Advanced Structural Optimization Capabilities of Scia Engineer

Mark Flamer, P.E., M.I. Flamer & Associates

Astrid Bastiaens, Product Engineer, Nemetschek Scia

One of the key benefits of a structural analysis and design application such as Scia Engineer is the ability to optimize the members in a structure. In our Tips and Tricks article published last month, we looked at two types of optimization capabilities of Scia Engineer: Parametric design and Auto design. In this follow-up article, we will look at some additional optimization capabilities of Scia including ESA XML solver, Input/Output interface, and Batch optimizer.

ESA XML Solver

This is a great way to link Scia Engineer to other software programs. Using XML, Scia Engineer can operate in a “hidden” mode, where a project may be created in another program. Then using XML, the other program can launch the calculation process in Scia Engineer, and results can be fed back to the other program for further results or documentation. All defined documents may be refreshed and updated from outside of Scia Engineer, and finally all values in the document can be read from outside.

Many firms use this capability to link Scia Engineer with their in-house Excel-based application. Scia Engineer also uses the ESA XML solver in its partnership with Tiltwerks for the design of tiltup wall panels. The wall panels can be brought into Scia Engineer for whole building analysis. The FEM results can then be pushed back to Tiltwerks for the final wall panel design and documentation.

Input/Output Interface

To illustrate the use of ESA XML, we will use a third party software application called “Beam Moment Iterator.” The sample project consists of a simple beam on two supports loaded by a lineload q, as shown.

The user wants to calculate the project for different values of the lineload q until a specified maximal moment Mmax is reached.

More specifically, this consists of an iterative calculation:

• Step 1: The moment M is calculated for a value of the lineload q.
• Step 2: The moment M is compared to the maximal moment Mmax.
• If M < Mmax, the lineload q is augmented and M is recalculated.
• If M ³ Mmax, the calculation stops.

The Beam Moment Iterator asks the user to specify the maximal moment, the initial value of the lineload, and the loading increment.

The Beam Moment Iterator then uses ESA XML to update the project with this data, to calculate the project, and to return the bending moment in the middle of the beam.

Using the Process Explorer, it can be seen that Solver.exe is indeed started by ESA XML, which is in turn started by the Beam Moment Iterator.

The calculation then continues until the specified maximal moment is reached.

This same procedure could be used, for example, for a cable stayed bridge to calculate the prestress forces in the cables. The condition here would be such that the bridge deck is +/- horizontal. The prestress forces would then need to be altered in each iteration until the bridge is nearly horizontal.

Batch Optimizer

The Batch Optimizer is a special function in Scia Engineer.

Using the Batch Optimizer, the user only defines limits for the desired parameters and the step of variation for the parameters. In addition, it is possible to define additional constants and formulas which Scia Engineer can use to calculate almost any results. For example, one constant can be used to represent the price of 1kg of the used material; the formula can then calculate the total price of the whole structure.

Let us use the example of the haunched steel beam shown below.

We can see the weight and price of this beam for different dimensions of the haunch.

All variants are designed optimally, but their prices differ from 2000 to 2800 Euro. With the Batch Optimizer, we can calculate the most cost effective design.

The formula can be even more complex. For example, it can eliminate all the calculated variants where the deflection exceeds a specific value.

All the results obtained from the calculation of the project and from the specified formulas may be summarized in a clear and simple table in Scia Engineer.

In order to make the optimization an even more productive tool, the results can be exported into the comma separated value (CSV) format file or into an MS Excel format file. This enables the user to prepare state-of-the-art tables and eye-catching graphs of the results.

Conclusion

In the last Tips and Tricks article, we saw the use of parameters and auto-design for structural design optimization in Scia Engineer. In this article, we looked at its more advanced optimization capabilities such as the Batch Optimizer. Through a parametric project, the user needs to create an input and output file defining the input parameters for which a range of values need to be calculated. These results can be exported to Excel for creating explanatory diagrams.

If users want to link Scia Engineer with external applications, e.g. an Excel based spreadsheet, the external solver is the right solution. With this method, Scia Engineer operates in the hidden mode. All tasks, including project modification, calculation, checking results, and so on happens outside of Scia Engineer and can be done in the external software application.

With the input/output data interface, structural data can be modified from outside Scia Engineer. In a document, the user can define which design values should be incorporated.

This shows that Scia Engineer has several options that go beyond standard optimization and allow you to quickly find the best solution to a structural design problem.

For more information on Scia Engineer, please visit www.scia-online.com.

About the Authors

Mark Flamer, P.E, of M.I. Flamer & Associates, is a registered engineer in California and an early adopter of 3D and BIM technologies. He has successfully completed over 15 BIM projects. Mark consults with leading software developers on BIM technologies and is a member of the SEI-CASE BIM committee.

Astrid Bastiaens is a Product Engineer at Nemetschek Scia. She graduated with a degree in Civil Engineering from Katholieke University, Leuven, Belgium and has worked at Nemetschek Scia since 2006 .

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