HY8:Concrete Open Bottom Arch: Difference between revisions

From XMS Wiki
Jump to navigationJump to search
No edit summary
No edit summary
Line 14: Line 14:


For information on the exact coefficients used and to view diagrams showing the different culvert wingwall configurations, see the help describing the [[WMS:HY-8_Polynomial_Coefficients#Table_5._Polynomial_Coefficients_-_Concrete_Open-Bottom_Arch|HY-8 polynomial coefficients]].
For information on the exact coefficients used and to view diagrams showing the different culvert wingwall configurations, see the help describing the [[WMS:HY-8_Polynomial_Coefficients#Table_5._Polynomial_Coefficients_-_Concrete_Open-Bottom_Arch|HY-8 polynomial coefficients]].
==''Related Topics''==
===Introduction===
* [[WMS:HY-8|Introduction]]
===Culvert Data===
====Culvert Data====
:* [[WMS:HY-8 Culvert Data|Culvert Data]]
:* [[WMS:HY-8 Shapes|Shapes]]
:* [[WMS:HY-8 Material|Material]]
:* [[WMS:HY-8 Plastic Pipe Materials|Plastic Pipe Materials]]
:* [[WMS:HY-8 Concrete Open Bottom Arch|Concrete Open-Bottom Arch]]
:* [[WMS:HY-8 Inlet Type|Inlet Type]]
:* [[WMS:HY-8 Inlet Edge Conditions|Inlet Edge Conditions]]
:* [[WMS:HY-8 Inlet Depression|Inlet Depression]]
:* [[WMS:HY-8 Embedment Depth|Embedment Depth]]
====Site Data====
:* [[WMS:HY-8 Site Data Input Option|Site Data Input Option]]
:* [[WMS:HY-8 Culvert Invert Data|Culvert Invert Data]]
:* [[WMS:HY-8 Embankment Toe Data|Embankment Toe Data]]

Revision as of 00:16, 17 June 2011

HY-8 Version 7.3 and later has coefficients for computing inlet control depths for concrete open-bottom arch (commonly called Con/Span) culverts.

Geometric Characteristics

Con/Span culverts have unique geometric configurations, and several sizes and shapes are available. The exact coordinates used in HY-8 to compute areas and other geometric cross section parameters are available in this document. Since the culverts can be made to accommodate any required rise for a given span, HY-8 contains culvert geometry in 3-inch increments of rise.

Inlet Control Polynomial Coefficients

The polynomial coefficients used by HY-8 were derived from a study and document prepared by Don Chase at the University of Dayton, Ohio (1999). Dr. Chase determined a different set of coefficients for culverts with different span-to-rise ratios. Con/Span culverts with a 4:1 span-to-rise ratio performed better (resulted in a lower headwater) than culverts with a 2:1 span-to-rise ratio. Because of this, separate polynomial coefficients were determined for culverts with each of these span-to-rise ratios.

Dr. Chase's study determined the K, c, M, and Y NBS coefficients described in HDS-5, and these coefficients were fitted to a 5th degree polynomial equation so they can be used in HY-8.

In HY-8, the 2:1 coefficients are used if the span:rise ratio is less than or equal to 3:1 and the 4:1 coefficients are used if the span:rise ratio is greater than 3:1. If the culvert you are modeling has less than a 2:1 or greater than a 4:1 span-to-rise ratio, you will see a note in HY-8 saying that your culvert is outside of the tested span-to-rise ratios. Further testing may be required to account for these large or smaller span-to-rise ratios, but it is likely that your computed headwater will be higher than the observed headwater if your span:rise ratio is greater than 4:1 and your computed headwater will be less than that observed if the span:rise ratio is less than 2:1.

For information on the exact coefficients used and to view diagrams showing the different culvert wingwall configurations, see the help describing the HY-8 polynomial coefficients.

Related Topics

Introduction

Culvert Data

Culvert Data

Site Data