Decomposition and Effects of Pulse Components in Near-Field Ground Motions

2010 ◽  
Vol 136 (6) ◽  
pp. 690-699 ◽  
Author(s):  
Zhou Xu ◽  
Anil Agrawal
Keyword(s):  
Ground Motions ◽  
Near Field

scholarly journals Seismic Fragility Analysis of Mid-Story Isolation Buildings

2021 ◽  
Keyword(s):  
Fragility Curves ◽  
Ground Motions ◽  
Near Field ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Plastic State ◽  
Far Field ◽  
Analysis Method ◽  
Isolation System ◽  
Isolation Layer

Abstract. Seismic fragility analysis is essential for seismic risk assessment of structures. This study focuses on the damage probability assessment of the mid-story isolation buildings with different locations of the isolation system. To this end, the performance-based fragility analysis method of the mid-story isolation system is proposed, adopting the maximum story drifts of structures above and below the isolation layer and displacement of the isolation layer as performance indicators. Then, the entire process of the mid-story isolation system, from the initial elastic state to the elastic-plastic state, then to the limit state, is simulated on the basis of the incremental dynamic analysis method. Seismic fragility curves are obtained for mid-story isolation buildings with different locations of the isolation layer, each with fragility curves for near-field and far-field ground motions, respectively. The results indicate that the seismic fragility probability subjected to the near-field ground motions is much greater than those subjected to the far-field ground motions. In addition, with the increase of the location of the isolation layer, the dominant components for the failure of mid-story isolated structures change from superstructure and isolation system to substructure and isolation system.

Near-field directionality of earthquake strong ground motions measured by displaced geological objects

2020 ◽  
Author(s):  
Tamarah King ◽  
Mark Quigley ◽  
Dan Clark
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Reverse Fault ◽  
Surface Rupture ◽  
Ground Shaking ◽  
Strong Ground Motions ◽  
Rock Fragments ◽  
Test Models ◽  
Elastic Rebound ◽  
Strong Ground

<p>Coseismically displaced rock fragments (chips) in the near-field (less than 5 km) of the 2016 moment magnitude (M<sub>W</sub>) 6.1 Petermann earthquake (Australia) preserve directionality of strong ground motions. Displacement data from 1437 chips collected over an area of 100 km<sup>2 </sup>along and across the Petermann surface rupture is interpreted to record combinations of co-seismic directed permanent ground displacements associated with elastic rebound (fling) and transient  ground shaking, with intensities of motion increasing with proximity to the surface rupture. The observations provide a proxy test for available models for directionality of near-field reverse fault strong ground motions in the absence of instrumental data. This study provides a dense proxy record of strong ground motions at less than 5 km distance from a surface rupturing reverse earthquake, and may help test models of near-field dynamic and static pulse-like strong ground motion for dip-slip earthquakes.</p>

DESIGN OF ISOLATED BRIDGES USING POLYNOMIAL FRICTION PENDULUM ISOLATOR

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
T. Y. Lee ◽  
L. Y. Lu ◽  
K. J. Chung
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Design Procedure ◽  
Design Parameters ◽  
Seismic Responses ◽  
Nonlinear Responses ◽  
Seismic Design Code ◽  
Friction Pendulum ◽  
Isolated Bridges ◽  
Restoring Stiffness

This paper is aimed to develop a design procedure of Polynomial Friction Pendulum Isolator (PFPI), a various-frequency sliding isolator, for decreasing the seismic responses of isolated bridges. Although sliding isolators have been widely used to mitigate seismic hazard, it may be not effective in decreasing the seismic responses of isolated structures subjected to near-field ground motions. The sliding surface of the PFPI is defined by a sixth-order polynomial function to avoid resonance under near-field ground motions. The restoring stiffness of the PFPI possesses softening section as well as hardening section. The structural acceleration response can be decreased by decreasing the restoring stiffness in softening section while the structural displacement response can be decreased by increasing the restoring stiffness in hardening section. However, it is difficult to determine the design parameters of PFPI in practical implementations. This study proposes a design procedure for the PFPI based on the bridge seismic design code in Taiwan. Designers can follow this procedure to easily design the bridge with PFPIs which satisfies the requirements of the code. The bridge with PFPIs designed by using this procedure is analyzed to realize the dynamic nonlinear responses of the bridge under artificial strong earthquake. The results show that the PFPIs effectively decrease the seismic responses of isolated bridges as compared with non-isolated bridges.

Comparison of Damage Criteria for Structures to Near-Field Blast-Induced Ground Motions

2012 ◽  
Vol 40 (1) ◽  
pp. 103822
Author(s):  
M. R. Mitchell ◽  
R. E. Link ◽  
D. Mehmet Özcan ◽  
Alemdar Bayraktar ◽  
Ahmet Can Altunişik
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Damage Criteria

Seismic Hazard Assessment in the Southeastern United States

1995 ◽  
Vol 11 (1) ◽  
pp. 129-160 ◽  
Author(s):  
Paul C. Rizzo ◽  
N. R. Vaidya ◽  
E. Bazan ◽  
C. F. Heberling
Keyword(s):  
North American ◽  
Peak Ground Acceleration ◽  
Ground Motions ◽  
Near Field ◽  
Southeastern United States ◽  
Seismic Hazard Assessment ◽  
Response Spectra ◽  
Seismic Hazards ◽  
Far Field ◽  
Ground Acceleration

Comparisons of response spectra from near and far-field records to those estimated by attenuation functions commonly used in evaluating seismic hazards show that these functions provide reasonable results for near-field western North American sites. However, they estimate relatively small motions for far-field eastern North American sites, which is contrary to the empirical evidence of the 1886 Charleston and 1988 Saguenay Earthquakes. Using the 1988 Saguenay records scaled for magnitude, and several western North American records scaled to account for the slower attenuation in the east, we have developed deterministic median and 84th percentile, 5 percent damped response spectra to represent ground motions from a recurrence of the 1886 Charleston Earthquake at a distance between 85 to 120 km. The resulting 84th percentile spectrum has a shape similar to, but is less severe than, the USNRC Regulatory Guide 1.60 5 percent damped spectrum tied to a peak ground acceleration of 0.2g.

Shake Table Studies on Viscous Dampers in Seismic Control of a Single-Tower Cable-Stayed Bridge Model under Near-Field Ground Motions

2018 ◽  
Vol 12 (05) ◽  
pp. 1850011 ◽  
Author(s):  
Jiang Yi ◽  
Jianzhong Li ◽  
Zhongguo Guan
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Far Field ◽  
Viscous Damper ◽  
Viscous Dampers ◽  
Damping Force ◽  
Seismic Control ◽  
Cable Stayed Bridge ◽  
Bridge Model ◽  
Cable Stayed Bridges

To investigate the effectiveness of viscous damper on seismic control of single-tower cable-stayed bridges subjected to near-field ground motions, a 1/20-scale full cable-stayed bridge model was designed, constructed and tested on shake tables. A typical far-field ground motion and a near-field one were used to excite the bridge model from low to high intensity. The seismic responses of the bridge model with and without viscous dampers were analyzed and compared. Both numerical and test results revealed that viscous dampers are quite effective in controlling deck displacement of cable-stayed bridges subjected to near-field ground motions. However, due to near-field effects, viscous damper dissipated most energy through one large hysteresis loop, extensively increasing the deformation and damping force demand of the damper. Further study based on numerical analysis reveals that to optimize deck displacement of cable-stayed bridges during an earthquake, a viscous damper with relatively larger damping coefficient should be introduced under near-field ground motions than far-field ones.

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