Dear Young Engineer,
A friend and I were talking not long ago and I mentioned my “I’ll never do that again” list. He asked if he could see it for his own benefit and I told him that it wasn’t written down, although my boss seemed to enjoy quoting from it. Even though these have been hard lessons and are not flattering, I trust that publishing some of them here can help you avoid the same problems.
- Remember the Live Load – I performed a preliminary design of a two-story structure using RAM Structural System, dutifully adding 20psf of roof live load. After returning from a week away, I learned that my boss had found a small problem: the general criteria in the program were set such that roof snow load was considered rather than roof live load. Fortunately, this was early in design and did not cause any more problems beyond my embarrassment. Ironically, it was yours truly that had warned the entire office of this possibility some months prior to this incident.
- Watch the Hatch – Strictly speaking, this was not my error, but I was responsible for catching it and did not. A metal deck roof diaphragm was properly designed with tighter weld patterns at the perimeter, which were shown with a hatch pattern on the drawing. However, the legend was switched such that the tighter spacing was shown in the field. This wasn’t noticed by anyone until a site observation during construction. We were able to show that the existing pattern did work at the perimeter, thankfully. Lesson: just because it looks right doesn’t mean it is.
- Dicey Splice – I designed a moment frame lateral system for a small parking structure. I failed to notice that the typical detail shown for the column-to-footing detail specified a compression lap splice. The saving grace here was the ample conservatism in the generic code splice lengths, allowing a much shorter length to suffice in a particular situation such as this one.
Note that none of these errors has led to dramatic consequences, let alone danger to the public. They have, however, increased my humility and my near-paranoia about checking my work in every way possible. They’ve also brought home the absolute necessity of another set of eyes on a set of drawings. As project engineer, you are incapable of seeing your own design clearly, making even basic errors more likely to be missed.
Remember that you are not perfect. Be humble enough to seek out feedback and correction, and not just of your drawings. Over time, you will become a far better engineer with this attitude than one of overconfidence.
So, do you have any ‘lessons learned’ you can share?