Issue 47

Y. Mizuno et alii, Frattura ed Integrità Strutturale, 47 (2019) 209-220; DOI: 10.3221/IGF-ESIS.47.16 218 Table 4 : Structural change list No.1 for newly constructed bridges . E FFICIENCY UNDER D IFFERENT C ONDITIONS Ab. 6 compares the efficiency between three types of structural systems, including a suspension system, a beam system, and an arch system, with corresponding construction states of construction, completed, retrofitted and retrofitting. The suspension system generally exhibits good material efficiency, but the efficiency is low in the retrofitted state, because of the difficulty of reinforcement. It is difficult to maintain the cable as a series of elements in order to conduct the reinforcement in such a manner that the tension force is not interrupted but flows to the end portion. The beam system has better material efficiency because it requires a small number of temporary structures for the advantage of cantilevering. In addition, time efficiency can be improved by using the launching-type erection method. It functions well in the construction state, and it is efficient in the retrofitting state if a diagonal system is used for stiffening. The arch system is not efficient in the construction state because it is not easy to build without support from another system. However, in the retrofitting state, it is efficient for reinforcing existing structures. The arch system can accept various types of reinforcement in the retrofitted state because countermeasures, such as rolling up reinforcement, can be easily taken afterwards. Material Time Suspension Bridge ◎ ○ Vertical Cable Erection Method × △ Single-operation Method of the Suspension Bridge ○ ◎ Cable-Stayed Bridge ◎ × Dischinger-Type Bridge ◎ × Vetrical Rotation Method ◎ ○ Pylon Method × △ Diagonal Cable Erection Method × △ Construction Method / Names of Completed Bridge Efficiency （ Dimensionless ） Transition Construction Process / Life Cycle T