Issue 47

Y. Mizuno et alii, Frattura ed Integrità Strutturale, 47 (2019) 209-220; DOI: 10.3221/IGF-ESIS.47.16 215 In this manner, live load and dead load of the floor construction beam are supported by the combination of a cable-stayed system as one of the truss systems and a suspension system. In this method, there are no large temporary support structures. Thus, this method is efficient because of material efficiency and is suitable for long bridges. This Dischinger method is currently the best method for constructing long span bridges. Although the cables visually clash with each other and appear complicated at the spot where both structural systems overlap, the completed bridge appears light because many cables are used in the cable-stayed system and suspension system. Figure 9 : Construction method of the Dischinger-type bridge (The Yavuz Sultan Bridge [7]). Lowering Method (Fig. 10) In the lowering method, precast arch rib members are rotated on hinges installed on both banks, which eventually make up the arch system. In the rotation process, cables receive reaction force from outside the system and arch rib members constitute a cantilever truss system, which resemble triangles. The truss system changes its stress state during the rotation process. Finally, the arch rib members are closed and function as an arch system. This method features good the material efficiency because no huge temporary support structure is used during construction. However, the axial force occurring in the arch rib members during the rotation process is converted into the bending moment because their shape bends in relation to the arch structure. Thus, this method is not suitable for very long bridges because the truss system is not structurally efficient. Almost nothing from the rotation process remains in the construction state. Nevertheless, stress analysis is necessary for every angle because internal stress changes along with the form change of the truss structure. Figure 10: Lo wering method [8].