4 ms·

Are the side walls of the bridge specified to take directional load like that?

deleted 12y ago
[deleted]
diarmuidie 12y ago
I thought the same thing. It seems like it would have been a better idea to bring the cables/ropes in through the hole at the bottom of the wall, rather than over the top. The lateral compressive load would then have been taken up by the bridge itself, rather than the walls.
- jacquesm 12y ago
  Exactly. Really really dumb this.
jacquesm 12y ago
Spectacularly dumb idea to hang that much weight (6 Tons!?) from the top of those walls. Those walls are clearly meant for vertical loads. And a much better option (if you feel you have to do this) was available so I really don't understand what made them choose this particular setup. Anybody with an ounce of structural engineering knowledge would have looped the cables through the drainage ports. Right now this looks like a Darwin award candidate. They're very lucky that those walls contained enough rebar vertically to withstand this load, it's at the worst possible attachment point and at the worst possible angle (especially for the inner wall). Edit: looking more closely at the picture it seems as though the cables under tension are actually running through the drainage ports of the back wall, the ropes at the top seem slack or loaded both top and bottom of the opposite so there is in fact mostly compressive load on the front wall and about 50% of sideways load on the opposing wall. Still, that structure was definitely not meant to be loaded like this.
- gambiting 12y ago
  Yeah, in this picture you can see the cables running through the drainage port: http://jaccuzzi.ch/photos/700/1754_264_seb_7_.jpg http://jaccuzzi.ch/photos/700/1754_264_seb_7_.jpg So I "think" most of the load would be applied vertically, but that would be my biggest concern still.
  - onion2k 12y ago
    This image best shows how they did it - http://jaccuzzi.ch/photos/700/1758_264_seb_11_.jpg http://jaccuzzi.ch/photos/700/1758_264_seb_11_.jpg - they looped the ropes over the top of the sides on both sides, suspending the platform directly under the bridge so there shouldn't have been any sideways force. Still seems a bit stupid to put that much additional load on a 70 year old pedestrian bridge though.
    - nappy-doo 12y ago
      I doubt it's any more load than the bridge sees during a rainstorm.
      - onion2k 12y ago
        The bridge is 168.36m long and (I guess) about 2m wide. If there was 1" deep water all the way along that'd be about 10 tons of loading. But that'd be distributed along the entire length of the bridge, not concentrated at a point in the middle...
    - mkuhn 12y ago
      This bridge was most likely not constructed as a pedestrian bridge. What you see in the back probably is the bridge that replaced this one when a one way bridge did not provide enough capacity anymore and the old bridge was re-purposed as a passenger and probably cyclist bridge. Based on that it was definitely built for higher load than just a few pedestrians. Edit: The German language Wikipedia article actually confirms this [1]. It states that the bridge was built for a traffic load of 13 tons and that the new bridge was built in 1993 to increase capacity. The old bridge was thoroughly renovated after the new bridge had been constructed. The bridge actually is well documented and is under protection as an architectural landmark. It was exhibited in the MoMA for a long time. Based on the amount of prep these guys put into this and the available documentation I don't see why they should not have checked if what they wanted to do is possible. [1] http://de.wikipedia.org/wiki/Pont_de_Gueuroz http://de.wikipedia.org/wiki/Pont_de_Gueuroz Edit 2: Some fascinating pictures from the time of construction: http://www.swiss-timber-bridges.ch/detail/193 http://www.swiss-timber-bridges.ch/detail/193
- stolio 12y ago
  To be fair those walls were designed to take horizontal wind loads, too. 100mph wind translates to 0.17psi[0] which is ~220 lbs/square yard (of course you assume the force happens halfway up, not at the top of the wall!) If the ropes were spread out over 5 yards then that span should hold ~1500lbs against the face of the wall. If that thing weighed 6 tons they may have made it out of the "designed to handle" range and into the "safety factor" range of inward forces on those walls. Surely those drainage ports weren't designed to handle upward loads? I really can't believe some of them took their harnesses off while in the pool. [0] - https://www.physicsforums.com/threads/wind-speed-100mph-to-pressure-psi.364785/ https://www.physicsforums.com/threads/wind-speed-100mph-to-p...
jkot 12y ago
To make it even worse ropes go over top of second side wall.
cmsmith 12y ago
No, but they are designed to take a lateral load from a vehicle impacting them. In the US currently that load is about 4.5 tons at any one point. In a bridge like this where the parapet walls are an integral part of the structure, that would likely not be the limiting case and the walls would be even stronger than that. Some more evidence that they had considered these things would have been nice, but civil structures are quite a bit stronger than people here seem to be giving them credit for. For example, the vertical design load from people walking on a bridge like this is something like 100 lb/ft^2. Meaning the bridge is designed to hold one jacuzzi every 10 or 15 feet, depending on how wide it is.

deleted 12y ago

[deleted]

I thought the same thing. It seems like it would have been a better idea to bring the cables/ropes in through the hole at the bottom of the wall, rather than over the top. The lateral compressive load would then have been taken up by the bridge itself, rather than the walls.

jacquesm 12y ago
Exactly. Really really dumb this.

jacquesm 12y ago

Spectacularly dumb idea to hang that much weight (6 Tons!?) from the top of those walls. Those walls are clearly meant for vertical loads. And a much better option (if you feel you have to do this) was available so I really don't understand what made them choose this particular setup. Anybody with an ounce of structural engineering knowledge would have looped the cables through the drainage ports. Right now this looks like a Darwin award candidate. They're very lucky that those walls contained enough rebar vertically to withstand this load, it's at the worst possible attachment point and at the worst possible angle (especially for the inner wall). Edit: looking more closely at the picture it seems as though the cables under tension are actually running through the drainage ports of the back wall, the ropes at the top seem slack or loaded both top and bottom of the opposite so there is in fact mostly compressive load on the front wall and about 50% of sideways load on the opposing wall. Still, that structure was definitely not meant to be loaded like this.

gambiting 12y ago
Yeah, in this picture you can see the cables running through the drainage port: http://jaccuzzi.ch/photos/700/1754_264_seb_7_.jpg http://jaccuzzi.ch/photos/700/1754_264_seb_7_.jpg So I "think" most of the load would be applied vertically, but that would be my biggest concern still.
- onion2k 12y ago
  This image best shows how they did it - http://jaccuzzi.ch/photos/700/1758_264_seb_11_.jpg http://jaccuzzi.ch/photos/700/1758_264_seb_11_.jpg - they looped the ropes over the top of the sides on both sides, suspending the platform directly under the bridge so there shouldn't have been any sideways force. Still seems a bit stupid to put that much additional load on a 70 year old pedestrian bridge though.
  - nappy-doo 12y ago
    I doubt it's any more load than the bridge sees during a rainstorm.
    - onion2k 12y ago
      The bridge is 168.36m long and (I guess) about 2m wide. If there was 1" deep water all the way along that'd be about 10 tons of loading. But that'd be distributed along the entire length of the bridge, not concentrated at a point in the middle...
  - mkuhn 12y ago
    This bridge was most likely not constructed as a pedestrian bridge. What you see in the back probably is the bridge that replaced this one when a one way bridge did not provide enough capacity anymore and the old bridge was re-purposed as a passenger and probably cyclist bridge. Based on that it was definitely built for higher load than just a few pedestrians. Edit: The German language Wikipedia article actually confirms this [1]. It states that the bridge was built for a traffic load of 13 tons and that the new bridge was built in 1993 to increase capacity. The old bridge was thoroughly renovated after the new bridge had been constructed. The bridge actually is well documented and is under protection as an architectural landmark. It was exhibited in the MoMA for a long time. Based on the amount of prep these guys put into this and the available documentation I don't see why they should not have checked if what they wanted to do is possible. [1] http://de.wikipedia.org/wiki/Pont_de_Gueuroz http://de.wikipedia.org/wiki/Pont_de_Gueuroz Edit 2: Some fascinating pictures from the time of construction: http://www.swiss-timber-bridges.ch/detail/193 http://www.swiss-timber-bridges.ch/detail/193
stolio 12y ago
To be fair those walls were designed to take horizontal wind loads, too. 100mph wind translates to 0.17psi[0] which is ~220 lbs/square yard (of course you assume the force happens halfway up, not at the top of the wall!) If the ropes were spread out over 5 yards then that span should hold ~1500lbs against the face of the wall. If that thing weighed 6 tons they may have made it out of the "designed to handle" range and into the "safety factor" range of inward forces on those walls. Surely those drainage ports weren't designed to handle upward loads? I really can't believe some of them took their harnesses off while in the pool. [0] - https://www.physicsforums.com/threads/wind-speed-100mph-to-pressure-psi.364785/ https://www.physicsforums.com/threads/wind-speed-100mph-to-p...

jkot 12y ago

To make it even worse ropes go over top of second side wall.

cmsmith 12y ago

No, but they are designed to take a lateral load from a vehicle impacting them. In the US currently that load is about 4.5 tons at any one point. In a bridge like this where the parapet walls are an integral part of the structure, that would likely not be the limiting case and the walls would be even stronger than that. Some more evidence that they had considered these things would have been nice, but civil structures are quite a bit stronger than people here seem to be giving them credit for. For example, the vertical design load from people walking on a bridge like this is something like 100 lb/ft^2. Meaning the bridge is designed to hold one jacuzzi every 10 or 15 feet, depending on how wide it is.