While AASHTO LRFD
Bridge Design Specifications provide design guidance, notes C13 member and American Concrete Pipe Association Director of Technical Services Josh Beakley, small communities and agencies are not always as familiar with AASHTO requirements as state departments of transportation that use them on a more regular basis.
Course 132094A LRFD
Seismic Analysis and Design of Transportation Geotechnical Features addresses the earthquake engineering aspects of the original course.
The objective of this research is to summarize the current practice and augment the AASHTO LRFD
Bridge Design Specifications (BDS) on the use of long-span precast pretensioned girders.
The goal of this research is to recommend changes to the AASHTO LRFD
Bridge Design Specifications for lightweight concrete, including a new definition of lightweight concrete to expand the range of unit weights and eliminate the definitions for terms relating to the constituent materials in the concrete.
Other aspects of this study according to the modified load distribution factors based on LRFD
design formulas are being studied and the results will be published as a sequel to this study.
These include the need for more demonstration projects, cost-benefit studies, and a new design and production document based on the American Association of State Highway and Transportation Officials' Load and Resistance Factor Design BridgeDesign Specifications and the AASHTO LRFD
Bridge Construction Specifications.
The modernized LRFD
is the first phase of upgrades for the M-DSA program.
ASTM WK38166, Specification for Manufacture of Precast Reinforced Concrete Three-Sided Structures for Culverts and Storm Drains Designed According to AASHTO LRFD
, is being developed by Subcommittee C13.
Shallow and deep foundations are analyzed, including special articles on laterally loaded piles, retaining structures including MSE and Tieback walls, slope and trench stability for natural, cut and fill slopes, geotechnical uncertainty, and geotechnical LRFD
(Load and Resistance Factor Design).
Specifications contain requirements for strength design and some serviceability checks.
The document also offers potential revisions to the American Association of State Highway and Transportation Officials' LRFD
[Load and Resistance Factor Design] Bridge Design Specifications.
Prior to the LRFD
Bridge Specification revisions, engineers were limited in their designs to only include reinforcing steel up to 75 ksi for bridge structures," notes Russo.