Abstract Summary
The scissors mechanism, which consists of a chain of rotating discrete elements pin-connected to multiple framework members, can be deployed and retracted, making it highly functional and compact. This useful module can be used on bridges close to unmanned automated bridges. In order to use this useful module in bridges that are similar to unmanned automated bridges and meet various performance requirements, it is necessary to consider structural stability and optimal dimensional design for dead and active loads, buckling, and vibration. For the finite element method (FEM) of the scissors structure, the objective is to construct a program that updates the optimum cross-sectional dimensions from each cross-sectional stress of each member to achieve the minimum weight. Based on the analysis from the axial stress and bending moment stress states calculated using FEM, the cross-sectional dimensions b_i, c_i of each member were updated, and a new method was developed to modify the cross-sectional area and cross-sectional secondary moment of the member based on the sensitivity. In this study, the cross-sectional dimensions of each member unit were efficiently updated to the optimum by distinguishing each cross-section of each scissors member into axial stress and bending moment stress components. The optimal structural configuration obtained using this method is discussed. In this study, a deployable bridge with a series of 5 units was used as a model. The analysis was performed for different models with different loading conditions and different boundary conditions, and the optimal structural configurations were compared. The results showed that the optimal structural configuration for all models corresponded to the overall bending moment distribution. The stresses in each member also asymptotically approached the allowable stress. Therefore, the optimal structural configuration is considered to have been obtained. The optimal structural configuration corresponding to various conditions was obtained by combining the optimized members under different conditions. The method proposed in this paper is optimally updated for the stresses in each member, and the optimal dimensions of each member are determined. As a result, the overall structural form was determined and the weight was minimized.
