cable suspended bridge

[JasonG]

Yowza!

[mattp]

Thanks for the ideas. Any personal references, pictures, stories, information or just fluff would be appreciated. Trees are cool. Catestrophic failure would be bad. We hope to build something cool.

[lummox]

The force distribution at your bridge's anchors does not have to be equal. The SAS going up for east span Bay bridge is an extreme example. Course, you probably have a budget.

[RuMR]

Matt,

 

You being a lawyer, i don't have to advise you on the legal/ethical issues of erecting a semi-public structure where a structural failure has the potential to injure or kill someone.

 

You better get this engineered by a professional engineer. Fees will likely be high but will pale in comparison to what it will be if you kill someone. Also, you don't want that on you either ethically.

 

Rudy Ruana, PE

[RuMR]

My wife is a bridge engineer (she built the new red bridge over the NF Snoqualmie on the way to Little/Mt Si). She said suspension bridges are a whole different ball of wax. Good luck.

 

Damn...we tried to get that bridge!! We did get the index bridge waaaay back when...

[Ed_Hobbick]

I'm wondering if you could bore a hole directly through the middle of the anchor tree's trunk and then run a long eye bolt through the tree, finishing with a washer and a nut. The eye of the bolt could be set out a ways so that the tree would not grow over it for a long time. I think that this way might have less impact on the tree than an anchor method that circumscribes the tree. This is just a thought.

[AlpineK]

Circumscribes or girdling the tree is a bad idea. If you want the tree to live and or keep failure risks low that is. It does take a little longer to choke a woody plant compared to a human or animal, but it will happen as the tree grows.

 

A cable with a eye bolt may work. It depends on bridge load requirements. Threw bolts and cables are used to reduce risks of failures in trees at times.

 

80-feet is a long way up. Maybe an elevator is a better idea. A nice set of stairs descending to near the base of the tree then an elevator. You could set up zip lines for folks exiting the tree. Using a harness and signing a waver that is

[Stefan]

Matt,

 

After visiting www.treehouses.com , I suggest that you either hire a PE or SE to design your bridge, or devise another means of access. You are incapable of designing this structure yourself.

 

In 2008, a suspension bridge at the Treehouse Hotel failed, pitching a family from Kirkland off and to the ground. Because the owner is a scum sucking asshole who designed the bridge himself, has no permits or building inspections, Josephine County ended up party to the suit because they allowed continued use of these non-inspected structures. So now the tax payers need to pony up $1.2 million.

 

I don't know what fiduciary responsibility Mr Treehouse was held to. But now Josephine County is shutting him down, and he is aghast at the county for doing so. Which is reasonable, because his fuck ups have only cost the county $1.2 million, he should be allowed to continue until he costs them another $1.2 M.

 

Holy canneloni. I was there in 2008! this musta happened after I was there. Wow. I did not know about that!

[DPS]

DPS: our bridge won't have to carry cars. I think we can stretch some cable across the void and it'll "work" but we may have to guy it out to trees or other anchor points off to the side of mid-span in order to make it comfortable.

 

My comment of susupension bridges being a whole different ball of wax was meant to convey that even within the bridge engineering community, suspension bridges are considered a specialized niche.

[RuMR]

DPS: our bridge won't have to carry cars. I think we can stretch some cable across the void and it'll "work" but we may have to guy it out to trees or other anchor points off to the side of mid-span in order to make it comfortable.

 

My comment of susupension bridges being a whole different ball of wax was meant to convey that even within the bridge engineering community, suspension bridges are considered a specialized niche.

+1

 

Also, AASHTO pedestrian loading often will exceed truck loading.

[Ed_Hobbick]

I'm thinking that a guy could cut to the chase by talking to an Arborist and an Architect. The engineers seem to get too anxious when it comes to actually building/doing.

[RuMR]

 

[num1mc]

I'm thinking that a guy could cut to the chase by talking to an Arborist and an Architect. The engineers seem to get too anxious when it comes to actually building/doing.

 

I'll cut to the chase, that's sub-retard level idiocy

[DPS]

The engineers seem to get too anxious when it comes to actually building/doing.

 

I have a hard time believing any municipality would issue a building permit without plans stamped by a P.E./S.E. and building anything without a permit sets one up for huge liability not to mention if an inspector sees it they will likely make you dismantle the structure. (Inspectors can be a bit vindictive this way). As a third generation builder I've seen it happen.

 

I recall one family who built a waterfront home on Bainbridge (or was it Vashon) Island on a steep slope. The homeowner built a concrete retaining wall without engineering or permits. An inspector 'red tagged' the home citing the retaining wall was improperly engineered and built. The homeowner went through political channels to reverse the inspector's decision and the red tag was removed. Next heavy rain event the retaining wall catastrophically failed and the hillside slumped, knocking the house off the foundation and into the water, burying it in the process. The entire family died.

Edited September 22, 2011 by DPS

[Tyson.g]

The engineers seem to get too anxious when it comes to actually building/doing.

 

I have a hard time believing any municipality would issue a building permit without plans stamped by a P.E./S.E. and building anything without a permit sets one up for huge liability not to mention if an inspector sees it they will likely make you dismantle the structure. (Inspectors can be a bit vindictive this way). As a third generation builder I've seen it happen.

 

I recall one family who built a waterfront home on Bainbridge (or was it Vashon) Island on a steep slope. The homeowner built a concrete retaining wall without engineering or permits. An inspector 'red tagged' the home citing the retaining wall was improperly engineered and built. The homeowner went through political channels to reverse the inspector's decision and the red tag was removed. Next heavy rain event the retaining wall catastrophically failed and the hillside slumped, knocking the house off the foundation and into the water, burying it in the process. The entire family died.

 

Wow!

Holy Shit!

I guess engineers do learn something in school after all.

[AlpineK]

I'm thinking that a guy could cut to the chase by talking to an Arborist and an Architect. The engineers seem to get too anxious when it comes to actually building/doing.

 

I believe you would want to include an engineer along with the architect and qualified arborist (not some dude with a chain saw and pick up ). The project probably requires a few other specialized skills. I don't think there is any cheap way to build something like a public or semi-public tree house.

 

Maybe building a cabin overlooking the ravine is a better idea. You could set up rope courses and a small platform in the tree for folks interested in climbing the tree. Less potential damage to the tree and less liability overall. Ski areas keep the base lodge open and maybe a few limited lifts open during adverse conditions like high winds or avy danger.

[num1mc]

 

I recall one family who built a waterfront home on Bainbridge (or was it Vashon) Island on a steep slope. The homeowner built a concrete retaining wall without engineering or permits. An inspector 'red tagged' the home citing the retaining wall was improperly engineered and built. The homeowner went through political channels to reverse the inspector's decision and the red tag was removed. Next heavy rain event the retaining wall catastrophically failed and the hillside slumped, knocking the house off the foundation and into the water, burying it in the process. The entire family died.

 

I call bullshit on this one. Unless DPS has a source, I think this is a grossly exaggerated urban myth. It is probably a synthesis of a real life structural failure during a suburban mass wasting event, and the avalanche deaths of the entire Eggers family at their Yodelin cabin in 1970

[DPS]

I call bullshit on this one. Unless DPS has a source, I think this is a grossly exaggerated urban myth.

 

From the USGS: http://pubs.usgs.gov/of/1998/ofr-98-239/ofr-98-239.html

 

"The Bainbridge Island landslide at Rolling Bay Walk is about three houses north of one that was pushed off its foundation on April 23, 1996 (#20, plate1.html; fig. 2). The landslide scar, deposits, and overturned house were still intact at the time of our observations, except for the disturbance caused by recovery operations. The scar of the slide was about 15 m wide, 15-20 m high, and averages 1 m deep. News reports indicated that the owner had built a retaining wall of unknown quality and design (Maier, 1997; Crist, 1997). Newspapers and a local resident indicated that the landslide happened shortly before 8:00 a.m., Sunday, January 19, 1997 (Maier 1997). A neighbor stated that the landslide lasted only a few seconds (Bjorhus and Tu, 1997). The row of houses appear to be constructed in a cut at the base of a steep bluff that rises from a narrow beach area. We observed scars of many old landslides on the bluff to the north of the houses. About five recent slides from 1996 and 1997 storms were visible along undeveloped bluffs not far north of the houses. More slides occurred at Rolling Bay Walk on March 18 and 19, 1997; these slides damaged two houses and pushed another house onto the beach (Wallace, 1997).

 

The Oregonian: http://geography.uoregon.edu/mcdowell/geog322/newspaper_stories/seattle_area_mudslide_kills_family.htm

 

The Seattle Times: http://community.seattletimes.nwsource.com/archive/?date=19970120&slug=2519698

 

"The force of the slide flattened recently built retaining walls on the slope, officials said, pushing the house off its foundation and across a concrete walkway along the shore called Rolling Bay Walk. The two bottom floors of the house were buried in mud 8-feet deep in spots. Only the unfinished top floor of the house, which toppled on its side into the water, was visible."

 

 

 

 

Edited September 22, 2011 by DPS

[DPS]

BTW, do you like apples?

[sobo]

BTW, do you like apples?

Good one, Dan!

 

[ivan]

BTW, do you like apples?

:lmao:

[sobo]

I'm thinking that a guy could cut to the chase by talking to an Arborist and an Architect. The engineers seem to get too anxious when it comes to actually building/doing.

Too anxious, eh? OK, we'll remember to slack off on our "anxiety" a bit when we come around to engineering anything for you and your family...

 

FYI, engineers have a professional AND ETHICAL DUTY to protect the public in whatever we design and build. This duty can be traced all the way back to Babylon, in the Code of Hammurabi.

See Canon #1 below, from the American Society of Civil Engineers Canon of Ethics.

 

1. Engineers shall hold paramount the safety, health and welfare of the public and shall strive to comply with the principles of sustainable development in the performance of their professional duties. (emphasis added)

 

From here: ASCE Canon of Ethics, which is required reading for all registered professional civil engineers in America.

Adherence to the Canon in its entirety is compulsory and mandatory - it is not discretionary.

 

Yeah, we're just too damned anxious about that "safety, health and welfare of the public" thing...

[sobo]

My wife is a bridge engineer (she built the new red bridge over the NF Snoqualmie on the way to Little/Mt Si). She said suspension bridges are a whole different ball of wax. Good luck.

 

Damn...we tried to get that bridge!! We did get the index bridge waaaay back when...

Didn't your firm and another (in a JV or partnership) win the D/B of the new Tacoma Narrows Bridge? I'd say that's a true winner and quite a prestigious grab...

[DPS]

My wife is a bridge engineer (she built the new red bridge over the NF Snoqualmie on the way to Little/Mt Si). She said suspension bridges are a whole different ball of wax. Good luck.

 

Damn...we tried to get that bridge!! We did get the index bridge waaaay back when...

Didn't your firm and another (in a JV or partnership) win the D/B of the new Tacoma Narrows Bridge? I'd say that's a true winner and quite a prestigious grab...

 

My wife is a DPW now. She managed the project for King County when she was a bridge engineer there. The design was done by a consultant, but she did pick the colors - her school colors to be exact.

[sobo]

Your wife's a Director of Public Works? Where? Can you get me a job?