The purpose of this study is to evaluate uncertainties of actual steel structures. In this paper, the axial strain on the columns of steel structures was measured in the construction stages and after completion. The uncertainties involved in the design stage and construction stage are statistically evaluated by analyzing the differences between the measured values and theoretical values. The uncertainties on the design stage and construction stage are introduced into the design method, and a design factor concerned with the errors of construction and structural analysis is presented.
