Research On Fatigue Analysis Of Open Type Wharf On Piles Under Cyclic Loading

Fatigue failure is the property degeneration of material under cyclic loading, which is the main failure mode of material, component and structure. In harbor engineering, high-piled wharf is an common structure form. At present, researchers have done large quantity work on the durability of high-piled wharf. Those years, with the continuous development and application of the high strength reinforced concrete, the weight of the structure and the dead load are all reduced; with the port scale continuous expansion, the proportion of cyclic loading has relatively increased. All those make the fatigue problem of high-piled wharf components become an key issue.When the high-piled wharf is under cyclic loading, the components of it are in bending status. Flexural member of reinforced concrete is a very complicated stressed member. For the fatigue life evaluation of bending member, this paper studies this from two aspects. On the one hand, for the component's compression area, the paper studies from the view of concrete's fatigue damage. On the other hand, for the component's tensile area, the paper studies from the view of debonding fatigue failure between steel bar and concrete. The paper's main contents are as follows:First, for the concrete's damage of compression area, this paper mainly studies how to use fatigue failure criterion to evaluate the component's fatigue life, specific contents are as follows:a, on the basis of concluding the form of S-N curve under uniaxial compression, collecting large quantity experiment data, establishing the bilinear S-N curve which considers the whole fatigue stress range.b, on the basis of the concrete's fatigue deformation presenting very stable low of three stage, and the ultimate strain is material constant, study on fatigue failure criteria in strain space based on the second stage of fatigue deformation strain rate and the ultimate strain.c, study the applicability of Miner's rule to variable amplitude fatigue of concrete material based on the concepts of normal stress ratio and actual stress ratio, nonlinear fatigue damage accumulation criterion is established. Second, for the fatigue failure of component's tensile area, the debonding between steel bar and concrete is the main failure mode. Numerical simulation is done in this paper by using shear-lag model, and we attempt to apply this model to practical engineering.Third, combining with concrete engineering practice, using finite element software ANSYS to carry out dynamic analysis of portal crane girder of open type wharf on piles, according to the result of dynamic analysis and related fatigue damage theory, calculating fatigue life of portal crane girder of open type wharf on piles.