Existing Mezzanine Rating

[TaylorBL]

I have been asked to provide a live load rating in psf of existing mezzanines in a manufacturing facility, I assume for insurance purposes. ASCE 11.1.2 says "Existing structures and alterations to existing structures need only comply with the seismic requirements of this standard where requried by Appendix 11B."
I believe the client is only looking for vertical loading rating, but not sure this is the only consideration that should be incorporated - i.e. seismic considerations.
Thoughts of whether seismic forces should be used in the evaluation of the ratings?

 

[JAE]

You have two compelling tasks to perform here:

1. Meet the expectations of the client in terms of their need to satisfy their insurance company - i.e. gravity check to post live load capacities.

2. As an engineer - protect public safety and welfare and if you suspect there is no complete lateral load path for the mezzanine - inform them separately in a letter that you suspect (you don't positively know for sure) that there may be a problem with the lateral stability of the mezzanine and that you would recommend that they have it investigated further either by you or any competent structural engineer.

 

[dhengr]

I absolutely agree with JAE. But would add, that your compelling tasks include; don’t make assumptions in cases like this, talk with the client and find out exactly what they need and explain JAE’s two comments to them in detail. ‘We want to know what it’ll carry’ is what they would ask you, they don’t know any better, but you should. You can’t ignore the possibility of lateral loads if they are likely, and they can’t afford to B.S. their insurance company if they expect coverage. The insurance company wants to know what they’ll be insuring against, not what will this mezz. carry under ideal conditions. I would assume that the intent of the code is to say that you don’t have to redesign or rebuild the entire building if it meet code, when built; but you do have an obligation to inform the client of the real situation as it relates to today’s standards and codes. And, furthermore this mezz. is, in effect, a separate structure, maybe braced by the building, and the insurance company may insist that it meet current codes to be insured. They will likely find any deficiency if/when asked to cover a claim, and your explaining then is no fun and is ruinous to your reputation.