Jesus joint - a single piece, the failure of which is fatal - thus “the only Savior”. This can be a nut, bolt, cable, screw, any fastener or item used as a fastener. You don’t want a design which uses these.
Think about the difference between the single spin-on nut used to hold wheels on Indy cars - having the ability to knock the spinner once and have the wheel off, replaced, and the nut back on in 8 seconds is handy in a pit stop. I like having 5 lugs on my wheels - those spinners are Jesus joints.
I think it was on these boards where an architect and an HVAC contractor got into the natural enemy mode.
It seems a convention center (IIRC) was found to be falling down rather soon. Inspection revealed that the HVAC people, needing somewhere to route the huge ducts required to ventilate the place, had cut massive holes in the 7’ transfer beams supporting the tower above the huge open space.
The KC catwalks was not a strength-of-the-suspenders issue. It was the more subtle issue that, as built, the walkway beam was required to carry the load. As designed, it was only required to support the pedestrians
| |
| | |
---- vs. ------
| |
| |
In the first one, there is no load on the horizontal member - as designed.
In the second one, the horizontal member is carrying the weight of the lower catwalk - as built.
Why the substitution?
The design required the rods to be threaded in the center - it was to be a single rod, passing through the upper catwalk (with a nut to hold the horizontal beam) and terminating at the lower.
2 small rods with threads only on the ends were MUCH cheaper and easier…