•Estimation of human-structure interaction when no statistical model is available.•Reduced numerical complexity for the computation of human-induced effects.•Capability to describe transients of structures affected by human interaction. This article addresses the estimation of the effects of human-structure interaction on the dynamic behaviour of slender structures. The paper proposes a method able to provide predictions of human-structure interaction effects in cases in which no models of human dynamic behaviour can be used/are available and only experimental data have to be used. The proposed approach describes the coupled system composed by the structure and the people on it, splitting the action of people into two components: passive and active forces. The sum of the two provides the global action of each person on the dynamics of the structure. Furthermore, an analytical treatment based on modal coordinates and convolution operations is proposed in order to use experimental data, related to the dynamic behaviour of humans, for predicting the vibration level of the occupied structure. An experimental campaign on a slender staircase provided data employed to validate the approach discussed in the article.