A Metric to Screen Acceptable Velocity and Displacement Time Histories of Modified Ground Motions

2017 ◽  
Vol 33 (4) ◽  
pp. 1495-1512
Author(s):  
Clinton P. Carlson ◽  
Dimitrios Zekkos
Keyword(s):  
Goodness Of Fit ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Visual Assessment ◽  
Acceleration Response ◽  
Earthquake Scenarios ◽  
Target Spectrum ◽  
Time Histories ◽  
Acceleration Response Spectrum

Ground motion modification is extensively used in practice to modify a seed acceleration time history in intensity and frequency content until its acceleration response spectrum matches a target spectrum. However, the decision to accept or reject a modified motion commonly relies on a subjective process where the time histories of the modified motion are visually compared to those of the seed motion. Various metrics were used to quantify the similarity between the modified time histories and their scaled counterparts for hundreds of modified ground motions from three different earthquake scenarios. Of the metrics considered, the inverse modified RMSE metric for time histories ( imRMSE t) was found most appropriate as it resulted in the least amount of dispersion in the goodness-of-fit values with respect to spectral mismatch. The imRMSE t was then found to be correlated to qualitative rankings assigned to the modified time histories through a visual assessment. The correlation between the quantitative imRMSE t values and qualitative rankings is used to establish threshold values to screen modified velocity and displacement time histories that are likely acceptable or likely unacceptable.

A Semi-Automated Procedure for Selecting and Scaling Recorded Earthquake Motions for Dynamic Analysis

2008 ◽  
Vol 24 (4) ◽  
pp. 911-932 ◽  
Author(s):  
Albert Kottke ◽  
Ellen M. Rathje
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Ground Motions ◽  
Acceleration Response ◽  
Analysis Process ◽  
Target Spectrum ◽  
Acceleration Response Spectrum ◽  
Individual Scale ◽  
The Individual ◽  
Selection Of

Suites of earthquake ground motions play an important role in the seismic design and analysis process. A semi-automated procedure is described that selects and scales ground motions to fit a target acceleration response spectrum, while at the same time the procedure controls the variability within the ground motion suite. The basic methodology selects motions based on matching the target spectral shape, and then fits the amplitude and standard deviation of the target by adjusting the individual scale factors for the motions. The selection of motions from a larger catalog of motions is performed through either a rigorous method that tries each possible suite of motions or an iterative approach that considers a smaller set of potential suites in an effort to find suites that provide an acceptable fit to the target spectrum. Guidelines are provided regarding the application of the developed procedures, and example applications are described.

The Comparative Analysis on Calculation Methods of Vertical Seismic Response to Suspended-Dome Structure

2013 ◽  
Vol 351-352 ◽  
pp. 849-853
Author(s):  
Lan Chen ◽  
De Long Lu ◽  
Xiao Gang Yin
Keyword(s):  
Response Spectrum ◽  
Time History ◽  
Seismic Effect ◽  
Time History Analysis ◽  
Vertical Acceleration ◽  
Analysis Method ◽  
Calculation Methods ◽  
Acceleration Response ◽  
History Analysis ◽  
Acceleration Response Spectrum

Based on the vertical seismic information, the vertical seismic response spectrum was calculated by Matlab Lsim function. The seismic effect of Kiewitt-Lamella suspended-dome was measured by dynamic to static ratio. According to the EL-Centro seismic wave, it analyzed and compared the dynamic to static ratios which were calculated by the following four vertical seismic calculation methods respectively: the simplified method of specification, the mode-superposition response spectrum methods based on the horizontal earthquake affecting coefficients and the vertical acceleration response spectrum respectively, and the time history analysis method. Analysis shows that: For the seismic effect, the time history analysis method is larger than the other three methods, and the method based on the vertical acceleration response spectrum is closer to the time history analysis method. Owing to large difference of the four methods for seismic effect, various methods should be adopted to ensure the safety of vertical seismic design.

Smooth Acceleration Spectra for Pulse-Like Ground Motions

2020 ◽  
Vol 110 (6) ◽  
pp. 2755-2765
Author(s):  
Cuihua Li ◽  
Guofeng Xue ◽  
Zhanxuan Zuo
Keyword(s):  
Seismic Design ◽  
Amplification Factor ◽  
Response Spectrum ◽  
Ground Motions ◽  
Response Spectra ◽  
Acceleration Response ◽  
Constant Acceleration ◽  
Step Procedure ◽  
Acceleration Response Spectrum ◽  
Smooth Acceleration

ABSTRACT Idealization of acceleration response spectra is the basis for construction of target spectra for seismic design and assessment of structures. The adequacy of current methods to reasonably idealize (or smooth) the acceleration spectra of pulse-like and nonpulse-like ground motions is examined in this study. The influence of separated pulses on different regions of acceleration response spectrum is first investigated using wavelet transform. One representative method is selected as the benchmark to examine the effectiveness of the Newmark–Hall-based methods to smooth the acceleration spectra of pulse-like and nonpulse-like ground motions. Presented are some important insights into why the plateau (or amplification factor) associated with the constant-acceleration branch may be underestimated and the ending cutoff period Tg be overestimated by Newmark–Hall-based methods. This study highlights the intrinsic characteristics and the importance of the constant-acceleration branch, based on which a two-step procedure is proposed to idealize the acceleration spectra. The results show that the proposed methodology can accurately identify the constant-acceleration branch regardless of the influence of pulses on the descending branch of acceleration spectra.

Bi-Directional Pseudo-Acceleration Response Spectra

2016 ◽  
Vol 10 (04) ◽  
pp. 1650007
Author(s):  
Anat Ruangrassamee ◽  
Chitti Palasri ◽  
Panitan Lukkunaprasit
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Response Spectra ◽  
Acceleration Response ◽  
Acceleration Response Spectra ◽  
Acceleration Response Spectrum ◽  
Two Degree Of Freedom ◽  
Ratio Response

In seismic design, excitations are usually considered separately in two perpendicular directions of structures. In fact, the two components of ground motions occur simultaneously. This paper clarifies the effects of bi-directional excitations on structures and proposes the response spectra called “bi-directional pseudo-acceleration response spectra”. A simplified analytical model of a two-degree-of-freedom system was employed. The effect of directivity of ground motions was taken into account by applying strong motion records in all directions. The analytical results were presented in the form of the acceleration ratio response spectrum defined as the bi-directional pseudo-acceleration response spectrum normalized by a pseudo-acceleration response spectrum.

Analysis of RMS Acceleration Response Spectrum for Random Pedestrian Loads

2011 ◽  
Vol 261-263 ◽  
pp. 292-298 ◽  
Author(s):  
Jie Song ◽  
Zhi Gang Song ◽  
Yi Jie Shen
Keyword(s):  
Response Spectrum ◽  
Damping Ratio ◽  
Uniform Design ◽  
Structural Response ◽  
Time History ◽  
Step Length ◽  
Acceleration Response ◽  
Step Frequency ◽  
Time Histories ◽  
Dynamic Time

Pedestrian loads are affected by such uncertain parameters as walking step frequency, step length, dynamic load factors and phases of harmonic components, which lead to the uncertainties of structural response. A new method for calculation random response spectrum based on uniform design is introduced to reduce calculation work. A few representative samples of loads time histories are simulated using uniform design, and then the RMS acceleration response spectrums are obtained by dynamic time-history analysis of beam structures with different spans and damping ratios. The RMS acceleration response spectrums which have certain percentiles are obtained by reliability analysis based on response surface. Ultimately the general forms of RMS acceleration response spectrums are deduced from the analyses of sensitivities for damping ratio and span.

Analysis of Different Seismic Response between Low and High Stories of Buildings

2012 ◽  
Vol 166-169 ◽  
pp. 2115-2119
Author(s):  
Kun Xia ◽  
Ling Xin Zhang ◽  
Jie Ping Liu ◽  
Lin Dong
Keyword(s):  
Seismic Response ◽  
Response Spectrum ◽  
Displacement Velocity ◽  
Response Analysis ◽  
Acceleration Response ◽  
Seismic Response Analysis ◽  
Time Histories ◽  
Acceleration Response Spectrum

In general, the higher story of the building, the stronger effects on humans and objects. In this paper, seismic response analysis for two buildings is carried out. The time histories of displacement, velocity, acceleration and acceleration response spectrum of each floor are obtained. By analyzing these results, the phenomenon of "the higher story of the building, the stronger effects on humans and objects" is demonstrated. And reasons of this phenomenon are preliminary analyzed.

scholarly journals Dynamic response of a structure due to different vibration sources

2019 ◽  
Vol 106 ◽  
pp. 01014
Author(s):  
Janusz P. Kogut ◽  
Tomasz Śmierciak
Keyword(s):  
Numerical Model ◽  
Response Spectrum ◽  
Time History ◽  
Ground Level ◽  
Vibration Source ◽  
Acceleration Response ◽  
Existing Building ◽  
Dynamic Excitation ◽  
Time History Response ◽  
Acceleration Response Spectrum

The aim of the work is to acquire the answer for a question if, and to what extent the dynamic excitation forced by underground movement of metro carts or another vibration source impacts the condition of the existing building. To get that assessment, a corresponding numerical model of the tunnel and soil and the structure is created. As input, the acceleration response spectrum computed for the Gulf of Aquaba earthquake is used, as well as the quasi-static axle loading of typical metro carts. The output is shown as the time-history response of the ground-level nodes that will later be used to assess the influence of vibrations with the help of Ciesielski (SWD) scales.

Seismic Response Characteristics of Deep Soft Site with Depth under Far-Field Ground Motion of Great Earthquake

2011 ◽  
Vol 378-379 ◽  
pp. 477-483
Author(s):  
Ji Yan Zhan ◽  
Guo Xing Chen ◽  
Dan Dan Jin
Keyword(s):  
Peak Ground Acceleration ◽  
Response Spectrum ◽  
Ground Motions ◽  
Great Earthquake ◽  
Far Field ◽  
Acceleration Response ◽  
Ground Acceleration ◽  
Long Period ◽  
Reduction Coefficient ◽  
Acceleration Response Spectrum

Considering the dynamic nonlinear characteristics of soil by equivalent linear method, one-dimensional wave models were established to study the seismic effects along depth of deep soft sites under far-field ground motions of great earthquake. The results show that the magnified effect of acceleration response spectrum of each layer present more outstanding under far-field ground motions than under Suzhou artificial waves, with the increasing of bedrock peak ground acceleration, there is probability that the peak of long-period component of acceleration response spectrum appears higher than that of the short-period within 15m depth, which may adversely affect the long-period building structures. However, the reduction coefficient of peak ground acceleration (PGA) along depth according to the three levels of earthquake fortification standard was relatively higher when inputting far-field ground motions of great earthquake. As the curve fitted by Longjun Xu et al. based on records collected California Strong Motion Instrumentation Program geotechnical arrays of the United States and Hosokura Mine arrays of Japan, is not suitable for Suzhou area, suited quantitative formula about reduction coefficient curve of PGA with depth in deep soft site is given. Besides, maximum shear strain at the depth of approximately 15m and 40m present to be greatly changed when inputting far-field ground motions of great earthquake, with the growth of inputting bedrock peak ground acceleration, the layer in the depth of about 15m comes to be the most unfavorable position of shear deformation.

Seismic response analysis of steel–concrete hybrid wind turbine tower

2021 ◽  
pp. 107754632110075
Author(s):  
Junling Chen ◽  
Jinwei Li ◽  
Dawei Wang ◽  
Youquan Feng
Keyword(s):  
Wind Turbine ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Seismic Action ◽  
Response Spectrum Method ◽  
Spectrum Method ◽  
Wind Turbine Tower ◽  
Ground Types ◽  
Nonlinear Time History

The steel–concrete hybrid wind turbine tower is characterized by the concrete tubular segment at the lower part and the traditional steel tubular segment at the upper part. Because of the great change of mass and stiffness along the height of the tower at the connection of steel segment and concrete segment, its dynamic responses under seismic ground motions are significantly different from those of the traditional steel tubular wind turbine tower. Two detailed finite element models of a full steel tubular tower and a steel–concrete hybrid tower for 2.0 MW wind turbine built in the same wind farm are, respectively, developed by using the finite element software ABAQUS. The response spectrum method is applied to analyze the seismic action effects of these two towers under three different ground types. Three groups of ground motions corresponding to three ground types are used to analyze the dynamic response of the steel–concrete hybrid tower by the nonlinear time history method. The numerical results show that the seismic action effect by the response spectrum method is lower than those by the nonlinear time history method. And then it can be concluded that the response spectrum method is not suitable for calculating the seismic action effects of the steel–concrete hybrid tower directly and the time history analyses should be a necessary supplement for its seismic design. The first three modes have obvious contributions on the dynamic response of the steel–concrete hybrid tower.

Response spectral matching of horizontal ground motion components to an orientation-independent spectrum (RotDnn)

2020 ◽  
pp. 875529302097098
Author(s):  
Luis A Montejo
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Major Axis ◽  
Component Level ◽  
Nonlinear Characteristics ◽  
Target Spectrum ◽  
Horizontal Ground Motion ◽  
Median Spectrum

This article presents a methodology to spectrally match two horizontal ground motion components to an orientation-independent target spectrum (RotDnn). The algorithm is based on the continuous wavelet transform decomposition and iterative manipulation of the two horizontal components of a seed record. The numerical examples presented follow current ASCE/SEI 7 specifications and therefore maximum-direction spectra (RotD100) are used as target for the match. However, the proposed methodology can be used to match other RotDnn spectra, like the median spectrum (RotD50). It is shown that with the proposed methodology the resulting RotDnn from the modified horizontal components closely match the smooth target RotDnn spectrum, while the response spectrum for each horizontal component continue to exhibit a realistic jagged behavior. The response spectra variability at the component level within suites of spectrally matched motions was found to be of the same order than the variability measured in suites composed of amplitude scaled records. Moreover, the spectrally matched records generated preserved most of the characteristics of the seed records, including the nonlinear characteristics of the time history traces and the period-dependent major axis orientations.

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