Time-History Identification of Physical Properties of a Single-Storey Steel Frame Subjected to a Seismic Excitation

This study examines the performance of simple piecewise linearisation in time series (SPLiTS) for the time history identification of physical parameters (i.e., damping and stiffness) of a single-storey steel frame subjected to a seismic excitation. SPLiTS treats a nonlinear structure as a set of piecewise linearised structures, based on half-cyclic waves of its displacement data whose central shift components (e.g., residual displacement or offset) are minimised. The physical parameters of the linearised structures are then obtained by the time history inversions of the structural responses. As SPLiTS is based on structural responses of acceleration, velocity, and displacement, estimations of unmeasured data are required when some responses are not directly measured by sensors. Depending on the measured data, there are two ways in SPLiTS. SPLiTS4ad [SPLiTS4a], which is the case for measured displacement and acceleration responses [acceleration response], it is necessary to estimate the velocity response [velocity and displacement responses]. In terms of the measurement cost, SPLiTS4a is preferable to SPLiTS4ad, because the cost is generally proportional to the number of measured data points. This study examines the accuracy of SPLiTS4ad/a by identifying damping and stiffness in time history from experimental results of a single-storey steel frame subjected to a severe seismic excitation. In the examination, the physical parameters of the frame, identified by SPLiTS4a and described as time-history data, were sufficiently similar to those identified by SPLiTS4ad. This result demonstrates the high practicality of SPLiTS4a for the time-history identification of damping and stiffness of seismically damaged structures.