Fatigue Performance Study Of Bamboo Bridge

China is now at a historical stage of large-scale construction.Steel and cement are the two most common materials used in construction,but their production process not only consumes valuable energy,but also produces large amounts of harmful substances.Advancement of science and technology has made it possible to recombine bamboo into various kinds of components by modern recombination technology.Bamboo has become a new type of environment-friendly consrtuction material due to its light weight,high strength,good toughness and excellent seismic performance.Fatigue performance study is a indispensable part of new material research,which can provide reference for engineering applications.This paper illustrates the stain and deflection changes,development of cracks,fatigue life under cylic load test of glued bamboo beams and failure modes and features of fatigue or static damage through the tests of six glued bamboo beams under different conditions.Using the acquired data of fatigue life and stress amplitude to plot the S-N curve of glued bamboo beams at the stress ratio of 0.2,a high reliability linear regression equation has been obtained.Glued bamboo beams and bridge static loading models were established with the help of finite element software Abaqusand Ansys to analyze bamboo beam layer cracking locations and layer destruction process during static loading stage.According to the degree of damage,a stiffness degradation model of glued bamboo beams has been built,based on which,another carrying capacity degradation model has been built.Corresponding fitting formula was proposed using MATLAB.Analysis of the degeneration law of stiffness and bearing capacity of glued bamboo beams is included.The calculation of fatigue parmeteres using Seeger algorithm in Fe-safe and simulation of the material's S-N curve are both inclued.The fatigue model of bamboo beams has been build to make comparison between test results and finite element results.Studies have shown that during cyclic loading process,the beam section accord with flat section assume.The fatigue life is in proportion to the stress ration under the same lower fatigue limit.Vertical cracks appeared when the load was at the support.After the fatigue test,the static failure modes includ bending,adhesive layer cracks from the loading point to the end of beam caused by tangential failure,leading to inconsistent beam deformation and eventually bamboo layers' disengagement.When the fatigue limit is less than 96 kN,fatigur process has less of a effect on the ultimate bearing capacity and stiffness of bamboo beams.The stiffness degeneration low shows the curve of Type-S.The bearing capacity declined relatively slow at early stage.As the cyclic loading ratio turned 0.7,a rapid fall arose.Seeger algorithm has a comparatively high accuracy in fatigue applications of glued bamboo beams.The finite element results conform roughly with experimental results,making it feasible to use this method to evaluate the fatigue life of glued bamboo beams.