About the Bridge Design Assistant

The Bridge Design Assistant helps you design the deck and support elements of a bridge starting from a simple schematic wireframe model to the generation of a detailed 3D model. This assistant allows you to study various design solutions and lets you easily edit the design taking constraints into account.

The design of the bridge is facilitated by the usage of object types and its edition is easily manageable in the tree.

This page discusses:

Bridge-related Object Types

Bridge elements must be defined with valid object types when using Bridge Design Assistant.

Object Type Definition

The definition rules for a valid bridge-related object type are the following:

  • The object type must contain a Feature-Based Design model with an axis system input named "Base Axis System".
  • For object type inputs:
    • Other inputs must not be added to reference object types.
    • Specific inputs can be optionally added to adaptive and distribution object types.
  • For object type outputs: specific outputs can be optionally added to some object types.

Note: Optionally, an object type can contain configurations.

Specific Inputs and Outputs

Function in the bridge List of available types Optional inputs Optional outputs
Deck
  • Deck
  • Span
  • Mandatorily, Base Axis System corresponding to deck/span start extremity. Usually, it lies on alignment.

  • Optionally, a supplementary axis system corresponding to deck/span end extremity, named End Axis System.

    If it exists, a sequential next axis pattern is automatically generated to define it under Deck Set.

    If there exists only one axis system input (excluding Base Axis System), it can be of any name, with advised name End Axis System. Otherwise, it is ignored, and you must manage it by editing Deck Set.

  • Optionally, a guiding curve, named Alignment. If there exists only one curve input, it can be of any name. The advised name is Alignment. Otherwise, it is ignored, and you must manage it by editing its corresponding Support Set.
  • Optionally, other inputs. You must manage them by editing Deck Set.

  • Optionally, two axis systems with given names Input for support 1 and Input for support 2.

    If such outputs exist, they must mandatorily correspond to the position of supports.

    Otherwise, the support positions are computed by the shift of alignment downward to ground with an offset value equal to deck height. In this case, make sure that the deck height defined in the bridge layout is compatible with the actual deck height in user-feature.

  • Optionally support system outputs. If the inputs of support elements require support system meta-inputs, then the outputs of deck support system must contain the geometrical outputs with names defined in the meta-inputs.

    Example: The support system meta-input Span 1 of the middle support requires two geometrical elements named Support system surface front 2, and Front 2 of the span. All deck/span user features must contain two outputs of the same names.
Middle supports
  • Pier
  • Pile
  • Crosshead
  • Tower
  • Mandatorily, Base Axis System corresponding to support origin.

  • Optionally, a ground level point, named Point on Ground.

    If it exists, a projection pattern is automatically generated to define it under Support Set, by projecting the origins of Base Axis System on the terrain.

    If there is only one point input, it can be of any name, with advised name Point on Ground. Otherwise, it is ignored, and you must manage it by editing Support Set.

  • Optionally, two support systems, defined as meta-inputs (not geometrical inputs), mandatorily named Span 1 and Span 2, corresponding respectively to support system outputs at deck/span start and end extremities.

    The meta-input is defined by a list of any number of geometrical elements with given names. The deck outputs must contain all geometrical elements of same names as those defined in the meta-inputs.

    Example: Span 1 is defined by two geometrical elements named Support system surface front 2, and Front 2 of the span. All span/deck user feature outputs must contain at least two outputs of the same names, Support system surface front 2 and Front 2 of the span. Otherwise, the pattern update will fail.

    For each support system, a selection pattern is automatically generated. It takes the user feature results from Deck Set as input. Before the creation of the selection pattern, all deck user features must have been instantiated.

    The support system inputs are permitted under two conditions:

    • The bridge must be isostatic, since they need outputs for all spans, and non-isostatic bridge cannot generate outputs for all spans.
    • All deck/span user features must contain all geometrical outputs with their names defined in the inputs of the support system meta-inputs.

  • Optionally, a guiding curve, named Alignment. If there exists only one curve input, it can be of any name. The advised name is Alignment. Otherwise, it is ignored, and you must manage it by editing its corresponding Support Set.
  • Optionally, other inputs. You must manage them by editing the Support Set.
 No specific outputs.
Start and end supports
  • Abutment
  • Pier
  • All remarks about middle supports apply to start and end supports, except for support system.

  • Optionally, one support system, defined as meta-input (not geometrical input), mandatorily named Span, corresponding to deck/span support system outputs at start or end extremities.

    All other remarks about middle support system inputs apply to start and end support system input.

  • Optionally, a guiding curve, named Alignment. If there exists only one curve input, it can be of any name. The advised name is Alignment. Otherwise, it is ignored, and you must manage it by editing its corresponding Support Set.
 No specific outputs.

Bridge Parameters

The Bridge Design Assistant defines the following bridge parameters: Deck Height, Support Length, Tower Height, Abutment Height, Abutment Length and Abutment Seat Length.

The meaning of each parameter is illustrated by the two figures below:

A deck and supports

Deck Height

Alignment

Support Length

Tower Height

An abutment

Abutment Height

Abutment Length

Abutment Seat Length

Mapping between bridge parameters and object type parameters

The Bridge Design Assistant defines a list of bridge parameters that you can edit directly in the Bridge Design Assistant.

On the other side, when object types are assigned to different bridge elements, some object types define their own parameters.

A mapping between the bridge parameters and parameters of object types is shown in the table below. If both names match, the corresponding parameter of object types is set equal to its related bridge parameter, and the bridge parameter is the driving parameter.

Bridge Parameter Object Type Parameter Name Object Type
Deck Height Deck, Span, Span Segment Height
Support Length Pier, Tower Length
Tower Height Tower Height
Abutment Height Abutment Height
Abutment Length Abutment Length
Abutment Seat Length Abutment Seat Length

For example, if a deck, span, or span segment object type contains a parameter named “Height”, a relation “Height = Deck Height” will be created, so that the deck height of instantiated user feature will be equal to “Deck Height” defined in the bridge design. If you modify the valued of “Deck Height”, the corresponding user features will be updated, and its height remains equal to the new “Deck Height”.

A bridge parameter applies to a given list of object types. For example, “Abutment Height” is only meaningful to abutments. It does not apply to other object types. But “Support Length” applies both to pier and tower object types.

The mapping is case-sensitive.

The Tree

After the 3D generation of your bridge, specific bridge-nodes appear in the tree.

Bridge specifications are aggregated under the Bridge Set node as follows:

  • Bridge Layout Set: A geometrical set containing the bridge layout feature results (the Deck and Support Layout Sets that are the component-based design).
  • Bridge Deck Set
  • Bridge Start Support Set
  • Bridge Middle Support Set
  • Bridge End Support Set

Bridge results are aggregated under two different nodes created automatically by the Bridge Design Assistant:

  • Bridge Deck Results
  • Bridge Support Results

Clicking the Bridge Set node allows you to edit the bridge specifications after the bridge generation.