horizontal spring and push on it, we see that the beam “collapses”, because we only have a beam with a hinge connection.

Let’s add some moment stiffness to the connection. We have 2 options:

• Fix the balcony/cantilever to the wall or

• Fix it to the slab

Cantilever beam rigidly connected to the wall

We add a momentstiff connection between column and cantilever beam and push on the end of the cantilever beam to simulate a point load.

Here’s the deformed shape of the structure.

Cantilever beam rigidly connected to the slab

We add a continuous connection between beam (=slab) and cantilever and push again on the end of the cantilever beam to simulate a point load.

Now, the static system looks like this:

Here’s the deformed shape of the structure.

Why is this important to know?

Different static systems lead to different internal forces. If you use a wrong static system, you might underestimate the internal forces of the walls or slabs. And this again might lead to underdimensioning of the structural elements and in the worst case scenario to collapse.

3. Modelling a continuous beam

If you want to catch up on continuous beam, then check out → this article ←.

The static system of continuous beams is characterized by having a 1 pin support and 2 or more roller supports for a continuous beam, which means that the beam isn’t split up into 2 parts by a hinge connection.

Some real world-examples of continuous beams are:

• roof rafters supported by 3 or more horizontal beams

• horizontal beams of a garage supported by 3 or more columns

• foundation beams supported by piles

How do we model a cantilever with Mola?

Let’s look at a continuous beam with 3 supports, which are in this case columns.

For that, we model 3 columns with hinges at the top and 2 beams connecting to the hinges. To make the beam continuous, we add a continuous connection to the hinge in the center. To stabilize the system out-of-plane, we add 3 tension rods.

But we need to add some rigidity in-plane, because right now the structure isn’t stable. If we push horizontally on one of the corners, the structure collapses.

Let’s add 2 tension rods. Now the structure is stable. We could also add moment stiff connections to the supports or a shear wall.

Here’s the static system of this 2d system:

If we apply a load on one of the spans, we can again investigate the deflection and behaviour of the static system.

The advantage of continuous beams over simply supported beams is that they have a much smaller deflection for the same span, load and cross-section, because the other span is taking up some of the forces.

See for yourself.

Deflection of continuous beam

Deflection of simply supported beam

To sum it up, if you have a simply supported beam that verifies in ULS for bending, shear, etc. but not in SLS for the deflection requirements, consider using a continuous beam. The connection might be more expensive, but at the same time you can save material of the beam.

Let’s have a look at the last system..

4. A stable system with a diaphragm, tension rods and shear walls

Maybe you have already realized that I talk a lot about the importance of understanding stability and horizontal load transfer of structures.

That is because our universities spend too little time for it. 95% of the content taught at university is about vertical load bearing systems and elements like slabs, beams, columns, etc.

For example, when I left uni and started my first job as a structural engineer, I didn’t know enough about stabilizing systems and elements. But it’s as important as vertical load bearing systems.

Mola is such a great way to understand stability better.

In this example, we model a 3d structure (could be a building) which isn’t stable in the beginning, and we’ll add stabilizing elements step-by-step.

Stabilizing elements are

• floor diaphragms

• tension rods / wind braces

• moment stiff connections and

• shear walls

We start off by modelling 6 columns with hinges at the top and pin supports. We connect all hinges with beams. The vertical bearing system is “stable” meaning that vertical loads applied to beams find their way down to the foundations. They travel from beam to column to foundation and then to the soil (= base plate).

But the system is by no means stable for horizontal loads. By just applying a small horizontal load, the system collapses. To make the 3d system stable, we need to make the

• horizontal floor/roof system stable and

• the vertical wall/column/beam system stable

Stabilizing the horizontal floor/roof system

The current floor system is not stabile because if we apply a load, it deflects and changes its shape until it collapses.

Now, let’s make it stabile. We can either add a diaphragm which is in many cases already a load bearing element like an in-situ concrete slab or a CLT slab. Or we add tension rods, which are often used for roof structures.

Let’s do both. If we now apply a horizontal load, the floor system keeps it right angles and doesn’t change its shape any more. However, because the vertical stabilizing system isn’t stable yet, the structure still collapses.

To make the vertical system stable, we need to add a minimum of 3 stabilizing elements (shear wall, tension rods or moment stiff connections (=frame)). But these 3 elements mustn’t be in the same grid line.

Let’s start off by adding tension rods and a shear wall on both sides in longitudinal direction. Now the system is stable in longitudinal direction. But not in transverse direction.

Finally, we add moment stiff connections in one of the fields in transverse direction.

Tip: If you only use 1 stabilizing element in transverse direction (shorter direction), I recommend using a shear wall there, because shear walls are much stiffer than wind braces or frames and the horizontal load in that direction will be much greater than in the other direction (because the facade area is larger).

Final words

I am a big fan of Mola’s structural Kit (in case you haven’t noticed yet). I can really recommend their Structural Kits. Especially if you are in your civil or structural engineering bachelors or just learning about structural engineering in your spare time. Like many of you are doing.

I am not just saying this because they send me a Kit for free. It’s a great way to learn about static systems and understand how they behave for different loads and different connection types.

And it’s really fun!

I wish I had one when I was in my first semesters learning everything about static systems. I remember that I had no clue for 4 semesters how these abstract static systems would translate into real structures.

This is one of the main things I am trying to teach you here on Structural Basics: How we turn a static system into a concrete beam with reinforcement or a timber frame. I hope it helps some of you.

I’ll see you next Wednesday the next newsletter.

Let’s design better structures together,

Laurin.

P.S. Have you already seen my YouTube video where I introduce myself and Structural Basics? You can check it out → here ←.

Enjoy the newsletter? Please forward to a friend you think could like our structural engineering content. It only takes 15 seconds. Making this one took a few hours. Just forward this link: https://www.structuralbasics.com/newsletter/

Today, I am extremely happy to share that we hit a big milestone for the Structural Basics newsletter and our community: We just hit 10.000 subscribers to the newsletter.

To me, this is still mind-blowing that there are 10.000 nerds out there reading my engineering stuff.

Thanks to everyone who has joined me on this journey. Without you, I would have quit by now.

I am proud of what we have achieved together and more motivated than ever to grow Structural Basics further, create more and new content, try out new formats and ultimately make Structural Basics better than it is today.

This isn’t our usual Wednesday episode. So, I want to keep this short. I know you are all busy.

But I do quickly want to recap what we have built over the last 3 years.

02.01.2022

I published the first article on structuralbasics.com about different roof structures (check it out here). I was so nervous putting myself out there on the internet for getting bad feedback on my writing, visuals or whatever. In the first couple of months, I was even scared of getting sued because I wasn’t sure if I was allowed to put URL links from other homepages into my content.

Why did I create a homepage for structural engineering content in the first place?

A friend from uni who was into architecture asked me how she can quickly design and verify timber beams of a flat roof. Everyone who has studied structural engineering knows that there is no “quickly” in structural engineering. Quickly is dangerous and beginners are very likely to do mistakes.

My idea was to find an in-depth tutorial on the internet that I can send to her with a couple of comments where she might find the missing information. I started searching on Google and couldn’t find anything. I googled more for other structural engineering topics and was shocked how little information there was. If I found an article, the quality was terrible. At that moment, I knew that I need to change that.

From October 2021 until December 2021, I watched a bunch of YouTube videos on how to create a blog, brainstormed names for the blog and wrote the first blog post. I think it took me 30–40 hours to write the first one. If I am looking at this blog post now, I am laughing because it’s one of the most unsuccessful and shortest ones that I have ever written. But I had to start somewhere.

July 2022

I published one blog post every week since the 2^nd of January. At the time I was still in uni, having 5 hours of Danish class a week, working 15 hours in my student job and I had a girlfriend who wanted to see me. Some weeks I struggled a lot to find the time to write. To publish on time on Monday, I often got up at 5 am on the weekends, cause otherwise I wouldn’t have made it.

The first 3-4 months only 30-40 people visited the homepage per month (besides me and my ex-girlfriend). But then in the end of July things started to change.

June 2022 was the first month with 1000 visitors.

December 2022

We continued to publish one blogpost a week and by the end of the year we had 8000+ visitors per month. Things started to grow.

February & March 2023

I finished my master’s at DTU (Technical University of Denmark) and took 1.5 months off to travel to Thailand and Cambodia with my brother before I started my full-time job as a structural engineer. Before the trip, I wrote 10 blog posts within 2 weeks, because I wanted to be completely off (also from Structural Basics) for at least a month on my travels. But I didn’t want to break my streak of publishing a blog post every week.

The trip was amazing, but I am never completely “off”. I always think about what I want to work on next and how I can make things better. On the trip (probably while I was laying at the beach) I came up with the idea of starting a weekly newsletter and (because a newsletter alone wouldn’t be enough haha) a YouTube channel.

My brother left 10 days before me, and in those 10 days I set up the newsletter on Substack and the YouTube channel. At the time, I was in Chiang Mai and Pai in Northern Thailand. And I am always with my laptop.

April 2023

I published the first newsletter and the first YouTube video.

1^st newsletter

1^st YouTube video

At the time we already had, 17000+ visitors/month to the homepage and I thought that many of the people visiting the homepage would sign up for the newsletter.

November 2023

The growth of the newsletter was very underwhelming in the beginning.

There were maybe 50-70 new sign-ups a month, and I was publishing one newsletter every week.

December 2023

In December 2023 I introduced the Structural Design Cheatsheet and that’s when things started to change for the newsletter. The sign-up rate 10x because of this lead magnet.

In the end of December there were 838 newsletter subscribers and 27.400 website visitors (during Christmas the website numbers always drop).

I also managed to publish 8 YouTube videos in 2023 which resulted in 923 subs there.

July 2024

We kept publishing 1 newsletter a week and the newsletter kept growing by around 600-700 new Structural Basics members per month. By that time, my focus had already shifted from articles on structuralbasics.com to the newsletter. I put in much more time and effort into the newsletter because that is the place where I get to talk to you guys and where I also get feedback.

In April 2024, we were also hit by a Google Algorithm update which made our website visits drop by 30%-50%.

August 2024

In August, we experienced a spike in new subscribers to the newsletter. Some dudes with quite some following on LinkedIn posted my Structural Design Cheatsheet. In the beginning, they didn’t give credit to me or Structural Basics. One of them even put his name onto it. Thanks to our amazing community, some of you saw that and reached out to me. I texted them and asked them to add credit to Structural Basics and the download link, so everyone interested could get the original version.

That’s the reason why we gained 2000 subscribers in less than a week in August.

Btw., you can always use my content like images, cheatsheets, emails, etc. in your presentations, reports or whatever. Just please add a reference to Structural Basics if you post something online.

Also, just think about your credibility if you don’t add a reference and somebody finds out that the images/content isn’t from you, you are less trustworthy. Or, in my opinion, not trustworthy at all and a cheater.

Now, I am quite confident that my content on structuralbasics.com is of high quality. So, every time there’s a Google Algorithm update and my monthly homepage visits drop, I am not too worried because quality wins over the long time.

And after every drop, we have come back stronger with even higher homepage visits. In August, Google made a tweak to their algorithm again and had even more visits after that.

In August, we also published our first YouTube video after a break of 10 months.

05.12.2024

10.000+ subscribers to the weekly Structural Basics newsletter.

We’ve come a long way. Thanks to everyone for your feedback, spending your valuable time reading my newsletters and just being part of Structural Basics.

It is a pleasure and joy building Structural Basics. I learned so much and I enjoy every second of it.

Structuralbasics.com has almost had its first 50.000 visitors per month, and you might have noticed that I have been more active on YouTube recently. I introduced a monthly series where I talk about personal and professional stuff, and I published a couple of engineering tutorials.

We have a bit more than 2300 subs there, and I have plans to grow YouTube more in the future.

Final Words

Thank you again for being here. I appreciate every one of you. ❤️

Big things are coming. But I will be talking about my plans for next year in a video on the 2nd of January, which is Structural Basics’ 3rd birthday.

I hope you get value. I hope you return.

Talk to you next Wednesday.

Laurin.

I just published the 2nd vlog type video on the YouTube channel.

In the video, I talk about

• the reasons why I moved away from Denmark (video version of the newsletter from 2 weeks ago)

• the critical section for shear verification of reinforced concrete beams and slabs

• update and growth stats of Structural Basics.

This time I recorded most of the video in English Garden in Munich.

I hope you enjoy watching it.

See on Wednesday for the next newsletter.

Laurin

A couple of weeks ago, I told you that I made one of the biggest decisions of my life. But I didn’t tell what decision it was.

I moved from Copenhagen, Denmark to Munich, Germany.

By now (10.11.24) I have already been living in Munich for 2 weeks and I had my first week at the new job. I am completely in love with this city already. But more on how my first 2 weeks here have been later.

In this newsletter, I also want to talk about why I left Denmark, because most people consider Denmark and especially Copenhagen one of the best places to live and work as a structural engineer.

You get a good salary, only 37 working hours, great health and education system. Copenhagen is considered one of the most liveable cities in the world.

So why would I leave this place?

I wrote down the 5 main reasons why I moved away. Before we get into that, I just want to make sure you don’t misunderstand.

The last 3 years in Copenhagen have probably been the best in my life. And I didn’t move away, because I had a bad time. I am very grateful for the jobs I had, the friends I made, and the things I experienced. I also love Copenhagen.

It’s because there are a few things I started to miss as a Non-Dane in Denmark.

It’s becoming more common to work abroad and as an expat. And I want to share my thoughts and experiences.

→If you are a structural engineer living and working abroad, text me about your experience.←

Here are the 5 reasons why I moved away.

Reason #1 - not feeling 100% integrated

I speak fluently Danish. I had lived in Denmark for over 4 years, but I didn’t have any Danish friends, and I tried hard.

Even though I had many international friends, when you don’t have any local friends you don’t feel 100% integrated. I felt 95% integrated, but these last 5% made the difference. I want to live and work in a place where I feel 100% integrated.

Reason #2 - the weather

Summers are good, but winters are long, dark and grey. I grew up in the South of Germany. It’s even colder there in winter. But you get sun. Every 2nd or 3rd day on average it’s sunny. There were times in Copenhagen where I didn’t see the sun for 3–4 weeks because it’s always cloudy in winter.

Until I moved to Denmark, I didn’t know that the weather can impact my well-being. Now, I know it does. And this year is the first year in 5 years that I am actually looking forward to winter again. The Alps are close, Munich has sun and nature is just amazing here in the South of Germany.

Reason #3 - language

Speaking a language fluently doesn’t mean that you always feel comfortable speaking it. Going to the doctor, talking to the plumber or calling the municipality is always a bit of an extra challenge because there might be words you don’t know because you never use these words in your day-to-day life.

Reason #4 - nature

I grew up close to the Alps. I love hiking and spending time in the mountains. As a kid, I skied every weekend in winter.

Denmark is the complete opposite. It’s one of the flattest countries on earth. The highest elevation is 171m. 🏔️

Mountains are definitely something I missed a lot in Denmark, and I am happy to be close to the Alps again.

Reason #5 - culture

Danish and German culture are quite similar when you compare it to other countries. Both countries are pretty good at drinking alcohol (😐), most people do loads of sports and both nationalities love bread to mention a few things.

Still, there are many differences.

As someone who didn’t grow up there, you can’t contribute to a lunch discussion about kids TV series, the election or the school system.

Even in Germany there are big cultural differences between South & North, East and West.

I realized that I missed my culture - the German/Bavarian, and now that I live here again I feel home.

Living abroad is exciting and challenging. You grow 5x more than if you always stay in your home country. There’s just so many things you need to figure out yourself, and you are out of your comfort zone every day.

I would 100% move to Denmark again. I grew so much as a person. And I had a fantastic time.

But being an expat is also over romanticized often times. It comes with many challenges like the feeling of not belonging to the place. This ultimately made me move back to Germany.

The move and the first 2 weeks in Munich

What can I say. I am completely blown away by Munich.

Munich has so many parks like English Garden, public transport is cheap and well-connected, people are very active and sporty (especially running and cycling), great job opportunities, very ambitious people, a lot of internationals, cool cafés and nice nature outside the city.

I didn’t expect to have such a great time from the very beginning. This is the 3rd time that I moved to a new city (Innsbruck, Copenhagen and now Munich) and the first 6–12 months in Innsbruck and Copenhagen were super challenging. It took me quite a long time to find friends that I match with.

Like in Innsbruck and Copenhagen, people here are very active and sporty. But what’s quite different is that most people are very (very) ambitious in their professional lives.

I don’t want to say people aren’t ambitious in other places. But Munich is next level. A good friend of mine who lives here as well found the right words: “Munich is a hustler city.” From my conversations with the people I met, I agree 100%. Work is always a topic when you meet somebody new. You can feel that people here care a lot about their career, and I really like it.

In Denmark, for example, most people don’t understand if you work longer and extra hours because you care about the quality of your work or because you want to learn. People valued their spare time a lot. And I never felt I could be proud to work a lot. It had a negative taste for many people.

I joined already 2 run clubs and met up with the few friends I have here. I am doing a lot of socializing atm, because that’s something I didn’t do enough when I moved to Innsbruck and Copenhagen with the result that I felt lonely in the beginning, and it took quite some time to find friends there. So not too much work on Structural Basics, but that’s OK.

Now let’s talk about my first week at the new job. As for the city, I am also positively surprised by my new job.

I joined a structural engineering consultancy with around 200 employees in 8 different locations. My colleagues are super friendly, young, competent and ambitious, the company has a flat hierarchy, the office is central, and I am already busy with 3 exciting projects.

My colleagues work a lot because they really like their job. I appreciate that a lot. In Copenhagen, I often felt stressed when I was one of the last ones in the office at 16:30. Here many of my colleagues stay until 18:00-19:00 and nobody has a rush going home. That way, time flies by super quickly.

I am still settling and there are still a few things to organize like getting a bike or getting my German phone number to work. But as you can read, I am very happy about the move and excited for what’s coming.

If you live in Munich, reach out and we can go grab a coffee. I am always excited to connect with new people.

And to all expats: I know how difficult it is to live abroad. There are many challenges every day that people who never lived abroad don’t even think about. I really look up to everyone who lives abroad, and even more to those you managed to integrate into a new society.

On that note. Thanks for listening to my monologue. I thought you should also know about this big change in my life to get to know this guy better who emails you every Wednesday. ✌️✌️

I am very happy about my decision to move back to Germany. But at the same time, I don’t regret that I moved to Copenhagen.

We are back next Wednesday.

See you there.

Laurin.

PS: There are also amazing structures here in Munich, like the Olympic Stadium. Look at these cables and membranes. 😋😋

Masonry walls are commonly used in residential family houses. They resist vertical and horizontal loads from floors or external wind. And in some cases, masonry walls need to resist concentrated loads from beams.

I just uploaded a new video, where I show you, step-by-step, how you verify masonry walls that are subjected to point loads (click here to watch).

Enjoy the rest of your weekend, and I am hoping you’ll have a great start to the new week.

Cheers,

Laurin

I just published a new video on YouTube. You can check it out here.

In this structural basics series, I am sharing more personal stuff like learnings and failures of being a structural engineer.

This is the series I wish I had when I was in uni, because I had no clue how structural engineers work and how they actually design buildings from all these abstract static systems that we learn in mechanics classes.

We’ll publish one video a month and these vlog type videos will be split into 3 parts:

• story of the month

• structure tip of the month

• growth stats of structural basics and update on new articles, videos, etc.

In this first vlog (episode #1) I am introducing Structural Basics, this new series and me.

And as I said in the video, the quality will get better. There’s a lot of new stuff that I have to learn. Any feedback is appreciated, and let me know what topics and content you want me to cover.

I recorded this first video on Mallorca. I took a short 5-day holiday there with my dad and ran the marathon in Palma. Unfortunately, the race didn’t go as planned. I got my first cramp at km 31 and from km 34 I had to stretch and walk every 200 m.

I even fell to the ground 500 meters before the finish line, because I got cramps in both the front and back of my upper leg.

It was a big disappointment to be honest, because I put in so much training.

Now, a couple of days later, I am actually proud that I didn’t give up and completed it.

Reflecting on it, I have to train even more and focus more on muscle training to run a sub 3:30 marathon. During the last months I ran roughly 50 km/week, while for my first marathon I did 60 km/week. I probably also didn’t relax my muscles well enough the day before. I biked 25 km to pick up my bib number. Finally, I might have been too optimistic to run a sub 3:30 in a race with 220–240 meters of elevation.

But we’ll learn from it and come back stronger.

Talk soon,

Laurin

Today is the last post of the structural loads series before the announcement about the next series next week. But before getting into the topic, I feel like sharing some personal stuff today.

The last few weeks and months have been a blast. Lots of fun things happened, and I made one of the biggest decisions of my life. I’ll share more about that in a few weeks.

As I am writing this, I just came back from vacation. I spent time in my hometown Kempten attending our local beer festival (similar to Oktoberfest) which always happens in the middle of August. I love it because I always meet people from my past that I haven’t seen in years and everyone is in a good mood. We also call it the 5th season of the year because most people take vacation for the 10 days the festival is happening.

At the Structural Basics newsletter, we have also seen an incredible growth over the last month. We have grown by more than 2000+ people in the last 30 days (compared to 600/month before). Welcome to everyone who is new to our weekly structural engineering newsletter. It’s great to see the community grow. 🔥🔥

Another thing I am also spending a lot of time on, besides my full-time job as a structural engineer and content creation for Structural Basics, is preparing for my second marathon. I am running the Palma Marathon on Mallorca on the 20th of October.

I finished my 1st marathon in 3 hours 39 mins. This time, I’ll try to finish in under 3:30. You can see my runs on Strava. Let’s connect.

Structural Basics is a community about structural engineering.

But community is also about getting to know each other and sharing personal stuff. We learn and develop much better in an environment of friends.

Besides, the healthier we are, the more successful we are as structural engineers long-term. Being active and sporty has a big influence on our health. We can handle stress better and we feel overall better.

Alright, story time over, let’s get into the topic of today…

Horizontal Load Transfer

A building needs to transfer the horizontal and vertical loads that act on it down to the foundation. The loads travel from one structural element to another until they reach the foundation/soil. And of course all structural elements need to resist these loads.

Now, we don’t use the same structural elements to resist horizontal loads as we do for vertical loads. Here are examples of structural elements that stabilize structures:

• Shear walls

• Diaphragms

• (Wind) braces

• Frames

Usually, a building/structure consists of at least 2 of these 4 stabilizing elements.

In today’s article, you’ll learn how horizontal loads like the wind load are resisted by stabilizing systems of buildings and how these systems transfer the lateral loads down to the foundation.

The step-by-step process I always follow when transferring horizontal loads through a building:

• Step #1: Defining the static systems of the stabilizing elements (support conditions, hinge or moment stiff connections, etc.)

• Step #2: Applying the horizontal loads like wind load, seismic load, earth pressure and/or imperfection load to the structural elements they act on

• Step #3: Horizontal load transfer using the static systems

As said in last week’s article, mastering vertical AND horizontal load transfer takes a lot of practice. That’s why we’ll run through 2 different examples today.

Example #1: Precast concrete building

The stabilizing elements of a typical precast concrete building are shear walls and floor diaphragms.

Now, I have also designed precast concrete buildings which included steel/concrete frames and braces. But typically, at least 90% of all stabilizing elements are shear walls and floor diaphragms.

Step #1: Static systems of the stabilizing elements

Floor diaphragms are more tricky than other stabilizing elements and there are different methods to calculate these diaphragms but also to distribute the horizontal loads to the shear walls.

As mentioned above, there are a few ways to distribute the horizontal loads to the shear walls. We can use an elastic or plastic distribution. More on these methods in the future.

Step #2: Apply the horizontal loads

Let’s say the design horizontal wind load on the facade is 1.5 kN/m2 as the total of wind load area D and E. In the horizontal load transfer, we can simplify and apply the total load on one side of the building. But when you verify the diaphragms, you of course need to split them up and apply them separately.

Step #3: Horizontal load transfer using the static systems

We apply the load to the static system(s) and calculate the reaction forces. These reaction forces are then applied to the next structural element. We then again calculate the reaction forces of that element and apply it to the element that supports it.

The area load of 1.5 kN/m2 is applied to the facade. These facades distribute the area load to the floor diaphragms. Facade elements usually act as simply supported beams.

This line load we can now apply to the floor diaphragms. We apply 2 ⋅ p_d.f to the 1st floor.

The reaction forces of the beams are calculated as:

Which leads to the reaction forces of V_f.2 = 18.4 kN and V_f.1 = 36.8 kN.

Now, V_f.2 and V_f.1 are applied to the static system of the shear walls.

The horizontal loads on the shear walls lead to a bending moment at the bottom of the walls and a horizontal reaction force. This article isn’t about shear walls, but I also added a vertical reaction force because there are always vertical loads acting on shear walls.

And the bigger the vertical loads the better because it reduces the bending moment.

The bending moment is then transferred into a compression zone.

n_c and c depend on the magnitude of M. The bigger M the smaller c which means that the bigger the eccentricity of the load. If c become too small, we add reinforcement at the other side of the wall to take up tension.

You can check out our article about precast shear wall design to learn how you do these verifications.

Example #2: Steel warehouse

The next example is a steel warehouse that consists of frames and wind braces as the stabilizing elements.

Step #1: Static systems of the stabilizing elements

In the scenario of lateral load acting perpendicular to the facades, the stabilizing elements are the frames.

In the scenario of lateral load acting perpendicular to the gables, the stabilizing elements are wind braces, which act together with the rafters, beams and columns like a truss.

Step #2: Apply the horizontal loads

Let’s stick with the wind loading of 1.5 kN/m2.

Step #3: Horizontal load transfer using the static systems

Let’s split this up into lateral loading perpendicular to the facades and to the gables.

Lateral loading perpendicular to the facades

The area load of 1.5 kN/m2 is applied to the facade elements. These facades distribute the area load to the columns of the frame. You could also choose a design where the facade elements span vertically. Then the line loads would be applied to the roof and the foundation raft. In some warehouse designs you also see “horizontal purlins” which reduce the span of the vertical facade elements

The line load on the columns is calculated as:

This line load we can now apply to the columns.

The frame is now transferring the horizontal loads down to the foundations with its moment stiff connections.

Modelling the frame in a frame analysis tool like Ftool or any FE program leads us to the reaction forces which the foundations have to be designed for.

Lateral loading perpendicular to the gables

The area load of 1.5 kN/m2 is applied to the facade elements. These facades distribute the area load to the foundation raft and the beam of the frame.

The line load on the beam is calculated as:

This line load we can now apply to the beam/truss. How the loads travel through the compression and tension members is a topic for another article.

The reaction forces Vb are calculated like for a simply supported beam:

Vb can now be applied to the vertical wind bracing system.

With the SkyCiv truss calculator, we calculate the reaction forces, because the static system is statically indeterminate.

Now, you can design the pad foundation with these reaction forces.

Final Words

This was it! 5 example of how to do vertical load transfer last week, and now 2 examples explaining horizontal load transfer this week.

I hope these examples with 3D visualizations helped you understand load transfer better. It took me hours to write this article and model the 3D structures in Rhino. I hope the hours I put into it were worth it.

This was the last post from this series about structural loads.

I am excited!

If you missed episode #1 - #14 of this series, then you can find all previous posts → here ←.

See you next Wednesday, friends. 🙋‍♂️🙋‍♂️

Have a great rest of the week,

Laurin. 😎😎

When we structural engineers, design a building our job is basically to transfer the vertical loads from the roof and slabs through the building (through beams, columns, frames, trusses, etc.) down to the foundation/soil and making sure that the structural elements resist these loads.

As simple as it sounds, it’s not that easy. In most structural engineering degrees, we are not taught how to design structural systems like buildings, warehouses, parking garages. We mostly just learn how to design a reinforced concrete beam, a timber glulam frame or steel connections. The static system and loads are given.

But how do you actually pick the right static system? Should I use a simply supported beam, or a continuous beam? Should the connection be a hinge or momentstiff?

Where does this line load of 5 kN/m on the beam actually come from? And what happens with the reaction forces?

To design a building, a canopy or a warehouse, we need to understand how vertical loads travel through a structure from the roof to the foundation, from one structural element to the next.

So in today’s article, you’ll learn how the area load applied on a slab becomes a line load which acts on a beam and how this line load then turns into a point load on top of a column.

We’ll run through #5 different examples. I spent many hours writing this article and modeling the 3D structures, because of the complexity of the topic.

I hope that by the end of this article, you’ll understand better how loads travel from element to element until they reach the foundation and finally the soil.

Next week, we’ll learn how to transfer horizontal loads through a building and down to the foundations.

Now let’s get into it.

Understanding supports and reaction forces

Before getting into vertical load transfer, I want to recommend a video to you about the different support types we use in structural engineering. The tutorial also covers how to calculate reaction forces.

Knowing how to use supports will help you understand the vertical load transfer better.

And now back to vertical load transfer…

Vertical Load Transfer

Vertical load transfer is a very complex topic, and you need years of experience to master it. Every material works a bit differently, the type of connection determines what forces are transferred to the next element. There are endless examples.

• A hinge connection between beam and column will only transfer vertical loads to the column (and horizontal if a horizontal load acts in the beam).

• But a momentstiff connection will suddenly also transfer moments. Instead of using beam and column as the static system, we should use a frame to calculate the internal forces.

Here’s the step-by-step process I always follow when transferring vertical loads through a building:

• Step #1: Defining the static systems of the structural elements (slabs, beams, columns, etc.)

• Step #2: Applying the vertical loads like snow, dead, live load to the structural elements they act on

• Step #3: Load transfer from top to bottom using the static systems

As said, mastering vertical load transfer takes a lot of practice. That’s why we’ll run through 5 different examples today.

Example #1: Basic structure to understand load transfer from slabs to beams and to columns

Let’s start with a basic structure consisting of a 1-way spanning slab, beams, columns and pad footings.

Step #1: Static systems of the structural elements

Without knowing the static systems of the structural elements, we can’t transfer the loads through the elements correctly.

The easiest static system you can pick is the simply supported beam in terms of vertical load transfer. Note that you can’t use a simply supported beam for every structural element. Precast hollow core slabs are examples of simply supported beams, but in-situ slabs, supported by columns, beams and walls can’t be modelled as simply supported beams.

Please be also aware that the structure above is instable. It’s missing stabilizing elements like wind braces or shear walls. But that’s the topic of next week. The structure above works perfectly fine as an introduction to vertical load transfer.

Step #2: Apply the vertical loads

Let’s say the design load on the slab is 5 kN/m2.

Step #3: Load transfer from top to bottom using the static systems

We apply the load to the static system and calculate the reaction forces. These reaction forces are then applied to the next structural element. We then again calculate the reaction forces of that element and apply it to the element that supports it.

The area load of 5 kN/m2 is applied to the slab, and we’ll calculate the reaction forces.

The reaction forces of the simply supported slab are calculated as:

You can find all simply supported beam formulas → here ←.

Next, we’ll apply the reaction forces to the element that supports the slabs, the beam.

The reaction forces of the beams are calculated as:

Now, Vc is applied to the column and the pad footing.

Now, you can go ahead and verify the pad footing for its geotechnical properties and design the reinforcement/concrete.

Example #2: Carport

The next example is a carport that consists of roofing, timber beams and columns.

Step #1: Static systems of the structural elements

Let’s draw up the static systems again. Btw, timber columns and beams are in most designs simply supported.

Step #2: Apply the vertical loads

We’ll use a design load of 3 kN/m2 as the area load on the roofing.

Step #3: Load transfer from top to bottom using the static systems

The spacing of the secondary beams is set to 1m (see picture above). Therefore, the line load on the secondary beams is calculated as:

Note that the 3 kN/m need to be applied to all secondary beams. And 3 kN/m /2 = 1.5 kN/m on the edge beams.

The reaction forces Vb are calculated as:

These 9 kN are now applied to the primary beams, which support the secondary beams.

To calculate the reaction forces, I advise using a beam analysis software because continuous beams are statically indeterminate. This means that we can’t calculate reaction and internal forces using the 3 equilibrium equations.

At work, I use Polybeam. For this tutorial, I am using WinBeam because it’s for free.

We need to define E-modulus E and moment of inertia I of the beam, because they determine the stiffness of the beam and the stiffness has an influence on reaction forces of statically indeterminate beams.

E-modulus of structural timber C24:

Moment of inertia of a beam with width 20 cm and height 30 cm:

Applying the point loads to the beam result in reaction forces of 17.1 kN at start and end support and 55.8 kN at the center support.

These reaction forces can now be applied to the columns.

Now you can verify and design the timber columns for these loads.

Example #3: Rafter Roof

Here’s a YouTube Short explaining how the vertical loads travel down to the foundation/soil from a rafter roof.

Click to open video

Example #4: In-situ concrete slab supported by columns and walls

In-situ concrete slabs are already a bit more tricky. I’ll get to the reasons in a second.

Step #1: Static systems of the structural elements

This is where it gets tricky. For an in-situ concrete slab with a regular layout/spacing of walls and columns, we can in theory use continuous beams to calculate the reaction forces and internal forces of the slab. I personally recommend only doing that to get a good estimate. You can check out my article about flat slab design, where I show how to calculate the internal forces of a slab with continuous beams.

I personally model in-situ concrete slabs in a FE program. This approach leads to the most accurate result. Also be aware that you rarely have a slab with such a regular spacing of columns and walls like in the example above.

I will share my step-by-step process of how I model and design reinforced concrete slabs in a FE program in a future article.

Step #2: Apply the vertical loads

Step #3: Load transfer using the static systems

As mentioned above, I’ll dive into how to design in-situ slabs with FE in a future article. It’s quite an advanced topic. There are many parameters that influence a FE model, and I’ve seen many bad models. But if you are interested in learning how to use continuous beams to calculate internal and reaction forces, then → check this article out ←.

Example #5: Steel or timber warehouse

Step #1: Static systems of the structural elements

The static system depends on how you connect the beams to the columns and the columns to the foundation. But here are possible static systems of the structural elements.

In the picture above, you can see that the beam and 2 columns work together as a frame.

Step #2: Apply the vertical loads

Next, let’s apply a design load of 4 kN/m2 to the roof.

Step #3: Load transfer using the static systems

The spacing of the purlins is set to 1.75m (distance between them). Therefore, the line load on the purlin is calculated as:

We apply this line load on the purlins.

Next, we’ll calculate the reaction forces Vf and apply them to the frame.

I usually calculate the internal forces and reaction forces of a frame structure like this in a FE program as a 3D model.

For this tutorial, I use Ftool, because it’s free, so you can also model the same frame.

And visualising the normal forces shows us the vertical reaction forces.

Now, for this simple frame with only vertical loading (which is also symmetric) we didn’t need a frame analysis software, because both supports take half of the vertical load. But as soon as something is unsymmetrical, or we add horizontal loading, we need a frame analysis software because most frames are statically indeterminate.

Finally, the reaction forces can be applied to the pad footings and we can design the pad footings for these point loads.

Final Words

This was it! 5 example of how to do vertical load transfer.

It took me hours to write this article and model the 3D visualizations in Rhino. I hope you understand vertical load transfer better and the hours I put into it were worth it.

Next week, we’ll cover horizontal load transfer.

If you missed episode #1 - #12 of this series, then you can find all previous posts → here ←.

See you next Wednesday, friends. 🙋‍♂️🙋‍♂️

Cheers,

Laurin. 😎😎

Hello friends, 👋👋

It’s almost weekend, and I am happy to share that we just published a new design video tutorial on our YouTube channel.

We’ll run through what punching shear is, the step-by-step process I follow when I verify reinforced concrete slabs for punching shear and a calculation example.

So if you have time on the weekend, check it out and let me know what you think about the video format.

One way to support me and my work with Structural Basics is by liking the video and subscribing to the channel.

Thank you and I hope you’ll have a fantastic weekend.

I am really excited for Sunday. I will run the Copenhagen half-marathon, which I trained for the whole year.

And next week, I am on holiday travelling to the Faroe Islands.

Talk soon,

Laurin ✌️✌️

Today we’ll tackle the 2nd part of the load combinations guide - serviceability or SLS load combinations. Last week, we covered ULS, accidental and seismic load combinations. If you missed that article, then you can check it out → here ←.

In today’s article, you’ll learn how to set up SLS characteristic, quasi-permanent and frequent load combinations according to EN 1990, so you know with what loads you need to verify for example the deflection and cracking of a rc concrete beam.

8 Must-Have Softwares For Structural Engineers

Scroll down, if you are only interested in SLS load combinations.

It’s crazy to me how much technology has advanced in the last 10-20.

I was born in 1997, and I got my first smartphone at the age of 13. I wasn’t raised with a tablet or smartphone as a baby, but instead I grew up when all these new technologies came out. I am glad it was that way because I know both worlds.

I am among the youngest generation of structural engineers which grew up with software, but a lot of my older colleagues don’t use the latest software in their engineering projects or use paper and pen. This is absolutely understandable, as adapting is difficult. But this also slows them down in some tasks.

So here are my must-have software tools structural engineers should use in 2024.

Now, back to SLS load combinations…

Load Combinations According To Eurocode (Part 2 - SLS)

As already mentioned, SLS stands for → serviceability limit states ← and there are 3 actions structural elements might need to be verified for: characteristic, quasi-permanent and frequent.

(We’ll continue with the numbering from last week)

#4 SLS Characteristic Load Combinations

Due to SLS characteristic load combinations structural members are designed for example for deflection.

The formula of SLS characteristic combinations is (EN 1990 (6.14b)):

With,

• G_k = Dead load

• Q_k.1 = Leading variable action

• ψ_0.i = Psi factor of the accompanying actions/loads

• Q_k.i = Accompanying variable action

ψ₀ factors

We find the ψ factors in EN 1990 Table A1.1. Please be aware that every country might define these factors differently in its National Annex.

SLS characteristic load combinations applied to example structure

According to EN 1990 (6.14b) the characteristic load combinations can be written as:

Putting in the values of the characteristic loads and psi factors, we’ll get..

#5 SLS Quasi-Permanent Load Combinations

The SLS quasi-permanent load combinations are used to calculate for example the quasi-permanent moment, which is used to verify cracking of reinforced concrete beams or rc slabs.

The formula of SLS quasi-permanent combinations is (EN 1990 (6.16b)):

With,

• G_k = Dead load

• Q_k.i = Variable actions

• ψ_2.i = Psi factor of variable actions/loads

ψ₁ and ψ₂ factors

SLS quasi-permanent load combinations applied to example structure

According to EN 1990 (6.16b) in our example the quasi-permanent load combinations can be written as.

And if we put in the values, we will get..

#6 SLS Frequent Load Combinations

The formula of SLS frequent combinations is (EN 1990 (6.15b)):

With,

• G_k = Dead load

• Q_k.1 = Leading variable action

• ψ_1.i = Frequent psi factor of the leading variable action/load

• Q_k.i = Accompanying variable action

• ψ_2.i = Quasi-permanent psi factor of the accompanying variable action/load

SLS frequent load combinations applied to example structure

According to EN 1990 (6.15b) in our example the quasi-permanent load combinations can be written as:

Final Words

Load combinations are a very important part of structural design. Back when I was still studying at uni, I realized that many of my fellow students had problems understanding how load combinations work.

That’s because there isn’t really a course dedicated to load combinations. At most uni’s, you have to learn it yourself.

But it’s really dangerous if you don’t calculate the design loads correctly with load combinations because ultimately you design your element with wrong loads.

I hope this guide helped to understand load combinations better.

If you missed episode #1 - #12 of this series, then you can find all previous posts → here ←.

See you next Wednesday. ✌️✌️

Cheers,

Laurin. 😎😎

Timber beams, steel columns and reinforced concrete slabs are all designed and verified with design loads calculated from load combinations.

Load combinations combine different loads like snow, wind, dead, seismic and live load to represent a “real scenario”. A real scenario is for example the resulting force for a heavy wind storm. By setting up all possible load combinations we will find the worst-case scenario for a structural member which is in many cases the biggest load.

To put it in context, in load combinations we combine the characteristic loads we calculated in the last weeks (dead, live, snow, wind, impact load, earth pressure and imperfections). To account for material failure and to account for extra safety, we also apply safety factor to the characteristic loads.

I spent most of my weekend updating the blog post about load combinations, which is the basis of this newsletter. The blog post became sooo long that we’ll split up this article in part 1 (today) and part 2 (next week). Otherwise, it would be too long.

So, in today’s article, you’ll learn how to set up ULS, accidental and seismic load combinations according to EN 1990, so you know with what design load you need to verify your structure.

Next week, we’ll look at SLS characteristic, quasi-permanent and frequent load combinations.

13 Windows Shortcuts Everyone Should Know About

Scroll down, if you are only interested in load combinations.

As engineers, our “products” are drawings, calculation reports and 3D models which we create on our computers from which buildings and structures are built.

The more of those products we create in a certain time, the more we get paid or the less we have to work.

So it’s crucial to increase the productivity of our digital workflows to save time, document better and stay competitive in this fast-paced world we live in.

Today, I’ll share 13 Windows 🪟 shortcuts that save me minutes at work every day.

Now, back to load combinations…

Load Combinations According To Eurocode (Part 1)

As always, we’ll use an example structure to explain how to apply the design loads that we calculate in load combinations. This time, it’s a carport with timber beams and columns and wind bracing.

Before we jump into the load combinations, let’s clarify what ULS and SLS is and what it means.

ULS = Ultimate limit state

Structural members like columns, beams and slabs are designed for bending, shear, buckling, etc. in ULS.

SLS = Service limit state

Structural members like columns, beams and slabs are designed for deflection, vibrations and cracking in SLS.

Now, let’s check out how we set up these load combinations…

#1 ULS Load Combinations

Due to ULS load combinations, structural members are designed for bending, shear, buckling, etc. EN 1990 6.4.3.2 calls ULS load combinations “Combinations of actions for persistent or transient design situations”.

The formula of ULS load combinations is (EN 1990 (6.10)):

With,

• γ_G = Partial factor of the dead load

• G_k = Dead load

• γ_Q.1 = Partial factor of the leading variable action/load like live, snow or wind load

• Q_k.1 = Leading variable action

• γ_Q.i = Partial factor of the accompanying actions/loads like live, snow or wind load

• ψ_0.i = Psi factor of the accompanying actions/loads

• Q_k.i = Accompanying variable action

Partial factors

The partial factors are found in EN 1990 Table A1.2(A), A1.2(B), A1.2(C) and A1.3. Note that these factors might be defined differently in your National Annex.

ψ₀ factors

We find the ψ factors in EN 1990 Table A1.1. Please be aware that every country might define these factors differently in its National Annex.

ULS load combinations applied to example structure

According to Eurocode EN 1990 (6.10) in our example the load combinations can be written as:

Putting in the values of the characteristic loads, psi and gamma factors, we’ll get..

Don’t worry, you do not have to do this manually every time because luckily most FE programs do that for us.

But if we were to dimension a timber beam for bending now manually we would use the biggest value of the load combinations which is 4.0 kN/m² (LC3) and transform it first in a line load (kN/m).

Assuming that the beams have a spacing of 0.8m, we get the following line load:

That line load can now be applied to the static system of the secondary beams.

#2 Accidental Load Combinations

According to EN 1990 1.5.3.5 an accidental action is defined as:

Action, usually of short duration but of significant magnitude, that is unlikely to occur on a given structure during the design working life.

Example of accidental design situations are a fire, an explosion, impact loads from vehicles or the consequences of localized failure.

The formula of accidental combinations is (EN 1990 (6.11b)):

With,

• G_k = Dead load

• A_d = Accidental action/load like e.g. impact load from vehicle

• Q_k.1 = Leading variable action

• ψ_1.i or ψ_2.i = Psi factors of the variable actions/loads

• Q_k.i = Accompanying variable actions

ψ₁ and ψ₂ factors

Accidental load combinations applied to example structure

Let’s say the accidental action is an impact load from a car that crashes into one of the columns of the carport.

According to our article about impact loads from vehicles the accidental action A_d is defined as:

Now, let’s assume that the characteristic vertical loads on the column are:

According to Eurocode EN 1990 (6.11b) in our example the load combinations can be written as:

Now, you can go ahead and design the timber column for the horizontal and vertical design load.

#3 Seismic Load Combinations

Seismic actions and load combinations are the result of earthquakes. In many parts of the world this is the leading horizontal design load acting on a building and in other parts the seismic load is much smaller than the horizontal wind load.

The formula of accidental combinations is (EN 1990 (6.12b)):

With,

• G_k = Dead load

• A_Ed = Design value of seismic action

• Q_k.i = Variable actions

• ψ_2.i = Psi factors of the variable actions/loads

Seismic load combinations applied to example structure

According to Eurocode EN 1990 (6.12b) in our example the load combinations can be written as:

How you calculate A_Ed is a topic for another article.

Final Words

Well, final words don’t really fit here, because we’ll continue with part 2 next week.

Next Wednesday, we’ll look at:

• SLS characteristic load combinations

• SLS quasi-permanent load combinations and

• SLS frequent load combinations

If you missed episode #1 - #11 of this series, then you can find all previous posts → here ←.

Enjoy the rest of the week and see you next Wednesday. 🙋‍♂️🙋‍♂️

Cheers,

Laurin. 😎😎

When we design a building close to a street where in theory a vehicle could drive into the building, then walls and columns need to be designed for impact loads from these vehicles like trucks.

Or, an even more likely scenario: A column of a carport needs to withstand the horizontal load that a car exerts on the column when crashing into the column.

According to Eurocode (EN 1991-1-7 4.2 (1)) these impacts from vehicles need to be considered in the structural design by either dynamic analysis or an equivalent static force.

In the projects I’ve worked on, we always chose to use an equivalent static force. This is quicker and easier as the load values are given in EN 1991-1-7 Table 4.1 and Table 4.2 for different traffic categories. That’s also the method, we’ll explain in this article.

So, in today’s article, you’ll learn

• impacts on substructures and superstructures

• how to define impact loads and

• how to apply it on columns and walls according to Eurocode

As always, we’ll explain with examples and many pictures.

8 Must-Have Tools For Structural Engineers

Most of us structural engineers sit in front of a computer 95% of our time designing and verifying structures with different software programs (hopefully).

So, it really makes a difference in our productivity if we save 1 hour a week because of a better software or because of a software (in case you didn’t use any before).

Here is my list of the 8 must-have tools every engineer should have in 2024.

Now, back to impact loads…

#1 Impact Loads on Substructures

Examples of supporting substructures are according to EN 1991-1-7 4.3.1 (1) are:

• columns and

• walls of bridges or buildings

In the structural design, these columns and walls need to be checked for an impact load F_dx in the direction of normal travel and F_dy perpendicular to normal travel. Now, for everyone who isn’t a native English speaker (I didn’t know it either), normal travel means in the direction of the car. Both F_dx and F_dy are defined in EN 1991-1-7 Table 4.1 or in “our table” in the section #3.

If we look at the example of a canopy / carport with some columns, F_dx is the load applied in the direction of the car and F_dy perpendicular to this. We’ll look at the precise location of where the load has to be applied in one of the next sections.

#2 Impact Loads On Superstructures

A superstructure is mainly referred to bridges. Part of bridge superstructures are the deck, cables, arches, etc. Basically anything above the substructure which are supports like abutments, piers and bearings.

Impact loads on superstructures result for example from accidents where a truck is taller than the opening of a frame bridge and drives into it. You probably have already seen such an incident?

In the structural design, the bridge (its static and structural system) needs to be verified for an impact load F_dx in the direction of normal travel of the vehicle. The value of F_dx is defined in EN 1991-1-7 Table 4.2 or in the table in section #3.

Now, let’s look at the values of these impact loads…

#3 Values Of Impact Loads According To Eurocode

The equivalent static impact loads defined in Eurocode are summarized in the 2 tables below.

Note that these values are from the general Eurocode and could be defined differently in the National Annex of the country the structure is located in.

Impact loads on substructures like columns and walls according to EN 1991-1-7 Table 4.1

Impact loads on superstructures of bridges according to EN 1991-1-7 Table 4.2

#4 How To Apply Impact Loads On Columns And Walls

According to EN 1991-1-7 4.3.1 (3) the impact loads F_dx and F_dy should be applied at a height of 0.5m to 1.5m above the level of the pavement and the recommended application area is a = 0.5m in height and 1.5m in width.

Now, columns are of course in most cases not 1.5m wide, then the load is applied on the width of the column. Or, because columns are designed as beams, the load can be applied as a point load or as a line load with width (=a) =0.5m.

Let’s visualize these loads in 3D.

Impact loads on columns

Impact loads on walls

F_dx is applied to the wall as an area load. This helps distribute the load. Also, in case you design the wall with a finite element program using an area load instead of a point load also helps avoid singularities.

The area load is calculated as:

With,

• F_dx.a = The area impact load in direction x

• F_dx.p = The point impact load in direction x defined in the table in the next section

• w = Width of the impact load. In the example above, w = 1.5m

• a = Height of the impact load. In the example above, a = 0.5m

But you should always consider the most critical area. In the example from above, that would be the wall column between the 2 openings. It’s more critical because the cross-section is smaller due to a smaller width.

Final Words

Looking at the values of the impact loads, their influence on the design of structural elements close to a street can be quite significant.

You can check out Dlubal’s article where they show another calculation method which results in smaller impact loads from vehicles.

This was it! The last type of structural load we cover in this series. ✌️✌️

However, this series isn’t fully finished yet. In structural design we always verify elements like beams, columns and slab with design loads which are the result of combining different loads with safety factors. So, next week, we’ll cover load combinations.

If you missed episode #1 - #10 of this series, then you can find all previous posts → here ←.

See you next Wednesday, friends. 🙋‍♂️🙋‍♂️

Cheers,

Laurin. 😎😎

Deviation of the geometry of a structure such as slightly inclined columns/walls or imperfections of the cross-section in the execution phase happen. No structure is 100% as we calculate it.

To account for these deviations of the structure, we use imperfection loads in our structural calculations.

We calculate the imperfection load according to DS/EN 1992-1-1. And we take them into account in ULS and ALS, but not in serviceability limit states (SLS).

Loads from imperfections are calculated for each floor and applied as a horizontal load on the floor diaphragms.

So, in today’s article, you’ll learn how to calculate the imperfection load according to EN 1992-1-1, so you know how to include it in your designs. It’s a 2-step process. We’ll first calculate the inclination of the vertical elements θ_i and then the vertical design load in order to calculate the imperfection load.

Finally, we’ll show how to apply imperfection loads on floor diaphragms and shear walls in ULS design with the wind load.

Why I Started Structural Basics

Scroll down, if you are only interested in the imperfection load calc.

Creating content on Structural Basics has definitely uplifted my personal and professional life.

On the one hand, I learned new and improved existing skill sets and on the other hand, content creation excites me.

I broke it down into 6 reasons why I created Structural Basics and I can only encourage you to also start creating content. There is still a big lack of content in our industry compared to others.

Reason #1: The Need For Step-By-Step Structural Design Guides:

An architecture friend of mine asked me how she can learn how to design timber flat roof beams for a small summer house. I was sure I can simply google “timber flat roof beam”, send her the best guide I can find and add some additional information like where to find certain properties, codes and what software to use.

I was shocked how little structural design content I could find online, and knew that I have to change that.

Reason #2: Creating = Deepens Knowledge

Creating content around a topic you are knowledgeable about deepens your own knowledge a lot! By writing it down, I often find myself that I don’t remember any more how exactly things worked. Then I go back to study it again.

Reason #3: You’ll Learn New Skill Sets

When diving into the world of content creation, you have to learn a lot of new things. For me, that was:

• Homepage design

• Keyword research

• Thumbnail design

• SEO optimization

I definitely improved my writing skills. It became more engaging and my writing got easier to follow. I am not a big fan of long sentences with many technical words which you have to read twice before you understand it.

Reason #4: Creating Content Is Fun

Above all, it’s been a lot of fun to start Structural Basics.

Reason #5: Connecting With People

It’s inspiring to get good feedback from people you could help with your content. I really enjoy receiving loads of e-mails and connecting with you, readers.

Reason #6: Content = Digital Asset

A blog, Instagram page or YouTube channel is like a digital asset and portfolio where you can present to clients or employers what you know. If you build an audience, and you produce quality content, you’ll have it easier finding a job or even companies will come to you.

Now, back to the imperfection load calculation…

The 4 Steps To Calculating And Applying The Imperfection Load In Your Structural Design

As always, we’ll use an example structure to explain the calculation steps. This time, it’s a 1-storey concrete building with a flat roof slab and walls taking up the vertical and horizontal loads.

The imperfection load is calculated with EN 1992-1-1 (5.1):

With,

• N_d.i = Vertical design load on floor i in the given load combination; see next figure

• θ_i = Inclination of the vertical elements; see next figure (calculated in the next section)

Now, let’s run through the #4 steps to calculate the imperfection load of the roof diaphragm.

Step 1: Inclination of the vertical elements θ_i

The inclination θ_i, is given by (EN 1992-1-1 (5.1)):

With,

• θ₀ = Basic value. EN 1992-1-1 (5.1) recommends a value of 1/200. This means that this value could be defined differently in the National Annex. We’ll use θ₀ = 1/200 for our example

• α_h = 2l; 2/3 ≤ α_h ≤ 1. For l = 4m as the height of the structure, we get 2/√l = 1.0 > 2/3 → α_h = 1.0

• α_m = √(0.5⋅(1+1/m)). For m = 5 as the number of vertical members (number of walls in our case) contributing to the horizontal force on the bracing system, we get α_m = √(0.5⋅(1+1/m)) = 0.77.

With these values, the inclination is calculated as:

Now, we need to calculate the vertical load on the floor/roof…

Step 2: Vertical design load on the floor/roof

I usually create a table in Excel with all the quantities like area of floors and walls and length of columns and beams.

Note, that we only use half of the weight of the walls, because the other half is considered in the imperfection load of the floor below/raft.

Here’s a YouTube Short explaining how horizontal loads travel from the facades, to the floor diaphragms and to the shear walls.

Step 3: Calculation of the imperfection load on the roof floor

We can finally calculate the ULS imperfection load on the roof floor:

But the imperfection load is always used with other loads, like the wind or seismic loads. Let’s have a look at how we combine the loads and how to apply the total horizontal loads on the shear walls…

Step 4: Applying the imperfection load on floor diaphragms and stabilizing elements

The ULS imperfection load is used in the stability analysis of the structure due to wind. It’s added to the horizontal wind loads on the roof diaphragm.

When the stability of the structure is verified due to seismic loads, an accidental imperfection load need to be calculated. So basically without the partial safety factor for the live load.

Example

Let’s say:

• the design wind load of area D is calculated as 1.0 kN/m² and of area E as 0.65 kN/m².

• the wind direction is perpendicular to the facade of width 8m.

• half of the wind load is taken by the roof diaphragm and half is transferred to the raft.

These assumptions lead to a wind line load of area D of 1.0 kN/m² ⋅ 4m/2 = 2 kN/m and area E of 0.65 kN/m² ⋅ 4m/2 = 1.3 kN/m. When we design and verify the diaphragm, we would also need to add the imperfection load and distribute it as a line load. But I want to show you how to add the imperfection load to the stability analysis.

When verifying the stability, the line loads travel to the shear walls, which are placed in the same direction as the load. For this type of building, we can assume that half of the load is taken by the left wall and half by the right wall.

The total point load due to wind on the walls/diaphragm is calculated as:

We add the imperfection load to this wind load. This way, the imperfection load is included in the stability analysis of the shear walls.

Final Words

The shear walls can now be designed and verified for the horizontal design load of 14.8 kN, which includes the imperfection load.

Here’s a YouTube Short explaining how horizontal loads travel to shear walls and what they need to be checked for.

Next week, we’ll check out the last type of structural load. ✌️✌️

If you missed episode #1 - #9 of this series, then you can find all previous posts → here ←.

Enjoy the rest of the week and see you next Wednesday. 🙋‍♂️🙋‍♂️

Cheers,

Laurin. 😎😎

I was very surprised how HUGE the horizontal loads from the earth pressure were when I verified the stability of my first underground parking garage project.

In that project, the lateral loads from the earth pressure were 5-10 times bigger than from the wind load.

If you are lucky, then the earth pressure doesn’t have an influence on the stability of your structure because it might be of the same magnitude on the walls on the south and north side and the west and east sides.

But if the project has construction stages, where the full earth pressure is considered on one side and not on the other side, the resultant load will be very big.

In this article, you’ll learn how to calculate the earth pressure. At the end, you’ll know for what lateral loads you need to verify basement or retaining walls, or the stability of a basement.

My Professional Background

Scroll down if you only want to learn about how to calculate the earth pressure. ⬇️⬇️

Last week I already warned you, that this week I will give a quick intro to my professional background. So you understand better, what Structural Basics is based on. You can read in detail about my previous experiences (and even some things about my life) → here ←.

All jobs I’ve ever had were construction related. And there have been many over the years. From when I was a teenager until I got my first student job in a structural engineering consultancy, I worked the school/uni breaks helping my dad’s friends renovate houses or in their construction companies.

One summer I was working in a carpentry building timber roofs at 30°+ sometimes 12 hours a day, 6 days a week.

Another job (probably the hardest) I had, was scaffolding. Again, we worked 50+ hours a week. I still remember to this day how crazy hard it was. Have you ever tried to lift a steel scaffold? After the first day, I wasn’t able to drink from my bottle any more because by holding my bottle, I got cramps in both of my arms. I usually left the house at 6 am and didn’t return before 7 pm. They told me that 9 out of 10 students who help in the summer quit after the 1st week. I think that was what motivated me to not quit. I am not a quitter, and not like everybody else. And actually, after 6 weeks, it wasn’t that physically challenging any more.

My dad is a partner of a heating and sanitary installations company. I also worked there one summer.

Before I started my bachelor’s in Civil and Environmental Engineering at the University of Innsbruck, Austria, I worked in a few of these construction jobs for a whole year to earn money for my studies but also to travel South-East Asia for 3 months.

Then in the summer between my 4th and 5th semester I did my first internship in a structural engineering consultancy in Munich where I worked in the bridge inspections department. That was also the end of working on construction sites.

Right after the internship and when the 5th semester started I got a student job in another structural engineering firm where I joined the BIM Management department until I finished my bachelors.

When I started studying Civil Engineering, I thought I would become a site engineer. I didn’t even know what structural engineering was. Yeah, I mean, I had nobody to ask. I was the first one in my family who went to university. I only knew that I was good in Maths and Physics and that this program had a lot of it (😄). But during my bachelors, I started to fall in love with structural engineering. And I was also very excited about BIM. At the time when I graduated (2019) it was this new thing in Germany and I saw an opportunity to become an expert very quickly.

Back to my student job. I liked it so much working in BIM that I decided to take a break from studying. I worked for 1 year as a BIM modeller in the bridge department of a structural engineering firm. I got really nerdy about automating our workflows and implementing new ones with parametric design (Dynamo and later Python).

After the year as a BIM modeller, I moved to Copenhagen, Denmark to start my master’s in Architectural Engineering at the Technical University of Denmark (DTU). Why I moved to another country where I didn’t speak the language? That’s a topic for another time.

Anyway, I started my masters and started to get excited about structural engineering again. You know, this feeling when you study for example how to design and verify cable-stayed bridges, and you forget the time? That was me about all the structural courses I took.

When I moved to Denmark and started my masters, I worked in a student job in BIM Coordination in a construction company. I worked on some really big projects here in Copenhagen doing clash detection, BIM modelling of site equipment, 4D simulations, setting up digital check lists in Dalux, and much more. I chose a construction company to also see the other side of engineering - the execution, and to get an understanding of how people work in construction. I don’t regret having had that experience

But deep down, I knew that I wanted to work with structural engineering. So after 2 years and in my last master semester of my masters I changed to a structural engineering firm. I was lucky that I could join their computational/ parametric design team, which was and still is developing an in-house Grasshopper plugin. I helped to set up all the load bearing capacity tables of the elements that the plugin is verifying and get my first projects where I used the plugin. This was great because I could combine structural design with coding and parametric design. Also during that time I got my first small structural engineering projects, mostly renovation.

I wrote my master thesis about “Reuse of Structural Steel Elements - The use of non-destructive test methods to determine structural properties”. Maybe that’s also a topic for another article? Would you be interested in that?

After I graduated, I started a full-time position as a structural engineer in the same company I worked in as a student. I am still there and very happy as I get a lot of responsibility and challenges. 🙌🙌

I’ve been mostly working on precast concrete buildings and small renovation projects where I design, verify and document the structural design. Given my background, I often do drawings myself or make changes in the BIM model myself without the help of a BIM-modeller/ drafter.

Here’s a list of a few things I designed:

• Stabilizing systems of precast concrete buildings like shear walls, reinforced concrete frames, steel wind braces and floor diaphragms

• Robustness assessment and calculation of additional reinforcement to comply with robustness requirements

• FE analysis of in-situ concrete slabs (raft) supported by piles, pile caps and foundation beams

• Pile caps, piles, foundation beams, strip and pad footings, well foundations

• Openings in existing walls for doors and windows

• Reinforcement of existing masonry walls to take up additional horizontal loading

• Plywood roof diaphragm to distribute the horizontal loads to the stabilizing system

• 3D FE analysis of steel structures and connection design

• Timber roofs and timber connection design

• Timber frames

Most of these things I haven’t covered on Structural Basics yet. I am excited to so in the future.

This was a lot about my background. Now, back to calculating the earth pressure…

7 Steps To Calculating The Earth Pressure On Basement Walls

We learn best with examples. So in this article I show you how to calculate the earth pressure a retaining wall. We’ll use 2 different soil layers with groundwater starting 4m below terrain.

Now, this is a simple example of a retaining wall. But in my upcoming book (which I talk about alot - i know) we’ll calculate the earth pressure for an actual house and apply the loads from the earth pressure on the basement walls.

Step 1: Find the soil properties of the different soil layers

Most soils are either clay or sand, or a mix of the 2. In some parts of the world, like Sweden, structures are supported on rock. The soil properties are defined by a geotechnical report that has been done before a structural engineer designs the foundations or underground structures.

For this article, we’ll use the following soil properties:

The partial factors for angle of friction and effective cohesion are used to calculate the design properties of soil. Note that these values are different for each country, as every country has its own national annex.

Step 2: Calculate the Rankine earth pressure coefficents

The Rankine earth pressure coefficients are used to calculate the earth pressure for each layer at a depth z.

If we use these formulas with the soil properties of step 1, we’ll get the following earth pressure coefficients:

Step 3: Calculate the effective vertical stresses

The effective stresses depend on the weight of the soil (= unit weight γ) and are calculated for the depth z as:

Where γ is the unit weight of the soil layer above the groundwater table. Below the ground groundwater table γ-γ_w is used respectively.

Step 4: Calculate the Rankine active and passive earth pressures

The Rankine active and passive earth pressures are calculated with the vertical effective stresses and the Rankine coefficients that we derived in steps #2 and #3.

So, let’s calculate the earth pressures for the different depths.

Step 5: Define and apply the cohesion

Cohesion describes how well the soil particles stick together. The cohesion of a soil layer is actually beneficial, meaning that it reduces the lateral load on the retaining wall.

The cohesion is calculated as:

These values are now applied to the retaining wall.

Step 6: Apply the hydrostatic water pressure

The groundwater below the groundwater table also exerts load on the retaining wall. The pressure increases with increasing depth, which is calculated as hydrostatic water pressure.

The load distribution is triangular and the value of the hydrostatic pressure at depth z is calculated as:

We subtract 4m because that’s the depth/elevation where the groundwater starts. Here’s the water pressure for different depths z:

Step 7: Effects of live loading on terrain close to the structure

Another action on a retaining wall or sheet pile is a vertical load on the terrain close to the retaining wall.

This could be a live load from construction vehicles or even an existing building, a street or another permanent structure.

The vertical loading is located 1m away from the retaining wall. We can calculate the spread of the vertical stresses from this load with a 2V:1H slope.

From the vertical stresses we can calculate the horizontal pressure on the underground structure which is uniformly distributed.

Final Words

All these loads that we just calculated - earth pressures, cohesion, hydrostatic water pressure and pressure from vertical loads near the structure need to be combined in load combinations to calculate the design values.

That would be too much for en email, but we’ll do that in the book that I’ve mentioned many times by now.

Next week, we’ll check out another type of horizontal load. ✌️✌️

If you missed episode #1 - #8 of this series, then you can find all previous posts → here ←.

Have a fantastic rest of the week and see you next Wednesday. 🙋‍♂️🙋‍♂️

Cheers,

Laurin. 😎😎

In many parts of the world, the snow load doesn’t exist or is not very often in the governing load combination.

However, there are also regions where the snow load is greater as the wind load by a factor of 3-4.

I grew up in one of these regions. I also did my bachelor’s degree in Innsbruck, Austria, where the snow load is different for almost every village in the region due to its magnitude in some of these villages.

Today, we’ll learn how to calculate the snow load on flat and pitched roofs.

But since we are now over ❗ 5000 people❗ subscribed to the weekly Structural Basics newsletter, I think it’s a good idea to introduce myself. If you are only interested in how to calculate the snow load, then scroll down and skip the next section.

Who Is The Person Behind Structural Basics? Get To Know Me Better

Hi all,

I am Laurin.

Passionate structural engineer by day, blogger and athlete by night.

I am originally from Kempten, Germany. I grew up in Germany close to the Alps, did my bachelor’s in Innsbruck (Civil and Environmental Engineering - University of Innsbruck), Austria and my master’s in Copenhagen, Denmark (Architectural Engineering - Technical University of Denmark). Therefore, I also speak 3 languages fluently - German, Danish and English.

I work these days as a full-time structural engineer in Copenhagen, Denmark.

One of my big passions is backpacking and travelling in general. I use almost all of my vacation days and overtime hours to travel.

Another thing I love is sports. I hit the gym 4 times a week. I ran my first marathon in May 2024 here in Copenhagen and plan to run another one later this year. Triathlons next year. When I was younger, I played football and handball. Growing up close to the Alps, I also like skiing and hiking.

Besides travelling and sports, I love working on Structural Basics. I am very fortunate that I found a profession which I love. At this moment in my life, my work as a structural engineer feels like a hobby. I am very grateful that I get to share my knowledge with you readers.

This has now already been a lot of talk about me. I am sure you are much more interested in the structural engineering insights, which we’ll dive into now. I hope this short introduction has given you an understanding of the person whose guides you read every Wednesday.

To understand the full picture of Structural Basics, 2 things are missing:

• My professional background/experience

• Why I started Structural Basics

We’ll quickly touch base on these 2 things in the next 2 weeks.

But now, let’s get into the snow load calculation. 🔥🔥

The Snow Load Calculation

Let’s start with the formula of the snow load according to Eurocode. Then it’s a bit clearer which steps we have to follow to calculate the snow load.

Where,

• μ_i = snow load shape coefficient

• C_e = exposure coefficient

• C_t = thermal coefficient

• s_k = snow load value on the ground

This is the snow load formula from EN 1991-1-3 (5.1) and it’s used for any roof shape and type.

Alright, let’s look at how we define or calculate these 4 values.

Snow Load Shape Coefficient μ_i

μ_i depends on the shape of the roof. Snow accumulates much better on flat roofs than on pitched roofs. On the latter, snow can “slide” down the roof, which results in a smaller snow load.

In this newsletter, we’ll calculate the shape coefficients of a flat roof and a duo pitched roof.

There is, however, another design situation which happens very often. Flat roofs abutting to taller constructions. Like for example the roof of a garage which is lower than the roof of a residential building. We don’t cover this in our newsletter, but I included a very thorough explanation in the book of module 1 about loads on residential buildings. The next image is a screenshot from the book, showing the snow load on the garage roof. The launch of module 1 is in November/December.

Flat roof - snow load shape coefficient μ_i

The flat roof counts as a monopitch roof and therefore the value for 𝜇1 is given in EN 1991-1-3 Table 5.2. For 𝛼 = 0 which means that the slope of the roof is 0 we get a value of:

Duo pitched roof - snow load shape coefficient μ_i

It’s a bit more of a calculation for a duo pitched roof. When increasing the angle of the roof slope over 30°, the snow load shape coefficient 𝜇1 can be decreased below 0.8 due to sliding of the snow off the roof.

The value for 𝜇1 is given in EN 1991-1-3 Table 5.2. For 𝛼 = 40 which means that the slope of the roof is 40°, we get:

Exposure Coefficient C_e

EN 1991-1-3 5.2 (7) recommends C_e to be taken as 1.0. However, this value depends on the topography of the location. EN 1991-1-3 Table 5.1 categorizes the topography in windswept, normal and sheltered with different values for C_e.

In this post, we assume a normal topography for our design. Therefore:

❗❗Always double-check with your National annex because the 𝐶𝑒 values can be specified there for your country. ❗❗

Thermal Coefficient C_t

EN 1991-1-3 5.2 (8) defines C_t as 1.0. However, this value can be reduced if the roof is covered by glass, which would lead to melting of the snow. In our case, we are not using any glass.

Therefore:

Characteristic Snow Load Value On The Ground s_k

The characteristic snow load on the ground is found in the national annex of the country your roof is located in. However, there is a great online tool which calculates the snow load according to location and national annex.

Click on the link, enter the location and the national annex. If we do that for Copenhagen, Denmark, we get a value of:

Characteristic Snow Load

Now, we can calculate the snow load on both the flat and the duo-pitched roof with the formula we introduced in the beginning of the article.

Flat roof

The snow load of the flat roof is calculated as:

Duo-pitched roof

Inserting all values leads to a snow load of:

For a pitched roof, 3 different cases need to be considered due to drifted load arrangements (EN 1991-1-3 5.3.3 (3) + (4)).

Case 1: s = 0.53 kN/m² is applied on the whole area

Case 2: s = 0.53 kN/m² is applied on the left inclination and s/2 = 0.27 kN/m² on the right inclination

Case 3: s/2 = 0.27 kN/m² is applied on the left inclination and s = 0.53 kN/m² on the right inclination

Final Words

The snow load needs to be considered in every structural design. At least in most parts of Europe. If you are from a place where you don’t verify a building for the snow load, let me know in the comments.

As for the wind load, it’s vital to calculate the snow load correctly. We don’t want a building, garage or even a canopy to collapse because we didn’t calculate the snow load correctly.

By following the steps, we taught in this episode, you are able to calculate the snow load of flat and pitched roofs.

Next week, we’ll check out another type of load we need to consider as structural engineers.

If you missed episode #1 - #7 of this new series, then you can find all previous posts → here ←.

Have a great rest of the week.

Until next time. 🙋‍♂️🙋‍♂️

Cheers,

Laurin. 😎😎