Research On Sensitivity Of Concrete Component Size To Crack Damage Identification

Concrete materials rely on its superior engineering and mechanical properties,is widely used in various fields of construction engineering.Concrete structures dominate in all types of building structures.However,due to the nature of concrete materials and various complex environments,reinforced concrete structures are usually cracked during their initial service.With the load and other factors,some of the cracks will be diffused locally and form penetrating cracks and deep cracks,which inevitably lead to problems of structure,safety,durability and bearing capacity reduction due to crack damage.Therefore,strengthening the monitoring of crack damage in concrete structures has become an important topic for engineering academics at home and abroad.Piezoelectric ceramic(PZT)is a kind of smart material with dual function of sensing and driving.It has the advantages of high sensitivity,fast response,sensitive to damage and no damage to structure.It is widely used in structural damage identification and health monitoring.In this paper,piezoelectric ceramics are made into piezoelectric smart aggregates,the use of piezoelectric wave-based method to study the different sizes of concrete cracks damage sensitivity,aiming to improve the piezoelectric vibration method based on concrete health monitoring and crack damage Method of monitoring.There are the following main contents:(1)A piezoelectric smart aggregate calibration device is designed.The basic performance of the piezoelectric smart aggregate is calibrated by this device.A calibration method of piezoelectric smart aggregate is proposed.The advantages of piezo-smart aggregates(SA)and their manufacturing process are introduced.The basic properties of piezoelectric smart aggregates are calibrated,including electrical performance,sensitivity,frequency response and driving and sensing performance.That is,measuring the capacitance and the resistance of the piezoelectric smart aggregate by using a power meter;testing the sensitivities of the piezoelectric smart aggregate by using a piezoelectric hammer and a charge amplifier;setting up a piezoelectricity intelligent aggregate calibration device which drives And sensor performance calibration,the piezoelectric smart aggregate used in the follow-up test has good working performances.(2)The optimization test of monitoring signal and characteristic parameters of concrete crack damage is carried out.Active health monitoring by embedded in concrete specimens in the piezoelectric smart aggregates sensor to different crack damage condition of the beam,respectively in time domain and frequency domain analysis of three kinds of active monitoring signal extraction,signal amplitude,frequency and other parameters to determine the structural damage.By analyzing the change of signal parameters with damage degree under different damage conditions,we find out the parameters which are more sensitive to concrete structure crack damage and predict the trend of damage development as a sensitive factor to determine damage.(3)To study the influence of concrete specimens with different sizes and piezoelectric smart aggregate location on the sensitivity of crack damage identification.Through the crack damage monitoring of three different size specimens embedded with piezoelectric smart aggregate sensors,the relationship between the energy value of each size specimen and the percentage of fracture section is analyzed comprehensively to get the crack damage rules of each size component,and the size influence of crack damage identification rule.In addition,the piezoelectric smart aggregate is arranged in the form of an array of concrete specimens to study the influence of different layout locations on the damage identification sensitivity of the crack.