Suspension Bridge

Suspension Bridge Wizard automatically creates 2D or 3D suspension bridge models while it calculates the undeformed lengths of cables and hangers at the same time.  Based on the bridge model created from the wizard, additional modeling operations such as adding girders, modifying the shape of pylon, and entering the load and boundary conditions are done. Upon finishing modeling, the final undeformed lengths, the geometric shape, and the internal member stresses are calculated using the function in Analysis > Suspension Bridge Analysis Control.  

From the Main Menu select Structure > Wizard > Suspension Bridge.

Node Coordinates & Heights

Enter the coordinates of the basic nodes defining a suspension bridge

3-Dimensional: Check to model a 3-dimensional model.

A: Origin point of the cable

A1: Origin point of the girder

B: Top of the left tower

C: Center point of the cable

Asymmetric Bridge: Check if the bridge is asymmetric.

D: Top of the right tower

E: End point of the cable

E1: End point of the girder

H1: Height of the left tower

H2: Height of the right tower

Hanger Distances

Enter the distances between the hangers.

Left : Hanger spacing and loadings in the left span

Center : Hanger spacing and loadings in the center span

Right : Hanger spacing and loadings in the right span

Note
If the structure does not include hangers in the left span, enter the distance from the starting point of the deck to the pylon.  It applies the same to the right span.
The number of hangers in the center span must be an odd number because the nodal information at the most sagging point must be entered.

Properties

Material, Section: Enter the material and section properties for

Main Cable

Side Cable

Typical Hanger

End Hanger

Deck

Pylon

Note
End Hanger represents the first hanger in the left span and the last hanger in the right span.
Deck is generated as a Fish-born structure.

Deck System

Width : Width of the deck

Depth : Depth of the deck (If the depth remains blank, the wizard models the deck with a single girder system. However, if the depth is specified, it models a framing system with truss elements that connects a top and bottom girders.)

Deck depth is only used for formwork. For more detailed analysis, the user needs to accurately model the deck by including the stiffness.

Unit Weight : Enter the unit weight of the deck. Since 2D suspension bridge has mono-type main cables, one row of hanger supports the unit weight assigned. On the other hand, 3D suspension bridge model has dual-type main cables, and the unit weight assigned to two rows of hanger supports. Therefore, half of the unit weight of deck is supported by each row of hangers.  

Check this button to enter a different unit weight for the left, right, and middle span.

Note
During the process of designing the optimized suspension bridge shape, the wizard automatically considers the self weight of cables and hangers.   Therefore, only the self weight of the girder and the superimposed dead load need be applied. Other loads such as loads applied to the intersection of the main cable and hangers, are not a major concern in Suspension Bridge Wizard, but after generating the model using Wizard this type of load can be applied in Suspension Bridge Analysis Control.

In the case of a bridge without hangers, only uniformly distributed loads are permitted.

Distance from Deck to Pylon

G1 : Distance from the end of the deck on the left span to the left pylon.

G2 : Distance from the end of the deck on the center span to the left pylon.

G3 : Distance from the end of the deck on the center span to the right pylon.

G4 : Distance from the end of the deck on the right span to the right pylon.

Shape of Deck

Slope: Define the shape of deck simply by specifying the slopes of each side span and the arc length of the center span.

Left Slope(%) : Slope at the left end of the arc

Arc Length(m) : Arc length

Right Spole(%) : Slope at the right end of the arc

Note
Enter the arc length, (D-B) long if only the center span is sloped. In order to specify a slope throughout the entire length of the bridge, enter a length equal to or greater than (E1-A1).

Coordinate: Directly specify the Z coordinates of the deck to define the shape as desired by the user.

Note
1. Specify the coordinates from the left span to the center span. It is assumed that the coordinates of the right span is identical to those of the left span.
2. When "Distance from Deck to Pylon" option is used, two points with an identical X coordinate are generated on the deck. Z coordinates of these two points should be identical.
3. Deck coordinates entered by using "Coordinate" option cannot be saved as *.wzd.

View option

X-Y Plane : Display the model on the X-Y Plane.

X-Z Plane : Display the model on the X-Y Plane.

Bitmap: Display the position and shape representing the data.

Drawing: Display the overall shape of the bridge using the data entries.

: It is activated when Drawing is selected. It displays the entire shape reflecting the entered data.

Horizontal Force: Horizontal forces of the main cable, which is based on the initial equilibrium state defined by the user, is automatically calculated and displayed in real time.

: Generate the data by computing all the nodal coordinates and the initial tensile forces in the cables using the initial data, and close the Wizard window.

: Cancel the data entries and close the Wizard window

Note
The default data entries reflect the 3-D shape of a recent bridge project.

: Open a previously saved a Suspension Bridge Wizard data file in *.wzd file format. In this way, the previous entered data can be imported so that users do not need to enter the data again for a similar project.

: Save the entered data in Suspension Bridge Wizard in *.wzd file format.