Jump to content
Sign in to follow this  
ChinRey

Structural construction question

Recommended Posts

This is a question about RL structural engineering, not 3D modelling, but I hope somebody here can help me with that too.

I'm trying to build a replica of the old control tower at the Watertown air base. (Watertown was the original air base for U2, today it's better known as Area 51.)

This is for a cold war museum in SL so we want it to be as correct as possible and unfortunately only a few photos, one video and no other information have been declassified so far. So I'm desperately trying to figure out the details. Here is one.

The foundation to the tower looked something like this, four sturdy pillars (I'm almost sure they are square profile, not L-beams) joined with crossing flatbeams:

1886590043_Skjermbilde(1919).png.aadf10dfb3417c35655f72b15d50456a.png

Half the crossbeams are attached to the outside of the pillars, half to the inside. That means there is a huge gap between them were they cross:

1022756507_Skjermbilde(1920).thumb.png.8c46848bca4b6a80b13ddbf00ed52b7c.png

Is that structurally sound? And is it something they would have done?

Edited by ChinRey
Typos
  • Like 3

Share this post


Link to post
Share on other sites

Connecting them can bring extra stability (my statics knowledge is good enough to know it does not necessarily have to, but can... you have to calculate through this)... but you do not have to. In the Original the gap seems to have been there as far as I see (only found an old BW pic)

From my experience in building deerstands I know we never ever connected them in the middle - but that is wood, not steel.

Edited by Fionalein
  • Like 2

Share this post


Link to post
Share on other sites
50 minutes ago, arton Rotaru said:

In case this is the tower in question, and judging from this image, I would say there is a connection between the inner and outer wooden board.

Wow, thank you! Yes, that's the one and that picture is a great find. I already had it but only with a much lower resolution so I couldn't figure out such details. The picture also confirms that the pillars are indeed square, not L profies.

 

1 hour ago, Love Zhaoying said:

Have you considered whether rivets or welds are more authentic to the time period? Or bolts?

Yes and I'm not sure. Bolts seem to be the most plausible but I can't see any of them in any of the pictures.

For those interested, There are a lot of pictures from the base here:

https://www.laughlinheritagefoundationinc.org/in-the-beginning-u-2s-at-watertown.html

  • Like 1

Share this post


Link to post
Share on other sites
3 hours ago, Love Zhaoying said:

I don’t know if they used bolts back then!

They did. The bolt was invented early in the 19th centruy by Ben Bolt. He went nuts because he couldn't find a way to fasten them though, so he was screwed in the end.

The inventor's sad love life probably didn't help much either. It's a riveting story and Thomas Dunn English (1819-1902) wrote a famous heart breaking poem about it.

Edited by ChinRey
  • Like 2
  • Haha 2

Share this post


Link to post
Share on other sites

Sounds like an interesting project to be working on.

Having to work from a single photo instead of proper plans can be tricky so as a control for the dimensions of your tower base below are the measurements  I found when using Artons image as a background in Blender then scaling it up so that 10 rungs of that vertical ladder = 3meters. ( Google suggested that the spacing between rungs should be around 30cm ).

1188311257_frontview.thumb.png.e8f3675fb182d38352f10c3d2d6fc210.png

Comparing the mesh with the photo :

121474234_GIF2.gif.32bb8b006cc17c83a739d1a4635748c6.gif

the base and the platform probably would need to be a little larger.

 

For joining the wood (and metal) parts of the tower base  Googles carpentry community suggest that Carriage bolts  are the thing to use :) . Rounded head on the outside, washer and nut on the inside.

896167388_Carriagebolts.jpg.001091618d551c9848f7b31fcf4665eb.jpg

  • Like 2

Share this post


Link to post
Share on other sites

Welcome back Aquila, we missed you! ❤️

2 hours ago, Aquila Kytori said:

Sounds like an interesting project to be working on.

I'm beginning to get a feeling I should have asked you to do it  all. ;)

3 hours ago, Aquila Kytori said:

I found when using Artons image as a background in Blender then scaling it up so that 10 rungs of that vertical ladder = 3meters. ( Google suggested that the spacing between rungs should be around 30cm ).

I wish I had known of the picture Arton found earlier. As I said, I did have it but only at a much lower resolution:

847828306_Skjermbilde(1381).thumb.png.cfd55a02cc9699aadbe835be9be4f154.png

3 hours ago, Aquila Kytori said:

121474234_GIF2.gif.32bb8b006cc17c83a739d1a4635748c6.gif

the base and the platform probably would need to be a little larger.

Yes probably. The deck around the housing would be very narrow at that size. The ceiling would also become a bit on the low side. There is one picture of a man standing inside the tower:

626266651_Skjermbilde(1383).thumb.png.2b02dafff19b252cd832b26aacabc1eb.png

Using him a a measuring stick, I ended up with 6x6 m platform size, 5.4 m platform height. That seems to be too big though, I suppose he was a small guy. So it's probably somewhere in between.

I rezzed a copy of my rough prim draft, scaled to platfrom size 4.85x4.85 at Mesh Sandbox 3 <100.0,150.0,22.0> on the beta grid in case somebody wants to take a look. It's amazing how much more feel you get for a build when you're able to walk around it. It's also amazing how small it is, no matter which scale we end up with.

 

3 hours ago, Aquila Kytori said:

For joining the wood (and metal) parts of the tower base  Googles carpentry community suggest that Carriage bolts  are the thing to use :) . Rounded head on the outside, washer and nut on the inside.

It never thought they would have used woo until Love mentioned it. I assumed it would flex too much. But I didn't realize how small the structure actually is. It should work at this size and it explains a lot of details I couldn't figure out. But that means it's all wood and that again means nails.

  • Like 1

Share this post


Link to post
Share on other sites
53 minutes ago, ChinRey said:

It never thought they would have used wood until Love mentioned it. I assumed it would flex too much. But I didn't realize how small the structure actually is. It should work at this size and it explains a lot of details I couldn't figure out. But that means it's all wood and that again means nails.

400ft redwoods make themselves entirely out of wood! Wood is also making a comeback in large scale buildings.

That tower is made of wood. The cross braces are fastened to the posts with carriage bolts and the posts are fastened to the beams with steel beam joiners. There is blocking between the cross braces to resist twist from weathering and vibration from wind. I've highlighted all those features below...

16171892_TowerConstruction.thumb.jpg.8f0d9956cfbb64af9b68ce3bafebf68d.jpg

The blocking between the cross braces (shown in the leftmost magnifying bubble) is usually made from post stock, as that naturally sets the right spacing. It's not carrying a load, so it might be nailed or screwed.

Edited by Madelaine McMasters
  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites
15 minutes ago, Madelaine McMasters said:

400ft redwoods make themselves entirely out of wood!

That's true but generally they tend to go for something a bit heavier than the 6x6 beams used for the tower fundament. ;)

Quindío palms do have trunks just as rickety as those posts but they don't have much load to carry and live in Colombia where the laws of physics have been suspended anyway.

But most importantly, trees don't mind swaying a bit in the wind, they think it's fun. Air traffic controllers are less keen on that.

 

15 minutes ago, Madelaine McMasters said:

The cross braces are fastened to the posts with carriage bolts and the posts are fastened to the beams with steel beam joiners.

Now I'm beginning to wish Arton hadn't found that picture. In the pics I had the posts and beams seemed to be joined with lap joints sot hat's what I went for. One more detail to correct.

Edited by ChinRey
  • Like 2

Share this post


Link to post
Share on other sites

Palms are no trees, technically their xylem (wood body) isn't even considered wood as it is primary not secondary growth... wood is a very different beast. The problem with wood statics is predictibility: while most beams of wood hold more than 10 times their statics specifications some fail... in Germany we allow as much as 5% to fail (if less than 5% of your beams do not hold the intended weight your poduct is considered good - statistically the failing beams in a construction will be compensated easily by the more stable ones, but the statics guys do not like this :D)

Sorry silvicultural engineer kitty could not resist.

Edited by Fionalein
  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites
10 hours ago, Bitsy Buccaneer said:

I'm loving the cooperative work in this thread and wish I had an Impressed reaction for Aquila's work ?

Me too. I wish I had had the sense to ask here earlier. My deadline is only three days away.

Edited by ChinRey
  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...