Stiffness and Damping Identification for Asymmetric Building Frame With In-plane Flexible Floors

Abstract

In most building structures, floors with sufficient in-plane stiffness exist and an assumption of rigid in-plane stiffness is valid. However, in some building structures, an assumption of rigid in-plane stiffness does not hold. A method of system identification (SI) for physical parameters (stiffness, damping) is proposed for three-dimensional (3D) building structures with in-plane flexible floors. The stiffness and damping parameters of each vertical structural frame in the 3D building structure are identified from the measured floor horizontal accelerations together with the stiffness and damping parameters of each floor. It is shown that a batch processing least-squares estimation method for many discrete time-domain measured data enables the direct identification of both the stiffness and damping parameters of each vertical structural frame and the stiffness and damping parameters of each floor. The proposed method possesses an advantage that all stiffness and damping parameters of vertical frames and horizontal frames (floors) can be identified simultaneously without search iteration. The accuracy and reliability of the proposed method are made clear by numerical simulations for measured data without noise and measured data with noise. A method of noise elimination is proposed to enhance the identification accuracy. Finally, experiments using a shaking table are conducted for the accuracy investigation of the proposed identification method. It is confirmed that the proposed identification method possesses a reliable ability to identify the stiffness and damping parameters for 3D building structures with in-plane flexible floors.

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

“…On the other hand, let G [xj,yl] ki denote the in-plane shear stiffness of floor per unit length in the [xj, yl] span of the i-th story (see Figure 1C). More detailed explanation can be found in the reference (Shintani et al, 2019). Although these stiffnesses are used for the modeling of the objective building structures, only the hysteretic restoring-force characteristics of vertical frames and in-plane horizontal floors are identified directly in the present paper.…”

“…Investigations on identification of hysteretic restoring-force characteristics of structures have been conducted in the last four decades (Toussi and Yao, 1983;Cifuentes, 1984;Leontaritis and Billings, 1985;Masri et al, 1987Masri et al, , 1993Loh and Chung, 1993;Kitada, 1998Kitada, , 2000Kitada et al, 2000;Li et al, 2004a,b;Saadat et al, 2004;Zhang and Sato, 2006;Ikhouance and Rodellar, 2007;Tasbihgoo et al, 2007;Worden and Manson, 2010;Brewick et al, 2016;Pelliciari et al, 2018). Although these investigations are versatile, the problem of physical parameter system identification of 3D building structures with mass and/or stiffness eccentricity is a tough problem (e.g., Omrani et al, 2012;Nabeshima and Takewaki, 2017;Shintani et al, 2017Shintani et al, , 2019Fujita and Takewaki, 2018). Compared to the previous researches using neural networks (Saadat et al, 2004;Tasbihgoo et al, 2007;Brewick et al, 2016), wavelet transforms (Kitada, 1998(Kitada, , 2000Saadat et al, 2004), support vector regressions (Zhang and Sato, 2006), fast Bayesian bootstrap filter (Li et al, 2004b), multi-stage iterative approach (Li et al, 2004a), the present approach is suitable for vertical and horizontal framewise simultaneous identification of hysteretic restoring-force characteristics of structural frames with flexible floors within a small amount of computational load.…”

“…Shintani et al (2017) developed another method of system identification for linear 3D building structures with stiffness eccentricity and rigid in-plane stiffness of floors. Subsequently, Shintani et al (2019) extended their method to a linear model with in-plane flexible floors. However, the development for identification of hysteretic restoring-force characteristics is strongly desired.…”