Seismic Response of Plan‐Asymmetric Structures with Diaphragm Flexibility

Abstract

The seismic behavior of asymmetric structures with a flexible diaphragm was studied by conducting inelastic dynamic time-history analyses. Asymmetric structures with different configurations of mass, stiffness, and strength centers, in combination with a wide range of diaphragm flexibility, were evaluated. The behavior of structures was studied by considering three aspects: (1) effect of structural asymmetry on diaphragms deformation; (2) effect of diaphragm flexibility on demands of the lateral load-resisting elements; (3) optimum configuration of mass, stiffness, and strength centers to limit important engineering demand parameters in asymmetric structures with a flexible diaphragm. The results showed that the shear-dominant deformation of diaphragms is sensitive to both structure asymmetry specifications and the degree of diaphragm flexibility; therefore, it can be used for the qualitative classification of the seismic behavior of structures. Also, the center of strength in structures with flexible diaphragm is more important relative to the stiffness center and has a significant effect on engineering demands at all levels of diaphragm flexibility. Moreover, it was found that a suitable configuration of centers in torsionally stiff structures depends on the degree of diaphragm flexibility, in addition to the intensity of earthquakes (structure yield level) and selected engineering demand parameter.

Traditional High-rise Unreinforced Masonry Buildings: Modeling and Influence of Floor System Stiffening on Their Overall Seismic Response

“…Conversely, Eivani et al (2018) found remarkably greater shear deformation sensitivity in the diaphragms to the asymmetry and flexibility of the floor, which is why they considered the shear deformation component a clearer classification parameter. The conclusions of Eivani et al (2018) could be considered more reliable since they were based on more realistic models.…”

“…Although the categories are accompanied by descriptions of behavior, these are very general and unreliable (Tena-Colunga 2015;Nakamura et al 2017b;Srisangeerthanan 2018). Recently, Nakamura et al (2017b) and Eivani et al (2018) proposed more refined and useful classifications based on the dominant characteristics of diaphragm deformation and on how incremental flexibility of the diaphragm affects wall responses. From parametric studies, in which the fundamental period of the diaphragm constitutes the basic parameter of classification, four categories of diaphragm are established.…”

“…In the most recent literature on floor system flexibility effects on low-rise buildings with symmetric and asymmetric plans, the conclusions refer to aspects such as: 1) global seismic response: modal parameters, interstory drift profiles, base shear and displacement capacity (Giongo 2013;Nakamura et al 2017a;Kollerathu and Menon 2017;Ortega et al 2018;Lagomarsino et al 2018); 2) the lateral load pattern for pushover analysis Lagomarsino et al 2018); 3) displacement and ductility demands on in-plane walls (Nakamura et al 2017a;Eivani et al 2018); 4) in-plane deformability of the floor system in models of low-rise buildings and a review of the normative criteria of diaphragm classification (Tena-Colunga et al 2015;Nakamura et al 2017b;Eivani et al 2018); and 5) the applicability of nonlinear static procedures to low-rise URM buildings (Lagomarsino and Cattari 2015b;Nakamura et al 2017a;Guerrini et al 2017;Lagomarsino et al 2018;Azizi-Bondarabadi et al 2019;Diana et al 2019;Marino et al 2019). However, in European built heritage, specifically in the inventory of residential dwellings, high-rise URM buildings are common.…”

Experimental Study on Torsion Resistance of Foundation Ring Land-Based Wind Power Expanded Foundation Scale Model

“…Wind turbines, towers, and foundations belong to high-rise structures, which need to withstand complex external environmental loads during their operation, and face problems such as structure vibration [6][7][8][9][10], soil-structure coupled vibration [11], seismic dynamic response [12,13], and vibration reduction control [14][15][16]. Offshore wind turbines, especially, have to face many challenges in complex ocean environments, including waves, currents, and erosion.…”

Effects of diaphragm flexibility on seismic response of asymmetric-plan buildings

“…As a result of this assumption, distribution of inertial forces between lateral load-resisting elements (LLREs) of a structure is only dependent on its mass, stiffness and strength distribution. However, in many cases, fully rigid diaphragm assumption is not consistent with reality, and seismic diaphragms, especially in asymmetric-plan structures, can exhibit various degrees of flexibility [1][2][3][4]. Diaphragm flexibility can change the distribution of inertia forces between the LLREs and therefore can be the source of the difference between the results of the numerical analysis and the actual behaviour of the structure during the earthquakes.…”