Abstract | Buckling and post-buckling behaviour of beams resting on elastic foundation with an internal hinge is addressed in the present study, as a first step towards modeling upheaval buckling of buried pipelines with flexible joints, induced by a reverse fault activation during a seismic event. The mathematical model used is that of a simply-supported Winkler beam supported laterally by uniformly distributed transverse springs, with an internal hinge stiffened by a rotational spring, and subjected to constant axial force over its length. Linear Buckling Analysis (LBA) is firstly carried out to illustrate the effect of internal rotational stiffness on critical buckling load with respect to a continuous beam. Additionally, through LBAs the interaction of elastic soil stiffness and elastic rotational stiffness is presented in terms of critical buckling load and eigenmode transition. Then, geometrically nonlinear analyses with imperfections (GNIA) are performed, indicating descending post-buckling paths, thus unstable post-buckling behaviour, as well as buckling mode interaction for certain ranges of values of soil stiffness.