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Bridges of constant deck width |
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Number of girders greater than or equal to 4 |
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Parallel girders with approximately equal
spacing |
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Span length must exceed 2.5 times the deck width |
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Plan curvature of less than 12 degrees in any
one span |
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Conduct a detailed study of limits imposed by
the 1998 AASHTO LRFD Specifications |
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Investigate whether these limits can be
broadened to include typical box-girder bridge in California |
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Emphasis is placed on these three parameters: |
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Non-prismatic cross-sections |
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Plan aspect ratio (length/width) less than 2.5 |
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Plan curvature > 12 degrees in any one span |
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The current AASHTO LRFD distribution factor for
box-girder bridges is conservative with respect to the design bending
moment and shear force, even for bridges outside their range of
applicability |
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Plan aspect ratio may be expanded to L/W >1
instead of the current limit of L/W > 2.5 |
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The current LRFD distribution factor may be used
for non-prismatic bridges with flare up to the limit of 1-in-15 or 6.6% |
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The plan curvature limit of 12 degrees appears
to be unnecessary, and the limit may be increased to about 35 degrees |
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Notes