A structural engineer's logbook: step-by-step designs, Python automation and lessons learned in seismic and bridge engineering.
By Yordan Rocio Maldonado
Featured · Automation & code · Structural analysis
We have all computed a simply supported beam by hand. In this first part we move it to Python, line by line, and see what a calculator cannot do: compute twenty beams in one second.
Design log · Seismic
A bridge pier is not just a column: bearings sit on top and a foundation sits below, and all three deform. In a typical case, adding them takes the period from 1.3 s to 1.9 s.
5 min read
Lesson learned · Seismic
Copying the same damping coefficient into every model looks neutral, but it is not: a flexible structure ends up with 1.5% and a stiff one with 5%. I explain where that comes from and how to fix it.
3 min read
Lesson learned · OpenSees
I reran 20 analyses with the same code and the same inputs, and none matched. The cause was a material that keeps memory between models when they run in the same Python process. The fix is one line.
3 min read
Design log · Dams
In 1967 an earthquake cracked Koyna Dam, in India, right where its downstream face changes slope. I modeled it in OpenSees and the video shows how that damage appears, second by second.
3 min read
Code reading · Codes
A bearing fails when its rubber layers shear too much. AASHTO puts compression, rotation and displacement into one sum. I explain it from scratch and work it out for a 350 × 450 mm bearing.
3 min read
Lesson learned · OpenSees
OpenSees lets you model a column with two element types that look equivalent. Against a real test, one got the shear within 1% and the other overshot by 56%. I explain why, starting from the basic idea.
3 min read
Design log · Seismic
In seismic design we choose which part of the bridge gets damaged, like a fuse. Everything else is designed for what that fuse can transmit. In a two-column bent, that is almost twice what the analysis says.
3 min read
Opinion · Practice
For ten years I have kept notebooks on how I design, what I automate and which mistakes I make. This is the public version: a log of design, automation and lessons learned.
2 min read
In 1967 an earthquake cracked Koyna Dam, in India, right where its downstream face changes slope. I modeled it in OpenSees and the video shows how that damage appears, second by second.
Read the full note →Coming next
Move the inputs and watch moment, shear and deflection change. Simply supported concrete beam, 30 cm wide.
Deflection uses the uncracked section: the real one is larger. How to code this, step by step →
Ongoing series
1 of 6 published