how to assign P-delta force for a element?

[jiaochiyu2000]

I'm learning how to use the opensees,maybe the problem is fool.
But,in SAP we can direct assign a p-delta force for a element in order to consider the geometry stiffness contribution to the elsatic stiffness.
Do opensees has this kind of function?
For example ,I'v already know the internal forces of every elements of a cable-stayed brdige FEA model at the final construction state.
So I don't what to peform any addtional dead case to supply the dead load to some elements.
So by which ways can I directly assign the p-dela force (initial force) for some element so that the force can modifiy the elastic stiffness of the whole structure?

[silvia]

yes, look at the geometric transformation command in the manual.