Keeping it small

Before I give myself the gift of massive overwhelm, I’m going to stop and intentionally limit myself to a demo of just this lowest deck to get a proper sense of how long things will take to make to a standard I’m happy with.

The things I want to have to call this a successful demo:

  • Working inventory system to allow for fetch-quest style puzzles.

  • Logo/intro screen

  • Title screen

  • Deck 01 functionally complete and populated with approximately 50% my own sprite assets for characters.

  • Placeholder art is acceptable, but I’d like to at least get the walls/floors in my own art if possible.

Stretch goals if things go well:

  • Dialogue trees for unlocking progress.

  • Music

  • Sound effects

  • Combining items from inventory for point & click style puzzles.

Pencil Prototyping

Yesterday I started mocking up the entry deck, a spaceport which will function very much like an airport (allows for some lightweight humour). Before that, I’d started the other day by just drawing a load of different ‘spoke’ elements outside a common main hub for a few decks. I was just getting a feel for what sort of variation I can get, and then I plan to quickly test the spaces to see if they feel about the right size.

Mini-maps of 4 potential decks.

With no real plan in mind, I just took the first one and started to adapt it to my idea of a spaceport, thinking about how it would function as an opening chapter allowing me to set the tone of the game

First go at the lowest deck

I figured you get off your ship in the non-VIP hangers, and are directed through a series of airport style areas. I took the ring element to the right, made it a single linear loop for security, and everything else started to fall into place. Shortly after I’d finished this, I texted it to a friend, and by the time I’d finished typing out the message I’d already figured out a change I wanted to make…

Revision made in about 3 minutes.

So I’d quickly decided there’d be a visible (if not ever playable) route for VIPs to skip security, via some NPCs at barriers, and I thought why not send the payer through duty free on their way into the station. Having done this on my iPad (with iconfactory’s Linea Sketch app, naturally), I was then in a position to throw the basic blocks into Aesprite, and immediately into GB Studio. The whole exercise from picking up one of the mini-maps took about 30 minutes. Most pleasing.

USG - Not making life too hard

Yesterday I mentioned my solution to altering a deck not being likely to scale well. The way I’d implemented the change was simple: when the player interacts with the actor on Deck 01 a global variable changes from 0 to 1. Whenever the player interacts with the lift Dog, the game is using an IF statement to check that one variable, then directing the logic to take one of two paths. If the variable is 0, selecting Deck 06 takes the player to the original Deck 06, but if the variable is anything else, selecting Deck 06 takes the player to altered Deck 06 with a hole in.

My concern is that this won’t scale well. If I have 6 decks, and many of them have multiple states, there might be a dozen or more altered versions decks, and I can’t have nested IF statements tracking all that. I don’t even know how deep GBStudio can nest IF statements.

Luckily, I’ve got loads of options:

  • I could use different versions of the lift scene to break up progression, so when certain events occur in game, I could divert the player to a new, updated version of the lift with an altered deck menu.

  • I can rigorously plan the game to keep it linear, making tracking things simpler.

  • I could abandon the idea of a single lift core between decks, and have segmented lifts that only go between certain decks. That can be worked into the story, as I was toying with the idea of decks being analogous to a sort of class system. It might be that to get to the upper decks, a new lift has to be unlocked by completing certain tasks, proving that your character has enough wit/charm/brains/fashion sense/whatever to be allowed higher up the structure.

  • I can use a combination of all these - none of them are mutually exclusive

USG - Baby Steps

Here’s the entirety of the available gameplay of Untitled Space Game. The lift attendant (dog) can take you to any of the 6 decks, and talking to the only NPC in the game on Deck 01 will cause Deck 06 to change state.

All of the available ‘gameplay’ of Untitled Space Game as of right now.

My plan is to keep up a little bit of progress every few days, even if it’s just small proofs of concept. All I aimed to do in this session was get the lift working, but I was able to stretch it out and make a little gating/progression. I’m not sure how scalable this method of switching is. I’ll explain what I’ve done later. Hopefully writing out the problem will present a solution.

USG - Planning

To make consistent progress on Untitled Space Game, even in small steps, I need an outline plan of how to approach this. I’m going to draw on my experience designing structural frames, and work in a sort of ‘sculpting’ method. I usually start with the broad strokes of a building, then refine it down as I go.

I’ve identified some key pillars that I can also switch between as and when I need a change of scenery:

  1. Story

  2. Puzzles

  3. Dialogue

  4. Art

  5. Design/Layout

Right now, I’m working on Design and Layout of the main game areas, and I’ll sculpt them down as and when I can. I’ve got a picture in my head of how the main layout will work, and it won’t take long to finish a bare bones working prototype to get a feel of the space, and whether it’s too big or too small. To speed that up, I’m planning on spending a bit of time in Tiled this week so I can draw maps nice and quickly.

Untitled Space Game

Inspired by a friend of mine, I’m embarking on a side project. The plan is to make a simple Game Boy game very much in the Space Quest yet System Shock area. The tools I’ve got to work with are a 10 year old MacBook Pro, my 4 year old iPad Pro 12.9”, a little bit of software specifically for creating Adventure Games, and a couple of pixel art editors. It’s been in a state of gestation in my brain for years, but if I don’t just get off my backside and start it now, it’ll never happen. I’ve even started actually spending a little bit of cash on some software to give myself a bit of impetus to do this thing.

Current outlay:

Subtle Notebook - £25 (or thereabouts including shipping)

Aseprite - £15.49

Pixaki - £10

GBStudio - Free (donationware)

Tiled - Free (also donationware)

Yeah, it’s pretty boring right now, but it works!


A visit from the PM

Tomorrow our business will be receiving a visit from the Rt Hon MP for Richmond and Prime Minister of the UK, noted diminutive Rishi Sunak. We are told that after the initial tour of the factory, we can ask un-vetted questions. I’ve spent the last week trying to think of a single question that has a reasonable chance of actually being answered, and I don’t think I’m doing so well. Here is a non-exhaustive list of what I’ve come up with:

  • What’s the plan for economic growth in the face of a swiftly falling population? Birth rate in the UK is at less than 1.6 and still falling.

  • Two of your biggest success were arguably the Windsor Framework and your deal with Albania. Both were examples of quiet competency, diplomacy, and compromise. Why then do you waste time on divisive, noisy policies like your Rwanda legislation, which will never work as an effective deterrent?

  • In 2022 you lost 485 councillors at the local elections, and in 2023 you lost another 1063. How many councillors can you predict to lose in May’s local elections?

  • When and where is the Square One you say Labour will return us to?

    • Is it before Liz Truss put another £500 per month on the average mortgage?

    • Is it a time when you get NHS care in a timely manner?

    • Is it a time when the Education System was respectably funded?

    • Is it a time before post truth populism gripped the Conservative Party?

    • Is it a time before we were changing Prime Ministers every year or two?

  • If the Treasury has the confidence to brief out a potential suite of £20B tax cuts, when can our International Aid Budget return to 0.7% of GDP?

  • Given the world is becoming more unstable and only getting worse, why has Army recruitment failed to hit its goals every year since 2010, and what is being done about it?

  • Was it wise to grant such dubious resignation honours for disgraced former Prime Ministers Boris Johnson and Liz Truss? Do they not cheapen honours bestowed upon regular people for lifetimes of public service?

I’m not sure any of these would get a straight answer, but tomorrow I’ve got to pick at least one. We’ll see how it goes.

Project HoHoHo22 - The Beginning

As is now customary in the Pie Household, it’s time for me to decorate our windows with a festive silhouette design. This year I’ve decided on a simpler design than last, mainly to keep the cutting time down to something reasonable. Last year’s design probably took 40 hours all told, and that’s a bit much. This year it’s all about the hometown, with some iconic views that most tourist will recognise.

York Minster, as seen from Minster Gates

York Minster, as seen from Minster Gates

The Shambles, as seen looking towards Stonebow

The Shambles, as seen looking towards Stonebow

The two designs go one the two windows on the front of the house, and they’ll end up being cut and carved somewhat to make sure the important details don’t get lost between window frames. Initial cutting out of the panels is all done - next is the process of moving the designs onto the paper and cutting out the backgrounds.

People willing to tolerate Twitter can find a process thread at #HoHoHo22

Project Paperless

A long time ago, I was posting regularly here. There was a time when I even had ambitions of writing a series of posts about paperless working.

Well.

Now is the time. As part of an investor buyout in my company, paperless is officially on the agenda, and I am being asked to make recommendations to the new board.

Part of the problem of writing regularly has been that of lack of ideas and motivation. It’s easy to think “I shall write about area X or Y” but trying to gather the disparate threads of my monkey brain into coherent (and hopefully interesting) words is tough. Too tough, when alternatives are things like annoying my cats, doing parenting, occasional Netflix.

But now there is external pressure. The fear of the deadline. The ambition to make changes and the desire for the benefits they bring.

Time to truly get my thinking cap on.

Perspective drawings and lineweights

Today at work I was asked to give advice on perspective drawing to one of our younger staff members. I couldn’t resist a bonus lesson on lineweights once I was done with the basics.

Done on the fly in about 5 minutes.

Done on the fly in about 5 minutes.

So upon getting home I naturally couldn’t engage in any sort of leisure activity until I’d done a version I was a bit more happy with, and a touch more colourful.

New and shiny! Thanks to Linea Sketch

New and shiny! Thanks to Linea Sketch

Getting Back to Work

Bifurcated. That’s the best single word I can think of describing how things seem to me right now. We’re in this strange period of emergence, where things are half locked-down; half exactly as they ever were. 

My working time is now split 60:40 between remote working from home and the office. I’ve written a rota to get one engineer per day into the office for the next 6 weeks. Mini-pie is back in school 2 days a week. Next week I’m attending an actual, real, in-person, external meeting to kick off a new contract. I’ve just been to a book shop where I had to queue to get in and immediately use hand sanitiser upon entering, as directed by a staff member wearing a full plastic face shield. On my walk home, I saw crowds of people drinking beer in the sun, crammed in by the river.

So in this weird in-between phase I’ve found myself making some foundational changes to my approach to my work. There have been three broad areas of change: 

•  Task Management

•  Equipment

•  What’s on my Phone

Task Management - Bullet Journal No More

Since the start of the year, I’ve been using a physical bullet journal to track all of my tasks. Ever since I started using pen and paper, I knew that I was doing it out of sense of wanting to feel in control, but there was always a risk that the sheer amount of tasks I need to juggle would overwhelm the system. That point duly arrived in the middle of last week, when I started going over two pages, and I was losing the will to keep up with it. 

Sorry pen and paper; it was nice while it lasted.

Back to GTD

Whenever I feel overwhelmed or feel I’ve got too many tasks to keep track of, I fall back on the Getting Things Done (GTD) method. This new disjointed life I’m leading lends itself to a more systematised life management scheme than ‘write a list of all the things I need to do in a book that I carry everywhere’, and GTD’s contexts are going to be especially helpful. 

Previously, I used a bunch of Evernote hacks to create a GTD system, but Evernote’s pricing hikes pushed me off their system a couple of years ago. Luckily, an application called Notion has changed their pricing structure to be free to individual users with no limits.

Notion

Notion is difficult to describe in a few words, but for our purposes it can be thought of as something capable of creating a sort of personal website, and that website can have built in elements like databases. The really powerful feature that makes it useful for GTD is the ability to have linked databases. Conceptually, it’s like having a spreadsheet, where individual cells can also be spreadsheets. 

Barebones task table. Very much a work in progress.

Barebones task table. Very much a work in progress.

Above is my Task Table, as it currently stands. This is the master task list, where all tasks are logged with as much metadata as I can throw at them. It’s roughly analogous to my longform list of tasks from my paper notebook. It’s exactly as unwieldy as that, which is why I use the Dashboard to view what is most relevant to every working day.

Heath Robinson Dashboard

Heath Robinson Dashboard

Under each of the main visible headings in the main window, you can see ‘Task Table’. What that is telling you is that each of those two tables you see on the Dashboard are really like windows, peering into the master Task Table. The tables you see in the dashboard really represents a bunch of filters applied to the main table, so I can just look at what’s important.

I’ve got more work to do, especially with context filtering. I’ve made a page which shows me all the tasks tagged with ‘able to do from my phone’ on it, but I need to make a bunch more of those types of shortcuts.

Once I’ve got the full system up and running, I’ll post about setting it up.

Equipment - Mega Mobile Office

The time has come round for The Big Five Year Upgrade, and my venerable iPad Pro first gen is being put out to pasture. I’ve dropped all the pennies on a brand spanking new iPad Pro 12.9”, as well as the Magic Keyboard. This is now the one personal computer for me (home and travel edition). 

It’s not super-grammable, but there’s a snoozing kitty in the background. You’re welcome.

It’s not super-grammable, but there’s a snoozing kitty in the background. You’re welcome.

For the structural analysis software our company uses, I need a PC running Windows 10. Right now at home that’s done by my 15” MacBook Pro (2015) under Boot Camp, which although slightly long in the tooth, is still as capable as any desktop in our office for the work I do. The difference is that now, the laptop will be parked at home, and become effectively a small desktop. 

If I’m in the office, I have a desktop PC. If I’m remote working from home I’m using the MacBook. 

In the medium term future, there may come a time again when I need to travel and design, and under those circumstances I’ll be forced to pack up the fairly chunky MacBook and take it with me. Even in the Before Times though, these events were rare. Usually if I’m travelling for meetings, I’m rarely doing design work: I’m participating in the meeting, taking notes, making sketches. Maybe if there’s a break I’m answering a few emails, or firing off a few Slack messages. This sort of work is iPad Nirvana, and I’ve been doing it for years.

This breaks my computing life down into nice structured, discrete areas. 

1.  Work from home primary computer: MacBook Pro running Boot Camp

2.  Work from the office primary computer: Desktop PC

3.  Constant Companion computer: iPad Pro

Phone

I’ve had to do The Bad Thing

Oh nose. Work emails. Outlook. Bad Martyn.

Oh nose. Work emails. Outlook. Bad Martyn.

I’ve had to relent, and put my work email on my phone. And yes, that is 31 unread emails.

One utterly ruined weekend circa 2009 has kept work emails off my personal devices for the better part of a decade, but alas, the fallout from Covid-19 has pushed even my sacred belief in work/life separation past its usual breaking point. I just receive so much email that I can no longer afford to not to keep on top of incoming messages. Those 31 unread messages came from a productive Thursday spent with focus on one task, and a Friday which ended up revolving around troubleshooting site issues and a scheduled internal meeting. The good news was that even though those 31 emails are marked unread, I was able to glance at them as they came in on either my phone or my watch. Without some sort of mobile access to email, that would just have been a millstone around my neck.

I hope this doesn’t mark a permanent shift for me to routine email access out of work hours. I am acutely aware of the need to keep work and home separate, and that’s what I tell my team. I want people who can switch off as they leave their office, or their home workspace - I believe it makes for healthier staff. I just hope I can kick the habit if and when things go back to ‘normal’.

Hello isolation my old friend

Well it’s safe to say things are somewhat unusual right now.

  1. I am now both designing steelwork and managing my team remotely, which is a bunch of challenges, big and small.

  2. I am now responsible for the care and education* of a mini-me, which is fine and dandy of a weekend, but difficult to juggle with item 1 midweek.

  3. I am troubled about the wider governmental response to the global pandemic, and also very troubled regarding the way in which the construction industry in particular has been handled.

*educational merit of my ‘lessons’ are up for debate

Headlines out of the way, I can say that my entire family thus far has thankfully been unaffected from a physical health point of view; nobody has had the illness as yet. For that, I count myself very lucky. From a mental health point of view, I’m juuuust about coping.

Things which contribute to the near-constant feeling of despair which keep me up at night, staring at twitter, the ceiling, and an ever-growing to-do list:

  • Feeling of responsibility to my colleagues. Working for a small to medium sized business in this uncertain period is plenty stressful enough. When I stop and remember how cash flow affects a steel fabrication business it sends me into a short-lived panic.

  • The briefest of moments when I let my stoic guard slip and think “how is that person managing to do all their normal day-to-day things so well and blog about how their new online classical guitar lessons are going?". I objectively know that whilst some people have accrued time in lockdown, and even though I’m just about treading water and that is fine, every now and again those negative thoughts do slip in and they really affect me. Sometimes it’s jealousy, sometimes disbelief, and sometimes it’s self-loathing because I know that I’m objectively one of the luckiest ones and shouldn’t even be thinking of complaining. None of it is helpful.

  • Constant fatigue. No amount of rigidly trying to keep to even the simplest of schedules can keep someone on top of their game under constant stress like this. Even when I manage to keep to the schedule I’m still usually knackered by mid-afternoon. My attempted schedule is simply:

    • Get up at 5:45 to 6:15am like I do usually

    • Get to my desk by 7am, because I’m usually in my car at that point

    • Eat somewhere vaguely near midday

    • Attempt to be in bed about 10:30 - 11:00pm

On the other side of the scales - Responsibility for keeping me the right side of sane comes from a few places:

  • My immediate family. Everyone is chipping in to help each other keep on top of spinning all the plates. Huge thanks in particular to Mrs Pie for being a total badass about keeping everything going.

  • Being super-fortunate in the place we live, at a macro and micro level. Firstly, York has one of the highest compliance records of Staying at Home, so we feel like we’re in good company. We’re also lucky enough to have a dedicated study where Mrs Pie works from home, and I have commandeered the dining room to set up my Heath Robinson home office.

Not massively Instagram-friendly, but an accurate depiction of my work space right now.

Not massively Instagram-friendly, but an accurate depiction of my work space right now.

  • We also have a small garden, which considering we live in a terraced house in a city centre is an utter luxury. During a working day, Mini Pie has his own room, a playroom and the living room to bounce between.

  • Pets. I know I bang on about my cats, but they’re a great source of comfort and of regular entertainment.

  • Being comfortable not being perfect, or even in the same timezone as perfect for that matter. I have cultivated a mostly-healthy mindset of knowing when good enough is good enough, and I have realistic expectations of how days will pan out. For example, a full working from home day is a success if I complete my work, everyone gets fed, and nobody catches fire. Everything over and above that is a massive bonus.

  • My age and upbringing. I’m a borderline Millennial by definition: I grew up with computers and the internet, so I’m used to getting a lot of my social interaction via a keyboard and a screen. The abundance of video-conferencing now available to me means that if anything, I see more people outside of work than in the Before Times. We’ve been using Slack within my team for internal communications for a few years now, so the day-0 dash to get everyone working remotely wasn’t as big a shift for the design team as it was for all the other departments.

  • Friends both met online, and of the real world. There’s plenty of support out there, and just picking up the phone or joining a WhatsApp group or two can make a big difference.

I’ll make a concession to the weirdness of the times and open the comments. How are you all managing? I hope you’re all safe and well.

What? It's 2020 already?

Oh no, I’m supposed to have a Yearly Theme all ready to talk about aren’t I?

Here’s the problem. Been a bit busy with the old Christmas family hosting gig I took on, so let’s try to figure it out now as we go.

Last year’s theme was definitely a ‘one and done’ theme which revolved around the Big Move. The year previous to that was my Year of Lean, which actually worked pretty well. I’ll chuck that one into my figurative box of potential themes. With that in mind let’s consider the year in review, what’s going on this coming year, and what I’d like to improve upon.

Work

Work, attitude towards work, and work-life balance can always be improved. How did I do this year?

The things that I think went well this year at work were:

  • Training for our newest graduate. He’s coming on brilliantly, and the bulk of the credit for that goes to the rest of the team. My main part in helping has been in trying to give the team the time to dedicate to him.

  • Work-life balance. I don’t feel like I’ve let work invade my home life to an unreasonable degree at all. I think I managed to successfully limit the work I brought home to only that which was necessary given the nature of my work. I can say I’ve probably done a 50+ hour working week just once or twice this year, usually when multiple external deadlines have fallen together.

  • Keeping the plates spinning. I’ve just about managed to keep everything up in the air without significant droppage, and it has been a hectic year.

    Things I think can definitely be improved:

  • People management. I’ve been an accidental manager for a few years now, but I constantly feel like I fail at getting the balance right between getting my head down and doing the same work my team members do (because that is part of my role), and keeping my head up to keep an eye on how they’re doing. It’s too easy to put the blinkers on and say “I’ve got to do my thing” and forget there are a team of people with similar or identical tasks to complete which require my input.

  • Allowing time for self-development. I haven’t done a great job in keeping up with CPD this year. Sadly, it’s one of the things that’s easiest to drop when you need to already be working late to get a tender in.

  • Delegation. I feel a physical, tangible reluctance to give up certain tasks to others. There is quite the list of excuses I regularly tell myself:

    • Oh, it’ll just be quicker if I do it myself

    • This way I won’t need to check the work coming back in at a potentially inconvenient time

    • I don’t want to overload my team*

    • It won’t be done exactly the way I like it

    • Most of these excuses are exactly that. Excuses.

*Ok, so this one is less of an excuse and more of a reason. I know I get the best out of my team when everyone is focussed on a single task at any given time. I do not believe that anyone performs well when multitasking. The way I try to act as a manager is to do everything I can to protect my team from the hosepipe of incoming crap from above me, allowing them the freedom and space to get on with their own work to the best of their abilities.

What this means is that I try to spin as many plates as possible, and pass them onto team members one at a time as soon as they’ve got the last task off their desk. This way the minimum number of people (ideally just me) are multitasking, and the maximum number of people (everyone except me) are focussed on exactly one task. The downside is that is that I end up spinning a lot of plates basically all of the time.

Home / Everything else

Ok, in this category let’s lump together everything else. Health, fitness, other things I want to aim to achieve or improve at, or even just try out.

Things that went well in 2019:

  • Our family successfully moved house in 2019. After making some repairs to the roof, and sorting out a manhole which had been concreted over in one of the downstairs room since the 1970s we have reached a stage where we’re about 95% happy with how the house looks. Hopefully, 2020 will be a year in which we simply get to enjoy our new place.

  • Cats. We doubled our cat quotient this past year, and I neither know nor care if this ends up affecting this year’s theme, but I love my 4 year old micropanther, and I love our new 5 month old tortoiseshell kitten. Cats are aces.

  • Reading. I didn’t read as much as I did last year, but I read a decent amount of books, and I branched out into a little bit of non-fiction too.

  • Tech. I fully broke out of my old habit of seeking out the New and the Shiny for the sake of it in 2019. My phone is now 3 and a half years old, my laptop is about 4 and a half years old, my iPad is about the same, and my Apple Watch is a few years out of date. I don’t care. They all still perform brilliantly, and they won’t be replaced until they start to show signs of letting me down.

  • Music! One of the co-hosts of a rather good podcast was kind enough to spend some serious time recommending some new artists to me, after having spent a decade in the musical doldrums. I’ve since discovered that many of the artists from the playlist are exactly to my tastes; some blindingly obvious (turns out Taylor Swift is good at doing songs - who’d have thunk it?), some a little less well known (hello Alice Merton!).

Things I want to improve in 2020:

Given we moved house in 2019 and that took up a massive amount of time, energy and heartache a good deal of little things necessarily had to make room. Here are things I’d like to improve upon in the coming year.

  • Fitness. I picked up a knee injury about 10 months ago, and I’ve struggled to get back running ever since. I know that what I need to do is build up the muscles around my dodgy knees with bodyweight exercises and very short runs, but I’ve lacked the time, inclination or energy. Got to do something about that.

  • Sketching. I miss sketching. I used to attend classes, but it was tough to fit into my schedule. This year I’d like to try to set aside some time at home with my drawing board and just put in some hours.

  • Writing. I’m very pleased with what output I managed on this website, but I’d like to produce more, even if only about a dozen people read it.

  • Attention span. I think I need to spend some scheduled time away from my phone and the wider internet. I can tell this year of obsessing over the news has been harmful to my ability to concentrate, but on the plus side has proved beyond doubt that obsessing over events which you cannot control is utterly futile.

Pulling it all together

Ok, let’s consider the improvements I want to make and see if we can make any obvious connections:

  • People management skills

  • Delegation

  • Self development (CPD)

  • Fitness

  • Sketching

  • Writing

  • Attention span

Most of these kind of fall under the banner of Self Improvement, which is a start, but it is rather generic. I wonder if Time can tie them together, because I need to make the time to actually improve myself, or dedicate to my team? Or maybe Awareness? Being aware of what I want to do to improve and being conscious enough of it to to make the effort to alter my behaviour? I’m warming to that. It’s punchy enough to stick in my brain, adaptable enough to cover the bulk of what I’m aiming for.

Let’s try it out: Year of Awareness.

Hmmm. Maybe not? How about Rebalance? After a year of being focussed on One Thing, I’m rebalancing and focussing on lots of small things? That covers everything, but refers to none of them. Is that ok? Maybe something that’s the opposite of my failings? Is there something that’s the opposite of being blinkered? Year of Heads Up? That kind of does come back to awareness. Being aware of the world around me, and not being too laser focussed on one thing but also being aware of the desire to improve myself.

You know what, I think we’re there.

2020 - the Year of Awareness.

Detailed design of open section truss nodes

A couple of weeks ago I was lucky enough view a live webinar from the SCI presented by my engineering spirit animal, The David Brown. The subject was one very close to my heart, the design of truss nodes.

I think it’s about time on martynpie.com to bring a little calculation to the fore, and see if I can get at least some of David’s ideas across in a written format.


Let’s get right into the example. A week or so after David’s presentation, I was able to put into practice the methods he described on a live estimate. This particular truss node has been sized by a consultant engineer, and one of our estimators asked me to assess the need for stiffening.

At this stage we have not been given any loadings to make the assessment with, so I was forced to make some rough assumptions.

A couple of notes: I will tend to use breadth and width interchangeably. The distinction isn’t important. I will also make a conscious effort to use the Eurocode term resistance instead of the old British Standard term capacity when talking about how strong members are, but again, the terms are interchangeable.

There are some spoilers in the image. Sorry.

There are some spoilers in the image. Sorry.

As you can see, I’ve assumed that vertical internal member (the 254 UC 89) is working at 80% of its compression capacity (using The Blue Book), which comes to about 3120kN. Furthermore, I am stipulating that the joint is in vertical equilibrium, meaning the tension in the diagonal will be 4412kN.

At this point I’ve also noted down for future use the yield strengths of the two members based on their flange thicknesses, 335N/mm² and 345N/mm².

First job is to check the interfaces where the flanges meet using the rules from BS EN 1993-8 (design of joints) for connections to unstiffened flanges. This should look very familiar to users of the equivalent section of BS 5950-1.

This should look familiar

This should look familiar

We’ll start by checking if the boom (the 356x368x393 UC) needs to be stiffened. Referring to the left half of the diagram above, we treat the left portion of each as the boom, and the right portion as the flange of the incoming 254x89 UC.

We will first establish what the effective breadth of the incoming flange is using the code. The effective breadth is a way of discounting the outermost, more flexible elements of the connection, and it is calculated as per the below.

Extract from BS EN 1993-8

Extract from BS EN 1993-8

As you can see, the effective breadth of the incoming flange is dependent on the thickness of the web of the boom, the root radius of the boom, and a 1 in 3.5 spread through the flange (that’s the 7 in the formula). There is also a dimensionless reduction factor k, which is dependent on the ratios of the yield strengths of the materials, and the relative thicknesses of the parts.

effective+breadths

In the first section, I calculate that the effective breadth is actually wider than the 254UC’s true flange width (owing to the the fairly monstrous size of the 356x368UC), so we allow common sense to take control, and deem that the effective breadth of the 254UC is simply equal to the actual breadth of the UC. I skip the step of checking if stiffening is required, because I know from experience that by inspection it is not required. We’ll see the actual check when considering the 254UC to 254UC interface … well right now actually.

When we move along to checking where the two 254UCs abut each other, we see that effective breadth of in the incoming member is much reduced, a mere 156.8mm compared to the actual width of the UC, 256.3mm. In this instance I have also done another quick skip: if you know two sections are identical, it follows that the reduction factor k = 1. Now we must check as per the code to see if stiffening is required. We compare the effective breadth to yet another reduced breadth, this time one derived from the ratio of the ultimate and yield strengths, and this time we find that stiffening is indeed required.

The quick amongst you may have noticed that there is something a little strange about the above. We have determined that the joint requires stiffening, despite not having compared the force in the members to any sort of member resistance. Personally, I think there’s something a little off about the idea that the code determines whether or not to stiffen a joint without considering how stressed the joint is, and relies on the geometry only. There could be a mere 0.001kN going through that joint, and by the rules of the code it doesn’t matter - stiffening is still required.

At this point in the CPD, David Brown walked attendees through the design of the stiffeners themselves and their required welds which, thankfully for fans of reality are actually related to the forces in the members. As I was performing this particular calc for an estimator, I was content to just assume some sizes of both stiffeners and required welds based on experience, and barrel on to the more interesting bits.

Next, we’re going to check the local tension resistance of the web of the 356x368UC where the diagonal is pulling up with 4412kN.

For now, you can ignore the rough shear diagram. We’ll come to that next.

For now, you can ignore the rough shear diagram. We’ll come to that next.

Boiled down from the verbose Eurocode subscript language, the web tension check is simple enough on the face of it. The resistance is equal to some dimensionless reduction factor ω, multiplied by the effective length of web we can justifiably call upon, multiplied by the width of the web (to give an area of web), multiplied by the yield stress. The partial factor on the bottom of the fraction is equal to 1.0, so can be safely ignored. The fun* comes in identifying the length of useable web, because of nailing down that reduction factor.

*Did I say fun? Sorry, I meant pain. Typical Eurocode document hopping pain.

web tension calcs

Both the tension resistance and the reduction factor are dependent on that effective length, so we hit that up first (well, actually I calculated the shear area of the web first, but we don’t need that juuuust yet). We’ll be ignoring the term with 2√2 in it, because it relates to weld, and if we elect to use a butt weld (which is perfectly possible in such heavily loaded trusses), that number should be zero. So to keep our options open, we do just that. Now we have everything we need, and the calc results in a useable web length of 346mm.

Next on the agenda is that dimensionless reduction factor, ω. All the horrid document hopping happened around here, and for the sake of sanity I’m going to skip it. The only missing variable for it is the shear area of the section (Av), which I calculated at the top of the previous section, because I was a little too eager. Our reduction factor can be seen to be 0.734. Wonderful, we’re making progress now.

With all the pieces assembled, the local check is completed simply. As I said before, when boiled down to its elements the calc is just a stress multiplied by an area, and it gives us a resistance of 2605kN. Our applied load is not the full tension in the diagonal member, just the force in the particular flange at the point of contact resolved to be vertical. Flange force can be reasonably taken as the axial in the member pro-rata to the area of the flange. Our flange force works out at 1600kN, and the resolved component is 1130kN, well below our calculated tension resistance of 2605kN. We press on, emboldened.

Next, we check for shear across the web section, and then combined shear and axial in the boom. Let’s recall the diagram where I scrawled on a rough shear force diagram:

This is just a crop from the larger calc above

This is just a crop from the larger calc above

In round numbers, the shear force at the leftmost flange is 1130kN (the flange force as a point load), then the shear varies up by another 855kN (the web force as a uniformly distributed load), then at the middle flange there are equal and opposite flange forces of 1130kN, so we assume the max shear force is 1130kN + 855kN = 1985kN before the shear force diagram tails back off to zero to the right.

Shear checks the first

The first quick and easy check is for shear alone across the web’s shear area. We calculated the shear area (Av) before when we were doing the dimensionless reduction for the web tension, so that’s a gimme. Shear resistance is the shear area multiplied the yield strength over √3, and the force to resist is that 1985kN drawn on the shear force diagram from before. We can see that the applied force 1985kN is less than the resistance of 2525kN, so on the face of it we are good to continue.

At this point though, we really should be starting to worry about the high shears present: we can see that the section is at about 80% of its shear capacity, which should definitely set alarm bells a-ringing because we also know from the initial assumptions that the boom is also at 75% of its axial capacity. It would be sensible to expect that a combined shear and axial check will not yield good news for our member.

The final chunk of calcs on the page included above are mostly dedicated to finding the elastic shear stress, τEd. When David Brown was giving the CPD he helpfully pointed us to the Blue Book to get the value of y-bar for Tees cut from UCs. What he failed to mention was that the book only has values for Tees up to and including those cut from 305x158 UCs, and so because of the sheer massiveness of our boom we have to resort to hand calcs to get y-bar. Ok, I did have a good time doing that little calc though, so all is forgiven David.

Ouch.

Ouch.

So, having calculated our elastic shear stress (182N/mm²), we simply Von Mises that together with our assumed axial stress of 0.75 and we see …

Oh dear. It’s out by quite a way. 44% over-stressed. Looks like we will have to investigate stiffening that web to bring down the elastic shear stress.

Like before, the full CPD then ran through the more interesting aspect of web stiffening plates, and their limitations. Of particular note: it doesn’t matter how much additional plate you weld to that web, you can only ever take the benefit from the section’s original web thickness again, and no more. In my case, I could take the benefit of an extra 30.6mm of web plate, but no more.

For my part, I again guessed some plate sizes and weld sizes and passed those onto estimating. In all honesty, the weld size to the web plate and the preparation of the plate for fitting over the root radius of the UC are the important factors from a cost perspective, rather than the thickness of the plate itself, so again I just used my judgement rather than spend any more time on hand calcs, as interesting as these were.

So, there we are. Whilst the initial image gave away the required stiffener in the vertical 254UC, it did not spoil the surprise that a 356x368x393 UC still requires some web plates where large forces combine, despite having a THIRTY MILLIMETRE THICK web.

Now the question is, whose responsibility is it to check that the members designed are strong enough in the first place?

Ok, so maybe let’s not do that one all over again…