The Distance Between Two Piers on a River is 432

To enter bridge data the user presses the
Bridge/Culvert
button on the geometric information window (Effigy 5-one). Once the span/culvert button is pressed, the Bridge/Culvert Data Editor will appear equally shown in Figure 5-12 (your bridge/culvert editor will come up with a blank window until y’all have entered the span information). To add a span to the model, do the following:

1. Select the river and reach that you would like to place the bridge in. Selecting a accomplish is accomplished by pressing the down arrow on the river and reach box, and then selecting the river and reach of choice.
2. Go to the
   Options
   menu and select
   Add a Span and/or Culvert
   from the listing. An input box will appear prompting yous to enter a river station identifier for the new span.
3. Enter all of the required information for the new bridge. This includes:

• Bridge Deck
• Sloping Abutments (optional)
• Piers (optional)
• Span modeling approach data

1. Enter any desired optional information. Optional bridge information is establish nether the Options menu at the acme of the window.
2. Press the Apply Data button for the interface to accept the data.

Figure 5
12 Bridge/Canal Data Editor

The required information for a bridge consists of: the river, achieve, and river station identifiers; a short clarification of the bridge; the bridge deck; bridge abutments (if they be); bridge piers (if the bridge has piers); and specifying the bridge modeling approach. A description of this information follows:

River, Reach and River Station. The River and Reach boxes allow the user to select a river and reach from the bachelor reaches that are divers in the schematic diagram. The reach characterization defines which reach the span will be located in. The River Station tag defines where the bridge will be located within the specified attain. The river station tag does non accept to be the actual river station of the bridge, only it must be a numeric value. The river station tag for the span should exist numerically between the two cantankerous sections that bound the bridge. Once the user selects Add a Span and/or Culvert from the options bill of fare, an input box will appear prompting yous to enter a river station tag for the new bridge. After the river station tag is entered, the two cross sections that bound the bridge will exist displayed on the editor.

Clarification. The description box is used to describe the span location in more detail than just the achieve and river station. This box has a limit of 256 characters. Just the first line of information is displayed, unless the button to the right of the box is pressed. Also, the showtime forty characters of the clarification are used as a label for bridge plots and tables.

Bridge Deck/Roadway. The bridge deck editor is used to describe the surface area that volition be blocked out due to the bridge deck, road beach and vertical abutments. To enter span deck data the user presses the
Deck
push on the Span/Canal Information Editor. Once the deck button is pressed, the Deck Editor volition announced equally in Figure 5-thirteen (except yours will be blank). The information entered in the deck editor consists of the following:




Figure v
13 Bridge Deck/Roadway Information Editor

Distance
– The distance field is used to enter the altitude between the upstream side of the bridge deck and the cantankerous department immediately upstream of the bridge (run into Figure 5 14, “Upstream Distance”). This distance is entered in anxiety (or meters for metric).

Width
– The width field is used to enter the width of the span deck along the stream (Figure 5 xiv, “Bridge Width”). The distance between the bridge deck and the downstream bounding cross section will equal the principal channel reach length minus the sum of the bridge “width” and the “distance” between the bridge and the upstream section. The width of the bridge deck should exist entered in feet (meters for metric).






Figure 5
fourteen Bridge Contour with Upstream Distance, Bridge Width, and Downstream Distance

Weir Coefficient
– Coefficient that volition be used for weir flow over the bridge deck in the standard weir equation.

Upstream Stationing, High Chord, and Low Chord
– This table is used to define the geometry of the bridge deck on the upstream side of the bridge. The information is entered from left to correct in cross section stationing. The deck is the expanse between the high and low chord elevation information. The stationing of the deck does not take to equal the stations in the bounding cross section, just it must be based on the aforementioned origin. The
Del Row
and
Ins Row
buttons allow the user to delete and insert rows.

Downstream Stationing, High Chord, and Low Chord
– This portion of the table is used to define the geometry of the bridge deck on the downstream side of the bridge. If the geometry of the downstream side is the aforementioned as the upstream side, so the user merely needs to printing the
Copy The states to DS
push. When this button is pressed, all of the upstream bridge deck data is copied to the downstream side. If the span deck data on the downstream side is different than the upstream side, then the user must enter the information into the table.

U.S. Embankment SS
– This field is used to enter the slope of the route embankment on the upstream side of the span. The slope should exist entered every bit the horizontal to vertical distance ratio of the beach. This variable is more often than not not used in the computations, but is used for display purposes in the contour plot. However, if the user has selected the FHWA WSPRO Bridge method for low menstruum, this field will exist used in the computation of the bridge discharge coefficient.

D.S. Embankment SS
– This field is used to enter the slope of the road embankment on the downstream side of the bridge. The slope should be entered as the horizontal to vertical distance ratio of the embankment. This variable is generally not used in the computations, but is used for display purposes in the profile plot. However, if the user has selected the FHWA WSPRO Bridge method for low period, this field will be used in the computation of the bridge discharge coefficient.

Max Submergence
– The maximum commanded submergence ratio that tin occur during weir flow calculations over the bridge deck. If this ratio is exceeded, the program automatically switches to energy based calculations rather than force per unit area and weir flow. The default value is 0.95 (95 percent submerged).

Submergence Criteria
– When submergence occurs in that location are two choices available to figure out how much the weir coefficient should be reduced due to the submergence. The commencement method is based on work that was done on a trapezoidal shaped broad crested weir (FHWA, 1978). The 2nd criterion was developed for an Ogee spillway shape (COE,1965). The user should pick the criterion that all-time matches their problem.

Min Weir Period El
– This field is used to set the minimum tiptop for which weir flow volition begin to exist evaluated. Once the computed upstream energy becomes higher than this elevation, the programme begins to calculate weir period. Nonetheless, the weir flow calculations are still based on the actual geometry of the deck/roadway, and are non affected by this elevation. If this field is left bare, the elevation that triggers weir flow is based on the everyman loftier chord meridian on the upstream side of the bridge deck. Also, weir flow is based on the elevation of the energy course line and non the water surface.

Once all of the bridge deck information is entered, the user should press the
OK
button at the lesser of the window. Pressing the
OK
push tells the interface to accept the data and close the window. One time the deck editor closes, the graphic of the bridge deck will appear on the Span/Culvert Information window. An case of this is shown in Figure 5-fifteen.
Note! The data are non saved to the hard disk at this bespeak. Geometric information can only be saved to the hard disk from the
File
menu of the Geometric Information window.





Effigy v
fifteen Instance Bridge Deck Plotted on Bounding Cross Sections

Sloping Span Abutments. The sloping span abutments editor is used to supplement the bridge deck information. Whenever bridge abutments are protruding towards the primary aqueduct (sloping in abutments), it will be necessary to block out boosted area that cannot be deemed for in the bridge deck/roadway editor. If the bridge has vertical wall abutments, then it is not necessary to use this editor. Vertical wall abutments can be included as office of the bridge deck/roadway data. To add sloping abutments, the user presses the

Sloping Abutment
button on the Bridge/Canal Data editor. Once this button is pressed the Abutment data editor will appear as in Figure five-16.

Sloping abutments are entered in a similar manner to the bridge deck/roadway. When the editor is open up, it has already established an abutment # of 1. Generally a left and right abutment is entered for each span opening. Sloping abutment data are entered from left to right, looking in the downstream direction. In general it is usually only necessary to enter 2 points to draw each abutment.




Figure 5
xvi Abutment Information Editor

The data for each abutment consist of a skew angle (this is optional) and the station and height information. The station and peak information represents the high chord data of the abutment. The depression chord information of the abutment is assumed to be below the ground, and it is therefore not necessary to enter it. The geometric information for each abutment tin vary from upstream to downstream. If this information is the same, then the user merely needs to enter the upstream geometry and then printing the
Copy Up to Down
button.

To add additional sloping abutments, the user tin either printing the
Add
or the
Copy
push. To delete an abutment, printing the
Delete
button. Once all of the abutment data are entered, the user should press the
OK
push. When the OK button is pressed, the abutment data is accepted and the editor is closed. The abutments are then added to the span graphic on the Span/Culvert Data editor. An case of a sloping span abutment is shown in Figure v-17. This graphic is zoomed in on the left abutment of the bridge.




Figure five
17 Example of a Sloping Abutment

Span Piers. The bridge pier editor is used to depict any piers that exist in the bridge opening.
Annotation! All piers must exist entered through the Pier Editor, they should not be included as role of the ground or bridge deck. Several of the depression menses span computations require that the piers exist divers separately in order to determine that amount of area under the water surface that is blocked by the piers. If the piers are included with the footing or the span deck, several of the methods will not compute the correct corporeality of energy loss for the piers.

To enter pier information, the user presses the
Pier
button on the Bridge/Culvert Data editor. Once the pier push button is pressed, the pier information editor volition announced as in Effigy 5-18 (Except yours will not have any data in it yet).




Effigy 5
eighteen Pier Data Editor

When the pier data editor appears it will have already defined the first pier as pier # 1. The user is required to enter a centerline station for both the upstream and downstream side of the pier. The pier geometry is entered as pier widths and elevations. The elevations must first at the lowest value and become to the highest value. Mostly the elevations should start below the footing level. Any pier area below the ground volition exist clipped off automatically. Pier widths that change at a single superlative are handled past entering two dissimilar widths at the same superlative. The lodge of the widths in the table is very important. Keep in heed that the pier is defined from the footing upwardly to the deck. If the pier geometry on the downstream side is the same every bit the upstream side, simply press the
Copy Upward to Down
push button afterwards the upstream side data are entered.

The user likewise has the option of defining floating pier debris. If the
Floating Debris
option is selected, the user will need to enter a width and a top for the droppings. The user can set up a different height and width of droppings for each pier, or there is a button that will allow the user to enter a single peak and width that volition exist used for all of the piers (Set Wd/Ht for all…). Additionally at that place are buttons to turn pier debris on or off for all of the piers of the span (All On…
and
All Off…).
Additional piers tin be added by pressing either the
Add together
or the
Copy
push. If the piers are the same shape, it is easier to use the re-create button and just change the centerline stations of the new pier. To delete a pier, just printing the
Delete
button and the currently displayed pier will exist deleted. Once all of the pier data are entered, press the
OK
button. When the OK push button is pressed, the data will be accepted and the pier editor will exist airtight. The graphic of the span will and then be updated to include the piers. An example bridge with piers is shown in Figure 5-nineteen. This graphic is only the upstream side of the bridge with a zoomed in view.




Figure 5
19 Bridge with Piers, zoomed in view

Span Modeling Approach. The Bridge Modeling Arroyo editor is used to define how the bridge volition be modeled and to enter any coefficients that are necessary. To bring up the Bridge Modeling Approach editor press the
Bridge Modeling Approach
button on the Span/Culvert Data editor. Once this button is pressed, the editor volition announced as shown in Effigy 5-twenty (Except yours will simply have the default methods selected).




Figure five
xx Bridge Modeling Arroyo Editor

When the Span Modeling Arroyo editor comes up it will be ready to enter data for the offset bridge opening (coefficient set # 1). If there is more i bridge opening at the current location, the user tin can either utilise a single set of modeling approaches and coefficients, or establish a dissimilar gear up for each span opening.

Establishing a bridge modeling arroyo consists of defining which methods the program volition use for low catamenia computations and loftier menstruum (flow at or above the maximum low chord) computations. The user tin can instruct the program to employ any or all of the low period methods during the computations by clicking the buttons nether the
Compute
column. If either the Momentum or Yarnell method are selected, the user must enter a value for the pier loss coefficient that corresponds to that method. If the WSPRO method is selected, the user must printing the “WSPRO Variables” button and enter boosted information that is required for the method. In one case the
WSPRO Variables
button is pressed, a information editor every bit shown in Figure 5-21 volition appear.




Figure 5
21 WSPRO Data Editor

As shown in Effigy 5-21, there are several variables that must be entered likewise equally some options that are available to the user. All of the required variables shown on the WSPRO data editor are used in the ciphering of the discharge coefficient, C, which is used in the WSPRO expansion loss equation. A detailed word of how the discharge coefficient is computed tin can be found in appendix D of the HEC-RAS Hydraulic Reference manual. The post-obit is a description of each of the variables on the WSPRO Data Editor:

El of the height of the Embankment
– These fields are used for entering the elevation of the top of the embankment (top of road) at the edges of the span opening. An elevation must exist entered for both the left and correct side of the bridge opening.

El of the toe of the Abutment
– These fields are used for entering the top of the abutment toe (elevation at the station in which the abutment toe intersects with the natural ground inside the bridge opening) on both the left and right side of the span opening.

Abutment Type
– This field is used for selecting the type of abutments. There are four abutment types available from this selection box.

Slope of the Abutments
– This field is used for inbound the slope of the abutments. This gradient is taken as the horizontal distance divided by the vertical distance. If the abutments are vertical walls, and so this field should be left blank or set to zip. If the left and right abutments do not have the aforementioned slope, have an average of the ii and enter that into this field.

Top Width of Beach
– This field is used for inbound the width of the top of the road embankment, in the area of the span opening. If the topwidth of the beach varies from one end of the bridge opening to the other, apply an average of the 2 widths.

Centroid stationing of the projected bridge opening at the arroyo cantankerous section
– For the WSPRO span method, it is necessary to summate the water surface topwidth inside of the bridge opening, and then project that width onto the approach cantankerous department. The program calculates the conveyance inside this projected width at the approach cantankerous section. This conveyance is used in computing a channel wrinkle ratio, which is an integral part in the adding of the discharge coefficient. If this field is left bare, the plan will automatically middle the computed topwidth, such that the center of the topwidth volition be at the center of conveyance at the approach cantankerous-department. The user can override this by entering their own centroid stationing value for the arroyo cantankerous section.

Wing Walls
– This field is used for selecting the type of wing walls. At that place are iii choices available in the choice box: No wing walls present; Angular fly walls; and Rounded wing walls. If the user selects “Athwart fly walls”, and then the fields labeled “Angle of Fly Wall” and “Length of Fly Wall” become active and must exist filled out. If the user selects “Rounded wing walls”, then the fields “Length of wing walls” and “Radius of entrance rounding” become active and must be filled out. If the user selects “No wing walls present” then no other information on fly walls is necessary. For more information on fly walls see appendix D of the HEC-RAS Hydraulic Reference transmission.

Guide Banks Type
– This field is used for selecting the type of guide banks if any exist. In that location are three choices available from the choice box: No guide bank present; Direct; and Elliptical. If the user selects “Direct” then the fields labeled “Length of guide banks”, “Offset of Guide Banks”, and “Skew of Guide Banks” become active and must be filled out. If the use selects “Elliptical” then only the fields “Length of Guide Banks” and “Outset of Guide Banks” go active. If the user selects “No Guide Banking concern nowadays” then no other information well-nigh guide banks is necessary. For more information on Guide Banks see appendix D of the HEC-RAS Hydraulic Reference manual.

Optional Contraction and Expansion Losses
– This box allows the user to turn on contraction and expansion losses at locations that are traditionally non in the WSPRO methodology. The bones WSPRO bridge method simply computes expansion losses in the expansion reach (betwixt the exit cross section and the department just downstream of the bridge). This option allows the user to turn on wrinkle and expansion losses individually at the post-obit locations: downstream inside of the bridge; upstream within of the bridge; upstream outside of the span; at the terminate of a guide bank (if guide banks exist); and at the approach cantankerous department. The default for the WSPRO method is that contraction and expansion losses will not be calculated at these locations. Users should not turn these options on unless they feel that the standard WSPRO bridge approach is non producing enough free energy loss through the bridge.

3 other options that the user has control over are: specifying that the piers are continuous the whole manner through the bridge or not; using the Geometric Mean friction gradient averaging technique through the bridge computations (from exit to approach section); and using the WSPRO tables to compute the C_d
coefficient, rather than the theoretical equation. The default for the WSPRO methodology is to assume that the piers are continuous through the bridge, to use the Geometric Mean friction slope method, and compute C_d
with the theoretical equation.

Afterward all of the variables have been entered, the user must printing the
OK
push button for the WSPRO variables to be accustomed. For more information nigh the computation of the belch coefficient, and these data variable, meet appendix D of the HEC-RAS Hydraulic Reference manual.

Once the user has selected which low flow span methods will be computed, they must likewise specify which of those methods will exist used equally the terminal answer to keep the computations on upstream with. Only 1 of the methods can exist selected as the answer to
“Use”
in club to proceed the computations upstream. An culling to selecting a single method to use is to instruct the program to use the answer with the highest computed upstream energy elevation. This is accomplished by pressing the push button under the
“Use”
column that corresponds to the
Highest Energy Answer
text field.

For a
Loftier Menstruum Method, the modeler tin can cull betwixt Energy based calculations or pressure and weir flow calculations. If pressure and weir flow is the selected high menstruum method, the user must enter coefficients for the pressure level menstruation equations. The first coefficient applies to the equation that is used when only the upstream side (inlet) of the bridge is submerged. If this coefficient is left blank, the program selects a coefficient based on the amount of submergence. If the user enters a coefficient, then that value is used for all degrees of submergence. The second coefficient applies to the equation that is used when both the upstream and downstream end of the bridge is sub-merged. Generally this coefficient is around 0.viii. For more information on pressure level flow coefficients see Hydraulics of Bridge Waterways (FHWA, 1978).

Max Low Chord
– This field is used to gear up the maximum elevation of the deck low chord, and therefore the elevation at which pressure level flow begins to be calculated. If this field is left blank, then the elevation that triggers force per unit area flow calculations is based on the highest low chord elevation on the upstream side of the bridge deck. If the user enters a value in this field, and then the value fix will be used to trigger when pressure flow calculations begin. Pressure flow is triggered when the energy elevation exceeds the maximum depression chord. When pressure flow is calculated, the respond is compared to the depression flow reply and the higher of the two is selected. Alternatively, the user tin tell the program to utilize the h2o surface instead of the free energy elevation to trigger force per unit area period calculations. This option can be found under the
Bridge and Culvert Options
section of this manual.

Once all of the bridge modeling approach information is entered, the user should printing the
OK
button. When the OK push is pressed the data will be accepted and the editor will close.
Recall! The data are not saved to disk at this point, it is simply accepted as being valid.
To salvage the geometric information, use the
File
carte from the Geometric Data Editor window.