Embedment of Guardrail Post in Concrete slab

[Lina]

I am looking for a good reference or a tip to design the embedment of aluminum or steel guardrail's posts in concrete slab. The post as per local codes is subject to a lateral load of 200lb or it could be much higher if the post is a member of an exterior glaized railing where the system is subject to wind loads. I have seen other engineers using formulas that I am not familiar with and I could not locate any reference material on these formula.

a= 2 M2 + 3L.M /3M + 6L


P2= a2 x P / [M(2a-M)]

M is the embedment length of the post in the concrete slab
L is the height of the guardrail post
P is the lateral load applied on the top of the post described abve
P2 is the resisting force to P below concrete slab

 

[Lina]

I have made a mistake in the formulas while typing please review these corrections.

a= 2 M^2 + 3L.M /3M + 6L


P2= a^2 x P / [M(2a-M)]

 

[ishvaaag]

You will have guide for railings in AASHTO specification of 1989 Guide Specifications for Bridge Railings.

In any case I see your problem one of taking Moment and shear at the base by embedment. Normally this will be taken the moment by a pair and the shear be added when otwards in the edge of the slab to force coming from the moment be in the same sense. Then you have to check the aluminum tube be stron enough for what intended, and if the lateral cover of the embedment is scarce, add reinforcement anchoring the concrete in the outwards part in proper manner.

Furthermore in architectural applications no cement contact to aluminum is permitted since it stains it. So maybe a base anchoring plate with a stup protruding to which to bolt or so may be one alternative solution...what metal, if inoxidable might be the aluminum the sacrificial then maybe ordinary steel painted would be good enough; ensure no liquid water enters then the steel part.

 

[atilashorse]

Hello!

You can embed aluminum posts in concrete if you coat them with rubberized aspahlt or other material (search the web, there are many materials).

The 200 lb requirement is a minimun requirement, I iunderstand it is people's load. By the way, I have seen engineers don't usually factor this load as per AISC. If you have wind loads in panels, you will have to consider them.

What usually governs is the concrete shear strength. I am having trouble right now finding the appropiate concrete shear area calculation for a post embeded in concrete, subject to lateral load. Can omebaody can give me some indication, please?