Finding the Warping Constant for back-to-back Cold Formed Channels using Python

This blog post is inspired by a recent post which I responded to on the EngTips forum. The question was related to finding the warping constant of back to back cold formed channels. The poster was querying the validity of some random formula for calculating the warping constant for back to back channels that they found in another post. Comparing this to values that were published for the shape they were interested in, and they were ultimately getting limited agreement.

The Ruskies are coming?

When setting up the WordPress software on which this blog runs, I wanted it to be secure, who wouldn’t. I mean nothing can be guaranteed as being 100% secure, but we can certainly do our best to address known weaknesses and harden the installation of WordPress and the underlying web server.

Parabolas, Rectangles, Triangles & Snakes (Part 8)

Part 8 – Documentation, the Necessary Evil Love it or hate it, I’ve already decided documentation is required so you are stuck with it. Code comments and docstrings aside, part of the planned documentation is this series of blog posts (so I can remember what I did basically). Hopefully these demystifying some of the mysteries behind the general methods involved. For the remainder I’ll leave it up to a readthedocs page to explain the ins and outs for the end…

Parabolas, Rectangles, Triangles & Snakes (Part 7)

Part 7 – Documentation & Verification, Better Than More Integration? At some point in any projects life cycle you should start thinking about the need for documentation and verification. This post and probably the next few will be dedicated to exploring these aspects. As a structural engineer, if you are designing a building you have to produce some drawings, calculations, specifications, etc to describe what is being built, and someone probably needs to check these deliverables. Often the drawings are…

Pi Massacre

This site is hosted on a Raspberry Pi 3, I like to tinker with these things. I don’t use this particular Raspberry Pi for anything else but the WordPress server on which this site runs for fear of breaking it. However, I usually update/upgrade the underlying operating system on a regular basis to ensure it’s running the latest and greatest fixes for peace of mind. This includes runningsudo rpi-update to update the firmware to the latest and greatest. Today I…

Parabolas, Rectangles, Triangles & Snakes (Part 6)

Part 6 – Slicing & Dicing Based on the last two posts, I’d now reached the stage where I’d determined the general basis for calculating the force and centroid of the concrete compression force. This seemed like one of the major challenges had been overcome, just a matter of coding it now I guess. Going Off Script… However for a moment I’d like to touch on the inherent errors in other approaches, because you’re probably thinking all this integration is…

Parabolas, Rectangles, Triangles & Snakes (Part 5)

Part 5 – Centroids, More Integrals…. In the last post we went through a process to find a general force integral which involved knowing the width and height of the stress block in terms of how far from the neutral axis depth you are. Then by using numerical integration methods we would be able to calculate the concrete force by evaluating this integral. Note that except for certain cases like a constant stress or constant width I don’t think you…

Parabolas, Rectangles, Triangles & Snakes (Part 3)

Part 3 – Class Hell Week At some point I came to the realisation that I’m going to need classes in my code, I didn’t know what they were exactly, but I needed them! Everyone else used them, so I must have them and they seemed the solution to a number of limitations I was coming up against or problems that needed solving according to good old google. So I split up my code and copied it to the four…

Parabolas, Rectangles, Triangles & Snakes (Part 2)

Part 2 – Bits & Pieces of Geometry A large part of the previous issues I was having with implementing a tool like this in Excel is the fact you have to generate your own routines (or find suitable ones by others) for all the geometrical calculations required to assess a given section at any given angle of loading or neutral axis angle. Simple shapes is probably ok, but it get exponentially harder as things get more complex in terms…

Parabolas, Rectangles, Triangles & Snakes (Part 1)

Part 1 – Prelude So for a while I have been playing around with the idea of creating some kind of tool for the analysis, design and detailing of reinforced concrete sections. In the past I have used SPColumn at a previous employer (that could afford it) for the analysis of concrete members, and some other basic free tools at those employers that could not. I’d also started (and stopped) a few times working in Excel to develop my own…