A New Data Extension Scheme for Low-Cut Filtering-Based Strong-Motion Record Processing

Abstract

ABSTRACT Strong-motion records often show unrealistic displacements with drift, making them unsuitable for direct use in analyzing structural responses. To remove the drift, low-cut filtering is commonly used. However, the conventional zero-padding scheme to extend the accelerogram before filtering leads to unwanted effects, such as filter transients and an artificially extended duration. Furthermore, stripping off the added portion afterward may cause compatibility issues, resulting in inaccurate velocity and displacement time series derived from the acceleration data. To overcome these limitations, we introduce a new approach for extending and filtering velocity data. In this approach, the velocity trace is extended linearly at the end to double its length, followed by mirroring the data around the starting point. An adjustment function is then applied to ensure that the filtered velocity trace starts with zero after the extensions are removed. This novel technique effectively minimizes distortions in the resulting traces, producing compatible traces while preserving the original data duration. The advantages of this approach are illustrated through two case studies, showcasing its superiority over the zero-padding scheme and its performance compared to the Pacific Earthquake Engineering Research Center data. Moreover, a quantitative assessment using an extensive dataset of ground motions from Japan, encompassing a broad spectrum of magnitudes (Mj 2.3–7.2, in which Mj denotes Japan Meteorological Agency magnitude), epicentral distances (0–1500 km), and site conditions, validates the robustness of the proposed method. Our method completes the drift correction of ground motion in one shot, eliminating the need for subsequent baseline correction required by current approaches to yield consistent acceleration, velocity, and displacement traces.