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{live-template:Tutorial}
{info}While this tutorial was developed for the [SAP2000|sap2000:home] bridge modeler, the concept also applies to [CSiBridge|csibridge:Home].{info}
h1. Key modeling steps
* Create a parametric variation through the Bridge > Parametric Variations option.
* Assign the parametric variation through the Bridge > Bridge Objects > Modify/Show Bridge Object > Spans > Modify/Show > Modify/Show Section Variation Along Selected Span option.
h1. Example
Consider a two-span bridge with two 15m long spans. The deck superstructure consists of four steel girders supporting a cast-in-place slab. Total superstructure width is 12m, girder spacing is 3m, and the overhang on each side is 1.5m.
These specifications may be defined as shown in Figure 1:
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!Variable_girder_spacing_-_bridge_deck_section_definition.png|align=center,border=1!
{center-text}Figure 1 - Bridge deck section definition{center-text}
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For the second span, the width linearly increases from 12m to 15m. Uniform flare and one-sided flare will be considered.
h2. Uniform flare
Girder spacing increases from 3m to 4m. The structure is symmetric about the [layout line|tutorials:Layout-line geometry]. This may be modeled as follows:
* For all girders in the second span, assign linear parametric variation (from 0m to 1m) to girder spacing.
* For the second span, assign linear parametric variation (from 0m to 3m) to the total deck width.
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!Variable_girder_spacing_-_uniform_flare_screenshot.png|align=center,border=1!
{center-text}Figure 2 - Variable girder spacing for uniform flare{center-text}
h2. One-sided flare
Girder spacing increases from 3m to 4m, while for both spans, the right edge of the bridge is straight. This may be modeled by assigning, in addition to the parametric variations for uniform flare, the following:
* Linear parametric variation (from 0m to 1.5m) to X offset from the reference point to the insertion point.
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!Variable_girder_spacing_-_one_way_flare.png|align=center,border=1!
{center-text}Figure 3 - Variable girder spacing for one-sided flare{center-text}
h1. Attachments
* [Relevant SAP2000 models |Variable girder spacing^SAP2000 models.zip]| Info |
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While this tutorial was developed for the SAP2000 bridge modeler, the concept also applies to CSiBridge. |
On this page:
Key modeling steps
Create a parametric variation through the Bridge > Parametric Variations option.
Assign the parametric variation through the Bridge > Bridge Objects > Modify/Show Bridge Object > Spans > Modify/Show > Modify/Show Section Variation Along Selected Span option.
Example
Consider a two-span bridge with two 15m long spans. The deck superstructure consists of four steel girders supporting a cast-in-place slab. Total superstructure width is 12m, girder spacing is 3m, and the overhang on each side is 1.5m.
These specifications may be defined as shown in Figure 1:
Image Added
Figure 1 - Bridge deck section definition
For the second span, the width linearly increases from 12m to 15m. Uniform flare and one-sided flare will be considered.
Uniform flare
Girder spacing increases from 3m to 4m. The structure is symmetric about the layout line. This may be modeled as follows:
For all girders in the second span, assign linear parametric variation (from 0m to 1m) to girder spacing.
For the second span, assign linear parametric variation (from 0m to 3m) to the total deck width.
Image Added
Figure 2 - Variable girder spacing for uniform flare
One-sided flare
Girder spacing increases from 3m to 4m, while for both spans, the right edge of the bridge is straight. This may be modeled by assigning, in addition to the parametric variations for uniform flare, the following:
Linear parametric variation (from 0m to 1.5m) to X offset from the reference point to the insertion point.
Image Added
Figure 3 - Variable girder spacing for one-sided flare
Attachments
Metadata
Name: Variable girder spacing
Description: Procedure for developing a model with variable girder spacing.
Program: SAP2000
Program Version: 14.1.0
Model ID: na