Hello Stressers,
I have an query when I muse stiffness factor as 1 in dynamic analysis?
and what the concept behind that default of stiffness factor in dynamic analysis 0?
thank you

Please refer to section 9 of Caesar-II user's guide.

This "stiffness factor for friction" establishes a stiffness value to be used dynamic analysis for friction points defined in your system. The value of zero indicates that the will be no model component to retard transverse motion at restraints where friction is defined. The value specified here will be used to set a stiffness in the dynamic model; this stiffness will be applied in two normal directions to every restraint with the defined coefficient of friction. The applied stiffness will be this factor times the normal load (from the load case used to set nonlinear restraint status) times the coefficient of friction. The units for this value is (1/inch).
Friction is a damping term and CAESAR II does not have point damping. Including stiffness is one approach to better align the analysis with real-world response.

thank you Dave but I have also an question
Doy you recommend to use stiffness factor for friction as 1 or 0 ?

If I do not wish consider friction, I would specify a factor of zero. If I wish to consider friction (as a stiffness against sliding), I would specify a factor of, say, 1000.
The value is a multiplier, not an on/off (1/0) switch.