Modeling geometric imperfections for reticulated shell structures using random field theory

The load-carrying capacity of shell structures and shell-like space frames can be sensitive to initial geometric imperfections. Conventional methods of modeling geometric imperfections have focused on estimating the lower bound of the load-carrying capacity of reticulated shells. This paper proposes a random field model for the initial geometric imperfection of reticulated shell structures. The model accounts for the spatial distribution of the initial geometric imperfections, in which the correlation between imperfections at two different nodes depends on the length and number of the connecting members between the two nodes. The paper also presents the findings of the measurements of the initial geometric imperfections of a real reticulated shell structure. Based on the measurement data, the statistical characteristics of the random field model are determined. The role of initial geometric imperfections on structural ultimate strength is examined using numerical examples.