Deflection Distribution Identification Of Structure Under Unknown State

In recent years,the structural health monitoring system(SHM)has been rapidly developed.Compared with the traditional structural detection methods,the SHM can analyze the structure under an in-service state conveniently,efficiently and intelligently.As key engineering of traffic and transportation,the bridge has suffered varying degrees of damage under the coupling effect of multiple loads,which further affects the health state of the structure.Therefore,it is very important to deeply understand the bridge in-service state.Deflection is an important structure monitoring parameter and index,but the structural unknown state is not considered in the relevant deflection monitoring part of structure identification at current,so the structure virtual deformation cannot be obtained.Based on the above discussion,this paper studies the identification of structural deformation distribution under an unknown state.The research contents and innovation of this paper are as follows:Ⅰ.Summary of the basic theory of structural identification.Due to that this paper focuses on the research of structure with an unknown state,the primary task is to determine the structural state.This part introduces the advances research in equivalent stiffness,structural state identification,and structural flexibility identification.Besides,the present research results of the structural deformation distribution estimation are introduced briefly,and based on this,new research results about corresponding sensor layout theory are added.The finite element method is used to verify the effectiveness of the sensor layout theory under static and dynamic load conditions.Ⅱ.Propose the identification theory of structural deformation distribution in an unknown state.Based on the structural deformation distribution identification theory proposed by our research group and the relevant theoretical basis of structural deformation identification at the present stage,a structural deformation distribution identification theory considering the unknown state is proposed in this paper,which is divided into two parts:structural state identification and structural deformation distribution identification.In the part of structural state recognition,according to the flexibility identification theory,the virtual displacement is used to obtain the actual state of the structure.And the finite element model is used to prove the effectiveness of the method.Furthermore,the modified conjugate beam theory is proposed to identify the deformation distribution of unknown state structures.Ⅲ.Through the finite element analysis and laboratory tests under various unknown conditions of the structure,it is shown that the method of identifying the structure state based on the concept of virtual displacement and the modified conjugate beam theory can be applied to the recognition of the deformation distribution of the structure under unknown conditions.Besides,the reasons for the large error in the laboratory test are analyzed,and various error factors are analyzed completely.