求一个问题的解答

边界条件和载荷只有建立在某个分析步上才有意义。

例如：
** STEP: Step-1
*Step, name=Step-1, nlgeom=YES
*Static
1., 1., 1e-05, 1.
** BOUNDARY CONDITIONS
** Name: BC-1 Type: Displacement/Rotation
*Boundary
AD, 1, 6
** LOADS
** Name: Load-1 Type: Concentrated force
*Cload
BC, 2, -1000.
** OUTPUT REQUESTS
*Restart, write, frequency=0
** FIELD OUTPUT: F-Output-1
*Output, field, variable=PRESELECT
** HISTORY OUTPUT: H-Output-1
*Output, history, variable=PRESELECT
*End Step

因为该边界条件和荷载是作用在该分析步上，即在此步运行该边界条件和荷载