BDTM.111 - BDEM Part II Volume 5 Section 6 - Revised - Bridge Load Rating
Monday, September 12, 2022 at 2:33:00 PM


To all:

Please be advised that the subject Bridge Design Technical Memorandum (BDTM) has been approved by the Bridge Design Engineer Administrator and published on the DOTD Bridge Design Section website for implementation at:

http://wwwsp.dotd.la.gov/Inside_LaDOTD/Divisions/Engineering/Bridge_Design/Pages/Technical-Memoranda.aspx


The BDTM "active" index has been updated and posted.

BDTM Summary:
This BDTM revises the Bridge Design & Evaluation Manual.

The main revision adds Section 6, 6A.6.9 – I-Sections in Flexure, 6A.6.9.3 – Non-Composite Sections, which provides a method for load rating continuous steel stringers that is intended to improve such load ratings. Using the Moment Gradient Modifier, Cb, as calculated in accordance with the AASHTO LRFD Bridge Design Specifications may understate continuous stringer capacity, resulting in the requirement for bridge load posting or member strengthening. The new presented method may reduce or eliminate the need for posting or strengthening.

Other revisions consist of the following:
- Adding Emergency Vehicles EV2 and EV3 to the As-Designed Load Rating Table for bridges with HL-93 Inventory Rating < 1.0, as required by BDTM.90.
- Adding language to Section 6A.1.1 "General" to clarify requirements for As-Designed Load Ratings, As-Built Load Ratings, and Present Condition Load Ratings.
- Removes the Service II Limit State from rating steel members for Legal rating loads, as required by BDTM.90.
- Updating Section 6 to improve its coordination with the Manual for Bridge Evaluation, 3rd Edition, mostly by removing repeated information.

This email notification and BDTM are distributed to all DOTD in-house and consultant bridge designers.

This email notification is copied to those copied on the BDTM, and to Consultant Contracts Services staff in order to distribute the e-mail and BDTM to consultant firms on the DOTD solicitation list. If you are listed as the Principle-In-Charge for a consultant firm, please inform your design staff of this BDTM.

Thanks,
Kelly M. Kemp, P.E.
Assistant Bridge Design Administrator
Section 25 - Bridge and Structural Design Section - Unit 8
LA Dept. of Transportation and Development
Office: (225) 379-1809
DOTD Internal Quick Dial: 3-1809

Please do not reply to this e-mail from MyDOTD. The originating e-mail account is not monitored by Consultant Contract Services (CCS). If you need assistance with the information in this email, please contact Kelly Kemp directly.