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Computational tools for characterization, evaluation, and modification of strong ground motions within performance-based seismic design framework.

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Version 3.0 - published on 06 Oct 2011

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EQTools 3.0 is a Microsoft Windows based application that comprises of requisite computational tools to provide a rapid and consistent means towards systematic assembly of representative strong ground motions and their characterization, evaluation, and modification within a performance-based seismic design framework.  The application is graphics-intensive and every effort has been made to make it as user-friendly as possible.  The application seeks to provide processed data which will help the user address the problem of determination of the critical earthquakes by identification of the severity and damage potential of more than 700 components of recorded earthquake ground motions.  Computational tools are also developed to estimate the ground motion parameters for different geographical and tectonic environments and to perform one-dimensional linear/nonlinear site response analysis as a means to predict ground surface motions at sites where soft soils overlay the bedrock.


One of the most difficult tasks towards designing earthquake resistant structures is the determination of critical earthquake(s).  Conceptually, these are the ground motions that would drive the structure being designed to its critical response.  The quantification of this concept, however, is not so easy. Unlike the linear response of a structure, which can often be obtained using a single spectrally modified ground motion time history the nonlinear response is strongly dependent on the phasing of input ground motion and the detailed shape of its spectrum.  This necessitates the use of a suite (bin) of time histories having phasing and spectral shapes appropriate for the characteristics of the earthquake source, wave propagation path, and site conditions that control the design spectrum.  Computational tools are available in the EQTools environment to accomplish this.  The suite of assembled records may have to be scaled to match the design spectrum over a period range of interest, rotated into strike-normal and strike-parallel directions for near fault effects, modified for local site conditions before they can be input into time-domain nonlinear analysis of structures.  The generation of these time histories is cumbersome and daunting.  This is especially due to the sheer magnitude of the data processing involved. EQTools provides the means to carry out these operations in a systematic manner.



Below is a screenshot of the interface.



While EQTools may be used for professional practice or academic research, the fundamental purpose behind the development of the software is to make an available  integrated classroom/laboratory tool that provides a visual basis for learning the principles behind the selection of time histories and their scaling/modification for input into time domain nonlinear (or linear) analysis of structures. EQTools in association with NONLIN, a Microsoft Windows based application for the dynamic analysis of single and multi-degree of freedom structural systems may be used for learning the concepts of earthquake engineering, particularly as related to structural dynamics, damping, ductility, and energy dissipation.


For further information, please refer to the manual posted under attachments.



Developed by Finley A. Charney

Virginia Polytechnic Institute and State University

Department of Civil and Environment Engineering

200 Patton Hall

Virginia Tech, Blacksburg, VA 24061  USA



EQTools, Copyright © 2010, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.

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Researchers should cite this work as follows:

  • (2011), "EQTools,"

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