×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

sole plate design
2

sole plate design

sole plate design

(OP)
I am attempting to determine the required thickness for a sole plate to be used at the pier bearing for a 2 span continuous steel multi-girder bridge (177’-177’).  We have designed a circular laminated elastomeric bearing pad that will work at the location.  Typically we do not do sole plate designs.  We simply use a 1” thickness at the centerline of bearing, and bevel as necessary.  However, due to the high loading at the pier bearing in this case, it seemed appropriate to check that the sole plate thickness was adequate.  But I have not been able to find any design guidance/methodology in AASHTO or in our Design Manual.  The best I have been able to do is a method given in the AISC Manual Of Steel Contruction, Volume II (LRFD, 2nd Edition) on pg. 11-50 for finding the minimum thickness of bearing plates.  

Is there a method typically used for the design of sole plates?  And where might I find it?  Thanks for your help.

RE: sole plate design

Ohio DOT has a formula for sole plates for rectangular elastomeric bearings:  T = C(RW/(L+1))^.5 - beam flange thickness

where
T = sole plate thickness
C = .194 for grade 36 steel
  = .167 for grade 50 steel
R = total reaction in kips including impact
W = width of elastomeric pad transverse to centerline of beam
L = length of elastomeric pad parallel to centerline of beam

They recommend using 80% of the thickness where bearing stiffeners are used, but require a minimum thickness of 1 1/2" for loads up to 200 kips and minimum of 2" above.

Hope this helps

Mike

RE: sole plate design

I have never seen the Ohio DOT formula before, but sole plate thickness is usually governed by the greater of two conditions:

1. Allowable plate bending stress for overhang (from edge of flange to edge of pad).

2. Minimum thickness for load transfer and/or heat transfer during field welding (varies from owner to owner).

New York State DOT has a good example of #1 in their BDM which can be found at the following link:

http://www.dot.state.ny.us/structures/manuals/brman/sect12.pdf

Many States are moving towards 1.5" minimum sole plate thicknesses when field welds are used to connect the bottom flange to the sole plate directly above an elastomeric pad.  Heat crayons can be used to minimize melting of the pad during welding, but as I said, the trend is too just specify a thicker plate and not worry about melting the pad.

I am curious to know how the Ohio DOT formula was developed, since it does not seem to factor in the actual overhang?  It may assume their standard details are used so I would be careful on using that formula indiscriminately.

RE: sole plate design

(OP)
TTK:  The formula shown in the link you provided is almost exactly the formula shown for determining the thickness of bearing plates indicated in the Manual Of Steel Construction Ninth Edition (Allowable Stress Design).  The main difference being the length "free to bend" considered.  It would seem that the one formula was based on or derived from the other.  Do you know if this is true?

RE: sole plate design

I don't have the steel manual in front of me but the formula in the link I provided is just a simple cantilever beam theory.

The plate is assumed to be fixed at the edge of the flange (or bearing pad if it is smaller than the flange) and the moment in the plate is calculated assuming a uniformly distributed load on a cantilever beam.

The square root comes into the formula because the section modulus of the beam (plate) is cubic, and it cancels out to a squared term in the process.

Try deriving it yourself by solving for the stress in the beam (plate) but leave the thickness "t" as a variable.

Good Luck!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close