Liability for harness tie off 3

[glass99]

A glazier has asked me to provide structural calculations for a concrete anchor bolt use to tie off his harnesses which he will use in multiple locations on a skyscraper during glass replacement. They do the replacement from the inside of the building, and the anchor bolt will hopefully never see load.

Is this a high liability assignment? Would I be named in the lawsuit if there was an accident unrelated to the anchor failing ? Or is this more like designing a catwalk for an industrial plant?

 

[AELLC]

oops hit the send button .

La Fonda

http://www.lafondasantafe.com/accommodation/

 

[glass99]

Oy Vey is right. I would rather have a plywood floor. I have used cement board on top of light gage metal studs for floors, and its rock solid and cheap. Although maybe not cheap enough.

 

[AELLC]

The best most practical method for customs is 1-1/8" T&G, glued and screwed. The builders here have a cute slang for that which is unprintable.

 

[glass99]

Developers are so frigin' sketchy it makes me want to puke. No corner left un-cut! Why use metal when plastic is cheaper? The condo owners are too f*cking dumb to know the difference! That is until they wise up and hire someone smart like Ron to do a forensic investigation, and they turn into a lynch mob hell bent on retribution.

 

[AELLC]

Tract home builders are the worst, but the few that I deal with are relatively polite.

Tract is only about 10% of my biz anyway.

Back when I did wood condo and multi-family (I was an employee), it took 6 months for the daily revisions to stop. That left me burned out to the point I couldn't do that stuff anymore. The construction methods were not as shabby as tract, but it took 6 months to finish every project, and I like to get things done with less revisions and confusion.

 

[glass99]

Speaking of liability:

I have a client who wants to build a structural glass slippery slide on the outside of a skyscraper right on top of a seismic fault, from the 70th floor down to the 69th floor . Basically a big glass tube. Cost is no object. What could possibly go wrong?

 

[AELLC]

I am glad I am not in your biz.

I did work on the Stratosphere Tower in LV that made me very nervous, but am glad I survived that.

 

[glass99]

The difference between the glass slippery slide and the harness anchor bolt is that we are going to engineer the pants off the slippery slide. The whole enchilada, including fancy materials, prototypes, testing, fancy FEA, quality control to aerospace standards, peer review, and they are going to pay for it. Everyone expects the anchor bolt to be nothing and easy, so they pay for like 5 minutes of your time, but you are just as liable.

The roller coaster thing on the top of the Stratosphere tower is a similar concept.

 

[AELLC]

I had nothing to do with that roller coaster, but the stuff I did for the MGM Grand Amusement Park was a royal PITA.

I do have a slightly funny story about the "Stupak Tower" and a few not so funny.

 

[NorthCivil]

I imagine this customer is a repeat client, needs a stamp for his roof anchor, and because glass99 is his guy, he needs to do it. if not for this job, then to keep the next ones coming in.

What do they want to hang? a swing stage or just a bosun chair? I would over engineer the hell out of it, with backup supports should one fail for whatever reason. Tell them your going to need a big chunk of change to pay to up your insurance- this scope of work carries high liability. Inspect the installation, and stipulate that once the work is complete, the anchors must be removed.

Believe it or not, construction workers have been taking care of themselves for years, hanging swing stages and bosun chairs off the sides of buildings safely. They aren't just hopping on any shady line 300ft up. My guess is this request originated with the general contractor. Large contractors are so concerned with liability that the safety requirements on building construction sites have gotten ridiculous in recent years. I wouldn't be surprised if you give your client a bill, they'll pass it on to the general as an extra, and suddenly the glaziers won't need engineered supports anymore.

 

[glass99]

NorthCivil: You have described the situation pretty much bang on. Its a repeat client and a bit of an over-cautious request from the building owner to be "safer". The only difference is that these anchors will probably never see load because they are just a harness tie off on an as needed basis. If they have a broken facade panel on the 25th floor, 11th bay from the east, they want to pop an anchor in only at that location. No one should ever hang from the anchor because they do the work from the inside. They asked for some sort of powder actuated fastener so that the anchor can be installed quickly, though that's probably going to be hard for me to sign off on. Its going to be hard to inspect.

 

[miningman]

Well without wanting to get sucked into discussions on timber vs concrete , the rule of thumb I use for such anchors is they have to withstand 5000 lbs. Now in good rock conditions I can get this quite easily but the hardware I use, and installation techniques are a bit more substanstanial than the average dummy GC might be expecting, and I certainlly wouldnt trust any kind of explosive actuated tool. And the main practical issue is the quality of installation ...... I can and do a design for 40,0000lb loads , but if the guy doing the install is not the same guy whose life is on the line when a load is put on the anchor , my enginneering calcs arent worth a pinch of s**t

 

[NorthCivil]

glass99,

Now i see a little more clearly what you've got going on. I had thought you needed an anchor to the roof, to hang over the side. You really just need an anchor for the guys working on the inside, in case they fall out the open hole.

I'm really not a fan of the idea of powder actuated fasteners into concrete. you never really know what the shape of the concrete is that you are nailing to. into steel would let me fall asleep a little easier. Still surprised this is the way they want to go about it... why not let the tradesmen figure out where to tie their harness ropes around the nearest sound spot? Classic case of a bunch of suits over complicating things. And they say us engineers have our heads in the sky...

 

[NorthCivil]

I would have a quick word with your client about the absurdity of the situation, and give him a big fat quote for the job, quickly detailing why its so expensive. have your client pass it along to the owner, who can get all upset about it. Either he'll decide he doesn't need the anchors stamped, or he'll pay the bill. Win-win either way. If he pays it, then the next time you have a slow afternoon you can take your client out to a round of golf.

 

[glass99]

@NorthCivil. Yes, the situation is madness. Not only is the work being done from the inside of the building, but there is 3 ft tall solid wall above the floor before the glass starts, so you have this barricade preventing you from falling out. It is a matter of people in suits trying to transfer risk from their ledger to mine.

@miningman. Thanks, good to hear what other folks are using. 5000lb is a lot, but I guess you don't want to mess with safety.

 

[racookpe1978]

OSHA require a "PE-designed"/"engineered" certification for any anchor used to tie off a worker.

5,000 lbs load per person for each anchor requirement. That is, one anchor per person, that anchor needs to be rated to 5000 lbs for aperson to tie off their harness to. So, find an interior wall for each room, drill through to the other side and bolt a backing plate on each side. The anchor bolt goes through the wall with a loop on each end for the tie off hook.

to prevent future liability (er, use) require the anchor bolts and plates be removed when done.

 

[glass99]

rocookpe1978 - thanks, i didn't know that the 5000lb thing was actually an OSHA requirement. Good to know!