BDTM.112.1 Swing Span Maximum Starting Torque - Revision 1
Tuesday, April 25, 2023 at 11:28:26 AM

To all:


1. The Recently published Bridge Design Technical Memorandum (BDTM) titled BDTM.112 has been revised and replaced with the subject BDTM.112.1, which has been approved by the Bridge Design Engineer Administrator and is published on the DOTD Bridge Design Section website 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 showing BDTM.112.1.

The BDTM "archived" index has been updated and posted showing the original BDTM.112.

BDTM Summary:
The BDTM.112.1 revision involves text that needed to be added to the Clean and Redline copies of Bridge Design and Evaluation Manual (BDEM), Part II, Volume 2, Section 5.4.3 (which is attached to the BDTM).

What did not change, was the BDEM revisions, which are summarized as follows:

· The wind load to be used for the determination of swing span movable bridge Maximum Starting Torque is reduced from the previous value of 10 psf minimum to 7 psf minimum.
· The commentary is revised to direct designers to ASCE 7 for wind load calculation.
· The background for this revision is addressed in commentary C5.4.3 (attached).

2. This notification email and BDTM are:
· Distributed to all DOTD in-house and consultant bridge designers.
· Copied to those copied on the BDTM.

3. This email requests the copied Consultant Contracts Services staff to distribute this e-mail and BDTM to consultant firms on the DOTD solicitation list.

4. This email requests consultant firm Principle-In-Charge to 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.