Seismic Response Analysis of an Isolated Structure with QZS under Near‐Fault Vertical Earthquakes

Abstract

Seismic isolation devices are usually designed to protect structures from the strong horizontal component of earthquake ground shaking. However, the effect of near-fault (NF) vertical ground motions on seismic responses of buildings has become an important consideration due to the observed building damage caused by vertical excitation. As the structure needs to maintain its load bearing capacity, using the horizontal isolation strategy in vertical seismic isolation will lead to the problem of larger static displacement. In particular, the bearings may generate large deformation responses of isolators for NF vertical ground motions. A seismic isolation system including quasi-zero stiffness (QZS) and vertical damper (VD) is used to control NF vertical earthquakes. The characteristics of vertical seismic isolated structures incorporating QZS and VD are presented. The formula for the maximum bearing capacity of QZS isolation considering the stiffness of vertical spring components is obtained by theoretical derivation. From the static analysis, it is found that the static capacity of the QZS isolation system with vertical seismic isolation components increases when the configurative parameter reduces. Seismic response analyses of the seismic isolated structure model with QZS and VD subjected to NF vertical earthquakes are conducted. The results show that seismic responses of the structure can be controlled by setting the appropriate static equilibrium position, vertical isolation period, and vertical damping ratio. Adding a damping ratio is effective in controlling the vertical large deformation of the isolator.

Design of cab seat suspension system for construction machinery based on negative stiffness structure

“…According to equation (9), it can be seen that there are four design parameters a, g 1 , g 2 , h, and their variation can have the influence on the dynamic stiffness of system.…”

“…South Korean scholars Lee et al 8 developed the seat vibration isolation mechanism with negative stiffness based on thin shell theory, and gave the theoretical derivation and experimental verification, which achieved good results. In the theoretical research area, Liu et al 9 used a seismic isolation system including quasi-zero stiffness and vertical damper to control near-fault vertical earthquakes. The formula for the maximum bearing capacity of quasi-zero stiffness isolation considering the stiffness of vertical spring components is obtained by theoretical derivation.…”

Strong Far‐Field Vertical Excitation and Building Damage: A Systematic Review and Future Avenues

“…Several other studies perform analysis of building systems with base isolation to quantify the effects of vertical excitation (e.g., [49,74,[92][93][94][95], among others). From the above discussions and broad literature review, it should be noted that the necessity of consideration of vertical excitation in design and code formulation is a must to capture the anomalous behavior of buildings during earthquakes.…”

Design and Research of Semiactive Quasi‐Zero Stiffness Vibration Isolation System for Vehicles

“…In recent years, QZS vibration isolation has become a research hotspot because of its large bearing capacity and extremely low natural frequency, which can effectively isolate low frequencies. It has various forms, such as cam roller [4][5][6], oblique spring [7][8][9], disk spring combined with vertical linear springs [10], circular ring [11], magnet [12], inert elements [13], X-shaped structure [14], strut structure [15,16], and other structural forms [17][18][19][20]. And some researchers studied the resonance response of nonlinear vibration [21] and the damping characteristics [22].…”