Performance of seismically isolated buildings with variable friction pendulum bearings under near-fault ground motions

Owing to quite different features and hysteretic behavior of friction pendulum bearings (FPBs) and sloped rolling-type bearings (SRBs), their control performances might not be readily compared without some rules. In this study, first, on the premise of retaining the same horizontal acceleration control performance, the effects arising from different sloping angles and damping forces on the horizontal maximum and residual displacement responses of SRBs are numerically examined. For objective comparison of passive control performances of FPBs and SRBs, then, some criteria are considered to design FPBs with the same horizontal acceleration control performance by referring to the designed damping force and the maximum horizontal displacement response of SRBs under a given seismic demand. Based on the considered criteria, the passive control performances of FPBs and SRBs under a large number of far-field and pulse-like near-fault ground motions are quantitatively compared. The numerical comparison results indicate that the FPB models might potentially have better horizontal acceleration and isolation displacement control performances than the SRB models regardless of whether they are subjected to far-field or near-fault ground motions, while the opposite tendency is observed for their self-centering performances, especially when the SRB model designed with a larger sloping angle or a smaller damping force.

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Seismic optimum design of triple friction pendulum bearing subjected to near-fault pulse-like ground motions

Structural and Multidisciplinary Optimization ◽

10.1007/s00158-014-1079-x ◽

2014 ◽

Vol 50 (4) ◽

pp. 701-716 ◽

Cited By ~ 7

Author(s):

Hesamaldin Moeindarbari ◽

Touraj Taghikhany

Keyword(s):

Optimum Design ◽

Ground Motions ◽

Near Fault ◽

Friction Pendulum

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Seismic Response of Triple Friction Pendulum Bearing under Near-Fault Ground Motions

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455415500212 ◽

2016 ◽

Vol 16 (06) ◽

pp. 1550021 ◽

Cited By ~ 4

Author(s):

Gholamreza Ghodrati Amiri ◽

Pejman Namiranian ◽

Mohamad Shamekhi Amiri

Keyword(s):

Seismic Response ◽

Spherical Surface ◽

Ground Motions ◽

Damping Ratio ◽

Radius Of Curvature ◽

Seismic Responses ◽

Base Shear ◽

Near Fault ◽

Inner Surface ◽

Friction Pendulum

The seismic response of a stiff single-story and a flexible multi-story building isolated with triple friction pendulum bearing (TFPB) are investigated under the pulse-like (near-fault, NF-Pulse) and (NF-No Pulse) NF nonpulse ground motions. By varying the geometric parameters, such as the effective spherical surface radius, or by specifying different friction coefficients for each surface, one can adjust the behavior of the bearing. Consequently, the stiffness and damping ratio of the system can be optimized for multiple performance objectives under multiple levels of hazard. The seismic responses are evaluated under different isolation parameters for the displacement of isolation and the superstructure demand functions of the system, including the base shear, maximum inter-story drift and top floor absolute acceleration of the isolated structure. First, the seismic response of twenty TFPBs with different stiffnesses and damping ratios are investigated under NF motions. A comparison of results suggested that the displacement of the TFPB under the NF-Pulse motion is about twice that of the NF-No Pulse motions. The best performance of the system is found when the TFPB works in its third stage of motion. Next, from the sensitivity analysis, the effect of each parameter of the TFPB on the seismic response of system is investigated and the trends for optimal parameters of TFPB are presented. The criterion selected for optimality is to minimize the performance function that considers all seismic responses simultaneously. The optimum ranges for the related parameters are: (a) 0.02–0.04 for the coefficient of friction of the inner surface; (b) 0.06–0.14 and 0.04–0.12 for the bottom concave plate under the NF-Pulse and NF-No Pulse, respectively; (c) 0.06–0.18 and 0.06–0.16 for the top concave plate under the NF-Pulse and NF-No Pulse, respectively; (d) 200–500 mm for the radius of curvature of the inner surface; and (e) 2500–4500 mm for the outer surface.

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Seismic Experimental Assessment of Remote Terminal Unit System with Friction Pendulum under Triaxial Shake Table Tests

Metals ◽

10.3390/met11091428 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1428

Author(s):

Sung-Wan Kim ◽

Bub-Gyu Jeon ◽

Da-Woon Yun ◽

Woo-Young Jung ◽

Bu-Seog Ju

Keyword(s):

Shaking Table Test ◽

Ground Motions ◽

Shaking Table ◽

Nonstructural Components ◽

Seismic Isolator ◽

Remote Terminal ◽

Remote Terminal Unit ◽

Seismically Isolated ◽

Friction Pendulum ◽

Strong Ground

In recent years, earthquakes have caused more damage to nonstructural components, such as mechanical and electrical equipment and piping systems, than to structural components. In particular, among the nonstructural components, the electrical cabinet is an essential piece of equipment used to maintain the functionality of critical facilities such as nuclear and non-nuclear power plants. Therefore, damage to the electrical cabinet associated with the safety of the facility can lead to severe accidents related to loss-of-life and property damage. Consequently, the electrical cabinet system must be protected against strong ground motion. This paper presents an exploratory study of dynamic characteristics of seismically isolated remote terminal unit (RTU) cabinet system subjected to tri-axial shaking table, and also the shaking table test of the non-seismically isolated cabinet system was conducted to compare the vibration characteristics with the cabinet system installed with friction pendulum isolator device. In addition, for the shaking table test, two recorded earthquakes obtained from Korea and artificial earthquakes based on the common application of building seismic-resistant design standards as an input ground motions were applied. The experimental assessment showed that the various damage modes such as door opening, the fall of the wire mold, and damage to door lock occurred in the RTU panel fixed on the concrete foundation by a set anchor, but the damage occurred only at the seismic isolator in the seismically isolated RTU panel system. Furthermore, it was considered that the application of the seismic isolator can effectively mitigate the impact and amplification of seismic force to the RTU panel system during and after strong ground motions in this study.

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