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waterslide steel supports

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发表于 2009-9-16 19:17:18 | 显示全部楼层 |阅读模式
waterslide steel supports
i posted this in "corrosion engineering" earlier today, but no responses yet.  i trust other structural engineers have dealt with steel structures in contact with pool water...
i am working on a job where an existing wood platform with steel supports for a water slide (appx 32' tall) has severe corrosion of all the steel members used to support and connect the wood.  the steel beams and columns are experiencing large amounts of section loss.  the pool operator says it is from the chlorinated water that drips off the bodies of the people waiting, but also because when someone sits in the slide at the top the water jets will shoot the water at their back and it will reflect back and pour down over the platform.
the slide design is set, and we will have this problem with large amounts of chlorinated (or maybe it's bromine?) water pouring down the steel and wood.  they will be replacing much of the platform and stairs.  what is the best way to protect this steel and the steel fasteners in wood?  is galvanizing enough?  stainless steel or galvanized fasteners?  do we just have them prime and paint on regular intervals?  any suggestions?
structural shapes and   
civilperson,
this twenty years, to my knowledge is theoretical only. these products do not have long usability history yet.

over thirty years use in dairy and milk processing plants.
civilperson,
i did not mean to offend u in any way. just want to learn my self too. i only know steel, aluminium and concrete as structural   
stainless oe even aluminum will work just fine - but very expensive....and still must be inspected regularly. painting or galvanizing is cheaper but must be maintained on a regular basis....or what about all wood ----
how long did the original project last??? if its 10 or 15 years then what are they complaining about??
the original project lasted almost 25 years now.  but if i can add $10k to the original cost and make it 50 years that's what i want to do.  it's not cheap to replace the whole thing every 10-15 years.
can you tell what coating system was on the original structure?
i would think hot dip galvanizing is best for this application, combined with using heavier than structurally necessary   
hot dipped galvanized is fine.  make sure you specify the thickness of the galvanizing (g90 or greater)and then have it testeds.  also visually check it for insufficient coverage.  have the galvanizing done after any welding, then use bolted connections from there on.
both chlorinated and brominated water will cause corrosion.
you can go to stainless steel; however,i've worked on 4 or 5 major water slides and they were performing as expected with galvanized steel.  a couple of them had some stainless parts, but if there is a good annual inspection program (as required in my home state) stainless is probably not worth the extra cost.
on the point of no intenationally recognised codes for frp and gfrp, try the following:
can/csa s806 "design and construction of building components with fibre-reinforced polymers"
and for fibre reinforced pulltruded plastics (the stuff you're really talking about in this thread), i know that there was a model astm code in the works five years ago.  i would expect it is either about to be released, or perhaps is already available.  the draft code document was x-20-43 "draft structural grade plastic lumber standard"
and good luck with the project;  i would not hesitate to specify/recommend/use structural plastics for this application.
cheers,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...
apparently still no consensus on the draft standard as of 2007, but i did note a name change!
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