scholarly journals Optimal Design of Liquid Dampers for Structural Vibration Control Based on GA andH∞Norm

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Linsheng Huo ◽  
Wenhe Shen ◽  
Hongnan Li ◽  
Yaowen Zhang
Keyword(s):  
Optimal Design ◽  
Ground Motion ◽  
Structural Response ◽  
Optimal Solution ◽  
Time History ◽  
Optimization Procedure ◽  
Structural Vibration ◽  
Earthquake Excitation ◽  
Liquid Dampers ◽  
Ground Motion Records

This paper focused on the optimal design of liquid dampers for the seismic response control of structures. TheH∞norm of the transfer function from the ground motion to the structural response is selected as the optimal objective. The optimization procedure is carried out by using Genetic Algorithms (GAs) in order to reach an optimal solution. The proposed method has the advantages that it is unnecessary to solve the equation of motion for the control system and that the obtained optimal parameters of dampers are not dependent on the ground motion records. The influences of weighted functions on the optimization results are analyzed. The generality and effeteness of the proposed method are verified by the time history analysis of a 3-story structure subjected to earthquake records in different sites. The results show that the structural responses can be effectively reduced subjected to earthquake excitation at different sites.

Ground Motion Intensity Measures for Rocking Building Systems

2017 ◽  
Vol 33 (4) ◽  
pp. 1533-1554 ◽  
Author(s):  
Mehrdad Shokrabadi ◽  
Henry V. Burton
Keyword(s):  
Ground Motion ◽  
Structural Response ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Braced Frame ◽  
Residual Drift ◽  
Engineering Demand Parameter ◽  
Frame System ◽  
Ground Motion Records ◽  
Steel Braced Frame

This paper investigates the effectiveness of various ground motion intensity measures (IMs) in estimating the structural response of two types of rocking systems: (a) a controlled rocking steel braced frame system with self-centering action and (b) a rocking spine system for reinforced concrete infill frames. The IMs are evaluated based on the dispersion in engineering demand parameter (EDP) predictions (efficiency) and the sensitivity of the conditional distributions of EDPs to the distributions of the magnitudes, distances and spectral shape parameter (ε) of ground motion records (sufficiency). The EDPs include maximum transient and residual story drifts and peak floor accelerations. The spectral acceleration averaged over a range of periods (Sa avg) is most effective for predicting transient and residual drift demands and peak ground acceleration (PGA) is generally the best predictor of peak floor accelerations. The proximity of the frequency range most affecting an EDP to that best reflected in an IM is found to be a good indicator of the performance of that IM.

scholarly journals A Wavelet-based Approach for Truncating Pulse-like Records

2021 ◽  
Author(s):  
Vicky Dimakopoulou ◽  
Michalis Fragiadakis ◽  
Ioannis Taflampas
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Time History ◽  
Response Spectra ◽  
Degree Of Freedom ◽  
Seismic Performance Assessment ◽  
Analysis And Design ◽  
Nonlinear Time History Analyses ◽  
Ground Motion Records ◽  
Nonlinear Time History

Abstract The seismic performance assessment of structures using truncated pulse-like ground motion records is discussed. It is shown that it is possible to truncate pulse-like signals using a novel wavelet-based definition that identifies the duration of the predominant velocity pulse. The truncated time history can efficiently reproduce the increased seismic demand that near-field records typically produce. Substituting the original ground motion with the truncated signal, significantly accelerates structural analysis and design. The truncated signal is the part of the original accelerogram that coincides with the duration of the predominant pulse, which is identified using a wavelet-based procedure, previously proposed by the authors. Elastic and inelastic response spectra and nonlinear time history analyses for SDOF (single-degree-of-freedom) systems are first studied. Subsequently a nine-storey steel frame is examined in order to demonstrate the performance of the proposed approach on a multiple-degree-of-freedom system. The proposed approach is found very efficient for pulse-like ground motions, while it is also sufficient for many records that are not characterized as such.

The Effects of Discretization Errors on the High Frequency Content of In-Structure Response Spectra

2016 ◽  
Author(s):  
Greg Mertz ◽  
Robert Spears ◽  
Thomas Houston
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Time History ◽  
Response Spectra ◽  
Frequency Content ◽  
Time Step ◽  
Structure Response ◽  
Time History Response ◽  
Ground Motion Records ◽  
High Frequency Content

The next generation ground motion prediction equations predict significant high frequency seismic input for rock sites in the Central Eastern United States (CEUS). This high frequency motion is transmitted to basemat supported components and may be transmitted to components supported on elevated slabs. The existing ASCE 4 analysis requirements were initially developed based on seismic motions having lower frequencies, typical of ground motions in the Western United States (WUS). The adequacy of the existing ASCE 4 analysis requirements are examined using high frequency CEUS spectral shapes and the potential error inherent in using the existing approach to computing in structure response spectra is quantified. Modifications to reduce potential error in the existing ASCE 4 criteria are proposed. In structure response spectra are typically generated for a subsystem given the time history response of a building region. The building time history response is based on analyses that use either modal time history superposition, direct integration or complex frequency response analysis of the building and supporting soil. Input to the building analyses consist of either real or synthetic discretized ground motion records. The discretized ground motion records are often based on recorded ground motion seeds and are often limited to a 0.005 second time step. Thus the time step of the seed record often limits the frequency content of the problem. Both the building analyses and in structure response spectra subsystem analysis may interpolate the discretized ground motion records to obtain stable results. This interpolation generates errors that are propagated through the analyses used to calculate in structure response spectra. These errors may result in extraneous high frequency content in the in structure response spectra. Errors are quantified by comparison of time history parameters, Fourier components and in structure response spectra.

A Stochastic Model for Simulating Vertical Pulseless Near-Fault Seismic Ground Motions

2021 ◽  
Author(s):  
Xi Zhong Cui ◽  
Yong Xu Liu ◽  
Han Ping Hong
Keyword(s):  
Stochastic Model ◽  
Ground Motion ◽  
Ground Motions ◽  
Time History ◽  
Structural Deformation ◽  
Time Frequency ◽  
Motion Models ◽  
Near Fault ◽  
Simulation Techniques ◽  
Ground Motion Records

ABSTRACT The vertical near-fault seismic ground-motion component can cause significant structural deformation and damage, which can be evaluated from time history analysis using actual or synthetic ground-motion records. In this study, we propose a new stochastic model for the vertical pulseless near-fault ground motions that depends on earthquake magnitude, rupture distance, and site condition. The proposed model is developed based on the time–frequency characteristics of 606 selected actual vertical record components in strike-slip earthquakes. The use and validation of the model are presented using simulated records obtained by two simulation techniques. For the validation, the statistics of time–frequency-dependent power spectral acceleration estimated from the simulated records using the proposed stochastic model are compared with those from the actual records and the ground-motion models available in the literature.

Seismic assessment of a cable-stayed arch bridge under three-component orthotropic earthquake excitation

2020 ◽  
pp. 136943322094875 ◽  
Author(s):  
Salar Farahmand-Tabar ◽  
Majid Barghian
Keyword(s):  
Ground Motion ◽  
Numerical Study ◽  
Epicentral Distance ◽  
Ground Motions ◽  
Dynamic Responses ◽  
Earthquake Excitation ◽  
Arch Bridge ◽  
Stay Cables ◽  
Horizontal Ground Motion ◽  
Ground Motion Records

The occurred damages during the past significant earthquakes have proved that vertical seismic excitation has tremendous effect on bridges. Three-component earthquake excitations are preferred to resemble the earthquakes. In this article, a cable-stayed arch bridge, a new type of bridge with the hybrid system of half-through arch and stay-cables, was analyzed under a set of different earthquake excitations (more than 21 ground motion records). Both vertical and horizontal components of the ground motions were considered to act simultaneously at the bridge supports. By using different three-component earthquake excitations, the dynamic responses of the bridge, including the displacements and accelerations of the main parts of the bridge, were obtained. The effects of various parameters such as soil type, epicentral distance, spatial variation of the ground motions, and dimensional variation of the structure were investigated. The results of the numerical study indicate that the cable-stayed arch bridge subjected to both horizontal and vertical components of earthquakes are more vulnerable than those subjected to horizontal ground motion only.

scholarly journals A sectionalized-dual-band method for the selection of ground motion record sets

2021 ◽  
Vol 9 (3A) ◽  
Author(s):  
Hongmei Hou ◽  
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Seismic Design ◽  
Response Spectrum ◽  
Time History ◽  
Spectral Shape ◽  
Dual Band ◽  
Base Shear ◽  
Period Range ◽  
Ground Motion Records

It is of great importance to select appropriate ground motion records for time-history dynamic analysis of structures. The consistency between record response spectral shape and seismic design response spectral shape is the basic principle for records selection. A sectionalized-dual-band (SDB) method considering influence of higher modes was proposed to select ground motion records according to the seismic fortification intensity requirements and the site characteristic. Furthermore, the newly proposed method has been employed to construct record sets within the whole response spectrum period. As compared with other traditional methods, the records obtained from the SDB method are more effective in predicting base shear derived from time-history dynamic analysis. When the period of a structure is determined, the records in the matched period range of the records set can be directly used to conduct time-history dynamic analysis. This method can avoid tedious work for reselecting ground motion records for different structures in the same seismic design intensity and site conditions.

scholarly journals Seismological and Engineering Demand Misfits for Evaluating Simulated Ground Motion Records

2019 ◽  
Vol 9 (21) ◽  
pp. 4497 ◽  
Author(s):  
Shaghayegh Karimzadeh
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Goodness Of Fit ◽  
Structural Response ◽  
Evaluation Methodology ◽  
Engineering Practice ◽  
Input Energy ◽  
Structural Demand ◽  
Ground Motion Records ◽  
Descriptive Set

Simulated ground motions have recently gained more attention in seismology and earthquake engineering. Since different characteristics of waveforms are expected to influence alternative structural response parameters, evaluation of simulations, for key components of seismological and engineering points of view is necessary. When seismological aspect is of concern, consideration of a representative set of ground motion parameters is imperative. Besides, to test the applicability of simulations in earthquake engineering, structural demand parameters should simultaneously cover a descriptive set. Herein, simulations are evaluated through comparison of seismological against engineering misfits, individually defined in terms of log-scale misfit and goodness-of-fit score. For numerical investigations, stochastically simulated records of three earthquakes are considered: The 1992 Erzincan-Turkey, 1999 Duzce-Turkey and 2009 L’Aquila-Italy events. For misfit evaluation, seismological parameters include amplitude, duration and frequency content, while engineering parameters contain spectral acceleration, velocity and seismic input energy. Overall, the same trend between both misfits is observed. All misfits for Erzincan and Duzce located on basins are larger than those corresponding to L’Aquila mostly placed on stiff sites. The engineering misfits, particularly in terms of input energy measures, are larger than seismological misfits. In summary, the proposed misfit evaluation methodology seems useful to evaluate simulations for engineering practice.

Seismic Zonation and Default Suite of Ground-Motion Records for Time-History Analysis in the North Island of New Zealand

2012 ◽  
Vol 28 (2) ◽  
pp. 667-688 ◽  
Author(s):  
Claudio A. Oyarzo-Vera ◽  
Graeme H. McVerry ◽  
Jason M. Ingham
Keyword(s):  
New Zealand ◽  
Ground Motion ◽  
Time History ◽  
Time History Analysis ◽  
Seismic Zonation ◽  
The North ◽  
History Analysis ◽  
Ground Motion Records ◽  
Site Classes ◽  
Selection Of

A seismic zonation to be used in the selection of ground-motion records for time-history analysis of buildings in the North Island of New Zealand is presented. Both deaggregations of the probabilistic seismic hazard model and the seismological characteristics of the expected ground motions at different locations were considered in order to define the zonation. A profile of the records expected to apply within each zone according to the identified hazard scenarios is presented and suites of records are proposed for each zone, based on region-wide criteria, to be used in time-history analysis in the absence of site specific studies. A solution for structures with fundamental periods of between 0.4 and 2.0 seconds is proposed, considering a 500-year return period and two common site classes (C and D, according to the New Zealand Loadings Standard).

scholarly journals Optimal Design of Earthquake-Resistant Buildings Based on Neural Network Inversion

2021 ◽  
Vol 11 (10) ◽  
pp. 4654
Author(s):  
Carlo Calledda ◽  
Augusto Montisci ◽  
Maria Cristina Porcu
Keyword(s):  
Neural Network ◽  
Optimal Design ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Structural Response ◽  
Time History ◽  
Optimal Choice ◽  
Design Parameters ◽  
Earthquake Resistant ◽  
Non Linear

An effective seismic design entails many issues related to the capacity-based assessment of the non-linear structural response under strong earthquakes. While very powerful structural calculation programs are available to assist the designer in the code-based seismic analysis, an optimal choice of the design parameters leading to the best performance at the lowest cost is not always assured. The present paper proposes a procedure to cost-effectively design earthquake-resistant buildings, which is based on the inversion of an artificial neural network and on an optimization algorithm for the minimum total cost under building code constraints. An exemplificative application of the method to a reinforced-concrete multi-story building, with seismic demands corresponding to a medium-seismicity Italian zone, is shown. Three design-governing parameters are assumed to build the input matrix, while eight capacity-design target requirements are assigned for the output dataset. A non-linear three-dimensional concentrated plasticity model of the structure is implemented, and time-history dynamic analyses are carried out with spectrum-consistent ground motions. The results show the promising ability of the proposed approach for the optimal design of earthquake-resistant structures.

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