One of the challenging issues in modern civil engineering analysis is the typically large number of random quantities defining the input and system parameters. One approach to making such problems tractable is to identify the most important sources of uncertainty. The influence of uncertainties of input and system parameters on the uncertainty of system response expressed by mathematical models is studied using sensitivity and uncertainty analyses. The stochastic sensitivity analysis will be carried out with the aim of assessing the relative sensitivity of the random variability of a monitored event to the random variability of individual input variables. The objective of the study is to assessment the influence of initial imperfections and excitation uncertainties on the response of a single storey steel plane frame. The influence of the variance of initial imperfections and excitation uncertainties on the variance of the response was calculated by Monte Carlo based procedure.
