How can I lose weight quickly?

Emily was doubting herself. “How can I lose weight quickly?” she thought as she looked first at her design for the concert screen and then at the stacks of now useless parts. Beyoncé started rehearsing her final song “Remember those walls I built…” in the background, Emily felt sick. To be able to lift the screen into place, she would have to use all her engineering skill to lose weight from the structure with only six hours left.

Dan, the construction manager, wasn’t helping. He always thought he knew best, and he just couldn’t bring himself to accept that the crane wasn’t going to start again. He had his eyes closed, phone pressed to his ear and was talking passive aggressively as he rubbed his shaved head “Just try and start the crane engine one more time. We really need this”.

She tried to think of happier things to calm herself down. She thought of Thomas, then her mind wandered to the camping holiday they were planning. Then she had a brainwave.

Guy ropes! The structure wouldn’t need to­­ be so strong and heavy if we stabilised it with guy ropes! She’d seen a drum of wire outside for the lighting rigs that she could use. It wasn’t perfect but if she re-designed it carefully, the wires wouldn’t block people’s views. She crouched down, and flipped her drawings over, sketching the new design in biro on the back, while resting them on her knee. To check that it was strong enough, she did some quick calculations on her phone, while talking softly out loud and jotting things down “1kN/m2… 6mm diameter wire.. cos theta.. tension force.. bending moments.. expected deflection..”. There that should do it. She’d write it up properly later.

Dan was shouting into his phone “Come on, it has to work! Try again! Switch it off and then back on again!” She took the phone out of his hand, and handed him her new design.

“Here you go, all sorted”

Dan looked like Emily had cast a stupefy spell over him.

“No need to thank me, just some VIP tickets for that box over there will do it. I’ll see you in five hours, I need to go and get changed!”

Structural Engineering Blogs

If you’re interested in structural engineering, you may have found that it’s not the easiest profession to learn about. There are a few sources – there are some organisations that are trying to raise its profile, there are a few good books and some youtube videos.

I found the most helpful was talking to a family friend who was a structural engineer about what it was like. He had trained as both an architect and engineer, worked for a famous company, and then was lecturing and inspiring others by teaching creativity and good design.

But for those who don’t know any structural engineers, I think personal blogs are a good place to start. I’ve found blogging to be a lot harder than it looks, so these people are obviously very passionate about what they do to have been so persistent in writing about it. I hope they open up another world for you.

Being Brunel – I heard the author of this blog – Tom Wallace – speak a few years ago and he inspired me to start my own blog. He’s written something every week for 4 years, which is a very impressive achievement in itself; but more than that he’s said lots of interesting things that I’ve never heard of before, like this blog on Conway’s Law. He’s got some great photos that make it real and some helpful tips if you’re interested in starting your own blog.

The Happy Pontist – I love this blog. HP’s infectious enthusiasm is backed up by an incredible depth of knowledge. Structural engineering is designing how things stand up, which could be for anything, but the particular fun with bridges is that the structure is on display (unlike most buildings for example). Very difficult to pick favourites from amongst the 750+ posts but would recommend this one on one of Robert Maillart’s gem’s in Switzerland, and this piece of one of Calatrava’s bridges that broke the mould.

My Passion for Structural Engineering – Waseem Rana writes this popular blog, which mostly focuses on particular technical challenges with engineering. Probably most useful for if you’re in the first few years of working but it does give a flavour of the maths and science aspects of the job. Particular highlights for me were reading about his passion for what he does, and also some signposts to his other favourite structural blogs. I was inspired by the layout he’s used when I was setting up my own blog.

Civil Engineering Gyan – I enjoyed reading this blog, which is co-authored by Rakshita Nagayach an Indian civil engineer by training, and a prolific blogger (this is just one of hers). She writes on a wide range of topics related to engineering but I particularly enjoyed this post about great engineers. It’s nice to hear a few names outside the British and American ones I’ve heard of elsewhere.

Structural Madness – If you’re lucky as an engineer you get to work at the cutting edge of what is possible, I think that is what co-authors Jinal Doshi and Darshan Pala mean by the name of their blog Structural Madness. For example, some people may have considered it madness when the the Burj Khalifa smashed the world record for tallest building by 300m; but it has proven to be a success. This blog, started when they were both in Grad School in the US is the top result when searching for structural engineering blogs. They tackle difficult concepts but use lots of pictures to make this an accessible way to learn about structural engineering.

Clifton Suspension Bridge: How Brunel Avoided Disaster

Two weeks ago I was back in my university city of Bristol, and had the chance to have a guided tour of the Clifton Suspension Bridge. I’d heard previously that one of the abutments was hollow, and I was secretly hoping that we would get to abseil into one of them, but it wasn’t to be. One thing did really strike me though during the guided tour.

The Clifton Suspension Bridge built in 1864 was famously designed by Brunel. It wasn’t built in his lifetime due to a lack of funding but was then erected in memorial to him after his death. It is the picture postcard advert for both the city of Bristol and engineering in general; however based on what the guide said, I think it could nearly have ended in disaster.

The bridge span is 214m and the width is 9.5m. Therefore the ratio of span/width is 22.7. As far as I’m aware in Brunel’s time that wasn’t a ratio that people considered but it’s become significant since 1940 when the Tacoma Narrows Bridge collapsed. That had a span/width ratio of 71, which for the technology at the time was the highest of any bridge in the world. It really pushed the boundaries of innovation, but unfortunately the designers weren’t aware of the impact this would have on the resonance of the bridge. And as you can see in the youtube link here it oscillated in even relatively light winds until it was torn apart only a few months after it was finished.

What the guide said that caught my attention, was that Brunel’s design had been for one horse and cart, but after his death, the bridge design was widened at the request of one of the donors, who wanted two horse and carts to be able to pass each other. The bridge also now has space for pedestrians either side.

Could it be that Brunel’s original design was only 3m wide ? If so then it would have had a span/width ratio of 70 and could have suffered the same fate as the Tacoma Narrows Bridge. Who knows but maybe that extra horse and cart was the saviour of Brunel’s reputation!

If you’d like to read more about engineering failures, you might like this book I reviewed.

Book Review: To Engineer is Human

Lots of meat, without the maths that makes it hard to swallow.

When I was preparing to apply to become a chartered member of the Institution of Civil Engineers, a mentor – I think as a warning against complacency – challenged me that I should be reading at least 6 books about engineering a year. From my experience, most engineering books are text books, so I asked him which books he suggested, and he couldn’t think of a single example of a readable book about engineering!

Petroski’s books then are rare gems of attempting to span that large distance between the remote island of engineering knowledge and the mainland of public imagination. Reading it as a structural engineer there was plenty that I was already familiar with, but also lots that was new. He draws on examples from both sides of the Atlantic, so having learnt my trade in the UK I found the discussion of iron bridges particularly Othmar Ammann (Quebec Bridge) and the Roeblings (Brooklyn Bridge) fresh and new. While others may be less familiar with Beauvais Cathedral, cracks in Big Ben or Paxton and the Crystal Palace.

His opening chapters suggest that the book is for a non-technical audience, but he sometimes lapses into advice for professionals such as lamenting that our drawings are no longer as beautiful as Galileo’s. The vocabulary is probably only accessible for teenagers and up (discussion of monographs, commissions, cantilevers etc.) but other than that, in my opinion it is accessible for a non-technical reader.

If I was being picky, I would like to have seen an over-arching story arc. Like there is in the excellent Fermat’s Last Theorem, which keeps you turning the pages. Petroski has research and includes an impressive amount of breadth – references to nursery rhymes, poetry, photos, quotes and lots of stories – but there is no one thread drawing it all together.

I think it could also benefit from more detail of the human side of the characters. For example my impression is that Brunel was quite a risk taker, he sought his father’s advice for the Clifton Suspension Bridge, but then ignored it when he was advised to include a central support; which was quite bold for a 20-year-old designing the longest spanning bridge in the UK!

So in summary, this book is a good introduction to engineering with plenty of nuggets and reminders for the more seasoned professional. It’s not a gripping page turner because there isn’t an over-arching narrative arc, but I enjoyed reading it and got several pages of quotes and stories from it that have broadened me out a bit and I’ll no doubt use again.

Emily was an engineer

This story is for Lucy, an undecided 15 year old, wondering what to do next.

Emily was an engineer.

“Is that like an architect?” asked Thomas as he gazed at her steadily, placing his wine glass carefully back on the table.

“kind of, not really”.

She’d met him online – well to be honest on Tinder. So she knew he had a nice smile, but in person he had quite a presence too. He had nice shoulders. They’d texted a few times, then a lot. He’d rung her while she was swimming, she’d rung him back. He’d suggested this little place and now here they were… talking. It was all a bit awkward, but in a good way.

“architects are like GP’s, structural engineers are like brain surgeons”

She liked putting it like that. It sounded more dramatic than just saying she was a specialist. And it wasn’t just brain surgeons that were smart, it had been such hard work becoming an engineer, and now she’d got chartered as well. It was a real achievement, so she forgave herself for a bit of boasting. It was a first date after all. And those letters after her name had required all her intellect and all her persistence. She studied maths, science and art for A-level. Then she’d had done a masters in engineering at university, with placements in different firms over the holidays. After working for a few years, she’d got enough experience and responsibility to pass the Institution of Civil Engineers membership process.

“oh really” Thomas looked impressed. “So what kind of stuff do you do?”

She noticed while he was talking that he had freckles on his nose. And she was about to answer his question when the pizza arrived (she’d asked if they could get a big one and share, so she could test his generosity – and make sure he didn’t eat any garlic!). They refilled their wine glasses from the bottle and chewed thoughtfully in silence for a few minutes.

“well.. “ she tried to think of a good way to explain it. Thomas caught her gaze while she was staring at his arm muscles, he smiled, but she was sure she was blushing. Before it got any worse, she stammered on.

“well … have you ever been to a gym where the floor was bouncy ?”

“yeh my one at uni was like that”

“well one thing I do, is I advise architect’s how to stop that.”

“oh”

“I guess you could say structural engineers design the skeleton of a building, how it stands up. But every building is different, so every structural skeleton we design is a bit different. Weight-lifters need bigger bones than jockeys, women and men have different skeletons. Our bodies just adapt over time, but when you’re designing a block of flats you have to know how big the skeleton will be, before you start the foundations. Most buildings you can’t see the skeleton, but sometimes you can like the Eiffel Tower, or the Millenium Brid..”

Emily was cut short. She’d been getting quite passionate about engineering and been waving her hands about, she was just about to talk about her favourite structures, when Thomas seized the moment and leant in for a kiss.

What’s the point of having a structural engineer?

Building is expensive. The recent financial crisis proved that construction is a luxury, because during hard times we can do without it. For many people, property is the most expensive outlay in their lives. So when it comes to embarking on an expensive building project it’s important to make sure every pound counts.

So avoiding hiring a structural engineer may seem an easy saving. The Romans built all their great structures with an architect to provide the vision and experienced builders to make it stand up. What’s a structural engineer for? What’s the point of them?

What you get with a structural engineer is someone who can – using a scientific approach – tell you exactly how much structure you need. One element of that is judging the strength of the structural frame. In order to design a structure that is strong enough without additional materials, which are wasteful and expensive.

A brilliant demonstration of the potential of structural engineering came from a group of students a few years ago. They had to build a dome structure, 40cm high and hollow, with a kilo of spaghetti and some glue. The winners would be the group that supported the biggest weight with the least spaghetti.

A common sense approach might be to use triangles to make the dome shape. To make it easy to build you might use the same size triangles throughout and estimate the strength by averaging out several different people’s opinions. A reasonable strength to achieve from a bag of spaghetti is hard to gauge, maybe a few kilograms is achievable.

The engineering students in question, tested the spaghetti to calculate its material properties (how much force it could take and how much it bent for a certain amount of force). Instead of designing the whole dome as one unit, they approached it as a series of 10 arches, which combined together make a dome. Using some trigonometry they were able to work out the best shape for the arches. They then used some engineering software to check that there were no particular weak spots and that the whole structure would be working hard before any one part broke. By separating the dome into 2D arches, they could build the dome flat and them assemble it, making it easier to build well.

Spaghetti dome 3D and section
Spaghetti dome 3D and section

So what was the benefit of having a structural engineer? Well if a smart person had designed something and built it well, it might be expected to hold a few kilograms. The ‘engineered’ spaghetti dome held 195.5kg! Slightly more than the 190kg predicted. It performed so well that the engineering department had to bring in a new testing rig, as their first one only went up to 100kg.

So what’s the point of having a structural engineer? Well a structural engineer helps you to get every ounce of strength out of the structure. So although their services cost money, they can design something which is easier to build and without additional materials, which are wasteful and expensive.

If you speak German, you can read more about this example here.

What makes a good engineer?

We were off to the pub. I was walking with two architects with a mutual intent to enjoy the sunshine with a glass of something fermented in hand. We’d just made a careful incision through the London traffic. Suddenly the conversation opened up and one of them asked me exactly what was it that made a good structural engineer. Good question. Obvious question maybe, but not something I’d ever heard posited before. And looking back I was quite pleased with what I came up with in the space of a few pounding heartbeats.

If they’d asked what a structural engineer does, that would have been easy. Hours spent sketching or calculating the size of bending moments are not quickly forgotten. Or you can just ask Google. For example the Institution of Structural Engineers website explains that ‘Structural engineers design, create, solve problems, innovate and use maths and science to shape the world.’

But what’s the difference between a good one and an average one? What does it mean to design better, solve better or innovate better? Are good engineers mined from exotic locations? Or can they be moulded? Are they like wizards, born of engineerkind. Or are they more like hobbits, who just need an invite to a great adventure to rise about expectations?

I mean obviously it’s subjective. There’s no golden rule to measure engineers by. Of the many good engineers who have achieved fame – Brunel was lauded for his bold innovation; Peter Rice thought it was about imagination and Bill Baker gives the impression it’s all perspiration.

I mean a good engineer must be dependable, scientific, able to think through a situation logically, prudent, a good communicator, understand contracts, party wall agreements and the management of risk. They must have integrity, work to improve the environment and ensure worker safety.They must be cautious but brave, striving for the best while preparing for the worst. They must be lifelong learners, questioning, curious. Widely read and deeply knowledgable.

But I wanted to answer succinctly. To lay down the shield of jargon and the breastplate of verbosity and wrestle with the question unarmed. I didn’t want to give a list post – the 37 things that all good structural engineers do and how you can emulate them. I wanted something pithier, punchier, peppier. I wanted a tweet not a novel.

To cut to the crunch, I feel that if you boil it all down, what separates the good from the rest, is that the good ones understand what everything does. This means that crucially, they know what you can justify doing without. It’s tempting to add strength to the structure to cover the weakness in our understanding. The better the engineer, the less structure you’ll get. Good engineers give you less. Less is better. Less is more.

So back to my conversation. The good question about good engineers. Well after a deep breath I slowly opined ‘a good structural engineer knows exactly what’s needed’. And I’m still not sure how I would improve on that.