Lighter and slender structural members of a typical grandstand leads to a significant reduction in the frequencies, that is why such structures are more easily induced to vibrations. The aim of the present paper is to show the results of the experimental tests and the numerical analyses focused on the behaviour of a part of a typical temporary steel grandstand under dynamic loads. The peak values of accelerations of a steel scaffolding grandstand under human-induced excitation have been determined and compared with the limit values concerning the perception of vibrations by people. The results of the study indicate that the human-induced excitation may induce structural vibrations which substantially exceed the allowable limits.