Structure Properties Analysis And Experiment Study Of Self-Anchored Cable-Stayed Suspension Bridge

Self-anchored cable-stayed suspension bridge is a new type of bridge. It will become a competitive bridge type in the long- span bridge system because of strength rationality, construction safety and economy. It is very fit for the natural condition such as soft soil foundation and violent typhoon. At present, there are few relevant papers on self-anchored cable-stayed suspension bridge. But this bridge type has a particular advantage under specifically condition. So it is necessary to carry out systematic study on this new bridge type. Under the background of Dalian Gulf Bridge, this paper studies the static mechanical property, limit span and optimization lectotype of the self-anchored cable-stayed suspension bridge with the model test. The main research work covers the following aspects:1. The structure behavior of self-anchored cable-stayed suspension bridge is described with continuum method. The incomplete potential energy functional of three-span self-anchored cable-stayed suspension bridge is established by considering pressure-bending of girder and tower. And the differential equations of self-anchored cable-stayed suspension bridge are approximately derived based on the region-wise variation. A self-anchored cable-stayed suspension bridge is taken as an example, and the results of analytic method agree with those of numerical analysis. The theory and method can provide theoretical basis for the static analysis of self-anchored cable-stayed suspension bridge.2. The nonlinearities of self-anchored cable-stayed suspension bridge are studied. The influences of shrinkage and creep of concrete, rise-span ratio and girder camber on the system have been also discussed. A self-anchored cable-stayed suspension bridge, with 800m main span, is analyzed with nonlinear finite element method. The moment and displacement of main components under difference rise-span ratio and girder camber stages with living load are gotten. According to the result of the analysis, the system is strongly influenced by geometrical nonlinearities. Shrinkage and creep of concrete affect much on the structure. As the rise-span ratio becomes larger, the axial force of main cable becomes weaker and structure gets stronger. The system rigidity increases if girder camber is setting.3. The paper discusses the fatigue problem of the end suspender and the continuity problem of the girder between the cable-stayed part and Suspension part. The construction method of self-anchored cable-stayed suspension bridge is also expounded. The investigation indicates that the stress amplitude of the end suspender can be reduced to avoid fatigue damage by setting auxiliary piers or cross suspension cables and increasing the bending stiffness of the girder. The anti-fatigue capability of suspender can be enhanced remarkably by increasing the suspender sectional area. An appropriate construction form should be selected for transition section, which can alleviate the stress mutation on the transition section.4. The limit span of self-anchored cable-stayed suspension bridge is deduced. And the relations among the geometrical parameters, the loads and the material characteristics are also analyzed. Based on the material strength and the common used material, the limit spans of self-anchored cable-stayed suspension bridges with concrete girder, steel girder and composite girder under vertical load are discussed in detail. The corresponding-upper limit spans and the influence of the factors on the span are given. The results indicate that increasing rise-span ratio, height-span ratio, cable-stayed segment length or reducing the second dead load can increase the cooperation system span.5. The multi-level and multi-objective fuzzy optimization model of self-anchored cable-stayed suspension bridge selection is built based on fuzzy decision theory, which combines binary comparison method. The model coordinates the complex relationship among the factors, which are divided into several levels. Fuzzy method is adapted to calculate the weight vector, which can overcome the limitation of linear method. Base on the analysis of the model, the self-anchored cable-stayed suspension bridge is the most suitable type for Dalian Gulf Bridge.6. In order to check the design of structure and study on the structure characteristics, a model of Dalian Gulf Bridge is made, which similarity scale is 1/100. The results of the experiments are consistent with those of theoretical analysis. The static force performance of self-anchored cable-stayed suspension bridge can be analyzed by finite displacement theory. The conclusions can offer the helpful basis for research and design on self-anchored cable-stayed suspension.