The imperfection-sensitivity of a class of nearly double-bucklings in singly Z2-symmetric structures is investigated. Two types of imperfections are distinguished: the first is the imperfection of an auxiliary parameter, denoted by A, whose variation from its critical value Mc splits the double-buckling load into two simple ones; the second is a geometric imperfection with amplitude r. In the case of r = 0, such structures display secondary bifurcations for values of M 54 Mc near tic. Based on the scaling technique and the implicit function theorem, the explicit asymptotic expressions of the first unstable point of bifurcation or local maximum load of the imperfect structures are established. The derived formulas are applied to an imperfect cylindrical panel subjected to axial compression to account for its load-bearing capacity.
