The Vertical and Horizontal Spectra of Near-Fault Ground Motions

2012 ◽  
Vol 204-208 ◽  
pp. 3335-3339
Author(s):  
Jiang Yin ◽  
Xian Yan Zhou ◽  
Guo Jing He
Keyword(s):  
Ground Motions ◽  
Response Spectra ◽  
Vertical Acceleration ◽  
Period Range ◽  
Seismic Reliability ◽  
Design Spectrum ◽  
Near Fault ◽  
Seismic Design Code ◽  
Short Period ◽  
Near Fault Earthquakes

Based on the horizontal and vertical components of a set of 30 acceleration records obtained from 10 near-fault earthquakes, the horizontal and the vertical response spectra are established, and have been compared with each other in this study. Statistical analyses show that, for the selected 30 acceleration records, the maximum mean of vertical acceleration spectra is slightly higher than which of horizontal acceleration spectra. That means the near-fault earthquake really have significant vertical effect. Consulting the domestic and international research achievement, the normalized near-fault design spectrum adapted to Chinese seismic design Code (GB50011-2010) is established in horizontal direction. The results show that, within short period range, the horizontal near-fault design spectrum obtained in this paper is obviously higher than which derived from Chinese seismic code. Subsequently, the spectra of horizontal components for the selected 30 records are each scaled to match the horizontal near-fault design spectrum at two periodic points of 1.0 and 1.5 sec respectively, and the corresponding vertical spectra are scaled with the horizontal spectra at the same time. The scaled results reveal that the vertical spectra have much higher discretion than horizontal spectra, hence the study in this paper could initiates the research interest to a new aspect concerned with the randomness of vertical spectra for near-fault ground motions, which would affect the seismic reliability of structures significantly.

Significance of Ground Motion Scaling Parameters on Amplitude of Scale Factors and Seismic Response of Short- and Long-Period Structures

2019 ◽  
Vol 35 (4) ◽  
pp. 1663-1688 ◽  
Author(s):  
Esengul Cavdar ◽  
Gokhan Ozdemir ◽  
Beyhan Bayhan
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Scaling Method ◽  
Period Range ◽  
Long Period ◽  
Scale Factors ◽  
Short Period ◽  
Response History Analysis

In this study, an ensemble of ground motions is selected and scaled in order to perform code-compliant bidirectional Nonlinear Response History Analysis for the design purpose of both short- and long-period structures. The followed scaling method provides both the requirements of the Turkish Earthquake Code regarding the scaling of ground motions and compatibility of response spectra of selected ground motion pairs with the target spectrum. The effects of four parameters, involved in the followed scaling method, on both the amplitude of scale factors and seismic response of structures are investigated. These parameters are the number of ground motion records, period range, number of periods used in the related period range, and distribution of weight factors at the selected periods. In the analyses, ground motion excitations were applied to both fixed-base and seismically isolated structure models representative of short- and long-period structures, respectively. Results revealed that both the amplitudes of scale factors and seismic response of short-period structures are more prone to variation of investigated parameters compared to those of long-period structures.

scholarly journals The Seismic Response of High-Speed Railway Bridges Subjected to Near-Fault Forward Directivity Ground Motions Using a Vehicle-Track-Bridge Element

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Chen Ling-kun ◽  
Jiang Li-zhong ◽  
Guo Wei ◽  
Liu Wen-shuo ◽  
Zeng Zhi-ping ◽  
...  
Keyword(s):  
High Speed ◽  
Ground Motions ◽  
Element Model ◽  
Railway Vehicle ◽  
Vertical Acceleration ◽  
High Speed Railway ◽  
Near Fault ◽  
Pulse Effect ◽  
Short Period ◽  
Track Bridge

Based on the Next Generation Attenuation (NGA) project ground motion library, the finite element model of the high-speed railway vehicle-bridge system is established. The model was specifically developed for such system that is subjected to near-fault ground motions. In addition, it accounted for the influence of the rail irregularities. The vehicle-track-bridge (VTB) element is presented to simulate the interaction between train and bridge, in which a train can be modeled as a series of sprung masses concentrated at the axle positions. For the short period railway bridge, the results from the case study demonstrate that directivity pulse effect tends to increase the seismic responses of the bridge compared with far-fault ground motions or nonpulse-like motions and the directivity pulse effect and high values of the vertical acceleration component can notably influence the hysteretic behaviour of piers.

Evaluation of base shear provisions in the 1985 edition of the National Building Code of Canada

1989 ◽  
Vol 16 (1) ◽  
pp. 22-35 ◽  
Author(s):  
T. J. Zhu ◽  
W. K. Tso ◽  
A. C. Heidebrecht
Keyword(s):  
Yield Strength ◽  
Seismic Response ◽  
Structural Damage ◽  
Ground Motions ◽  
Response Spectra ◽  
Building Code ◽  
Base Shear ◽  
Response Factors ◽  
Period Range ◽  
Short Period

A statistical analysis is performed to evaluate the base shear provisions in the 1985 edition of the National Building Code of Canada (NBCC 1985). Three sets of real earthquake records are selected to represent seismic ground motions with low, normal, and high peak acceleration to velocity (a/v) ratios. Single degree of freedom stiffness degrading systems are used as structural models; three damage indicators are employed to measure structural damage. The yield strength of the systems is specified in two different ways: (a) a single seismic response factor is used, irrespective of the a/v ratios of the input ground motions; (b) three different seismic response factors are used in the short-period range, depending upon the a/v ratios of the input ground motions, as suggested in NBCC 1985. A comparison of the statistical results of the three damage parameters for the systems designed with these two methods of strength specification indicates that the NBCC 1985 base shear provisions provide consistent control over structural damage when the structural systems are subjected to ground motions with different a/v ratios. Key words: earthquakes, ground motions, response spectra, stiffness degrading systems, seismic design, base shear, yield strength, inelastic response, damage parameters.

Response Modification Factors for Earthquake Resistant Design of Short Period Buildings

1989 ◽  
Vol 5 (3) ◽  
pp. 571-590 ◽  
Author(s):  
Rafael Riddell ◽  
Pedro Hidalgo ◽  
E. Cruz
Keyword(s):  
Response Spectra ◽  
Elastic Response ◽  
Period Range ◽  
Response Modification Factor ◽  
Seismic Codes ◽  
Design Spectrum ◽  
Linear Elastic ◽  
Elastic Response Spectra ◽  
Short Period ◽  
Earthquake Resistant

Most recent seismic codes include response modification factors in the definition of the equivalent lateral forces that are used for the design of earthquake resistant buildings. The response modification factors (R) are used to reduce the linear elastic design spectrum to account for the energy dissipation capacity of the structure. The evaluation of these response modification factors for various sets of earthquake records and ductility factors is presented herein. Special attention is given to the short period range where the reduction of linear elastic response spectra is smaller than the values for intermediate and long period structures. An idealized and simple variation of the response modification factor as a function of the period of vibration, suitable for seismic codes formulation, is also presented.

Performance of bi-directional elliptical rolling rods for base isolation of buildings under near-fault earthquakes

2017 ◽  
Vol 21 (5) ◽  
pp. 675-693 ◽  
Author(s):  
Aruna Rawat ◽  
Naseef Ummer ◽  
Vasant Matsagar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Frictional Resistance ◽  
Curved Surface ◽  
Isolation System ◽  
Near Fault ◽  
Earthquake Ground Motions ◽  
Base Isolation System ◽  
Near Fault Earthquakes ◽  
Storey Building

Rolling base isolation system provides effective isolation to the structures from seismic base excitations by virtue of its low frictional resistance. Herein, dynamic analysis of flexible-shear type multi-storey building mounted on orthogonally placed elliptical rolling rod base isolation systems subjected to bi-directional components of near-fault earthquake ground motions is presented. The orthogonally placed rods would make it possible to resist the earthquake forces induced in the structure in both the horizontal directions. The curved surface of these elliptical rods has a self-restoring capability due to which the magnitude of peak isolator displacement and residual displacement is reduced. The roughness of the tempered curved surface of the rollers dissipates energy in motion due to frictional damping. The seismic performance of the multi-storey building mounted on the elliptical rolling rod base isolation system is compared with that mounted on the sliding pure-friction and cylindrical rolling rod systems. Parametric studies are conducted to examine the behavior of the building for different superstructure flexibilities, eccentricities of the elliptical rod, and coefficients of friction. It is concluded that the elliptical rolling rod base isolation system is effective in mitigation of damaging effects of the near-fault earthquake ground motions in the multi-storey buildings. Even under the near-fault earthquake ground motions, the base-isolated building mounted on the elliptical rolling rods shows considerable reduction in seismic response. The isolator displacement with the elliptical rolling rod base isolation system is less in comparison to the pure-friction and cylindrical rolling rod systems.

EVALUATION OF SEISMIC DEMANDS IN A CONTINUOUS BRIDGE

2001 ◽  
Vol 01 (02) ◽  
pp. 235-246 ◽  
Author(s):  
CHIN-HSIUNG LOH ◽  
SHIUAN WAN ◽  
YI-WEN CHANG
Keyword(s):  
Earthquake Engineering ◽  
Ground Motions ◽  
Hysteretic Behavior ◽  
Earthquake Ground Motion ◽  
Far Field ◽  
Base Shear ◽  
Near Fault ◽  
Seismic Design Code ◽  
Cyclic Loading Tests ◽  
Earthquake Characteristics

This paper examines the dynamic behavior of a highway RC-bridge subjected to both near-fault and far-field ground motions. The bridge consists of a hinge supported continuous girder with six concrete piers and the bridge is designed according to the Taiwan seismic design code. To investigate the hysteretic behavior of the bridge piers, cyclic loading tests were carried out at the National Center for Research on Earthquake Engineering (NCREE). The Chi-Chi earthquake ground motion record was adopted as the near-fault earthquake characteristics whereas another earthquake record was selected for the far-field earthquake characteristics. The ductility demands and base shear demands due to the near-fault and the far-field earthquake ground motions are compared and conclusions drawn from the study. The stipulation of code limitations and the present calculated demands are discussed.

Earthquake Proof Efficiency of Sliding Base Isolator With Dog-Bone Type Damping

2005 ◽  
Author(s):  
C. S. Tsai ◽  
Tsu-Cheng Chiang ◽  
Bo-Jen Chen
Keyword(s):  
Ground Motions ◽  
Active Faults ◽  
Friction Behavior ◽  
Near Fault ◽  
The Past ◽  
Numerical Studies ◽  
Dog Bone ◽  
Base Isolator ◽  
Near Fault Earthquakes ◽  
Base Isolators

In recent years, there have been more and more seismic retrofit applications of using base isolators in seismic prone regions. In the past, the focuses of researches on the efficiency of various base isolators have been aimed at their behavior under earthquakes without long predominant periods. The doubts of efficiency of the base isolator nearby active faults or located at a soft deposit soil have been raised by researchers. It is revealed from previous studies that the seismic responses of the base isolated structure are significant due to the influence of resonance. In order to minimize the inherent shortcomings of base isolators, various base isolators with dog bone type of friction behavior have been proposed in this study. In the meanwhile, the exact solutions used to describe the behavior of the proposed isolators have also been derived in this study. The numerical studies show that the displacement responses of proposed isolators under near fault earthquakes and ground motions with long predominant periods are much lower than those of the traditional FPS and VCFPS devices. Hence, the required dimensions of proposed isolators can be smaller than those for the FPS and VCFPS isolators.

scholarly journals Fuzzy Control for Seismic Protection of Semiactive Base-Isolated Structures Subjected to Near-Fault Earthquakes

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Dahai Zhao ◽  
Yongxing Li
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Seismic Protection ◽  
Friction Damper ◽  
Design Spectrum ◽  
Near Fault ◽  
Isolated Structures ◽  
Near Fault Earthquakes ◽  
Elastic Design

This paper proposes a new fuzzy logic controller, which is designed for seismic protection of base-isolated structures utilizing piezoelectric friction damper against near-fault earthquakes for different ground sites. According to the elastic design spectrum that Eurocode 8 recommends, one 5% damped elastic design spectrum for Chi-Chi earthquake is proposed to generate artificial earthquakes of different ground sites. The proposed controller employs a hierarchic fuzzy control algorithm, in which a supervisory fuzzy controller governs a sublevel fuzzy controller by altering its input normalization factors according to current level of ground motion. In order to simultaneously reduce the base displacement and superstructure responses of the base-isolated structure during seismic excitations, genetic algorithm is employed to optimize the supervisory fuzzy controller and the preload of piezoelectric friction damper. The efficiency of the proposed controller is also compared with passive controller and a linear quadratic Gauss optimal controller. Numerical results show that the proposed fuzzy logic controller has favorable performance in mitigating the responses of the base-isolated structure.

scholarly journals A Study on the Sloshing Problem of Vertical Storage Tanks under the Action of Near-Fault Earthquakes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Lijian Zhou ◽  
Tian Xu ◽  
Zhaohong Lu ◽  
Dong Zhang
Keyword(s):  
Wave Height ◽  
Storage Tank ◽  
Small Sample Size ◽  
Ground Motions ◽  
Reference Value ◽  
Small Sample ◽  
Storage Tanks ◽  
Near Fault ◽  
Practical Engineering ◽  
Near Fault Earthquakes

In this study, through a vibration table test, finite element simulation, and research on the rationality of the wave-height fortification of national storage tank specifications, the sloshing response of vertical storage tanks under the action of near-fault ground motion was analyzed. The test results showed that the sloshing wave height of a vertical storage tank was larger under near-fault or long-period ground motions, and the relationship between the sloshing wave height and the peak acceleration of input ground motions was approximately linear. The numerical simulations of the model tank showed that the simulation wave height and the test wave-height data were well fitted. Therefore, it was feasible to simulate the sloshing of large vertical storage tanks using ADINA software. In addition, a large number of sloshing simulations of near-fault ground motions on 10,000 m3 vertical storage tanks were performed. The simulated wave height had a high correlation with the predominant period or pulse period of near-fault ground motions. Under the calculation with similar parameters, the wave height of the tank standard in several countries had a lower fortification of the near-fault excitation wave height. Through the root mean-square method using a small sample size, a wave-height correction under a near-fault effect was applied to the wave-height formula for the Chinese tank seismic specification. Finally, the problem of a double-damping correction was addressed by adjusting China’s GB50341 wave-height formula. This work provides a reference value for practical engineering applications.

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