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NSBA Collaboration
Update of AASHTO/NSBA Steel Bridge Bearing Design and Detailing Guidelines
AASHTO CBS Annual Meeting (Virtual)June 1, 2020
Technical Committee T‐2: Bearings and Expansion Devices
Michael P. Culmo, PECHA Consulting, Inc.East Hartford, CT
Why does the Collaboration exist?
Durable, low maintenance, performance
Economical
Why does the Bearing Task Group TG‐9 exist?• Designers of steel bridges have a tendency to complicate bearing designs • This leads to higher costs for steel bridge bearings • Does this need to be so?• We say no
Who is on the Task Group?• It is a true collaboration• DOT Bridge Engineers• Bearing Manufacturers• Bearing Fabricators• Consultants • Academia
NSBA Bearing Task Group – TG‐9• Formed in 2001• Developed G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Adopted by AASHTO and published in 2004• Available for free download– NSBA Collaboration Website– AASHTO Bookstore
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Covers – Elastomeric Bearings– High Load Multi‐rotational Bearings (HLMR)– Steel Bearings
• Focus is on economical detailing– AASHTO LRFD Bridge Design Specifications cover design very well
• Guidance on:– Anchor rods– Masonry Plates– Connections to beams– Beam rotation calculations – Thermal movement calculations
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Format– Guidelines on left
– Commentary on right
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Recommended Details– Options presented
–Welded options….
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Recommended Details– Options presented
– Bolted options….
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Recommended Details– Options for restraint
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Recommended Details– Options for restraint
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• HLMR Bearings– Hatched area is designed by fabricator
– Other plates designed by the EOR
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
• Anchor Rod Options
G9.1: Steel Bridge Bearing Design and Detailing Guidelines
Planned Update• Underway (will continue into 2021)• Proposed changes– Update to current AASHTO– Update details– Merge information for other documents
• NSBA Highway Structures Design Handbook– Add sections
• Corrosion protection strategies• Manufacturing• Inspection and Testing• Installation Practice• Seismic Isolation
Planned Schedule• Work is well underway• Finish edits during the summer of 2020• Collaboration Balloting in Fall 2020• We may get it to T‐2 in the beginning of 2021
• Potential review by T‐2 during the spring of 2020
• AASHTO Ballot in 2021• This is a very tight schedule, therefore it may push one year.
Questions?
