Selection and Scaling of Ground Motion Time Histories for Structural Design Using Genetic Algorithms

2004 ◽  
Vol 20 (2) ◽  
pp. 413-426 ◽  
Author(s):  
Farzad Naeim ◽  
Arzhang Alimoradi ◽  
Shahram Pezeshk
Keyword(s):  
Ground Motions ◽  
Response Spectra ◽  
Single Individual ◽  
Least Mean Square ◽  
Scaling Factors ◽  
Design Spectrum ◽  
Earthquake Ground Motions ◽  
Earthquake Records ◽  
Target Spectrum ◽  
Scaling Methods

This paper presents a new approach to selection of a set of recorded earthquake ground motions that in combination match a given site-specific design spectrum with minimum alteration. The scaling factors applied to selected ground motions are scalar values within the range specified by the user. As a result, the phase and shape of the response spectra of earthquake ground motions are not tampered with. Contrary to the prevailing scaling methods where a preset number of earthquake records (usually between a single component to seven pairs) are selected first and scaled to match the design spectrum next, the proposed method is capable of searching a set consisting of thousands of earthquake records and recommending a desired subset of records that match the target design spectrum. This task is achieved by using a genetic algorithm (GA), which treats the union of 7 records and corresponding scaling factors as a single “individual.” The first generation of individuals may include a population of, for example, 200 records. Then, through processes that mimic mating, natural selection, and mutation, new generations of individuals are produced and the process continues until an optimum individual (seven pairs and scaling factors) is obtained. The procedure is fast and reliable and results in records that match the target spectrum with minimal tampering and the least mean square of deviation from the target spectrum.

DAMAGE EVOLUTION SPECTRA FOR SEISMIC ANALYSIS OF HIGH-RISE BUILDINGS

2012 ◽  
Vol 06 (03) ◽  
pp. 1250021
Author(s):  
Y. B. HO ◽  
J. S. KUANG
Keyword(s):  
Damage Evolution ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Time History ◽  
Tall Buildings ◽  
Response Spectra ◽  
Seismic Damage ◽  
Analysis And Design ◽  
High Rise ◽  
Earthquake Ground Motions

Seismic response spectra are amongst one of the most important tools for characterizing earthquake ground motions. In design practice, the response spectra are presented without including any load history, hence the nonlinear analysis of structures based solely on conventional earthquake response spectra is theoretically unsound, particularly for long-period or vertically irregular high-rise buildings. In this paper, a concept of seismic damage evolution is introduced and the method of analysis for characterizing the process of seismic damage to structures under earthquakes is presented. Seismic damage evolution spectra for analysis and design of high-rise buildings are then developed as an effective means of describing and simplifying earthquake ground motions. These spectra are shown to be very useful in selecting the ground motion-time history and, particularly, validating the equivalent static-load analysis and design of high-rise buildings under near-fault pulse-like ground motions. Case studies of the seismic inelastic performance of two vertically irregular, tall buildings are presented considering the seismic damage evolution spectra.

Ground motions and damage observations in the Marlborough region from the 2013 Lake Grassmere earthquake

2013 ◽  
Vol 46 (4) ◽  
pp. 169-187 ◽  
Author(s):  
Gareth J. Morris ◽  
Brendon A. Bradley ◽  
Adam Walker ◽  
Trevor Matuschka
Keyword(s):  
Ground Motions ◽  
Central Business District ◽  
Response Spectra ◽  
Dam Failure ◽  
Ground Shaking ◽  
Design Spectrum ◽  
Future Design ◽  
State Highway ◽  
Damage States ◽  
Business District

This paper presents various aspects of the preliminary damage observations caused by ground motions in the Marlborough region following the Mw6.6 Lake Grassmere earthquake on 16 August 2013. To emphasize the severity of the ground shaking, the observed pseudo-acceleration response spectra are compared to those from the 21 July 2013 Mw6.5 Cook Strait earthquake and the NZS1170.5:2004 design spectrum. The near-source damage to State Highway 1 roads, bridges and buildings is presented within. Stainless steel wine storage tanks showed various damage states that were consistent with observations from previous earthquake events. The performance of wine tanks and other winemaking infrastructure are discussed with future design considerations. Eleven water storage dams within 12 kilometres of the earthquake source were inspected and preliminary observations are discussed. A 250,000 cubic metre dam located 10 kilometres southwest of Seddon suffered moderate damage following the 21 July event while significant further damage was sustained following the 16 August event and emergency earthworks were undertaken to reduce the risk of dam failure (to those living downstream). The performance of residential housing in rural townships of Seddon and Ward was satisfactory with respect to preserving life safety however there was moderate levels of damage which are presented within. Post-earthquake business disruption was minimal as commercial buildings in the Blenheim central business district sustained either minor or no damage.

Structure-Specific Scalar Intensity Measures for Near-Source and Ordinary Earthquake Ground Motions

2007 ◽  
Vol 23 (2) ◽  
pp. 357-392 ◽  
Author(s):  
Nicolas Luco ◽  
C. Allin Cornell
Keyword(s):  
Ground Motions ◽  
Linear Regression Analysis ◽  
Structural Performance ◽  
Intensity Measures ◽  
Earthquake Ground Motions ◽  
Long Period ◽  
Earthquake Records ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
A Site

Introduced in this paper are several alternative ground-motion intensity measures ( IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the “efficiency” and “sufficiency” of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions.

Effects of Frequency Content of Earthquake Ground Motions on Probabilistic Seismic Demand Assessment of Long-Span Bridge Structures

2011 ◽  
Vol 255-260 ◽  
pp. 982-987
Author(s):  
Liang Chen ◽  
Jin Song Zhang
Keyword(s):  
Ground Motions ◽  
Geometric Mean ◽  
Response Spectra ◽  
Seismic Demand ◽  
Frequency Content ◽  
Earthquake Ground Motions ◽  
Long Span ◽  
Long Span Bridge ◽  
Demand Assessment ◽  
Probabilistic Seismic Demand

Earthquake ground motions were reasonally selected for the nonlinear dynamic time-history analysis conducted for a two-tower long-span cable-stayed bridge. The correlation between frequency content of earthquake ground motions and probabilistic seismic demands reveals that the geometric mean and dispersion of response spectra from earthquake ground motions have significant effects on probabilistic seismic demand assessment of long-span bridge stuctures and these effects are related to the difference of the shape of geometric mean spectra in the important period ranges where cumulative modal mass participation is significant. Response spectra of selected earthquake ground motions should match well with target spectra in the important period ranges. If input ground motions are reasonally selected, analytic results can be obtained more precisely and effectively and more amplitude parameters can be selected as intensity measures.

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.

scholarly journals A New Spectral Shape-Based Record Selection Approach UsingNpand Genetic Algorithms

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Edén Bojórquez ◽  
Alfredo Reyes-Salazar ◽  
Sonia E. Ruiz ◽  
Juan Bojórquez
Keyword(s):  
Genetic Algorithms ◽  
Traditional Approach ◽  
Nonlinear Dynamic Analysis ◽  
Response Spectra ◽  
Spectral Shape ◽  
Optimization Approach ◽  
Design Spectrum ◽  
Target Spectrum ◽  
The Mean ◽  
Record Selection

With the aim to improve code-based real records selection criteria, an approach inspired in a parameter proxy of spectral shape, namedNp, is analyzed. The procedure is based on several objectives aimed to minimize the record-to-record variability of the ground motions selected for seismic structural assessment. In order to select the best ground motion set of records to be used as an input for nonlinear dynamic analysis, an optimization approach is applied using genetic algorithms focuse on finding the set of records more compatible with a target spectrum and targetNpvalues. The results of the newNp-based approach suggest that the real accelerograms obtained with this procedure, reduce the scatter of the response spectra as compared with the traditional approach; furthermore, the mean spectrum of the set of records is very similar to the target seismic design spectrum in the range of interest periods, and at the same time, similarNpvalues are obtained for the selected records and the target spectrum.

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