Study On The Mechanical Behaviors Of Long-Span Prestressed Concrete V-Shape 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 V-shape 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 V-shape rigid frame composite arch bridge and it is not found any relative documents doing systematic research in the mechanical behaviors of the bridges. Considering the situations mentioned above, based on Xiaolan channel super large bridge, the author carries out systematic researches on the mechanical behaviors of long-span V-shape 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 V-shape rigid frame composite arch bridge. The existing problems in the research of mechanical behavior are discussed. Researched on newly built railway Guangzhou-Zhuhai intercity rail transit project Xiaolan channel super large bridge, the author proposes the subject of mechanical behavior research of long-span V-shape rigid frame composite arch bridge.2. The author proposes the definition of nominal rigidity of long-span V-shape 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 V-shape pier-girder joint model tests by adopting basic design principle of the model. Based on choosing the constitutive relationships of concrete, steel and strand, the 3-D nonlinear finite element model of V-shape pier-girder joint is established to compare the results of the model tests with the theoretical ones. The focuse is on the local stress distribution of the V-shape pier-girder joint under various loading modes. Nonlinear mechanical behavior of the V-shape pier-girder joint is also studied by drawing the curve of load-reinforcement strain in negative moment area and load-deflection curve. The deflection and cracking behaviors and the change law of stiffness are obtained.4. The construction scheme of long-span V-shape rigid frame composite arch bridge is discussed. In process of simulation calculation of the construction, the author compiles APDL command flow program by using the unit birth-death technique, establishes simulation calculation model in the construction process. The creep characteristics of concrete are also taken into account. The whole process of beam first-to-arch later stage construction are calculated and studied. At the mean time, the force and rigidity of the structure system are studied, the effects of shrinkage and creep on structural internal forces distribution are analyzed, and the force ratio of the suspender, arch and beam is discussed. Finally, the author does a roughly studies on the three-plate webs's rule of shear stress distribution, the box girder's longitudinal bending normal stress on every construction stage, and the distribution law of longitudinal bending normal stress and transverse bending normal stress of completed bridge's box girder.5. The author establishes the construction control theory of long-span V-shape rigid frame composite arch bridge, determines the adjustment theories and methods of construction errors including identifying and correcting the design parameters, controlling the adaptive system and operating the analysis systems. By researching on construction control of Xiaolan channel super large bridge, the feasibility of the construction program is evaluated, the alignment and displacement in each construction ideal state are determined and the alignment and displacement in the following construction state are predicted. The stress controling sections and the testing principles are introduced and the stress controling results of the criticat sections are researched on to make the construction go along well as designed, make sure the safety during construction, the structural internal force under constant load and structural alignment are complied with the design requirements and the construction quality and safety are ensured.