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Dusan Biocanin Structural software developer



Purpose:Dynamic response calculations

Calculating eigenvalues of the dynamic matrix is certainly not a problem for present-day computing. However, after finding vibration mode periods of the structure, engineers often continue calculation with substantial assumptions regarding building response. Additionally, current seismic building design standards offer quite simple, but very inaccurate methods for bypassing response calculations.


Spektrum is a Matlab application designed for dynamics analysts to have better insight into structures behavior during earthquakes. The core algorithm is based on Newmark’s method of integration of Duhamel’s integral. Input data is parsed from valid XLS earthquake accelerogram records. By using Spektrum, an engineer can make his design process more elaborate. He can observe structure behavior in relation to specific or generic accelerograms without using the response envelope that standards promote.

Calculations are performed in two modes. In the “Spektrum response” mode user imports accelerogram data of one earthquake and chooses response type (movements, accelerations, normalized accelerations, quasivelosities, etc.). Results are shown as a series of graphs. An engineer can examine what will be the response of the structure by reading appropriate coordinates.

In the “Spektrum envelope” mode, the user can consequently import numerous accelerogram data. Idea is to set up the analysis with both existing and generic accelerograms. In that way engineer can apply accelerograms of the nearby earthquakes that have already happened, complemented with generic ones. Calculation results with an envelope of specific responses. After finding the appropriate structure response, the engineer can adjust structures rigidity in order to decrease the effects of the seismic load.

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