Criteria for Restoration of Longitudinal Barriers (2010) / Chapter Skim
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Pages 66-74
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From page 66... ...
Rail flattening was characterized by loss of depth in the w-beam rail element, which was often accompanied by rail deflection and post deflection. Concurrent with the loss of depth was an increase in the height of the guardrail, i.e., the upper edge of the guardrail extended higher while the lower edge moved closer to the ground.
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From page 67... ...
Rail flattening -- field example vs. finite element model.
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From page 68... ...
Results for rail flattening simulations. Undamaged 25% Flattening 50% Flattening 75% Flattening 100% Flattening Impact Conditions Speed (kph)
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-50 -30 -10 10 30 50 70 90 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Time (s)
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70 Figure 59. Velocity curves for flattening simulations: undamaged (top)
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D is ta nc e fro m G ua rd ra il (m m) Static Deflection Contour Max Deflection Contour (t=0.165s)
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72 Figure 61. Displacement of vehicle tires for the flattening simulations: front left tire (left)
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From page 73... ...
As an alternative method of determining the amount of rail flattening, the research team is proposing a method where the maintenance personnel can measure the maximum section width of the flattened w-beam cross section, a much easier measurement to obtain. Based on finite element simulations of flattened w-beam barriers, the research team has correlated the maximum deformed cross section height to the approximate portion of rail flattening.
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From page 74... ...
Rail Flattening Rail cross-section height less than 9 in. (such as a dent to top edge)
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