Question
How do you set the Boundary Change Assignment when analyzing underground structures?
Answer
If it is not possible to consider different boundary conditions within a single model, there may be a burdensome process of creating multiple models, analyzing them separately, and then calculating the combined member forces using Excel.
The 'Boundary Change Assignment' function in CIVIL allows for using different boundary conditions within a single model. This enables the analysis of different scenarios within the same model and facilitates the calculation of combined member forces. Thus, when conducting seismic analysis of underground structures, the Boundary Change Assignment function can be used to assign different boundary conditions for the permanent and seismic conditions, making it possible to analyze and evaluate each case accordingly.
Clicking on the Boundary Change Assignment displays the dialog box shown above. When you check the desired data in the Data Selection list in the upper left corner, the Boundary Group List defined on the right is displayed. If you check off the Filter Boundary Group at the bottom, all boundary condition groups will be displayed.
Entering a name in the upper right corner and selecting the desired boundary condition group from the Boundary Group List, then clicking Add/Replace will create a single boundary condition combination with the selected boundary condition groups.
At the bottom of the dialog box, you can specify the boundary condition combination that the user has defined for the Load Cases & Analyses, which can be static load conditions or analysis types.
Clicking on the '+' next to Static Load Case expands the table and displays the defined static load cases.