Study Of Damage Identification Method For Simple Support Beams Based On Mobile Loading

Damage identification of engineering structures is a hot topic of research,especially for the damage identification of the critical force parts of structures.In this paper,for simply supported beams with low redundancy,two cases of uniform and non-uniform longitudinal distribution of flexural stiffness were distinguished based on mobile loading and static performance indexes.(1)First,a theoretical analysis of a simply supported beam with longitudinally uniform distribution of flexural stiffness was carried out.The theoretical static displacement of each measurement point was derived by using the principle of virtual work,and a new index of damage identification based on vehicle movement loading and central differential curvature index-"Proximity differential curvature index D_i"was proposed.And the feasibility of this index considering the shear deformation condition was investigated.Finally,the damage identification method of simply supported beam based on"D_i"was established,and the location of damage of simply supported beam could be determined according to the variation law of this index when the structural damage identification was done.This method adopted the idea of mobile loading and established the relationship between the static index of the structure and the local damage of the structure under mobile loading.It was simple to measure,easy to load and low cost to identify in practical application.And the accuracy of this method was verified by numerical simulation.(2)For simply supported beams with longitudinal inhomogeneous distribution of flexural stiffness,a new damage identification method was proposed for two different moving loading conditions,considering the simplicity of loading.For the two working conditions,the vertical displacement data of the mid-span of the simply supported beam under each moving loading condition are collected.In turn,a system of joint equations was used to solve for the local flexural stiffness values in each interval.Finally,the damage information of simply supported beams could be identified by comparing the changes of flexural stiffness values in each zone of the beam before and after the damage.This method took into account the convenience of loading and the relevance of practical application,and the two mobile loading conditions of this method could be selected in practical application.And the accuracy of this method was verified by test.In this paper,a distinction was made between the uniform distribution of longitudinal flexural stiffness of simply supported beams in the intact condition.Then the damage identification in these two cases has been studied separately,and the corresponding identification methods have been established.The core idea of the two damage identification methods was based on mobile loading and static displacement indicators,without the need for complex modal analysis and processing.It is less dependent on the measurement sensor and has certain advantages in terms of simplicity of application and economy.