Geometric and material nonlinear behavior of slender webs in I-column girders having stocky flanges under the action of combined lateral and axial loads is investigated. Interaction curves corresponding to the application of compressive and shear loads at buckling and ultimate stages for both web plates and column sections are plotted. In addition, the effects of flange and web slenderness ratios on the behavior of columns are studied. Results show that the effect of compressive loads on decreasing shear buckling and ultimate capacities of slender web plates is more than the effect of shear on the relative axial capacities. In the case of dominant compressive loading, the increase of shear force does not reduce the ultimate axial capacity of web plates.