thanks you for replying.
i am new to karamba. Actually first, i applied initial force eps0 =-0.768 in X and Y direction,(i saw other discussing saying eps0 have to be minus to be tensile force) at this time max displacement was 0.1823 which is higher than the max displacement when no initial strain applied. Higher the eps0 in initial force , in my analyze max displacement increases, strange 
Hence, i thought my method of giving tension might have been wrong and changed it to that (previous post, which i am wrong too)
Plus when i check for the N2 in model view component, i see nothing. Does is mean no geometric stiffness effects due to tension in shell, right.
i saw this discussion
Defining Beam Element Types(end of the discussion) saying when structure is too flexible, no axial forces result from the pre-strain?
i tried to increase Youngs modulus, still n2 cannot be shown in model view.
Changing Max iteration=1 means, it will ignore Axial forces in beams and in-plane forces in shells influence the structural stiffness right? i dont want that. HElp me
11.24normalframe.gh (89.5 KB)