ANALYSIS OF INTERACTION BETWEEN THE ELEMENTS IN CABLE-STAYED BRIDGE

Large-span cable-stayed bridges design is impossible without a cable adjustment, which should be made in various stages of construction and for finished structure alike. There may be many concepts of regulation - the creation of design geometry (mainly used for relatively small- span pedestrian bridges), the optimization of shear or moment diagrams in carriageway's construction, the reduction of max tensile or compressive stresses in the load-bearing elements. Normally, the choice of mechanical and geometrical parameters for the main load bearing elements (cables, stiffness girder and pylons) which affect the flexibility of a bridge structure is an iterative process based on the structural engineering experience. The assumptions are to be tested by the Finite Element Method calculations and changed if necessary. This paper offers insight into the mathematical methods developed, based on the deformed shape of the cable-stayed bridge system. The method developed is demonstrated by example, where the system is optimized according to the type of cable-stayed bridge ("star" or "harp" design), geometrical parameters (lengths of stiffness beam sections, height of pylons) and the stiffness parameters (cross-section of cables, flexibility of the girder). This method allows analyzing the interactions between this data.