Numerical Analysis of Reinforcing Effect for Scissors-Type Bridge with Strut Members

Recently, a scissor mechanism was efficiently applied in the safety engineering field as an emergency structure owing to the advantages of mobility, transformability, and re-usability. This paper focuses on the advantages of this mechanism and puts forward a deployable emergency bridge called Mobile Bridge as a smart bridge. To deploy this bridge in an emergency situation, the structural safety, such as strength and stiffness, must be ensured through proper reinforcing methods. Several research studies concerning the reinforcing effect to scissors structures have been conducted using a cable and/or strut. However, the reinforcing situation was limited, and it is not clear where and how much reinforcement should be introduced. In this paper, we discuss the reinforcing effect of simple struts through a theoretical and numerical approach. Then, we evaluate their applicability to the Mobile Bridge based on numerical simulation. The advantage of the proposed reinforcing method is evaluated, focusing on the reduction of the bending moment which is the dominant sectional force in the scissor structure. We found the reinforcing effect has a nonlinear relationship between the stress and ratio of extension rigidity. The most effective reinforcing configuration was a double warren truss with the vertical element in a two-unit scissors-type bridge and a double warren truss without the vertical element in a three-unit scissors-type bridge. The necessary sectional area of the strut elements was more than 0.2 times that of the scissors member. These results imply that the smart bridge can enhance its performance by using proper reinforcement of the struts.