1
$\begingroup$

I was walking under a raised highway in Shibuya, and noticed these plates on some of the bridge supports.

They are flat metal plates with arrays of bolts. Some of the plates just have the bolts, but some of them have a wire zig-zagging through the groups of the bolts.

It can be seen here in Google Streetview (screenshot added below for convenience):

https://www.google.com/maps/@35.6544957,139.6940495,3a,20.5y,348.38h,130.11t/data=!3m6!1e1!3m4!1s1wselYCaNSGAXpi0WvguOA!2e0!7i16384!8i8192?coh=205409&entry=ttu&g_ep=EgoyMDI0MDkwMy4wIKXMDSoASAFQAw%3D%3D

A photo from Google Streetview (Captured September 2023) showing a square-shaped concrete support column for a bridge. There are two metal places with rectangular arrays of bolts. The plate on the left side of the bridge has wires zig-zagging between groups of 4 - 12 bolts. The plate on the right does not have any wires visible. There is a small informational plaque underneath the plates, but it is too blurry to read in this photo.

I have no structural engineering / civil engineering training, but I assume it couldn't serve a structural purpose because it's too small, and not applied to all of the bolts.

So, what is its purpose?

Because this is a bridge in earthquake-prone Tokyo, I assume there may be extra precautions taken to protect and diagnose structural issues. Is this some kind of strain or fracture sensor? Some kind of cathodic corrosion prevention system?

Improve this question
$\endgroup$
4
  • $\begingroup$ how do you know that it is a wire? $\endgroup$
    – jsotola
    Commented Sep 6 at 2:58
  • $\begingroup$ Visually, it is a metal wire/cable -- I don't necessarily mean wire in the "electrical wire" sense. It's just my best guess, because I can't see how it could have a structural role. $\endgroup$
    – Curtis Fenner
    Commented Sep 6 at 4:10
  • $\begingroup$ they look more like a spacers ... maybe they are retainers that prevent the nuts from turning on their own ... or part of protective caps placed on the nuts $\endgroup$
    – jsotola
    Commented Sep 6 at 6:07
  • $\begingroup$ In line with traffic movement, while other side has none. Counter vibration. $\endgroup$
    – StainlessSteelRat
    Commented Sep 7 at 18:59

1 Answer 1

Reset to default
2
$\begingroup$

This looks like safety retaining wire. see here
Here is an image
safety retaining wire
Used to stop bolts from unfastening due to vibration.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.