Memorandum

TO: All Design Section Staff
FROM: J. Kapur - 47340
DATE: December 4, 2001
SUBJECT: Long Span Prestressed Girders

  Long span prestressed girder bridges may result in increased cost due to fabrication, shipping and erection of girders.  Providing alterative design to long span prestressed girders based on the limitations in shipping weight and prestressing may eliminate the excessive cost through competitive biding.  The following procedure for alternative design to prestressed girders in the contract plans shall be considered

       All prestressed girders with shipping weight less than 155 kips (144 ft for           
     W83G  and 134 ft for W95G) shall be pre-tensioned only (no alternative design).

        All prestressed girders with shipping weight between 156 and 200 kips shall include both pre-tensioned      
      and post-tensioned spliced-girder alternatives with post-tensioning applied after slab casting.

       
All prestressed girders with shipping weight exceeding 200 kips shall be post-tensioned spliced-girder with post-tensioning applied after slab casting. 

 When spliced-girder alternative is considered in the contract plans, the substructure shall be designed and detailed for the maximum force effect
  case only (no alternative design for substructure).

Standard plans for post-tensioned spliced-girders are now available in M:\BRIDGELIB\Master6\Standards\Girders\PT Wide Flange and will be soon published in the BDM.

 

Background:

Difficulties in fabrication, shipping and erection of long span prestressed girders may results in higher cost than typically expected for prestressed girders.  Providing spliced-

girder alternative allows fabricating, shipping and erecting girders in smaller segments, feasible for remote locations.  

        

If you have any questions, please contact Gary Battin at 705-7188 for standard plans and Bijan Khaleghi at 705-7181 for other issues.

 JK:dm

BK

 cc:  J. Weigel, 47340

      F. Higgins, 47340