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{live-template:Tutorial}
{info}This tutorial was initially developed for the Bridge Modeler in SAP2000, but the concept applies also to [CSiBridge|csibridge:Home].{info}.
As of SAP2000 V14.1.0, it is possible to assign parametric variation to girder spacing and to offsets from reference point to the insertion points.
*On this page:*
{toc}
h1. Key modeling steps
The key modeling steps involve:
* Creating parametric variations via "Bridge > Parametric Variations".
* Assigning the parametric variation via "Bridge > Bridge Objects > Modify/Show Bridge Object > Spans > Modify/Show > Modify/Show Section Variation Along Selected Span".
h1. Examples
Consider a 2-span bridge with two 15m long spans. The deck superstructure consists of 4 steel girders supporting a cast in place slab. The total superstructure width is 12m, the spacing of the girders is 3m and the overhangs on each side are 1.5m long.
!Variable_girder_spacing_-_bridge_deck_section_definition.png!
The width of the second span linearly increases from 12m to 15m. Let's consider the following two cases: uniform flare and "one-sided" flare.
h2. Uniform Flare
The girder spacing increases from 3m to 4m, while the structure is symmetric about the layout line. This can be modeled as follows:
* Assign linear parametric variation (from 0m to 1m) to girder spacing for all girders in the second span.
* Assign linear parametric variation (from 0m to 3m) to the total deck width for second span.
!Variable_girder_spacing_-_uniform_flare_screenshot.png!
h2. "One-Sided" Flare
The girder spacing increases from 3m to 4m, but the right edge of the bridge for both spans is a straight line. This can be modeled by assigning the following parametric variation in addition to the parametric variations assigned for uniform flare:
* Assign linear parametric variation (from 0m to 1.5m) to X offset from reference point to the insertion point.
!Variable_girder_spacing_-_one_way_flare.png!
h1. Attachments
* [Relevant SAP2000 models|^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