Study On Integrity Inspection Technology For Quality Of Digital Strong Motion Accelerograph

As an important part of China Digital Seismic Observation Network, China Digital Strong Motion Network (CDSMN) has got higher investment than ever. With the formal operation of CDSMN, the quality and reliability of instruments attract much more attention. The thesis focuses on the detection technique and the performance evaluation of digital strong motion accelerograph, which was analyzed with the method of performance indexes testing and operation performance. The main contents of this thesis are as follows:Firstly, the measurement methods for accelerometer sensitivity and linearity are determined by the zero-frequency table test. Experimental results indicate that the calibration accuracy of zero-frequency table could satisfy the requirement for technical specification of the force-rebalance accelerometer, and zero-frequency table can replace the shaking table test to complete calibration of accelerometers to a certain extent.Secondly, vibration calibration by laser interferometry is introduced, which is applicated to determine the transfer function of accelerograph. Experimental results indicate that laser absolute calibration is of higher precision and stability than relative calibration method.Thirdly, the working principle and the dynamic analysis of FBA indicate that the natural frequency and damping ratio of accelerograph, which could help evaluate the performance of accelerograph, could be determined by function tests. It could be concluded that the response increases more quickly with higher natural frequency; and the overshoot decreases with the increasing of the damping ratio. Appropriate damping ratio could lead to better amplitude-frequency character of the FBA, and the best damping ratio is ranging from 0.65 to 0.68.Finally, the consistency of two different accelerographs was analysized through their waveforms, PGA, and frequency contents. The result indicated that the maximum relative error is as large as 13%, while the waveforms and the frequency contents are similar. The mechanism of inconsistency is analyzed, and a consistency test method by shaking table is proposed.