Function
- Initial forces, which are defined in Load > Initial Forces > Small Displacement > Initial Element Forces, are added to a specific load case. Or initial member forces are generated from Member forces due to specific load cases/combinations. The initial nodal and element forces resulting from such external load can be checked in Results>Result Tables> Equilibrium Element Nodal Forces / Initial Element Forces.
- For the backward stage analysis of a cable stayed bridge, the nodal forces of the completed structure subjected to tension and dead loads are calculated. This makes possible to consider the zero displacement condition while the internal forces exist in the structure.
- Also, by considering member forces induced by the self weight of a structure during a pushover analysis, we can avoid creating another time history load case for the self weight.
- The nodal forces are found after multiplying the nodal displacement and the stiffness of the structure, and the member forces are obtained by adding the fixed end forces (moments) to the nodal forces.
Call
From the Main Menu select [Misc.] tab > [Type : Initial Forces] > [Initial Forces] group > [Small Displacement] > [Initial Forces Control Data]
Input
Add Initial Force to Element Force
Check on to add Initial forces, which are defined in Load > Initial Forces > Small Displacement > Initial Element Forces, to a specific Load Case.
Initial Force Combination
Load Case
Select and enter a load case for which initial axial forces are to be saved or added.
Scale Factor
Enter a scale factor for the load case.
To enter a new or additional load case
Enter the relevant load case and scale factor, and click the Add Button.
To modify previously entered load case
After selecting the relevant load case, modify the scale factor, and click the Modify Button.
To delete previously entered load case
Select the relevant load case, and click the Delete Button.