When rolling I-sections in universal mills, workpiece is captured by horizontal rolls, while vertical rolls in that time passive, but they are directly involved in reduction process. Studied literary sources describe effect of stresses on forces arising during rolling, as on impact resistance of vertical rolls rolling mills. However, issues of gripping and braking workpiece and effect of vertical rolls passive rotation on the quality characteristics of rolled products, including thickness variation, require more attention and detailed consideration. The results of simulation of rolling I-beam 20K1 in DEFORM-3D program are given, taking into account effect of vertical rolls passive rotation and its experimental rolling with further rolled product 3D scanning along 12 control sections. In course of modeling, influence of multipolar stresses arising in process of gripping workpiece on formed profile elements geometry was evaluated. It is shown that capture of strip occurs unevenly by right and left rolls. The vertical rolls do not rotate at moment of capture, which leads to formation of metal thickening at beginning of workpiece rolling. After their begin rotation, process stabilizes and metal begins to deform evenly along the wall, which leads to decrease in load on the vertical rolls. It has been established that uneven compression, both over cross section and along length of strip, leads not only to increased loads during I-beam rolling, but also to a change in geometric dimensions of section and curvature of strip. Adequacy of model is confirmed by high convergence of simulation results and production experiment