| In the last century, devastating earthquakes have brought about great lose to people's lives and property. But at the same time, human have collected huge amount of Strong-Motion records. As research goes on, near-field permanent displacement became more and more noticed all around the earthquake engineering circles and the records with high accuracy are required. But it is the near field shakes most intensively, and this will force instrument platform to tilt. Moreover, the tilting degree and direction are time-varying. Even worse, near fields are likely to spin in great earthquakes. And, somehow, the according records may include spin components. All of these bring a lot of difficult to records correction. Scholars have managed to find correction methods, and have drawn many useful conclusions. But the records acquired form Wenchuan earthquake show more complicate records errors. Therefore, this paper research the correction method based on previous study, and compiled a program in MATLAB environment. Research specifics are as follow:1. Analyzed the error in digital strong motion seismograph, and studied the correction method of near field strong motion acceleration records.2. Revealed the reasons why the baselines usually drift in velocity and displacement tracks by conducted a shake-table experiment and compared the displacement integrated form acceleration and displacement measured directly.3. Compiled a correction software using MATALB, and acquired permanent displacement by integrated the corrected acceleration records from Wenchuan earthquake. And compared the displacement with GPS coseismic displacement. The result denoted that this method is effective against errors caused by instrument tilt.
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