Structural Damage Identification Based On Marine Predators Algorithm And Objective Function Updating

Structural damage identification(SDI),as the most important part of structural health monitoring,has become the research focus of many scholars.The SDI method based on model updating can realize the location and quantification of structural damage.Combined with the excellent searching ability of intelligent optimization algorithm,it can effectively promote the development of SDI method.In this thesis,marine predator algorithm(MPA)and SDI method are combined to achieve good identification results.On this basis,the index of sensitivity to damage was explored and the Transmissibility assurance Criteria(TAC)was proposed.The weighted Schatten- sparse regularization strategy is also used for SDI in order to reduce errors and misjudgments.Finally,through numerical simulations and experimental verifications,the proposed method is systematically studied.The main contents are as follows:(1)The research background and practical significance of structural damage identification are described.The existing structural damage identification methods are described in detail,and two common damage identification methods are introduced based on whether there is a model or not.Model-free methods are SDI methods based on signal characteristics,including time domain analysis,frequency domain analysis and time-frequency domain analysis.The other model-based methods are SDI methods based on model updating,including SDI method based on sensitivity analysis and SDI method based on swarm intelligence algorithm.In addition,the application of transmissibility function(TF)in SDI is introduced.At the same time,the advantages and disadvantages of each method are compared and analyzed.(2)A structural damage identification method based on marine predator algorithm(MPA)is proposed.The optimization principle,basic mathematical model and motion strategy of MPA are introduced.The method is combined with SDI to improve the efficiency and accuracy of SDI.The SDI method based on MPA was compared with that based on ant lion optimization(ALO)and salp swarm algorithm(SSA).The applicability and effectiveness of the proposed method are verified by numerical simulation of simply supported beams and two-layer rigid frames,Meanwhile,it is found that the proposed method still has some problems,such as insensitive objective function to damage and weak robustness of noise.(3)To solve the above problems,a structural damage identification method based on the transmissibility assurance criterion(TAC)and weighted Schatten- sparse regularization strategy was proposed.Since the TF is sensitive to damage,inspired by modal assurance criteria(MAC),the transmissibility function is combined with MAC to construct the TAC.TAC is combined with modal parameters to redefine a new objective function.In addition,a weighted Schatten- sparse regularization strategy is added to achieve better sparse regularization results.Finally,in order to verify the effectiveness and feasibility of the proposed method,numerical simulation is carried out for simply supported beams and planar trusses,and research on weak damage identification is carried out as well.(4)A simply supported steel beam model was set up in a laboratory environment,and different working conditions were set.The effectiveness of the SDI method based on the TAC and weighted Schatten- sparse regularization was verified.Modal analysis was carried out by hammering method,and the required frequency response function was extracted by LMS dynamic data acquisition and analysis system,and modal parameters were obtained.The MPA proposed in Chapter 2 is used to update model.Finally,the proposed method is used to identify damage,and the results are compared with traditional method based on natural frequencies and modal shapes.The effectiveness and superiority of the proposed method are proved.