Effect of 2013 Interim Revisions to the MBE on Legal, SHV and Permit Vehicles

Effect of 2013 Interim Revisions to the MBE on Legal, SHV and

Permit Vehicles

August 6, 2013Bryan J. Silvis, P.E.Structure and Bridge DivisionEngineering Services Section

Virtis Opis User Group Meeting, August 6, 2013

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VDOT Load Rating Background

Original purpose was to run a test suite to track changes in release versions.

When investigating changes in ratings for legal routine, legal SHV and permit (unlimited crossing) vehicles, became aware of more general effect of the changes to the MBE.

All tables shown are taken from the AASHTO 2013 Interim Revisions to the Manual for Bridge Evaluation, Second Edition.

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Sample Set

8 Bridge Types (3 structures selected for each type):

• Type 1 - Simple span concrete slabs• Type 2 - Continuous concrete slabs• Type 3 - Simple span concrete T-beams• Type 4 - Simple span rolled beams• Type 5 - Continuous rolled beams• Type 6 - Simple span plate girders• Type 7 - Continuous plate girders• Type 8 - Simple span prestressed AASHTO I-beams

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Legal - Routine

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Legal - Routine

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Legal - SHV

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Legal - SHV

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Permit – Unlimited Crossings

BP-115:

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Previous MBE - Permit

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2013 Interim - Permit

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Summary

2013 Changes (very general):

• Legal (Routine): Modest increase in rating for lower ADTT’s to substantial increase for higher ADTT’s

• Legal (SHV): Slight decrease in rating for lower ADTT’s to modest increase for higher ADTT’s

• Permit (Unlimited Crossing): General increase in ratings. Rating increase percentage increases with ADTT. Percentage increase where entire vehicle fits on structure is larger than where only a portion of the vehicle can.

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Questions??

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