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

2014 ◽  
Vol 50 (4) ◽  
pp. 701-716 ◽  
Author(s):  
Hesamaldin Moeindarbari ◽  
Touraj Taghikhany
Keyword(s):  
Optimum Design ◽  
Ground Motions ◽  
Near Fault ◽  
Friction Pendulum

scholarly journals Prof. Comparing H2 and H∞ Algorithms for Optimum Design of Tuned Mass Dampers under Near-Fault and Far-Fault Earthquake Motions

2020 ◽  
Author(s):  
Ali Kaveh ◽  
Mazyar Fahimi Fazam ◽  
Rasool Maroofiazar
Keyword(s):  
Objective Function ◽  
Optimum Design ◽  
Ground Motions ◽  
Optimization Technique ◽  
Large Set ◽  
Near Fault ◽  
Colliding Bodies Optimization ◽  
Controlled Structure ◽  
Robust Optimum Design ◽  
Far Fault

In this study, the robust optimum design of Tuned Mass Damper (TMD) is established. The H2 and H∞ norm of roof displacement transfer function are implemented and compared as the objective functions under Near-Fault (NF) and Far-Fault (FF) earthquake motions. Additionally, the consequences of different characteristics of NF ground motions such as forward-directivity and fling-step are investigated on the behavior of a benchmark 10-story controlled structure. The Colliding Bodies Optimization (CBO) is employed as an optimization technique to calculate the optimum parameters of the TMDs. The resulting statistical assessment shows that the H∞ objective function is rather superior to H2 objective function for optimum design of TMDs under NF and FF earthquake excitations. Finally, the robustness of the designed TMDs is evaluated under a large set of natural ground motions.

scholarly journals Control Performances of Friction Pendulum and Sloped Rolling-Type Bearings Designed with Single Parameters

2020 ◽  
Vol 10 (20) ◽  
pp. 7200
Author(s):  
Shiang-Jung Wang ◽  
Yi-Lin Sung ◽  
Cho-Yen Yang ◽  
Wang-Chuen Lin ◽  
Chung-Han Yu
Keyword(s):  
Passive Control ◽  
Ground Motions ◽  
Numerical Comparison ◽  
Far Field ◽  
Control Performance ◽  
Damping Force ◽  
Horizontal Acceleration ◽  
Near Fault ◽  
Comparison Results ◽  
Friction Pendulum

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.

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

2016 ◽  
Vol 16 (06) ◽  
pp. 1550021 ◽  
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.

Finite Element Formulations and Theoretical Study for VCFPS

2003 ◽  
Author(s):  
C. S. Tsai ◽  
Tsu-Cheng Chiang ◽  
Bo-Jen Chen
Keyword(s):  
Finite Element ◽  
Base Isolation ◽  
Ground Motions ◽  
Base Shear ◽  
Pendulum System ◽  
Near Fault ◽  
Base Isolator ◽  
Friction Pendulum ◽  
Finite Element Formulations ◽  
Friction Pendulum System

The friction pendulum system (FPS), a type of base isolation technology, has been recognized as a very efficient tool for controlling the seismic response of a structure during an earthquake. However, previous studies have focused mainly on the seismic behavior of base-isolated structures far from active earthquake faults. In recent years, there have been significant studies on the efficiency of the base isolator when subjected to near-fault ground motions. It is suggested from these studies that the long-duration pulse of near-fault ground motions results in significant response of a base-isolated structure. In view of this, an advanced base isolator called the variable curvature friction pendulum system (VCFPS) is proposed in this study. The radius of the curvature of VCFPS is lengthened with an increasing of the isolator displacement. Therefore, the fundamental period of the base-isolated structure can be shifted further away from the predominant period of near-fault ground motions. Finite element formulations for VCFPS have also been proposed in this study. The numerical results show that the base shear force and story drift of the superstructure during near-fault ground motion can be controlled within a desirable range with the installation of VCFPS. Therefore, the VCFPS can be adopted for upgrading the seismic resistance of the structures adjacent to an active fault.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

A simplified iterative approach for testing the pulse derailment of light rail vehicles across a viaduct to near-fault earthquake scenarios

2021 ◽  
pp. 095440972098741
Author(s):  
Ling-Kun Chen ◽  
Peng Liu ◽  
Li-Ming Zhu ◽  
Jing-Bo Ding ◽  
Yu-Lin Feng ◽  
...  
Keyword(s):  
Ground Motions ◽  
Simulation Software ◽  
Light Rail ◽  
Rail Transit ◽  
Light Rail Transit ◽  
Seismic Responses ◽  
Near Fault ◽  
Rail Vehicle ◽  
Pulse Type ◽  
The Impact

Near-fault (NF) earthquakes cause severe bridge damage, particularly urban bridges subjected to light rail transit (LRT), which could affect the safety of the light rail transit vehicle (“light rail vehicle” or “LRV” for short). Now when a variety of studies on the fault fracture effect on the working protection of LRVs are available for the study of cars subjected to far-reaching soil motion (FFGMs), further examination is appropriate. For the first time, this paper introduced the LRV derailment mechanism caused by pulse-type near-fault ground motions (NFGMs), suggesting the concept of pulse derailment. The effects of near-fault ground motions (NFGMs) are included in an available numerical process developed for the LRV analysis of the VBI system. A simplified iterative algorithm is proposed to assess the stability and nonlinear seismic response of an LRV-reinforced concrete (RC) viaduct (LRVBRCV) system to a long-period NFGMs using the dynamic substructure method (DSM). Furthermore, a computer simulation software was developed to compute the nonlinear seismic responses of the VBI system to pulse-type NFGMs, non-pulse-type NFGMs, and FFGMs named Dynamic Interaction Analysis for Light-Rail-Vehicle Bridge System (DIALRVBS). The nonlinear bridge seismic reaction determines the impact of pulses on lateral peak earth acceleration (Ap) and lateral peak land (Vp) ratios. The analysis results quantify the effects of pulse-type NFGMs seismic responses on the LRV operations' safety. In contrast with the pulse-type non-pulse NFGMs and FFGMs, this article's research shows that pulse-type NFGM derail trains primarily via the transverse velocity pulse effect. Hence, this study's results and the proposed method can improve the LRT bridges' seismic designs.

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