This Client Server article is republished in its entirety from 2002 for reference purposes.
By Thomas Taylor, Bentley Civil Engineering Support Consultant; and Jana Miller, Bentley Civil Engineering Marketing Coordinator, Bentley Huntsville, Alabama 10 June 2002
Civil engineers often need to make fast and accurate representations of bridge cross sections. InRoads Bridge and MicroStation V8 offer the tools required to do the job, extracting the cross section from the 3D model.
Bentley's InRoads Bridge and MicroStation V8 provide the tools engineers can use to quickly and easily create an accurate representation of a typical cross section of a bridge. This typical section is used to convey to a bridge contractor the dimensions and elements used in constructing the proposed bridge.
Normally, designers create a typical section and then proceed with design. Instead of typical 2D drafting techniques, this workflow involves extracting a typical section from a 3D model. This method is a by-product of the normal roadway and bridge design workflow.
This article outlines some of these tools by taking you through the basic steps for bridge design using InRoads Bridge. A bridge typical section is extracted from the 3D model using MicroStationV8. The key actions in the workflow are:
This workflow illustrates how to use InRoads Bridge to model and display the finished surface of the bridge deck. Bridge commands are used to display bridge objects. MicroStation commands are used to complete the 3D bridge objects and create the typical section.
The first step in the bridge workflow is to establish the horizontal and vertical geometry for the proposed roadway (see Figure 1). The horizontal and vertical alignments control the application of the typical section to generate the surface model(s). This baseline geometry also controls the location of the proposed bridge, and all bridge geometry will be based on this baseline alignment.
Figure 1. Establishing the horizontal and vertical geometry. Open a design file and create or load your InRoads geometry file:
With the alignments established, the next step is to create templates for the bridge approaches and the bridge itself and to establish a roadway definition (Figure 2). The Roadway Definition tool pulls together the stations and templates, as well as other controls (such as side-slope definition) for producing the roadway model (Figure 3).
Figure 2: Creating templates for the bridge approaches.
Figure 3: Producing the roadway model.
The next step in the workflow is to design the bridge geometry (Figure 4). InRoads Bridge provides the tools needed to lay out the geometric elements for bridge design. Certain critical bridge elements will be displayed in true three-dimensional space. These elements can then be used as a basis for MicroStation tools to be used in completing a true object model. The basic steps involved in defining the bridge geometry are:
Note: These steps outline the basics for minimal geometric layout of the bridge in typical section creation. They do not represent all steps required for final bridge plans.
Figure 4: Using InRoads Bridge to design the bridge geometry.
This section describes the steps involved in defining the remaining objects for the bridge design (Figure 5) and generating the typical section for final detail drafting.
Figure 5: Defining other necessary objects for the bridge design.
Figure 6: Using the Generate Section from a Plan View utility.
Figure 7: An elevation view of the design.
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