Tag Archive: Bridge

Aug 07 2012

Criteria for Selecting Hydraulic Models, Part 4

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Continuing with our coverage of the new HDS 7 manual from FHWA. Part 1, Part 2, Part 3 Countermeasure Design The HEC-23 manual provides guidance on designing countermeasures for stream instability and scour. Many countermeasures, including spurs, guide banks, and transverse dikes, significantly alter flow paths and flow distributions. Two-dimensional models that are set up …

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Aug 02 2012

Criteria for Selecting Hydraulic Models, Part 3

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Continuing with our coverage of the new HDS 7 manual from FHWA. Part 1, Part 2 Bends, Confluences and Angle of Attack Highly sinuous rivers are, by definition, not one-dimensional, especially during floods when water in the floodplain flows more directly down valley and moves in and out of the channel. One-dimensional models must consider …

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Jul 31 2012

Criteria for Selecting Hydraulic Models, Part 2

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Continuing with our coverage of the new HDS 7 manual from FHWA. Part 1 Skewed Roadway Alignment Roadways should be aligned perpendicular to channel and floodplain flows. FHWA (1978) indicates that skewed crossings with angles of up to 20 degrees produced no objectionable flow patterns. The HEC-RAS Reference Manual indicates that using the projected opening …

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Jul 26 2012

Criteria for Selecting Hydraulic Models, Part 1

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Continuing with our coverage of the new HDS 7 manual from FHWA. Multiple Openings Multiple openings along an embankment are often used on rivers with wide floodplains. Rather than using a single bridge, additional floodplain bridges are included. Although one-dimensional models can be configured to analyze multiple openings, the judgment and assumptions that are made …

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