Seismic Damage Assessment And Structural Damage Detection Of Transverse And Longitudinal Guiding System Of Gear Rack Climbing Type Shiplift

With the rapid development of hydro project in China,many gear rack climbing type ship lifts have been built,which are mostly located in the seismic zone and will inevitably suffer from different seismic impact.As the necessary structures in the process of seismic transmission,the damage of the chamber and transverse/longitudinal guiding system of gear rack climbing type ship lift will have potential safety risks for the ship lift operation.Therefore,the research on seismic damage assessment based on the Stress Damage Ratio Difference(SDRD)and structural damage detection has certain reference value for the repair and maintenance work after seism.The main work and research contents of this thesis are as follows(1)The finite element model of Xiangjiaba ship lift with chamber and the transverse and longitudinal guiding system was built by using ANSYS.The model includes the structure of the chamber(driving transverse beam,safety transverse beam,main longitudinal beam,flanking platform,water tank,),transverse guiding system(installation platform,hydraulic rod,guiding frame,spring and clamping plate),longitudinal guiding system(longitudinal guiding support,spring seat,spring and clamping block).The reasonable use of constraints and coupling can truly simulate the operation situation under seism and the transmission characteristics between each system.For other non-critical equipments,it will be transformed to load applied to the corresponding location of the chamber.(2)The stress and damage situation of the finite element model in seismic level-7,8,9 were analyzed and SDRD were calculated.The seismic damage assessment method of the chamber and the transverse/longitudinal guiding system was determined.The results demonstrate that in non-seism,the structures are not damaged.In seismic level-7,the maximum stress of longitudinal guiding system is 515.46 MPa and SDRD is 1.3,9.8% structures of longitudinal guiding system has slight damage,but the chamber is still safe and reliable with only local cracks.In seismic level-8,9,34.23% and 38.89% structures of guiding system are seriously damaged with the maximum stress 841.13 MPa and SDRD 2.2.The main longitudinal beam and water plate of the chamber are broken and the normal operation can not be continued safely.(3)Taking the transverse guiding system as research object and considering the natural frequency change rate,stress and strain as input characteristic parameters,a structural damage detection model was proposed combining with damaged structure classifier,damaged location classifier,damaged level classifier by using MATLAB.The modal analysis and static analysis under 18 damage conditions were carried out.1646 training samples’ and 100 testing samples’ characteristic parameters were calculated.The structural damage detection model for transverse guiding system was trained and tested based on BP neural network,Support Vector Machine(SVM)and Bayesian.The result demonstrated that the accuracy of the model based on BP neural network for damaged structure,damaged location and damaged level are 93%,90% and 91%,which was 7% and 13% higher than the model based on SVM and Bayesian.The model was effective for the damage detection of transverse guiding system.