Damage Identification Method For Transverse Connections Of T-girder Bridges Based On Modal Strain Energy Entropy

In recent years,small and medium-sized assembled T-girder bridges have been widely used due to the convenience and quality controllability of construction due to the acceleration of poverty alleviation and the construction of transportation network in China.Due to the increasing vehicle load and service time,the transverse connection members of the assembled T-beam bridge have been damaged to varying degrees,which seriously affects the normal operation of traffic and people’s safety.As one of the key links of bridge health detection,bridge damage identification has attracted wide attention from scholars at home and abroad.Damage diagnosis of transverse connection members has become the research focus of assembled T-beam bridges.However,due to the structural characteristics of excavation in tension concrete area of assembled T-beam bridge,little research has been done on damage identification of transverse connection members.Therefore,the following researches have been made to accurately identify the damage of the transverse connection members of small and medium-sized assembled T-beam bridges,mainly including:(1)The calculation theory of transverse load distribution of assembled T-girder bridge is introduced and discussed.Through literature review,the shortcomings of the calculation theory of transverse load distribution of assembled T-girder bridge are pointed out,which mainly include:the transverse connection member and the deformation of assembled T-girder flange plate are not considered except the vertical shear force.The above deficiencies lay a theoretical foundation and research direction for this paper.In addition,modal strain energy Entropy and generalized local information Entropy are introduced to provide a new method for damage identification of assembled T-beam.(2)In view of the shortcomings of load transverse distribution calculation theory,combined with actual force of transverse connecting member and existing research,the force and deformation of transverse connecting member are simulated by spring system considering transverse force,vertical shear force and deformation of transverse connecting member,and the calculation model of assembled T-beam bridge structure is established by spring system simulation method.Based on this model,a calculation method for damage factor D of transverse connecting member of assembled T-beam bridge is proposed,and the overall working performance of transverse connecting member is described by using this damage factor D.(3)Based on the finite element software ANSYS,the numerical model of the assembled T-beam bridge is established and compared with the theoretical calculation results.The results show that they have a good agreement,which verifies that the damage factor theory proposed in this paper can identify the damage location and extent of transverse connection members.In addition,the accuracy of damage identification for transverse connecting member is related to the distance between load and damage location.The closer the load location is to the damaged transverse connecting member,the higher the accuracy of damage identification is.(4)In order to accurately identify the local damage location of the transverse connecting member,based on the above calculation model and combined with modal strain energy and generalized local information Entropy,the local damage identification index D_L of transverse connecting member based on local modal strain energy information Entropy is constructed.The numerical simulation is carried out by ANSYS finite element software and the theoretical calculation results are compared and analyzed.It shows that this index can accurately locate single and multiple damage of transverse connecting member,quantitatively describe the damage extent of damage location,have high damage sensitivity and accurately identify 10%of minor damage.In addition,D_L has strong noise resistance in noise resistance analysis,and it can still accurately identify the damage location under noise interference with signal-to-noise ratio of 20 dB or more.