Light Pole to Handrail?

[Rabbit12]

Thoughts on this?

I know there's been some discussions on here about handrail posts and how it's tough to make those work on paper. What if you also add a light pole and a luminaire to the handrail? I can't imagine someone being on a service platform in a design wind event, but could see someone being up there with a 40 MPH wind. If that's the case and you combine LL+WL your posts almost certainly fail unless they've been upsized.

 

[r13]

I guess this is a vendor's illustration, the connections seem quite loose. I think you can/need to find ways to modify the way how it's attached/supported. The railing post may, or may not, require up-size.

 

[STrctPono]

For a permanent situation, my gut feeling is that I don't like it. I would consider welding a double stiffener plate to the girder below and connecting to that.

 

[dik]

Can you use shear connector plates welded to the handrail vertical and treat it as a Vierendeel truss? Just curious... and need to fix the base a bit.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik

 

[bridgebuster]

Some thoughts...Can you place the railing post and the light post on a single base plate? If not, can you anchor the light to your walkway, assuming you have concrete or steel grid deck? A few years back we did a sea wall replacement in a park along a river in NYC. There was one section where the owner wanted a walkway over the river - grid deck on steel stringers - so that pedestrians could see the moving water below them. We had a fancy railing, combination railing post and light post, bolted to the grid deck. A little annoying for the grid deck supplier because they had to beef up the bearing bars but it was doable.

 

[1503-44]

Lights supported by handrail? Wow. Great idea.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

 

[Rabbit12]

Thanks for the responses guys. I'm not looking for changes to the detail, I'm looking for your thoughts on the detail. Is this support condition a non-starter for you? If not, would you combine WL and the 200 lb code guardrail force? What WL would you use?

 

[r13]

Ideas,

 

[1503-44]

I've been shocked by touching a light pole once. I wouldnt like one connected to a metal handrail in any manner. I think the light poles could also act as a lightning rod, so you see where that might lead.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

 

[r13]

Will proper grounding alleviate your concern? Good point though.

 

[STrctPono]

Non Starter for me. But if you are to explore it then I do not think that it is required to combine both the 200lb guardrail force in combination with an extreme level wind load. My thought is that the wind load on the pole is going to govern the design of that guardrail post all by itself.

 

[1503-44]

I still don't see why it has to be connected to handrail.
Most of the time I see the deck extended outward with pole attached to deck.

Grounding Light Poles

https://www.eng-tips.com/viewthread.cfm?qid=228651

Hopefully the handrail would not provide a better ground path.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

 

[Rabbit12]

StrctPono, thanks for the response. For the most part I'm with you on the non-starter. However, this is the second time I've brought this up and the first time I got responses from the electricals saying, "We've done this forever!". I suspect no one has really put pen to paper on this and to really get any traction for change I'm going to have to have some numerical backup.

So let's say for the sake of argument we will entertain this. The load cases would be: 1) WL only 2) 200 Concentrated or 50 plf 3) Combo of the 2) and a reduced WL.

For a reduced WL does a 40 MPH wind sound reasonable? These are maintenance access platforms so I can't see someone being up there with a 120 MPH wind.

-twentytwo, good points. I'll use that too.

 

[r13]

Yes, put your numbers to show it won't work, or not worth the troubles, with the backup of your superior.

 

[JLNJ]

I think you could make a case for the two loads not having to be combined. Are you really going to have max guardrail loading and max wind load at the same time? No.

I say center the light between posts and don’t worry about it if the wind load doesn’t exceed 200 pounds.

 

[Rabbit12]

JLNJ, I agree max and max doesn't need to be combined I've said that a couple times. I do think you need to combined some level of wind with the guardrail force. It's a question of what that is IMO.

 

[dhengr]

Rabbit12:
Since they say…, "We've done this forever!", or ‘we’ve always done it that way,’ they should be able to show you all the details from the luminaries on down to the junction box, the hardware and its suppliers, all material sizes and grades, calcs. and permit approvals, meeting the codes. They should be able to show that their half-assed details, as shown, meet the code and have been accepted by various AHJ’s. More likely than not, the fact is, that they just put em up the simplest way possible for them, and didn’t give it a second thought. It didn’t fall or slip down when they tightened the second pipe clamp around the handrail post (self weight only), and that was that, and it hasn’t seen a design wind load since. And, now they want you to bless, or prove that their details are adequate, or warrant them with your stamp.

I would argue that it should be worst WL + 200lbs, or maybe the projected area of two workers and their tools in that wind. I wouldn’t expect anyone to go up there for the fun of it, in a wind storm, but they could get caught up there in a sudden storm or have to go up there in an emergency. So, I’d use something greater than a 40mph design wind. That’s the old engineering judgement thing rearing its head again. Since these are individual maintenance platforms (not 2 miles of city/river walkway, with a light post every 200’), they should give direction as to location and number of light posts and luminaries and you should design the platform for the added loads. They should assist you with their/any special detailing and hardware needed down to the base of their light post. It probably will be more practical/economical to use one pipe post for both functions, at those locations, but it will involve something other than std. pipe handrail hardware/fittings at those locations, for the larger light post. I assume that you control the platform framing, and it will have to be sized up at these locations. Maybe a fairly std. base detail can be developed which will work with many of your std. platform floor framing systems. A detail which distributes this new loading back into the platform fl. system, not just into the edge beam, in torsion.

 

[IFRs]

Seems to me that if you were up there in max wind, it is likely that you would need the handrail more than at any other time and therefore it should be designed for the combination. You could make the argument that the max wind is a short term gust and use a modification factor but I'd still combine them. I would not want to be in front of the judge who asked why the handrail was unsafe when the wind was blowing, since it makes sense that the worker would most need the help of the rail during adverse conditions. I for one don't want to be up on a piece of equipment that needed attention to secure it from a storm and needed to consider if the handrail would still keep me from getting killed because engineers might not have combined those loads.

 

[1503-44]

I have never used an "incidental load" < 1000 lbs when designing maintenance platforms. 200 lbs excludes a lot of people if they bring along a tool box and one or two replacement parts.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

 

[Settingsun]

If your local code doesn't cover combining wind load for this case, you might look to Eurocodes. I believe the general building code uses full live load plus 0.6*max wind, or full wind plus 0.7*live. There may be a more applicable code though.

How well does the I-section stringer handle the torsion?