An accelerogram is a graphical representation of the acceleration that occurs at a specific point in time. This acceleration – time diagram can be used to generate response spectra or to perform a time history analysis. Many accelerograms are available in the form of records of earthquakes that have occurred.
The accelerograms used in the model are managed in the Accelerogram dialog box.
Main
In the Main tab, you can specify the type of an accelerogram and define the parameters.
Defintion Type
Specify how you want to define the accelerogram. There are two definition types available in the list.
User-Defined
When selecting a user-defined accelerogram, you can specify the properties in the "Times & Accelerations" section: Enter the times t with the associated accelerations aX, aY, and aZ line by line in the table.
Using the table, you can individually define the acceleration – Time Diagram. The order of the lines entered can be arbitrary. This allows you to subsequently add value pairs that lie between the values that have already been defined.
Since there must be a consistent time diagram, the values are displayed in red in the case of the incorrect order. In this case, use the
button to sort the lines in ascending order.
You can delete the selected table row using the
button.
The
button allows you to import the table values of a diagram from Excel. You can use the
button to export the user-defined accelerogram to Excel.
The functions for saving user-defined accelerograms in a library and reading them back in from there are still under development. The buttons
are thus blocked.
If the accelerogram values have a constant time interval, activate the ΔT check box below the table. Then, enter the time step in the text box next to it
. If you now enter accelerations in the table, the time is automatically set with the steps ΔT. You can adjust the step ΔT at any time in order to enter further values with a different time step.
The diagram of the accelerogram generated from the specifications is shown in the lower section. You can use the X, Y, and Z buttons to the right of the diagram to control which accelerogram direction is displayed. The functions of the diagram are described in the chapter Response Spectrum .
From Library
The program includes an extensive library of accelerograms that were recorded during the occurrence of earthquakes. The function for using user-defined accelerograms in this library is still under development. Open the library by clicking the
button to the right of the list.
The accelerograms of the library are sorted by country.
Select the relevant earthquake from the list of "Accelerograms". The criteria in the "Filter" section can help you. Depending on the parameter, there are various options.
Each accelerogram is characterized by specific "Accelerogram Parameters", such as a country, the longitude and latitude, a distance from the epicenter, or the earthquake duration. These properties are displayed on the right of the library.
In the lower area, you can see the diagram of the selected accelerogram. Most accelerograms show different accelerations in three global directions. You can use the X, Y, and Z buttons to the right of the diagram to control which accelerogram direction is displayed. The functions of the diagram are described in the chapter Response Spectrum .
Click OK to transfer the accelerogram to the "New Accelerogram" dialog box. This also include the parameters like the earthquake location, the measuring station, and the distance from the epicenter. You can see the diagram in the dialog section below. Use the buttons X, Y, and Z to switch the acceleration directions.
Table Values
The Table Values tab is only available if the response spectrum is generated using the From Library definition type.
In this tab, you can check the time steps with the associated accelerations aX, aY, and aZ. Thus, the table corresponds to the accelerogram entry described in the User-Defined section. However, it is not possible to edit the values in this table.