CONSTRUCTION STAGE ANALYSIS OF CABLE-STAYED BRIDGE

Abstract

This thesis presents a comprehensive analysis of the advancements in the design and construction of cable stayed bridges over the past 50 years. The study focuses on various aspects, including the use of high-tensile strength stay cables, improved structural analysis techniques, and the introduction of multi-cable systems. The benefits of employing steel or composite girders in relation to increasing span lengths are also explored. Additionally, the influence of geometric nonlinearity and soil-structure interaction on the behavior of cable stayed bridges is examined. The research confirms the economic and aesthetic advantages of cable-stayed bridges, demonstrating their suitability as a bridge type. It emphasizes the need to determine the "ideal state" of the bridge under permanent loads, highlighting the importance of minimizing bending moments in the main girder and pylon through accurate calculation of cable forces. Structural analysis programs utilizing optimization methods are recommended to achieve reliable results, provided that user-defined restrictions for forces, moments, stresses, and displacements are carefully considered. Regarding geometric nonlinearity, it is observed that its effect is relatively small for short-span bridges but becomes more significant as the span length increases. The study emphasizes the consideration of factors such as initial stresses, cable sag, and large deformations for accurate analysis of geometric nonlinearity in long-span cable-stayed bridges. In terms of erection analysis for cable-stayed bridges with composite steel-concrete decks, the thesis reveals a lack of extensive literature on the subject. The backward and forward analysis methods are explored, highlighting the importance of modeling de-stressing and re-stressing operations to ensure consistent results. The influence of creep and shrinkage on internal forces and deformations is addressed, emphasizing the need for precise analysis and the incorporation of time-dependent material properties to achieve proper camber of the deck. The thesis concludes by emphasizing the criticality of the construction stage, particularly in cantilever construction. It emphasizes the necessity of meticulous attention to creep and shrinkage effects to avoid potential deformations and economic losses. The findings of this study contribute to a comprehensive understanding of the design and construction considerations for cable-stayed bridges, offering insights for engineers and researchers in the field.