Culverts and Storm Drains
Load and resistance factor design methodology developed by the American Association of State Highway and Transportation Officials plays a key role in a proposed ASTM standard on the design of culverts and storm drains.
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 C13.07 on Acceptance Specification and Precast Concrete Box Sections, part of ASTM International Committee C13 on Concrete Pipe.
In 1988, AASHTO launched a project to develop a modern and comprehensive bridge specification. The resulting document utilized load and resistance factor design and incorporated elements of working stress and load factor design. These elements were familiar to bridge engineers addressing events such as earthquakes, floods and ship collisions that could have catastrophic effects on bridges.
According to Balaram Singh, special structures engineer, Michigan Department of Transportation, and chairman, Subcommittee C13.01 on Non-Reinforced Concrete Sewer, Drain and Irrigation Pipe, WK38166 will be a comprehensive, well-organized and practical specification that will explain and provide background information on designing culverts and storm drains in accordance with the AASHTO LRFD standard.
"Culverts and storm drains designed according to LRFD have the inherent advantage of a more uniform level of safety, resulting in low life-cycle cost," says Singh. "LRFD allows the use of advanced methods in design and analysis. It provides flexibility for maintaining good and successful engineering practices or customizing load and resistance factors to meet the demands of a project. There will be many good reasons to use the LRFD methodology-based specification once it has been approved."
Singh notes that C13.07 is interested in developing a real time testing protocol for the proposed standard. All interested parties are invited to contribute to the ongoing development of WK38166.