In order to monitor the cavity defect development of concrete structure during service,the defect degree of concrete after defect repair and determine the corresponding compressive strength,it explores a monitoring method based on stress wave two piezoelectric sensors are pasted on the surface of concrete specimen,one is used as actuator,the other as sensor,and the signal source is used to generate voltage signal to excite the actuator to generate stress wave.At the same time,measure the output voltage of the sensor under different cavity defect diameters and after defect repair,introduce the characteristic value of the output voltage,then test the compressive strength of the corresponding test block,establish the quantitative relationship between the characteristic value and the compressive strength of concrete,and evaluate the mechanical properties of concrete.Through the finite element model,the propagation characteristics of stress wave under different cavity defect diameters are studied,and the feasibility of characterizing the degree of concrete defects by amplitude and phase is proved.Therefore,the damage parameter based on time of flight and the energy index based on amplitude are proposed to evaluate the state of concrete defects.Finally,the concrete cavity defect development and repair monitoring test is designed.The frequency sweep signal and pulse signal are used to monitor the test block and extract the characteristic values(energy index and damage parameters)to evaluate the defect status and compressive strength before and after the concrete defect repair.The feasibility of this method is verified and the applicable conditions of different excitation signals are given.
关键词
压电传感器/混凝土缺陷/混凝土修复/抗压强度/频段能量谱/波飞行时间
Key words
piezoelectric sensor/concrete defect damage/concrete repair/compressive strength/frequency band energy spectrum/wave flight time
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