Research On Hyperbolic Tower With Self-stiffened Plate Of Multi-span Cable-stayed Bridge

To solve the problem of relatively lower bending stiffness of the multi-spancable-stayed bridges, a hyperbolic tower with self-stiffened plates was proposed,which solve two key problems in the design of Chishi Bridge as follows:(1)Multi-span cable-stayed bridges are of relatively lower bending stiffness and resultin higher stress amplitude of main girder under service vehicle load overconventional cable-stayed bridges with three spans (one middle span plus two sidespans);(2) How to decrease additional internal forces and horizontal displacementof high pier due to seasonal temperature variation.The design of hyperbolic tower, static analysis, analysis of ultimate capacity,experimental research of tower and research of self-stiffened plate have done in thethesis. The main contents of this dissertation are described as following:(1) Researching on the reason of multi-span cable-stayed bridge with relativelylower bending stiffness and discussing some methods which could improve thebending stiffness of multi-span cable-stayed bridge. The stability of multi-spancable-stayed bridge and normal cable-stayed bridge were compared in the thesis.The hyperbolic tower was designed and applied in Chishi Bridge through learningthe design of tower in some famous cable-stayed bridges. The Chishi Bridge withsingle tower and hyperbolic tower were analyzed with finite element analysis,which included the static analysis, stability analysis and dynamic analysis,respectively. Parameter of hyperbolic tower which including space between tw oinclined leg columns of the A-type pylon, height of twin pier and connection amongthe A-type pylon, pier and main girder were analysed in the thesis.(2) The force transmission route that the vertical force caused by dead load andalive load flow from four legs of A-type pylon to twin pier and single pier, wereobtained through theoretical calculation and experimental research of test model①and test model②. The result of model test indicated the stress and cracksdistribution of hyperbolic tower. The design of tower was improved according to theexperimental result.(3) The concept of self-stiffened plate was proposed and applied in the towerof Chishi Bridge. Compared to the flat plate, the self-stiffened plate is of betterstability by changing its own geometry. The equivalent algorithm that self-stiffened plate was equivalent with orthotropic plate was proposed, and the equivalentconstants were deduced with principle of axial rigidity and bending rigidity,respectively. Some equivalent constants need to be modified in some boundarycondition and the elasticity coefficient which was used to modify the equivalentconstant was proposed. Some influence parameters were researched to analysebucking load and buckling modal of self-stiffened plate.(4) The formula about critical buckling load of orthotropic plate was deducedand vertified. The formula about critical buckling load of orthotropic p late was usedto calculate the critical buckling load of self-stiffened plate. The formula aboutcritical buckling load of orthotropic plate with one stiffener in the center of plate,and the formula about the amount of half-wave when the orthotropic plate was inthe buckling state were deduced, respectively. The critical buckling load and theamount of half-wave of self-stiffened plate with one stiffener in the center of platecould be calculated with the deduced formula. The analytical method aboutstabilization capability of self stiffened plate basing on geometric nonlinear,material nonlinear and initial deformation of plate was proposed. The bearingcapacity of self-stiffened plate with no stiffener and with one ribbed stiffener in thecenter of plate were analysed basing on three case: geometric nonlinear, materialnonlinear and double nonlinear.(5) Three criterions about ultimate bearing capacity of structure werecompared. Basing on the double nonlinear including geometric nonlinear andmaterial nonlinear, the ultimate bearing capacity of Chishi Bridge in state ofconstruction and service were calculated with criterion number one(stiffness matrix)and criterion number two(material damage), respectively. The ultimate bearingcapacity of Chishi Bridge with four different cross section of single pier, twoconstitutive relation of concrete and initial deformation were researched,respectively.The result of static analysis, ultimate bearing capacity and experimentalresearch of tower indicated the novelty hyperbolic tower with better aesthetics andmechanical property could be applied in the multi-span cable-stayed bridge throughthe research above. The calculation result of self stiffened plate indicated that thededuced formula about equivalent constants and critical buckling load were correctand valid. The result of model test indicated the hyperbolic tower satisfy thespecification in state of construction and service.