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Dynamic Impact Testing of Guardrail Posts Embedded in Soil




Brian Coon, John Reid, John Rohde




Dynamic properties of steel and wooden guardrail posts rotating in AASHTO M 147-65 Gradation "B" specifications were obtained and documented (NCHRP Report 350 Strong Soil). The steel and wooden posts were impacted with a bogie vehicle at 5.5, 8.9, and 13.4 m/s (12.3, 20, and 30 mph). Devices used to collect data consisted of an accelerometer on the bogie vehicle, strain gauges, S-VHS video, and high speed photography. W150x13.5 (W6x9) posts were initially used for testing, later W150x23.5 (W6x16) posts were used to prevent post deformations and to ensure only soil failure behavior. 150x200mm (6x8 in.) Southern Yellow Pine posts of DS-65 grading were used for wooden post tests. Dynamic effects were observed between the 5.5 and 8.9 m/s (12.3 and 20 mph) steel post tests. There were no measurable differences between the 5.9 and 13.4 m/s (20 and 30 mph) steel post tests. No dynamic effects for wooden posts were obtained due to wooden post fractures that occured at higher velocities. A significant decrease in energy absorption was observed when a wooden posts fracture instead of rotating in soil.


Guardrail Posts, Roadside Appurtenances, Soil-Post Interaction, Crash Test, Highway Safety, Bogie Test

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