Expansion Joint as a Gap element

[Varma A.]

I have to model the expansion joint by using gap model, but for this, I need the stiffness property. How to determine the compression and tensile stiffness of Compression seal Expansion Joint? The manufacturer provides a tensile strength of the material. How to derive stiffness of that expansion joint from tensile strength. Thank you.

 

[MIKE_311]

What are you trying to accomplish by modeling an expansion joint?

Only asking because you might be better off using the forces at the bearings instead, for example, friction.

 

[SlideRuleEra]

Varma A. - Is your question about neoprene preformed compression expansion seal?

http://www.SlideRuleEra.net

 

[Varma A.]

Thank you for your response Mike_311 and SlideRuleEra.

@Mike_311 I am doing research on the pounding effect of Simply supported bridge. For this, I am trying to define the stiffness offered by an expansion joint.

@SlideRuleEra Yes my question is related to that neoprene preformed compression expansion seal used for 50mm.

 

[BridgeSmith]

You would probably have to contact a manufacturer for the type of seal for that information. They should have the compression stiffness curve (I doubt the stiffness/movement is linear) readily available, since it directly affects the seal's ability to provide a weathertight joint. However, it's not generally in the published design information. For typical design, the effect of the stiffness of an elastomeric seal is ignored as being negligibly small in comparison to the other forces and imposed deformations.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[MIKE_311]

i would expect any stiffness to be negligible. They aren't design to provide any stiffness, if fact likely the opposite. You want the joint to open and close easily. You begin to notice problems with strictures when joints fill with less compressible material and debris and movement is impaired.

 

[SlideRuleEra]

Varma A. - As a former bridge contractor we installed early versions of neoprene compression seals (c. 1979). At that time, the seals were very stiff and difficult to compress.... they are much improved since then.

Today, I agree with BridgeSmith and Mike 311, compression force is very low. A lubricant/adhesive is used to make certain the seal remain in place. Videos show seals being installed completely by hand: Preformed Neoprene Compression Seal Installation.

http://www.SlideRuleEra.net

 

[Varma A.]

Thank you all for your responses.

I am trying to evaluate the impact force developed in pier due to collision between two decks rested on that pier. The pounding force between two bridge deck due to earthquake depends upon the stiffness offered by exapnsion joint and the gap in between them.
I referred some manufacturer manual but they have mentioned only tensile strength for elastomeric compression seal joint.
Thank you.

 

[SlideRuleEra]

The pounding force between two bridge deck due to earthquake depends upon the stiffness offered by expansion joint and the gap in between them.
I referred some manufacturer manual but they have mentioned only tensile strength for elastomeric compression seal joint.

In that case, do a sensitivity analysis by assuming a wide range of values for the joint compression force. I'll suggest:
10 kg / m
50 kg / m
250 kg / m

What are the results of each trial?
Does each assumed value make any significant difference in the results?

If the results vary, keep investigating to find an accurate value for the compression force.
If not... proceed to the next step of your work.

http://www.SlideRuleEra.net

 

[Varma A.]

Thank you so much SlideRuleEra