Bridge Design

[Anonymous]

I am designing a 3 span, Steel Beam Bridge.

Center Span is 400’ (this dimension is fixed)

I am using I360 to compare designs of different outer spans.

I use a  rule of thumb on long span bridges of this nature to use  1/3 to 1/2 the length of mid span should be length of outer two spans.

Basic Structural ……The outer spans  push up when center span is loaded down thus resulting efficient overall design.

Question is:

Using I360 with bridge spans of  250’-400’-250’ Three Span Steel Beam bridge, results are beam height  16’+ at piers and 8’+ height at  mid span.

Reducing the outer spans to 150’-400’-150’ the beam height should increase. In I360, there is no change in beam height.

There should be some difference between the two designs.

What is I360 doing to estimate beam design?

[Matt__W]

My understanding of Infraworks and all that it has to offer is that it is strictly a preliminary design/concept type of software, meaning that you would model up an idea in Infraworks and export it to a true design software package for the final detailed design. That being said, there's plenty of stuff hidden/buried in external XML/JSON files that Infraworks can read that maybe you can customize to have it auto-magically size the beams?

Maybe someone like @Willy_Campbell, @elliott.rosenfeld or @Eric_Chappell can chime in with some insight on this?

[austin_jephson]

At the moment in InfraWorks, steel girders are purely conceptual, so it is just picking a nominal value for mid-span, and applying it to all spans.  It isnt doing any design checks to calculate those girder depths.  You can select the girders in the end spans and set the 'Start/end web thickness' so that they look closer to what you are going for.  This is still very conceptual though.

Over the next few releases, we are planning to continue improving bridge modeling functionality to move it out of the conceptual space and into detailed bridge modeling.  So, we'll be working to provide more detailed steel girder support by adding a variety of steel girder types, which can then include diaphragms, bracing, transverse stiffeners, etc.  Then we are also working to introduce a more detailed Variable Depth Girder design workflow, which will allow you to fully customize the span lengths and depths at each point along each span.

Hope this helps and let us know if you have more questions.

-Austin

[Anonymous]

You can see the Idea being developed in future releases @Anonymous

http://forums.autodesk.com/t5/infraworks-360-ideas/detailed-bridge-control/idi-p/6363930

Hope it helps

I am sure, as everybody else, that a lot of improvements will be taken into account in the future and we will benefit!

Have a great day.

Nicola

[ara.ashikian · Accepted solution]

As indicated by Austin,  we are planning significant improvements to the modeling of steel superstructures. This will also include enhancements to the cloud services to carry out structural analyses and code checks to assist in the validation process.

At the moment, the modeling of steel girders is quite simplistic. The default span to depth ratio used for steel girders is 30 and the max span length before variable depth girders are used is 80m.  These values can be changed via the text based CLIPS files (for now).

-Ara

PM InfraWorks 360 / Bridges

Autodesk

[Matt__W]

Lots of good stuff in the Coffee Corner today.  Can't wait!!!