Use of neoprene gasket to minimize thermal transfer 1

[enigma2]

I have a situation where the architect has designed a trellis at a roof terrace that is offset from the main column line of the structure. As a result, it is necessary to affix a tube column to the flange of the main building column to carry the trellis. The architect is concerned about thermal transfer. Instead of welding the tube column to the main building column, I have welded plates to each member and created a moment connection. However, they are requesting a neoprene gasket between the two plates to minimize thermal transfer. Has anyone had any experience with this? I know there will be non-uniform load on the gasket and I don't want it to compress too much, but I don't want anything too thin that the steel will cut it and render it ineffective. It is different from a typical bearing pad because the installation is vertical and not horizontal. Any insight would be appreciated.

 

[Redfish205]

Is he dead set on neoprene or will he agree to something like a Teflon plate similar to what would be used at a slide bearing type condition? I believe Neoprene is going to compress considerably no matter the thickness.

 

[enigma2]

They are open to any product that will minimize thermal transfer. The neoprene gasket was the architect's suggestion, but I am open to any rational idea, especially because I only have about 1/2" wiggle room to fit in some kind of thermal barrier. Someone else has suggested Sorbtex to me. Does anyone know about this product?

 

[boo1]

Consider a bearing grade material (like Delrin), analysis is required to check bearing stresses.

 

[enigma2]

Is Delrin something that is readily used in structural applications? And, will the contractor be able to find it? I found a data sheet on the DuPont website, but I need info on compressive strength which was not avialable.

 

[Redfish205]

http://www.sepbearings.com/fluorogold.pdf

Not sure if this is applicable to your situation, but have used these before.

 

[boo1]

There are many polymers that can be used in this application. Delrin and Teflon are a two of the most common polymer bearing materials used.

Delrin® possesses high tensile strength, creep resistance and toughness. It also exhibits low moisture absorption. It is chemically resistant to hydrocarbons, solvents and neutral chemicals. These properties along with its fatigue endurance make Acetal DELRIN® ideal for many industrial applications. I find it is a very cost effective material. You buy it from McMaster carr.

Some of the factors to evaluate are:
Good dimensional stability
Good wear and abrasion properties. With its low
coefficient of friction and hard and resilient
surface, Acetal DELRIN® is the material of choice in
many wear applications.
High strength and stiffness properties
Low moisture absorption
Excellent machinability
High fatigue endurance
Superior impact and creep resistance
Chemical resistance to fuels and solvents
Temperture range
Yield strength
Cost
Availability

 

[prex]

Why not use the fiber material that's used to fabricate gaskets for pipe flanges?
You can buy it in sheets that can be cut to your shape, various thicknesses are available (up to 5 mm I believe), it is done to support high compressions and also should have a high thermal resistance (though I guess you won't find data for that).

prex

http://www.xcalcs.com

Online tools for structural design

 

[boo1]

What ever material selected make sure it has a very low water absorbsion characteristic.