scholarly journals Hysteretic Energy Demand under Superposition of Bidirectional Ground Motions

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Feng Wang ◽  
Jialin Shi ◽  
Pengyan Chen
Keyword(s):  
Energy Demand ◽  
Ground Motions ◽  
Energy Balance Equation ◽  
Correction Coefficient ◽  
Earthquake Excitation ◽  
Period Range ◽  
Vertical Coordinate ◽  
Hysteretic Energy ◽  
Sdof System ◽  
Response History Analysis

To address the irrationality of making a structure subjected to bidirectional ground motions equivalent to an SDOF system, a new approach method is presented in this paper. The ratio between modal participation factors of the two components of the structure is expressed as γ, and the superposition of bidirectional ground motions is regarded as one-directional earthquake excitation for the equivalent SDOF system. Based on this, an energy balance equation is established, and a method used to estimate normalized hysteretic energy (NHE) is proposed. Analysis of the ratio between NHE (γ ≠ 0) and NHE (γ = 0) is suggested in order to analyze the influence of bidirectional ground motions on hysteretic energy demand, and then, “α1 = NHE (γ ≠ 0)/NHE (γ = 0)” is defined, and bidirectional ground motion records for different soil sites are selected for establishing superimposed excitations. In addition, the period range of 0–5 s for the energy spectrum is divided into 6 ranges. In each period range, the means of α1 are defined as α. The curves of α of constant ductility factors for different soil sites are established, in which α is the vertical coordinate and γ is the horizontal coordinate. Through nonlinear response history analysis, the influence of soil types at different sites, the ductility factor, the ratio of modal participation factors, and the period on the values of α are analyzed. According to the analytical results, correction coefficient αs (the simplified value of α) is obtained so that the hysteretic energy demand under bidirectional ground motions can be determined.

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.

Attenuation of Hysteretic Energy Spectra of Strong Ground Motion

2012 ◽  
Vol 166-169 ◽  
pp. 2453-2456
Author(s):  
Mao Sheng Gong ◽  
Jing Sun ◽  
Li Li Xie
Keyword(s):  
Energy Demand ◽  
Ground Motions ◽  
Energy Spectra ◽  
Energy Structure ◽  
Site Class ◽  
Hysteretic Energy ◽  
Ductility Factor ◽  
Scenario Earthquakes ◽  
Nonlinear Regression Method ◽  
Strong Ground

Based on 266 strong ground motions from 15 significant earthquakes in California of America, the attenuation law of hysteretic spectra is established by using nonlinear regression method, and the effects of site class and ductility level on the hysteretic spectra constructed from the attenuation relationship are discussed in the paper. The results show that the site has significant effects on hysteretic energy spectra, and the more soft the site is, the more hysteretic energy structure will suffer from earthquake. Moreover, for ductility level scaled by ductility factor, the results show that structure with greater ductility factor can dissipate more input energy from the earthquake by means of the plastic deformation. The up limit design value of ductility factor for a structure is proposed as 4 because there is little difference between the hysteretic energy demand for ductility factor 4 and larger values. The hysteretic energy demand for structures at a given site in scenario earthquakes can be evaluated according to the results of the paper.

scholarly journals Hysteresis and Soil Site Dependent Input and Hysteretic Energy Spectra for Far-Source Ground Motions

2016 ◽  
Vol 2016 ◽  
pp. 1-29 ◽  
Author(s):  
Mebrahtom Gebrekirstos Mezgebo ◽  
Eric M. Lui
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Response Spectra ◽  
Energy Spectra ◽  
Period Range ◽  
Hysteretic Energy ◽  
Soil Site ◽  
Large Period ◽  
Motion Effect ◽  
Nonlinear Time History

Earthquake input energy spectra for four soil site classes, four hysteresis models, and five ductility levels are developed for far-source ground motion effect. These energy spectra are normalized by a quantity called velocity index (VI). The use of VI allows for the creation of dimensionless spectra and results in smaller coefficients of variation. Hysteretic energy spectra are then developed to address the demand aspect of an energy-based seismic design of structures with 5% critical damping and ductility that ranges from 2 to 5. The proposed input and hysteretic energy spectra are then compared with response spectra generated using nonlinear time history analyses of real ground motions and are found to produce reasonably good results over a relatively large period range.

A subset of CyberShake ground-motion time series for response-history analysis

2021 ◽  
pp. 875529302098197
Author(s):  
Jack W Baker ◽  
Sanaz Rezaeian ◽  
Christine A Goulet ◽  
Nicolas Luco ◽  
Ganyu Teng
Keyword(s):  
Time Series ◽  
Los Angeles ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Motion Time ◽  
History Analysis ◽  
Response History Analysis ◽  
Simulated Ground Motions

This manuscript describes a subset of CyberShake numerically simulated ground motions that were selected and vetted for use in engineering response-history analyses. Ground motions were selected that have seismological properties and response spectra representative of conditions in the Los Angeles area, based on disaggregation of seismic hazard. Ground motions were selected from millions of available time series and were reviewed to confirm their suitability for response-history analysis. The processes used to select the time series, the characteristics of the resulting data, and the provided documentation are described in this article. The resulting data and documentation are available electronically.

Inelastic Displacement Spectra and Its Utilization of DDB Design for Seismic Isolated Bridges Subjected to Near-Fault Pulse-Like Ground Motions

2019 ◽  
Vol 35 (3) ◽  
pp. 1109-1140 ◽  
Author(s):  
Yi-feng Wu ◽  
Hao Wang ◽  
Jian Li ◽  
Ben Sha ◽  
Ai-qun Li
Keyword(s):  
Design Method ◽  
Ground Motions ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Inelastic Displacement ◽  
Displacement Spectra ◽  
Near Fault ◽  
The Mean ◽  
Displacement Based ◽  
Isolated Bridges

A variety of research has focused on the inelastic displacement demand of a single degree of freedom (SDOF) system when subjected to near-fault pulse-like ground motions, in which the concerned ductility, μ, is typically lower than ten for normal structures. However, for seismic isolated structures that are more prone to large displacement, the corresponding research is limited. The purpose of this paper is to investigate the inelastic displacement spectra of an SDOF system with μ ranging from 5 to 70 and further proposes a direct displacement-based (DDB) design method for seismic isolated bridges. More concretely, a pool of near-fault pulse-like records is assembled, the mean C μ as a function of T/ T p is developed, and the influences of the ductility, μ, and the post-to-pre-yield ratio, α, on C μ are carefully investigated. Then the corresponding inelastic displacement spectra, S d, are obtained, and a comprehensive piecewise expression is proposed to fit S d. After that, the utilization of the spectra for the DDB design of a three-span seismic isolated continuous bridge is performed, and the principal of simplifying the bridge to an SDOF system is carefully explained and verified.

Evaluation of Hybrid Broadband Ground Motion Simulations for Response History Analysis and Design

2015 ◽  
Vol 31 (3) ◽  
pp. 1691-1710 ◽  
Author(s):  
Lynne S. Burks ◽  
Reid B. Zimmerman ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Spectral Response ◽  
Analysis And Design ◽  
History Analysis ◽  
Response History Analysis ◽  
Simulated Ground Motions ◽  
Broadband Ground Motion ◽  
New Buildings ◽  
Selection Of

Chapter 16 of ASCE 7 governs the selection of ground motions for analysis of new buildings and requires recordings that meet specified criteria. If a sufficient number of recordings cannot be found, it allows the use of “appropriate simulated ground motions,” but does not provide further guidance. This paper outlines a procedure for generating and selecting a set of “appropriate” hybrid broadband simulations and a comparable set of recordings. Both ground motion sets are used to analyze a building in Berkeley, California, and the predicted structural performance is compared. The structural behavior resulting from recordings and simulations is similar, and most discrepancies are explained by differences in directional properties such as orientation of the maximum spectral response. These results suggest that when simulations meet the criteria outlined for recordings in ASCE 7 and properties such as directionality are realistically represented, simulations provide useful results for structural analysis and design.

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