Influence Line-Based Design of Scissors-Type Bridge

Globally, large-scale natural disasters are occurring more frequently due to climatic and environmental changes. In addition, the disaster risk for infrastructures, mainly bridges, has become a vulnerability issue because reinforced concrete bridge structures are being directly exposed to the natural environment. Bridge structures linking cities or prefectures are destroyed in the aftermath of natural disasters and must be rebuilt. As a post-disaster measure, rapid reconstruction of damaged bridges and the reconnection of transportation systems between impacted locations and urban areas are the main problems encountered. This study aims to solve these problems through the application of a novel concept of an emergency bridge based on origami-inspired post-buckling theory, in conjunction with previous studies investigating the optimal deployable structure of scissors-type bridges. This study applied a novel design method for scissor-type bridges that use influence line diagrams and equilibrium equations. The proposed methods can determine the size of each member appropriately while providing the minimum and maximum values of the influence line border when carrying light vehicles by analyzing variations in the live load distribution on the structure. In the case of heavy vehicles passing over a bridge, the fundamental internal axial forces and bending moments were obtained, which provided design parameters for improving the load-carrying capacity of the structure. The proposed emergency bridge has a lower theoretical stress than that of a double-Warren truss.