An accelerogram expresses which acceleration occurs at a certain point in time. This acceleration - time diagram can be used to generate response spectra or to perform a time history method . Many accelerograms are in the form of records of earthquakes that have occurred.
The accelerograms used in the model are managed in the Accelerogram dialog.
Base
In the Basic tab, you can specify the type of accelerogram and define the parameters.
Defintion Type
Choose how you want to define the accelerogram. There are two types of definition to choose from in the list.
User-defined
If you describe an accelerogram in a user-defined manner, you can specify the characteristic values in the 'Times & Accelerations' section: Enter the times t with the associated accelerations aX, aY and aZ line by line in the table.
You can use the table to individually define the acceleration-time diagram. The order of the lines entered can be arbitrary. In this way, you can subsequently add value pairs that lie between values that have already been defined.
As a consistent timing diagram must be available, the values are displayed in red if the order is incorrect. In this case, use the
button to sort the lines in ascending order.
You can delete the selected table row with the
button.
The button
enables the table values of a diagram to be imported from Excel. You can use the
button to export the user-defined accelerogram to Excel.
The functions of storing user-defined accelerograms in a library and reading them back in from there are still under development. Therefore the buttons
are blocked.
If the acceleration values have a constant time interval, activate the check box ΔT below the table. Then enter the time step in the field next to it
. If you now enter accelerations in the table, the time is automatically set with the stepsΔT. You can adjust the step ΔT at any time to enter further values with a different time step.
In the lower section, the diagram of the accelerogram generated from the specifications is shown. You can use the X, Y and Z buttons to the right of the graphic to control which direction of acceleration is displayed. The functions of the diagram are described in the chapter Response spectrum described.
From Library
An extensive library of accelerograms is available in the program, which were recorded during the occurrence of earthquakes. The feature to use custom accelerograms in this library is still under development. Call up the library with the
button to the right of the list.
The library's accelerograms are sorted by country.
Select the relevant earthquake from the list of ' accelerograms '. The criteria in the 'Filter' section are helpful for this. Depending on the parameter, there are various options.
Each accelerogram is characterized by specific ' accelerogram parameters ', such as country, longitude and latitude, distance from the epicenter or earthquake duration. These characteristics are displayed on the right side of the library.
In the lower area you can see the diagram of the selected accelerogram. Most accelerograms show different accelerations in the three global directions. You can use the X, Y and Z buttons to the right of the graphic to control which direction of acceleration is displayed. The functions of the diagram are described in the chapter Response spectrum described.
Click OK to transfer the accelerogram to the 'New Accelerogram' dialog. There, the parameters such as earthquake location, measuring station and distance from the epicenter are also given. You can see the diagram in the lower dialog section. With the buttons X, Y and Z you can switch between the acceleration directions.
Table Values
The Tabular Values tab is only available if the accelerogram is generated using the definition type From Library .
In this tab you can check the time steps with the associated accelerations aX, aY and aZ. The table thus corresponds to the entry of an accelerogram described in section user-defined . However, the values cannot be edited in this table.