Research On Damage Identification Of Steel-UHPC Composite Structure Based On PZT Testing Technology

The team of Professor Shao Xudong of Hunan University proposed a lightweight steel-ultra high performance concrete(UHPC)composite bridge deck structure with advantages of large local stiffness,lightweight and etc.for the first time,which has been widely used in long-span bridges in recent years.With this new type of structure,the diseases like fatigue cracking of steel decks,rupture of pavement and etc.can be controlled effectively.Similar to the steel-concrete composite structure,debonding may occur at the steel-UHPC contact surface under the extreme condition,and local micro damage like cracking may occur at the surface of the UHPC layer.Piezoelectric ceramic has the advantage of the integration of the sensor and driver,so this material is suitable for structural health monitoring.Therefore,PZT technology are introduced to the field of the identification of steel-UHPC composite structure damage(debonding of contact surface and cracking of UHPC surface),here are the main works of this paper:Steel-UHPC composite beam entity model is designed and constructed,Loading course of the negative moment of the experimental beam is monitored using both conventional measuring methods and PZT techno logy--wave propagation method and piezoelectric impedance method,and the eigenvalue of multi-dimensional that is sensitive to local micro damage is collected.Comprehensive evaluation of damage is presented.The loading course of the negative moment of the steel-UHPC composite beam is simulated by Abaqus.The results are in good agreement.The principle of damage identification based on wave propagation method is discussed.The damage identification of steel-UHPC composite structure based on wave propagation method is simulated by Abaqus.The results show that for the identification of debonding,the amplitude of the received signal decreases significantly when the excitation frequency is between 4.5 and 8.5 kHz.The amplitude of the received signal is sensitive to the debonding,but only when the debonding size is larger,the amplitude of the received signal decreases further.For the identification of cracking,the amplitude of the received signal decreases significantly when the excitation frequency is around 5kHz and 7kHz.With the increase of the cracks width,the energy dissipation increases,and the amplitude of the received signal gradually decreases.The amplitude of the received signal is not sensitive to the change in cracks depth.Only when the cracks depth reaches 20mm,the amplitude is decreasing significantly.Also,the amplitude of the received signal is sensitive to the number of cracks,and the amplitude of the received signal decreases significantly when the numeber increases.The principle of damage identification based on piezoelectric impedance method is investigated.The damage identification of steel-UHPC composite structure based on piezoelectric impedance method is simulated by Abaqus.The results of numerical simulations show that the characteristic of impedance curve is obvious in the frequency from 100 to 400 kHz,so the frequency is suitable for damage identification.When the size of the debonding of the interface increases,the RMSD damage index increases.And when the size of debonding reaches a certain extent(100 x 100mm),the RMSD damage index rises rapidly.