We started the 100-foot long 10-foot wide deck high up in th

D

Danny D.

Guest
Just to keep you informed, and to get your advice on better ways to
tackle the engineering problems:
https://c4.staticflickr.com/4/3943/15315306567_5e25779b8b_b.jpg

After a lot of initial setup of ladders strapped to the trees:
https://c3.staticflickr.com/3/2948/15314802989_a57dd072da_c.jpg

And setup of the many utillity ropes, and tree-to-tree netting:
https://c4.staticflickr.com/4/3928/15501340972_e31032dcd7_c.jpg

We've finally got the 100-foot-long 3/8" steel cables hung well:
https://c4.staticflickr.com/4/3948/15314983930_3c606db7b4_b.jpg

The next step, was building the first 16-foot long set of the 10-foot-
wide decking from the top of the hill, which will eventually connect over
100 feet downslope to the gnarly big redwood at the bottom of the hill:
https://c2.staticflickr.com/6/5607/15498557171_df86936bcb_b.jpg

It's amazingly ungainly tying all the 16-foot long 10-inch wide boards to
the 100-foot long swinging 3/8-inch cables as we try to build the bridge:
https://c4.staticflickr.com/4/3949/15314983180_78420114c9_b.jpg

It took two people and a lot of rope to get things squared up at first:
https://c4.staticflickr.com/4/3944/15314801909_48b46268b6_b.jpg

In fact, it was so ungainly, that we put in temporary crossbeams, just to
hold the bridge square as we were assembling it on the hillside:
https://c4.staticflickr.com/4/3940/15314801829_a3eeb9395e_b.jpg

Even steps as simple as screwing in the self-tapping screws is difficult
when the entire 16-foot long 10-foot wide bridge-like structure is
swinging freely and nowhere bolted to the ground:
https://c4.staticflickr.com/4/3942/15315124677_c121c8def1_b.jpg

But, eventually, we managed to assemble the first 16-foot long 10-foot
wide lengths from the cables between the groups of redwood trees:
https://c4.staticflickr.com/4/3943/15315306567_5e25779b8b_b.jpg
 
What are the two vertical posts made of, and how are they secured into the ground/stone??
 
"Danny D." <dannydiamico@gmail.com> wrote in message
news:m1ahhg$qr2$2@dont-email.me...
Just to keep you informed, and to get your advice on better ways to
tackle the engineering problems:
https://c4.staticflickr.com/4/3943/15315306567_5e25779b8b_b.jpg

After a lot of initial setup of ladders strapped to the trees:
https://c3.staticflickr.com/3/2948/15314802989_a57dd072da_c.jpg

And setup of the many utillity ropes, and tree-to-tree netting:
https://c4.staticflickr.com/4/3928/15501340972_e31032dcd7_c.jpg

We've finally got the 100-foot-long 3/8" steel cables hung well:
https://c4.staticflickr.com/4/3948/15314983930_3c606db7b4_b.jpg

The next step, was building the first 16-foot long set of the 10-foot-
wide decking from the top of the hill, which will eventually connect over
100 feet downslope to the gnarly big redwood at the bottom of the hill:
https://c2.staticflickr.com/6/5607/15498557171_df86936bcb_b.jpg

It's amazingly ungainly tying all the 16-foot long 10-inch wide boards to
the 100-foot long swinging 3/8-inch cables as we try to build the bridge:
https://c4.staticflickr.com/4/3949/15314983180_78420114c9_b.jpg

It took two people and a lot of rope to get things squared up at first:
https://c4.staticflickr.com/4/3944/15314801909_48b46268b6_b.jpg

In fact, it was so ungainly, that we put in temporary crossbeams, just to
hold the bridge square as we were assembling it on the hillside:
https://c4.staticflickr.com/4/3940/15314801829_a3eeb9395e_b.jpg

Even steps as simple as screwing in the self-tapping screws is difficult
when the entire 16-foot long 10-foot wide bridge-like structure is
swinging freely and nowhere bolted to the ground:
https://c4.staticflickr.com/4/3942/15315124677_c121c8def1_b.jpg

But, eventually, we managed to assemble the first 16-foot long 10-foot
wide lengths from the cables between the groups of redwood trees:
https://c4.staticflickr.com/4/3943/15315306567_5e25779b8b_b.jpg
Click to expand...

I wish I had that much spare time on my hands ... :)

Arfa
 
Arfa Daily wrote, on Tue, 14 Oct 2014 11:35:38 +0100:

> I wish I had that much spare time on my hands ...

It's going to be a nice, 100-foot long, 10 foot wide, treehouse strung
between the redwood trees on a steep slope when it's done.

Here's the varnished decking laid in place but not attached yet:
https://c2.staticflickr.com/6/5604/15558189375_03e664d327_b.jpg

Right now, we just "hung" the first 16-foot section.
https://c2.staticflickr.com/6/5598/15372553580_9751d293de_b.jpg

It's 17 feet on the left and 18 feet on the right to the next straddling
set of redwood trees, which is too bad, given our beams are 16 feet long:
https://c2.staticflickr.com/6/5608/14937422664_148d70ba58_b.jpg

After the straddling redwoods, it's 20 feet to the big fat giant redwood.

So, we're not sure if we'll string four 16-foot lengths, or
maybe change the plan to go for one fewer section but of
a longer section length.

It's a design-as-you-go project, where advice is always welcome!
 
Danny D. wrote, on Fri, 17 Oct 2014 21:28:15 +0000:

After the straddling redwoods, it's 20 feet to the big fat giant
redwood.
Click to expand...

Ooops. It's around 40 feet to the final tree, far downhill.

So, we think, the total length is much less than the length of the 3/8-
inch steel cable, which was 250 feet long (and we had to cut a few feet
off the end).

The bridge itself starts about 15 feet from the end of the cable (simply
because that's a convenient point to get ON the bridge, at the crossing
of the old footpath).

The first section is 15 feet long.
The next set of redwoods is 18 feet away.
The big redwood is another 35 to 45 feet from there.

So, the total length of the bridge is gonna be more like 80 feet or so.
Once the bridge is done, then we can put the building up.

We're told that we don't need any permits for tree structures, so, we can
even put a bathroom, kitchenette, bar, etc., there, and not have to worry
about meeting code requirements.

So, it's probably not 100 feet long, but something like:
 
John Robertson wrote, on Fri, 17 Oct 2014 18:29:39 -0700:

I still don't like the cinched cables as shown in the pictures earlier,
those are stress points and the wire rope is quite a bit weaker now for
them.
Click to expand...

I see you noticed that the cables are currently bending in a sharp
"V" shape where they are holding up the first gang plank.

We all agree that any sharp bend in the cable is a bad thing, but,
that "V" is supposed to be temporary.

The end result "should" be either a catenary or a parabola (depending
on the amount of force downward per linear distance of cable). If that
weight (i.e., force downward) is evenly distributed, the cables will
form a catenary; otherwise they'll be a parabola.

In our case, the owner has stated that each cable can hold something
like 7,000 pounds (IIRC), so that's 14,000 pounds.

The *original* plan was to have the bridge free swinging, but, we
attached one end of the bridge to posts cemented into the hillside
and, we probably will attach the other end to the big redwood, and,
in the middle, we will probably make use of the two skinny redwoods.

So, exactly how much weight the cables will hold is not really
going to be something we'll be able to calculate on this home
DIY project.

I do know that this lumber is very heavy! I helped carry it, so,
I'd know. We lugged those 16-foot ten-inch wide beams hundreds of
yards into the woods along a narrow foot path, and my hands were
hurting by the time we put them down. Lugging the cement bags
was easier! So, each bridge section is probably something like
500 pounds, and there will be a minimum of four 16-foot sections,
maybe 5, depending on how far it is to the big tree.

We don't actually know the distance because the hillside is steep,
so, you can't just run a 100-foot tape measure, but, it's less
than 100 feet by ten or twenty feet.
 
On 10/17/2014, 5:39 PM, Danny D. wrote:
Danny D. wrote, on Fri, 17 Oct 2014 21:28:15 +0000:

After the straddling redwoods, it's 20 feet to the big fat giant
redwood.

Ooops. It's around 40 feet to the final tree, far downhill.

So, we think, the total length is much less than the length of the 3/8-
inch steel cable, which was 250 feet long (and we had to cut a few feet
off the end).

The bridge itself starts about 15 feet from the end of the cable (simply
because that's a convenient point to get ON the bridge, at the crossing
of the old footpath).

The first section is 15 feet long.
The next set of redwoods is 18 feet away.
The big redwood is another 35 to 45 feet from there.

So, the total length of the bridge is gonna be more like 80 feet or so.
Once the bridge is done, then we can put the building up.

We're told that we don't need any permits for tree structures, so, we can
even put a bathroom, kitchenette, bar, etc., there, and not have to worry
about meeting code requirements.
Click to expand...

I love the idea but think there are design issues that need serious
attention.

I always thought that most code requirements were to prevent people from
building structures that would kill them or their guests...

I still don't like the cinched cables as shown in the pictures earlier,
those are stress points and the wire rope is quite a bit weaker now for
them. Have you never looked at how cables are secured when done by
professionals? Clevis hitches, or good splices are best for securing the
rope end. Found a nice page on splices you may want to look at:

http://stoneycreeker.com/knots/knots.htm

I know you aren't the designer (you are one of the helpers), and I am no
expert on wire rope, but I do have a lot of respect for the people who
make it and when they say to follow certain rules I would think they are
the better adviser.

3/8 inch wire rope is rated at 2440 lb safe load...

http://www.engineeringtoolbox.com/wire-rope-strength-d_1518.html

....using well designed cinching. Now you have two ropes, however each of
them must be able to bear the entire load (if swinging for example) so
you really are limited to around 2500 lbs (a bit over a ton) for the
total weight of the rope, structure, and guests. If I am wrong then the
most safe weight load could only be 4800lbs. I'm not an engineer and
thus don't know how to work out the loading factors, but I can add.

Guests have weight.

Have they made allowances for any people to visit? Looks like you can
put five people in it plus a 1200 lb structure (if 2400 lb safe load),
if the average guest is around 200lb. Ten people and you can only have a
simple wooden platform that weighs 400 lbs...

John :-#(#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
On 10/17/2014, 8:47 PM, Danny D. wrote:
John Robertson wrote, on Fri, 17 Oct 2014 18:29:39 -0700:

I still don't like the cinched cables as shown in the pictures earlier,
those are stress points and the wire rope is quite a bit weaker now for
them.

I see you noticed that the cables are currently bending in a sharp
"V" shape where they are holding up the first gang plank.

We all agree that any sharp bend in the cable is a bad thing, but,
that "V" is supposed to be temporary.

The end result "should" be either a catenary or a parabola (depending
on the amount of force downward per linear distance of cable). If that
weight (i.e., force downward) is evenly distributed, the cables will
form a catenary; otherwise they'll be a parabola.

In our case, the owner has stated that each cable can hold something
like 7,000 pounds (IIRC), so that's 14,000 pounds.
Click to expand...

Better check the specs of the wire rope, the owner may be going by the
rated maximum capacity (12,200 lb for 3/8" wire rope) and only derating
it 50%. Note the manufacturer recommends only a 20% load factor for
safety. I don't think that is so they can sell thicker rope...

It also depends on how the load is distributed on the rope, and any
pressure points, bends etc. All of these are part of the 20% safety
factor, or may derate it further.

Please read this article:

http://www.safetysling.com/wr2.htm

and this:

http://www.thetreehouseguide.com/bridges.htm

note the recommendation that only one person at a time is on the
suspension bridge...

Weight of the wood used...

So, lets say you are using 2 X 6 pressure treated wood that is 10 feet
wide. 2200 lbs equals only 68.75 boards - or about 35 feet if laid side
by side. Check the math yourself:

http://www.engineeringtoolbox.com/green-kiln-dried-pressure-treated-lumber-weights-d_1860.html

All this is based on 3/8 inch wire rope with a safety factor of five.

If these guys can afford to build this, they can afford to get a
qualified engineer to aid in designing it to be safe enough that you
would be willing to risk your children on.

I wouldn't let any kids near this design based on what I've seen so far.
Adults can take their chances...

John :-#(#


--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
We don't actually know the distance because the hillside is steep,
so, you can't just run a 100-foot tape measure, but, it's less
than 100 feet by ten or twenty feet.
Click to expand...

The mind boggles ...

With a design factor that important, wouldn't it make sense to use a laser
measure ? These things are dirt cheap now, and accurate to better than a
half metre. Even if you had to shin up that final tree and pin a white paper
'target' to the trunk ...

Arfa
 
John Robertson wrote, on Fri, 17 Oct 2014 23:46:50 -0700:

Better check the specs of the wire rope, the owner may be going by the
rated maximum capacity (12,200 lb for 3/8" wire rope) and only derating
it 50%. Note the manufacturer recommends only a 20% load factor
Click to expand...

I asked the owner about the weight of the deck, where this came back:
https://c2.staticflickr.com/6/5608/14937422664_148d70ba58_b.jpg

Hello Danny:

Thanks for your help last week. I couldn't have done it without you.h

You seemed skeptical about my estimate of the first bridge section.
Given a 2x10 weighs 3.37 lbs per foot.
Given a 2x6 weighs 2.00 lbs per foot.

3x16x3.37 = 162 lbs for the three long boards
2x10x3.37 = 68 lbs for the two end boards

2x6 2.00 lbs/ft
10x2x32 = 640 lbs for the decking

870 lbs per 16 foot section.

So if there are 5 sections (80 feet), or 6 sections (96 feet) we have
4,350 lbs or 5,220 lbs for the deck.

The cables can support 28,000 lbs.

That gives us 22,780 lbs for the house and occupants, assuming the only
support is the cable.

If we allow that some of the weight is supported by the posts and the
trees, we have even more leeway.

If the house is 24 feet long and ten feet wide, it will weigh about 8,000
pounds.

Add 4,000 pounds for furnishings and appliances.
That gives us 10,780 pounds of leeway for occupants.

But I plan to have most of the house weight supported by the redwoods,
not by the cable.
 
On 10/21/2014, 1:10 PM, Danny D. wrote:
John Robertson wrote, on Fri, 17 Oct 2014 23:46:50 -0700:

Better check the specs of the wire rope, the owner may be going by the
rated maximum capacity (12,200 lb for 3/8" wire rope) and only derating
it 50%. Note the manufacturer recommends only a 20% load factor

I asked the owner about the weight of the deck, where this came back:
https://c2.staticflickr.com/6/5608/14937422664_148d70ba58_b.jpg

Hello Danny:

Thanks for your help last week. I couldn't have done it without you.h

You seemed skeptical about my estimate of the first bridge section.
Given a 2x10 weighs 3.37 lbs per foot.
Given a 2x6 weighs 2.00 lbs per foot.

3x16x3.37 = 162 lbs for the three long boards
2x10x3.37 = 68 lbs for the two end boards

2x6 2.00 lbs/ft
10x2x32 = 640 lbs for the decking

870 lbs per 16 foot section.

So if there are 5 sections (80 feet), or 6 sections (96 feet) we have
4,350 lbs or 5,220 lbs for the deck.

The cables can support 28,000 lbs.

That gives us 22,780 lbs for the house and occupants, assuming the only
support is the cable.

If we allow that some of the weight is supported by the posts and the
trees, we have even more leeway.

If the house is 24 feet long and ten feet wide, it will weigh about 8,000
pounds.

Add 4,000 pounds for furnishings and appliances.
That gives us 10,780 pounds of leeway for occupants.

But I plan to have most of the house weight supported by the redwoods,
not by the cable.
Click to expand...

It again all hinges on the diameter of the cable (wire rope) they are
using and how it is secured. If it is 3/8" then I wouldn't go near it
assuming he is going by the maximum load.

Based on his reasoning (28,000 load spread over two cables) he needs at
least 7/8" (12,900 lb safe load each), but 1" (16,700 lb) would be better.

Attaching the house to the tree will save a lot of weight, however trees
grow larger in diameter so the support must allow for that somehow.

Also his securing of the wire rope must be flawless, and the fact that
he has already stressed the rope in a few places with the clamps has
weakened the original wire rope significantly.

However he doesn't appear to be willing to get an inspector, so I'll
assume I'll read about this upcoming disaster in the newspaper in the
near future (next couple of years).

Just because you are clever doesn't mean you are right. Some of us can
be quite smug...(ducking)

John :-#(#



--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
"John Robertson" wrote:

It again all hinges on the diameter of the cable (wire rope) they
are using and how it is secured. If it is 3/8" then I wouldn't go
near it assuming he is going by the maximum load.

Based on his reasoning (28,000 load spread over two cables) he needs
at least 7/8" (12,900 lb safe load each), but 1" (16,700 lb) would
be better.

Attaching the house to the tree will save a lot of weight, however
trees grow larger in diameter so the support must allow for that
somehow.

Also his securing of the wire rope must be flawless, and the fact
that he has already stressed the rope in a few places with the
clamps has weakened the original wire rope significantly.

However he doesn't appear to be willing to get an inspector, so I'll
assume I'll read about this upcoming disaster in the newspaper in
the near future (next couple of years).

Just because you are clever doesn't mean you are right. Some of us
can be quite smug...(ducking)
Click to expand...
----------------------------------------------------------
You can buy them books, BUT if they eat the covers.

Lew
 
On 10/21/2014 4:35 PM, Lew Hodgett wrote:
"John Robertson" wrote:

It again all hinges on the diameter of the cable (wire rope) they
are using and how it is secured. If it is 3/8" then I wouldn't go
near it assuming he is going by the maximum load.

Based on his reasoning (28,000 load spread over two cables) he needs
at least 7/8" (12,900 lb safe load each), but 1" (16,700 lb) would
be better.

Attaching the house to the tree will save a lot of weight, however
trees grow larger in diameter so the support must allow for that
somehow.

Also his securing of the wire rope must be flawless, and the fact
that he has already stressed the rope in a few places with the
clamps has weakened the original wire rope significantly.

However he doesn't appear to be willing to get an inspector, so I'll
assume I'll read about this upcoming disaster in the newspaper in
the near future (next couple of years).

Just because you are clever doesn't mean you are right. Some of us
can be quite smug...(ducking)
----------------------------------------------------------
You can buy them books, BUT if they eat the covers.

Lew


Now days Lew you buy them books and they eat the Teacher!
Click to expand...
 
On Tue, 21 Oct 2014 20:10:10 +0000 (UTC), "Danny D."
<dannydiamico@gmail.com> wrote:

John Robertson wrote, on Fri, 17 Oct 2014 23:46:50 -0700:

Better check the specs of the wire rope, the owner may be going by the
rated maximum capacity (12,200 lb for 3/8" wire rope) and only derating
it 50%. Note the manufacturer recommends only a 20% load factor

I asked the owner about the weight of the deck, where this came back:
https://c2.staticflickr.com/6/5608/14937422664_148d70ba58_b.jpg

Hello Danny:

Thanks for your help last week. I couldn't have done it without you.h

You seemed skeptical about my estimate of the first bridge section.
Given a 2x10 weighs 3.37 lbs per foot.
Given a 2x6 weighs 2.00 lbs per foot.

3x16x3.37 = 162 lbs for the three long boards
2x10x3.37 = 68 lbs for the two end boards

2x6 2.00 lbs/ft
10x2x32 = 640 lbs for the decking

870 lbs per 16 foot section.

So if there are 5 sections (80 feet), or 6 sections (96 feet) we have
4,350 lbs or 5,220 lbs for the deck.

The cables can support 28,000 lbs.

That gives us 22,780 lbs for the house and occupants, assuming the only
support is the cable.

If we allow that some of the weight is supported by the posts and the
trees, we have even more leeway.

If the house is 24 feet long and ten feet wide, it will weigh about 8,000
pounds.

Add 4,000 pounds for furnishings and appliances.
That gives us 10,780 pounds of leeway for occupants.

But I plan to have most of the house weight supported by the redwoods,
not by the cable.
Click to expand...

I see a complete failure to account for wind loads. Wind loads on this
tree house will be larger than the dead loads. Ask the owner to calculate
the wind loads as well.

?-)
 
Danny D. wrote, on Tue, 21 Oct 2014 20:10:10 +0000:

But I plan to have most of the house weight supported by the redwoods,
not by the cable.
Click to expand...

We finished rigging up the second 16 foot section, which missed the
next set of redwood trees by about a foot or two.
https://c2.staticflickr.com/6/5611/15453538738_e049344c53_b.jpg

Unfortunately, those two redwoods straddling the end of the 32-foot
suspended section are just a tad under ten feet apart.

So, we're gonna have to engineer a slight bevel inward, to squeeze
in between those two trees, and then it's on to the next three or
four 16-foot long 10-feet wide sections, all of which is suspended
by ropes and temporary cables, at the moment, as we build it as we
walk out to the edge...
https://c4.staticflickr.com/4/3953/15637200951_f7b58d5ecf_b.jpg
 
josephkk wrote, on Thu, 23 Oct 2014 18:23:37 -0700:

I see a complete failure to account for wind loads. Wind loads on this
tree house will be larger than the dead loads. Ask the owner to calculate
the wind loads as well.
Click to expand...

This is a good point so I will mention it to him.

We worked on the second floating 16-foot section today, by the way.
https://c4.staticflickr.com/4/3955/15459997077_b22b960f68_b.jpg

So now we're suspended 32 feet straight out.

Only 60 or so feet to go!
 
dpb wrote, on Thu, 23 Oct 2014 07:36:12 -0500:

> T=W/sin(angle) = (W/2)/sin(11) --> 2500/0.2 --> 12,500 lb

Wow. Those were wonderful calculations.
I forwarded it all to my friend, and will reply back with his response.

Meanwhile, we worked on the second section today, and we ended up stopping
about 2 feet away from redwoods which we need to squeeze through.
https://c4.staticflickr.com/4/3937/15460483990_09bffcce41_b.jpg
 
CRNG wrote, on Thu, 23 Oct 2014 12:40:15 -0500:

I don't think they are taking heed. They have been successful with
their little neighborhood projects, and they are starting to get over
confident.
Click to expand...

I think the owner is taking heed, it's just that he's a third party
to this conversation (he doesn't know Usenet). :)

BTW, here's a view from below today, when I dropped my glasses
and had to climb down the steep hill to retrieve them.

https://c4.staticflickr.com/4/3943/15645979325_89a8481615_b.jpg
 
dpb wrote, on Thu, 23 Oct 2014 13:35:20 -0500:

Of course, if the droop angles are significantly larger than the assumed
10 degree or so, then they gain a fair amount by there being a larger
vertical component but it's too spooky by far as described and shown
Click to expand...

I'm sorry I haven't responded in a while. I hurt my back and was laid
up but hopefully I'm better now ...

The whole thing is supposed to hang from the cables, but we did anchor
one end because we needed a way for people to get "on" the decking.

Here's where we left it today...
https://c4.staticflickr.com/4/3945/15459995717_3722bf0914_b.jpg
 
CRNG wrote, on Thu, 23 Oct 2014 08:05:45 -0500:

Good analysis. Unfortunately Danny D and Friends just don't seem to
understand what the effect of the catenary configuration has in
increasing the tension in the cable. I really hope someone convinces
them to have a engineer look at their exact config and do some simple
calcs as you have done above.
Click to expand...

I'm sorry I haven't been able to respond lately.

We had to readjust all the cables today, with a set of 5 winches, as
we had to re-balance everything once the second 16-foot section was
planked.

Unfortunately, I ruined my clothing, as I hadn't expected the oil
to still be soaking wet ... even though it was drying outside for
a day ...

https://c2.staticflickr.com/6/5616/15645979935_55c2665284_b.jpg
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top