Model-Free Identification of Hysteretic Restoring-Force Characteristic of Multi-Plane and Multi-Story Frame Model With In-Plane Flexible Floor

Abstract

While linear system identification (SI) has been developed extensively, research advancement in the field of non-linear hysteretic SI is not satisfactory. An innovative method is proposed in this paper for identification of hysteretic restoring-force characteristics of three-dimensional (3D) building structures with in-plane flexible floors. The hysteretic restoring-force characteristics of vertical structural frames in the 3D building structure are identified from the measured floor horizontal accelerations together with the hysteretic restoring-force characteristics of floors without the assumption of hysteresis types or a priori knowledge of restoring force characteristics. Fourier expansion is applied to the time-history responses of story shear forces in vertical frames and in-plane shear forces in horizontal frames (floors). A batch processing least-squares estimation method for measured data is shown to be applicable to the identification of the Fourier coefficients on the story shear forces in vertical structural frames and those on the in-plane shear forces in floors. The proposed method is simple and direct because only Fourier expansion and batch processing least-squares estimation are required. Numerical simulations with and without noise are conducted for investigating the accuracy and reliability of the proposed method. It is demonstrated that the proposed method can identify successfully the hysteretic restoring-force characteristics of plane frames in 3D building structures with in-plane flexible floors.

An acceleration-oriented form of simple piecewise linearisation in time series to assess seismically damaged structures

“…Its effectiveness in linear structural systems has been well demonstrated (Kang et al, 2005;Shintani et al, 2017). However, for nonlinear structures, it has been mainly aimed at estimating the nonlinear hysteretic loops rather than time-varying physical parameters (Toussi and Yao 1983;Masri et al, 1987a;Masri et al, 1987b;Agbabian et al, 1991;Kitada 1998;Shintani et al, 2020).…”

Fishbone model-based inversion to estimate physical parameters of elastic structures under earthquake excitations

“…In this regard, a time domain inversion (TDI), which selects suitable parameters for an assumed model by the least squares method and time history structural responses (i.e., acceleration, velocity, and displacement), has been a useful approach, particularly for linear systems or those with little parameter variation (Agbabian et al, 1991); (Nakamura and Yasui 1999); (Shintani, Yoshitomi, and Takewaki 2017). However, regarding nonlinear systems, TDI has been mainly used for the estimation of the nonlinear restoring force within a system (Toussi and Yao 1983); (Masri et al, 1987(a)); (Masri et al, 1987(b)); (Shintani, Yoshitomi, and Takewaki 2020), rather than those physical parameters. This is mainly attributed to a feature of TDI: it requires enough sampling steps for the estimation, indicating its unsuitability for the exact identification of time-varying parameters.…”