Existing Vessel with Platform Inside a Buildiing 1

[MikaelaD]

Hello,

I am a mechanical engineer and I am tasked to add a small piece of steel on an existing top platform to support a 1000 lb pipe load. The top platform is installed on an existing small pressure vessel that is located inside an enclosed building with no windows, just doors. I’ve asked the help of a structural engineer to check the design of the top platform with the new pipe load. The top platform is failing. When I looked at the calculations, I noticed that wind loads were considered in the analysis. I asked the structural engineer why consider wind loads when the platform is located inside an enclosed building. He said per the building code, internal wind pressure needs ti be considered.

Questions: (please forgive my ignorance with building or structural codes)
1. Are the internal pressure or suction due to wind applicable to objects not attached to the building structure?
2. Are the internal pressure or suction due to wind more applicable to the structure itself, i.e. outer walls, top ceiling?

 

[1503-44]

I dont think it is logical. And, if there are internal wind loads, they must be relatively very small. What wind velocity did he use? That said, I might worry that what must be a relatively small lateral load causes failure of the platform. It must be quite a border line design. It also makes me think that it might not be fit for service, if you were to consider maintenance or other potential small lateral loads.

I guess it is not subject to earthquake loads either.

 

[r13]

Did any body ever apply wind load on the interior structures but the enclosure walls and roof? The answer apparently is no. The only occasions I've considered wind is when the equipment/platform been placed directly on the wind path without obstructions. It is rare though. Are you in a low/no seismic activity region? Otherwise it should govern. It seems the platform is too flexible, that would fail under wind load.

 

[dik]

Two different loads. Internal wind pressures are often used for design of interior partitions.

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

 

[JStephen]

I would say that there is a good chance that the vessel designer simply didn't know if the vessel was inside or outside, whether the building was enclosed or partly enclosed, or what. That should not be the case, but on a lot of these things, people act like it's some big secret just to tell you where the thing is even located.

 

[r13]

dik,

So do you place wind load on floors (similar to flat roof)?

 

[JoshPlumSE]

I'll also point out that there is a difference between a truly enclosed structure and a partially enclosed structure. It doesn't take all that much to be considered partially enclosed. 20% of one wall, or 10% of the walls in general (IIRC). For some industrial structures with roll up truck doors, getting to that 20% may not be all that difficult. And, some engineers may consider that partially enclosed (because those doors may be open for long periods of time.

 

[r13]

If anybody has examples on wind design for interior structures, or code provisions, please share, it will be worthwhile to know.

 

[dik]

not yet... but I have for partitions in some cases... in particular tall ones... like 30' high. Floor design loads are generally a magnitude greater...

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

 

[r13]

Here is an old thread. It seems the prevailing consensus of wind load on interior partition was 5 - 10 psf, with the majority lean toward 5 psf then. Link

 

[1503-44]

That sounds reasonable. I close the garage door when it rains.