The present document describes a music structure inference algorithm submitted to the MIREX 2011 evaluation campaign (structural segmentation task). It consists of 3 stages : symbolic feature extraction, structural segment boundary estimation, and structural segment clustering. We consider as inputs chord estimations from the system of Ueda et al., expressed at the 2-beat scale. Beats and downbeats are estimated by the system of Davies et al. The structural segmentation step uses a regularity-constrained Viterbi approach. It assumes that the structure of pop songs is generally based on a few typical segments, whose sizes are called structural pulsation periods. The segments are then clustered according to their similarity, through the minimization of an adaptive model selection criterion.