Spatial seismic modeling of base‐isolated buildings pounding against moat walls: effects of ground motion directionality and mass eccentricity

Abstract

Summary Structural impact between adjacent buildings may induce local and, in some extreme cases, severe damage, especially in the case of seismically isolated buildings. This study parametrically investigates in the three‐dimensional domain the effect of pounding on the peak response of base‐isolated buildings, which are simulated as nonlinear three‐dimensional multi‐degree‐of‐freedom systems. Firstly, it is shown that considering unidirectional, instead of bidirectional, excitations may lead to underestimation of the base drift demands. Subsequently, the peak responses of seismically isolated buildings utilizing lead rubber bearings are studied while varying important parameters, such as the incidence angle of seismic excitations, the available seismic clearance, and mass eccentricities, under the action of bidirectional horizontal excitations. A large number of numerical simulations are performed using a specially developed software that implements an efficient approach to model impacts, taking into account arbitrary locations of contact points. It is found that the peak interstory drift ratio is significantly influenced by the directionality of the ground motion. Therefore, the seismic performance of structures should ideally be assessed examining the peak structural response while bidirectional ground motions are imposed at various incident angles. Furthermore, it is also observed that the interstory drift ratios increase while decreasing the available gap size, up to a certain value. Finally, the parametric analyses indicate that the effects of impact are more severe for structures with mass eccentricities, and in which case, the estimation of the critical incidence angle becomes more laborious. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of Ground Motion Directionality on Seismic Response of Base-Isolated Buildings Considering Pounding to Adjacent Structures

“…The structures are analyzed for the 5 bidirectional ground-motions, each one rotated with a constant step of 5° in the range of 0° to 360°. The main results arising from these simulations with regards to the ground motion orientation effect, are in line with previous observations [18] (i) the incidence angle of excitation significantly affects the maximum response of the structures in the X-direction, (ii) the critical angle corresponding to the peak response over all possible excitation orientations varies with the selected ground motion and the dynamic characteristics of the structures, and (iii) the FN/FP drifts (θ=0°) are not always conservative. Figure 3: Peak unobstructed relative displacements of (a) the 3-story base-isolated building, and (b) the 2-story, (c) 3-story, and the (d) 4-story; fixed-based structures, in X-direction, in terms of the incidence angle.…”

“…This research work utilizes the computational methodology described in [18,20], aiming to thoroughly investigate the circumstances under which spatial pounding of base-isolated buildings may occur and assess the effect of some important parameters on the peak structural response due to potential structural pounding. In order to efficiently and effectively estimate the impact forces that should be applied at detected impact points on each structure in contact, an appropriate 3D impact model is used.…”

“…A number of recent research works that extend the simulation in the more realistic 3D space [10][11][12][13][14][15][16][17][18][19] have been reported. Matsagar and Jangid [10] investigated the seismic response of a single-story asymmetric structure supported on various base-isolation systems during impact with adjacent structures.…”

Vibration Control Performance Analysis and Shake-Table Test of a Pounding Tuned Rotary Mass Damper under the Earthquake

“…e lumped masses are assumed to be the same at each floor, i.e., 16.315 t. e stiffness and damping coefficients of each story reduce from the top floor to the ground floor. Instead of assuming a value for the pounding stiffness and the pounding damping, they can be obtained from a linear viscoelastic pounding model [22][23][24][25].…”

پاسخ سازه های جداسازی شده با درز لرزه یی ناکافی

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