AASHTO Issues Updated LRFD Bridge Design Guideeditor@aashto.org May 8, 2020 0 COMMENTS
The American Association of State Highway and Transportation Officials recently released the 9th edition of its LRFD Bridge Design Specifications guide, which employs the load and resistance factor design or LRFD methodology in the design, evaluation, and rehabilitation of bridges.
AASHTO noted that this 9th edition replaces the 8th edition – published in 2017 – and includes revisions to almost all of its specification sections.
That includes extensive changes to the “steel structures” material featured in Section 6 of the publication, such as:
- New design specifications for non-composite steel box-section members, which are often used as truss members, arch ribs and ties, rigid-frame members, columns, steel bent caps, edge girders, floor beams, and steel tower legs.
- Updates to the simplified design provisions for bolted field splices, which include the LRFD-8 Errata issued in 2018.
- Improvements to the post-buckling flange-stress reduction factor (represented by “Rb”) to account for the contribution of web longitudinal stiffeners to the overall flexural resistance of slender-web steel girders at the strength limit state.
- Updates to the shear lag reduction factor and the specifications needed to determine the factored flexural resistance of tees and double angles to bring the design specifications into conformance with the latest American Institute of Steel Construction Specifications.
- New design provisions for the determination of the factored shear resistance of concrete filled steel tubes or CFSTs.
- Addition of a new fatigue classification for large inspection access manholes in the bottom flange of a steel tub girder, and hand holes placed throughout the length of built-up steel truss members to reduce dead load and aid with fabrication and inspection.
The 9th edition LRFD Bridge Design Specifications guide is available in three formats: as a paperback book; as a PDF download for single- or five- or 10-user groupings; and as a discounted set that includes both the paperback version and the single-user PDF download version. It’s available via the AASHTO Store and can be ordered by clicking here.