Study On Crack Detection Of Reinforced Concrete Bridge Pier Models Under Impact With PZT Technology

The safety of long-span bridges relates to the people's life and property while ship collision incidents on bridge piers happen occasionally.Those incidents may not only cause casualties and other direct results,but also lead to structural safety problems.Thus,the damage condition of post-impact bridge piers is critical and it is of great significance to detect the cracks of the bridge piers under impact.In this study,a crack detection approach using stress wave measurement from piezoelectric ceramic(PZT)patches for a reinforced concrete(RC)pier specimen under free-falling-weight test facility is proposed.A series of scale RC pier specimens were designed and constructed and impact tests on those specimens with surface mounted PZT patches were carried out.The cracks of the specimen after impact were detected using the variation of the amplitudes of the stress wave measurement under sinusoidal excitation and the wavelet packet energy of that under sweep signals excitations.The specific study is listed as follow:1.The working principle of piezoelectric ceramic materials and fabrication of the PZT actuators and sensors are introduced in detail at first and their static and dynamic performances are studied and calibrated using sine excitation signals.2.A crack monitoring approach using stress wave measurement from PZT patches for a reinforced concrete(RC)pier specimen under free-falling-weight impact facility was proposed.A series of scale RC pier specimens were designed and constructed and a number of PZT patches were surface mounted on the specimens for the purpose of detecting the cracks.3.Impact test on the RC pier specimens were carried out by using different impact energies.Sinusoidal excitation and sweep excitation were employed to excite the PZT actuator respectively before and after impact.Response measurement of each PZT sensor was recorded.4.The variation of the amplitudes of the stress wave measurement under sinusoidal excitation and the wavelet packet energy of that under sweep signals excitation were analyzed and damage index was defined.Results show that the proposed method can monitor the crack development of RC pier models after collision.