Aesthetic Concrete Barrier Design (2006) / Chapter Skim
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Pages 56-65
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From page 56... ...
NCHRP Report 350 Test Designations According to NCHRP Report 350, two crash tests are required for Test Level 3 (TL-3) evaluation of length-of-need longitudinal barriers: • NCHRP Report 350 Test Designation 3-10: 820C vehicle impacting the length-of-need section at a speed of 100 km/h with the vehicle bumper at an impact angle of 20 degrees.
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From page 57... ...
Three levels of evaluation were established: acceptable if intrusion does not exceed 100 mm; marginal if intrusion is more than 100 mm, but less than 150 mm; and unacceptable if intrusion is significantly greater than 150 mm and at a location where serious injuries are deemed likely to result. Test Article Construction In November 2000, TTI performed a full-scale crash test on the Texas T501 longitudinal barrier (i.e., safety shape)
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From page 58... ...
either confirm or deny the ability to use a criterion similar to one approved for use on the single-slope barrier in the FHWA acceptance letter B-110. The internal energy thresholds used for pass/ fail criteria were to be adjusted up or down as appropriate based on the outcome of this test, effectively reducing the "marginal/unknown" region of performance at that asperity width in half.
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CRASH TEST 1 (474630-1) The New Jersey concrete safety shape barrier evaluated in the first test had asperities that were 559 mm wide and 25 mm deep.
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CRASH TEST 4 (474630-4) The New Jersey concrete safety shape barrier evaluated in the fourth test had asperities that were 279 mm wide and 13 mm deep.
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From page 61... ...
Recall that because of a lack of a robust concrete material model with damage capabilities, the barriers and their asperities were modeled as rigid materials in the simulations. Therefore, it was important to further investigate the effect of asperity spacing failure on the outcome of the results to help confirm the validity of using the crash test data to adjust the guidelines for aesthetic surface treatment of safety shape barriers.
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From page 62... ...
The barrier was impacted by an 854-kg Geo Metro at an angle of 19.4 degrees and a speed of 98.8 km/h. The barrier Figure 75.
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During the course of this simulation study on asperity spacing, it was discovered that identical finite element models (both barrier and truck) produced different results for the truck floorboard internal energy when different binary files of LS-DYNA were used.
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The New Jersey concrete safety shape barrier evaluated in the seventh test had asperities that were 559 mm wide and 51 mm deep. The asperity inclination angle was 45 degrees, and the asperity spacing was 203 mm.
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From page 65... ...
As a last step in formulating the final design guidelines, all of the available crash test data were evaluated and used to make adjustments to the preliminary guidelines developed through simulation. The details of these adjustments are presented in the next chapter along with the final design guidelines.
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