Elastomeric Isolation Bearings

[jrw501]

Does anyone here have experience designing elastomeric seismic isolation bearings with bolted connections (or doweled) I guess? If so, I was wondering how you go about checking stability at design/maximum displacement levels. For doweled connections you have rollover to consider as well, but I am primarily interested in regard to buckling.

Do you use AASHTO or other codes/specs? I'm more interested in the application to buildings, but 17.2.4.6 in ASCE 7-05 just basically states, "each element of the isolation system shall be designed to be stable under the design vertical load where subjected to a horizontal displacement equal to the total maximum displacement"

Thanks.

 

[jrw501]

A little more of what I'm after is if anyone has used the Overlapping Area Method (Reduce Area Method) before? This uses the critical load determined for shear flexible columns (Haringx, Engesser, Gent) then reduces the capacity linearly to 0 as the lateral displacement equals the bearing diameter. For example, if Pcr=100 kips for 5 inch square bearing, at a displacement of 3 inches I would use Pcr'=Pcr*(1-Delta/B)=100*(1-3/5)=40 kips.

Thanks.

 

[Den32]

Haven't run these Seismic Isolation Calcs but have worked with Isolators before.

Have you tried contacting a Isolator Manufacturer? We have worked with DIS, inc in the past (

http://www.dis-inc.com/).

You probably need some input from a Manufacturer anyway to get your stiffness (horizontal and vertical) values as well as bearing size and capacity.

They have an office here in the US and should be willing to assist. We tried tracking down other Isolator companies but most are not in US (Britain, Australia, Asia, etc.)

 

[jrw501]

Thanks!