Study On The Mechanical Behaviors Of Combination Area And Local Stress Distribution In Anchorage Zones For Long-Span Continuous Rigid Frame Composite Arch Bridge

Most of the bridges in early stage are simple bridge systems of beam, column, arch, cable, etc. The characteristics of this kind of bridge are stressing definitely and clearly modeled. However, as the development of technology and the unprecedented improvement of productivity level, the bridges have fully developed in the speed of span ability improvement, the trend of structure form combination and the application and rational allocation of diversity updated materials. It is worthy applying and researching continuous rigid frame composite arch bridge in large highway and railway bridges because it makes full use of each superiority of beam and arch, optimizes structural force bearing conditions, saves engineering quantity, and innovates the appearance of bridges. At present, there are still few documents in continuous rigid frame composite arch bridge and it is not found any relative documents doing systematic research in the mechanical behaviors of beam, arch and pier combination area and local stress distribution in anchorage zones of the bridges. Considering the situations mentioned above, based on Yi Chang Yangtze River Bridge, the author carries out systematic researches on the mechanical behaviors of combination area and local stress distribution in anchorage zones for long-span continuous rigid frame composite arch bridge. The dissertation includes five parts mainly:1. Based on collecting and learning correlative knowledge at home and abroad, the author preliminarily analyzes the development and mechanical characteristics of long-span continuous rigid frame composite arch bridge. The existing problems in the research of mechanical behavior are discussed. Researched on Yi-Wan Railway Yichang-Wanzhou segment newly built engineering Yi Chang Yangtze River Bridge, the author proposes the subject of mechanical behaviors of combination area and local stress distribution in anchorage zones for long-span continuous rigid frame composite arch bridge.2. The author proposes the definition of nominal rigidity of long-span continuous rigid frame composite arch bridge, analyzes the effects of structural parameters on nominal rigidity and derives the theoretical equation of nominal rigidity. The author also discusses the selection of the rigidity ratio of arch and beam and the effect of the ratio on the structure internal forces distribution, and analyzes the influence law of the ratio on the structure internal forces. Then the author gets the delimitation value between rigid arch-flexible beam and flexible arch-rigid beam. It provides a guidance of selecting the structural parameters to designers.3. Based on the similitude theory of structural test models, the author analyzes and derives the static similitude principle, determines similitude ratio of the model, completes the beam,arch and pier combination area model tests in side span and middle span by adopting basic design principle of the model. And the author tests the mechanical properties of the model materials, provides correct material parameters to the numerical analysis. Loading cases are determined by calculation analysis, loading programs are established under feasible loading method. At last, the author determines the testing contents, methods and arrangement scheme of the measuring points.4. The author introduces the space static analysis theory. Based on choosing the constitutive relationships of concrete, steel and strand, the3-D finite element analysis model of beam, arch and pier combination area is established by the combination of existing study results. The numerical analysis results are obtained. Comparing the results of the model tests with the theoretical ones, the stress distribution of concrete in roof, floor, web, arch foot and pier top are obtained. The complicated mechanical behaviors of beam, arch and pier combination area are further studied.5. The author establishes the basic theory of local concrete compression under anchorage zones, including the analysis and research of stress state in local compression area, failure characteristics of local compression, shearing failure mechanism of local concrete compression under anchorage zones, and also local bearing capacity. Then the numerical analysis of the stress distribution in roof and floor anchorage zones are performed. Based on the design of Yi Chang Yangtze River Bridge, the local stress distribution in anchorage zones are studied on model test. By analyzing the stress tesing results of concrete and comparing the results with the theoretical ones, the local stress transferring rules in anchorage zones are obtained, and the causes of cracking in anchorage zones are concluded. These provide evidence for design and have a reference value to develop the same kind of bridge design system.