An efficient algorithm to simulate site‐based ground motions that match a target spectrum

2021 ◽  
Author(s):  
Jawad Fayaz ◽  
Farzin Zareian
Keyword(s):  
Efficient Algorithm ◽  
Ground Motions ◽  
Target Spectrum

Response History Analysis for the Design of New Buildings in the NEHRP Provisions and ASCE/SEI 7 Standard: Part III - Example Applications Illustrating the Recommended Methodology

2017 ◽  
Vol 33 (2) ◽  
pp. 419-447 ◽  
Author(s):  
Reid B. Zimmerman ◽  
Jack W. Baker ◽  
John D. Hooper ◽  
Stephen Bono ◽  
Curt B. Haselton ◽  
...  
Keyword(s):  
Ground Motions ◽  
Structural Systems ◽  
The Third ◽  
History Analysis ◽  
Target Spectrum ◽  
Response History Analysis ◽  
Tectonic Settings ◽  
Local Results ◽  
New Buildings ◽  
Selection Of

This paper represents the third part of a series of four publications on response history analysis for new buildings. Three real-building examples designed to a prior version of the building code are chosen, having a range of target spectrum characteristics, tectonic settings, and structural systems to test the new procedure and document its appropriate implementation. This paper describes the process of determining both MCER spectra and scenario spectra for all three examples. It explores selection of appropriate recorded ground motions and the procedure for scaling and spectrally matching to a maximum direction spectrum. Global results such as drift and treatment of unacceptable response, and local results such as force-and deformation-controlled acceptance criteria checks, are shown for each example. Practical guidance is given on implementing response history analysis for engineers employing the new Chapter 16.

Effect of Ground Motion Modification Technique on Seismic Geotechnical Engineering Analyses

2012 ◽  
Vol 28 (4) ◽  
pp. 1643-1661 ◽  
Author(s):  
Dimitrios Zekkos ◽  
Clinton Carlson ◽  
Ahmed Nisar ◽  
Stephanie Ebert
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
A Priori ◽  
Earthquake Scenarios ◽  
Local Site ◽  
Intensity Parameters ◽  
Target Spectrum ◽  
Modification Technique ◽  
The Time Domain ◽  
The Impact

Ground motion modification (or spectral matching) has been criticized, but has many appealing characteristics and is widely used in practice. Modification of ground motions can be performed in either the time domain or the frequency domain. Depending on the choice of modification technique, modified ground motions can be significantly different from each other as well as from the original ground motion. This paper studies the impact of these differences on seismic geotechnical analyses for two different site profiles using two earthquake scenarios and a total of 20 ground motions. This study shows that the final results are influenced by many factors such as the original (seed) ground motion, the target spectrum, and the local site conditions, in addition to the ground motion modification technique used. The results also show that while both techniques can significantly modify the original ground motion, neither technique is consistently more conservative than the other. Therefore, a general conclusion that a particular technique results in ground motions that yield the largest intensity parameters cannot be made a priori.

An efficient algorithm to simulate hazard-targeted site-based synthetic ground motions

2020 ◽  
pp. 875529302097096
Author(s):  
Jawad Fayaz ◽  
Sarah Azar ◽  
Mayssa Dabaghi ◽  
Farzin Zareian
Keyword(s):  
Ground Motion ◽  
Efficient Algorithm ◽  
Ground Motions ◽  
Model Parameters ◽  
Graphic User Interface ◽  
Forward Selection ◽  
Intensity Measure ◽  
Input Event ◽  
Predictive Relations ◽  
Simulated Ground Motions

This study presents an efficient algorithm that can be used to simulate ground motion waveforms using the site-based approach developed by Dabaghi and Der Kiureghian, and Rezaeian and Der Kiureghian that not only correspond to a specified seismic scenario (e.g. magnitude, distance, site conditions) but are also certain to achieve a target ground motion intensity measure within a narrow range. The suggested algorithm alleviates the need to scale simulated ground motions generated using the above-mentioned site-based approach; the resulting hazard-targeted simulated ground motions have consistent amplitude and time- and frequency-domain characteristics, which are required for proper seismic demand analysis of structures. The proposed algorithm takes as input a set of seismic Event Parameters and the target hazard intensity measure [Formula: see text] and generates a corresponding set of Model Parameters (i.e. input to the site-based ground motion simulation model). These Model Parameters are then used to simulate ground motion waveforms that not only represent the set of input Event Parameters ( Mw, Rrup, Vs30) but also maintain the target [Formula: see text]. To generate the set of Model Parameters, predictive relations between the Model Parameters and [Formula: see text] of ground motions are developed. Among the Model Parameters, the ones classified as important by statistical procedures (such as Random Forests, Forward Selection) are used to develop the predictive relations. The developed relations are then validated against a large dataset of recorded ground motions. The final implementation is provided in terms of graphic-user interface (GUI) called “Hazard-Targeted Time-Series Simulator” ( HATSim), which efficiently simulates site-based ground motions with minimum inputs.

Using the Conditional Spectrum Method for Improved Fragility Assessment of Concrete Gravity Dams in Eastern Canada

2016 ◽  
Vol 32 (3) ◽  
pp. 1449-1468 ◽  
Author(s):  
Carl Bernier ◽  
Ricardo Monteiro ◽  
Patrick Paultre
Keyword(s):  
Fragility Curves ◽  
Ground Motions ◽  
Accurate Estimation ◽  
Gravity Dams ◽  
Eastern Canada ◽  
Proper Selection ◽  
Concrete Gravity Dams ◽  
Target Spectrum ◽  
Ground Motion Records ◽  
Selection Of

The accurate estimation of fragility functions requires the proper selection of ground motion records at different intensity levels. However, most of the available fragility assessments of concrete dams use the same records at all intensity levels and often selects them with an inadequate target spectrum. In order to improve the fragility assessment of such structures, this paper proposes the use of records selected with the Conditional Spectrum (CS) method within a multiple stripes analysis. The approach is applied to a dam in Eastern Canada, and a comparison with the methodology used by other studies is done. It is shown that the approach proposed herein allows for the reduction of the seismic response and fragility of the dam. Moreover, the uncertainty related to material properties becomes less significant when using the CS method, and the fragility curves could be reasonably estimated by considering the ground motions as the only source of uncertainty.

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.

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.

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