Damage Identification Of Bridge Erecting Machine Girders Based On Influence Line Of Deflection

This thesis summarizes the present situation of damage identification methods of existing structures,and studies on the damage identification methods bridge erecting machine based on influence line of deflection combined with the structural type and operation characteristics of bridge erecting machine.According to the operation mode and structure characteristics of bridge erecting machine,which is classified and analysed by the theory of influence line deflection based on energy principle.The models of different damage condition are established and analysed by the FEM software ANSYS,which verifies the availability of the curve of displace influence line,puts forward the damage degree quantification method of bridge erecting machine and discusses the application strategy and suggestion of damage identification of bridge erecting machine girders based on influence line of deflection.The related research can provide theoretical guidance and technical support for damage identification of bridge erecting machine girders.The main contents as follows:(1)The primary concern about structural safety of bridge erecting machine is analysed by summing up the safety accident cases of bridge erecting machine.By summarying the general methods of structural damage identification and the present situation of damage identification and evaluation of bridge erecting machines analyses the limitations of the existing methods applied to the damage identification of bridge erecting machine girders.(2)Bridge erecting machine is classified and analysed according to structure type and operation characteristics.The explicit formulas of influence line of deflection and its curvature are derived based on energy principle,combining with the present situation of the random variation of the main beam's pivot position during the work of bridge erecting machine.The theory proves that it is feasible to carry out the damage identification method of bridge erecting machine girders based on influence line of deflection.(3)Taking one of the type-SXJ900/32 bridge erecting machine as the research object,the simulation model of the bridge erecting machine is established by using the FEM software of ANSYS,and the numerical simulation analysis is carried out under different damage conditions.Through the data processing of the numerical simulation results,the influence line of deflection of different identification points,the influence line curvature of deflection after damage,the different curve of the deflection before and after the damage are obtained.Based on this,the damage location and damage quantity identification and the influence factors of damage effect are studied to verify the effectiveness of the damage identification method of bridge erecting machine girders based on influence line of deflection.(4)Through analysing damage identification effect of different measuring point influence line curvature of deflection comparative,the principle of setting up measuring points is sought in the process of identification.Combining with numerical simulation results with different damage degree,the method of quantifying the damage degree of bridge erecting machine girders is putted forward in the form of concrete examples,on the basis of which,the implement strategy and suggestion of damage identification of bridge erecting machine girders based on influence line of deflection are putted forward.