Stochastic Approach on Safe Designing of Double Layer Grid Space Structure against Member Length Imperfections

The imperfections in Double Layer Grid Space Structure (DLGSS) threaten the safety of designs. The imperfections in the member length of DLGSS may result from human-based causes such as manual cuts, tolerance sensitivity in CNC cuttings and variation in temperature. Therefore, analyzing the impacts of imperfections is vital to ensure the safety of DLGSS systems. Thus, a safe design of DLGSS against member length imperfections is the main focus of this paper. A novel and practical safe design approach, which considers member length imperfections, has been proposed based on linear elastic and probabilistic analyses methods. The impacts of member length imperfections on the DLGSS behavior were also evaluated in detail. Variation in positions of imperfect members, initial size of length imperfections (longer or shorter than the ideal size) and number of imperfect members were selected as the parameters to be analyzed. A 3D computer program, which considers the initial length imperfections of members, has been codded to analyze the space trusses. The impact of imperfection on a space structure was investigated by repeating the simulations for stochastic dispersion of imperfect member position and initial member length imperfection. The results revealed that initial length imperfection might have a considerable impact on the DLGSS behavior. The DLGSS systems can safely be designed by employing the proposed design approach to overcome the defined imperfections.