Optimization Problem of the size-scale for a Foldable Chain Scissors Structure based on Stress Analysis

Abstract

Abstract Emergency bridges are used to restore the lifeline of damaged bridges after disasters. However, the design specification of existing emergency bridges do not afford rapid bridging. Therefore, a trial deployable bridge (Scissors Bridge) using a scissors structure that folds compactly has been experimentally produced. But, the assembly process for the bridge has not been considered and there are no practical design examples or design methods for scissors bridges. In this paper, as for existing bridges, we established a design method of scissors bridges when considering the live load. In addition, a general-purpose member cross-sectional dimension optimization method, aimed at minimizing weight, was developed and proposed. Considering the problem of insufficient strength of the scissors bridge, the optimum reinforcing pattern and its cross-sectional dimensions were determined through two methods of reinforcement and optimization of the cross-sectional dimension of the member. Finally, a trial of practical design calculation was performed using the results of the study to determine whether a scissors bridge satisfying the standard of the Specifications for Highway Bridges can be designed.