Scaling methods for earthquake response spectra journal of. The results show that a threeparameter system of spectrum intensities, computed within low, medium, and high frequency regions, may afford a better means of scaling earthquake response spectra. Thus, if you can find out the natural frequency of the structure, then the peak response of the building can be estimated by. Software to download usgs earthquake hazard program. Some of these procedures are based on explicit physical models of the earthquake source, travelpath and recording site while others lack a strong physical basis and seek only to replicate observations. The scaling parameters are evaluated statistically using response spectra for elastic, elastoplastic, and bilinear hysteretic systems, computed from a set of twelve representative earthquake recordings. Elastic response spectrum file exchange matlab central. Scaling law of seismic spectrum k,iii axi department o geology and geophysics massachusetts institute oi technology, cambridge the dependence of the amplitude spectrum of seismic waves on source size is investigated on the basis of two dislocation models of. Other problems occur because the response analysis is linear. Sep 28, 2015 a new computerbased platform has been proposed whose novelty consists in modeling the local site effects of the ground motion propagation using a hybrid approach based on an equivalent linear model. Originally, when we were studying the dynamics of a simple single degree of freedom structure, we noticed that given one type of earthquake, we dont have to keep solving the equat. Efficient and accurate determination of floor response spectra frs is critical in seismic risk analysis and design.
This paper develops a new model for a damping scaling factor dsf that can be used to adjust elastic response spectral ordinates for the vertical component of earthquake ground motion at a 5% viscous damping ratio to ordinates at damping ratios between 0. Based on the static analysis method, the response spectrum method made improvement over it, transformed the dynamic problem into the static problem by applying the mode superposition theory. Damping scaling factors for vertical elastic response spectra. Earthquake source scaling and selfsimilarity estimation from stacking p and s spectra germa. Significance of ground motion scaling parameters on. How to scale base shear in etabs the structural world. Scaling methods for earthquake response spectra journal. Selection and scaling of real earthquake accelerograms to fit 1234 4. We have examined the data for peak horizontal acceleration, velocity, and response spectra and do not find support for a magnitudedependent shape refs.
The response spectrum method of analysis is developed using the following steps. Peer 201511 selection and scaling of ground motions for nonlinear response history analysis of buildings in performancebased earthquake engineering n. Practical guidelines to select and scale earthquake records. Selection and scaling of ground motion time histories for. Generated to match a target response spectrum earthquake motion as the output from filters and use of system response for. Records for nonlinear response history analysis of structures 1 abstract earthquake engineering practice is increasingly using nonlinear response history analysis rha to demonstrate performance of structures. The primary objective of this task was to develop guidance for selecting, generating, and scaling earthquake ground motions for effective use in performing responsehistory analyses for use in performancebased seismic engineering. The followed scaling method provides both the requirements of the turkish earthquake code regarding the scaling of ground motions and compatibility of response spectra of selected ground motion pairs with the target spectrum. Stateoftheart for assessing earthquake hazards in the united states 14, miscellaneous paper s731, u. To solve the equation of motions for different periods, the newmark linear method was used. Practical guidelines to select and scale earthquake. Is there any software for scaling earthquake records. The scaling parameters are evaluated statistically using response spectra for elastic, elastoplastic, and bilinear hysteretic systems, computed from a. The response spectrum of an earthquake is the most favored seismic input for earthquake engineers.
All the preceding scaling methods utilize ims based on elastic response of the structure. Multicomponent ground motion response spectra for coupled horizontal, vertical, angular accelerations and tilt, iset, journal of earthquake technology invited paper for the special issue on response spectra. Selection and scaling of real earthquake accelerograms to fit. This was then further developed into a design response spectrum for use in structural design, and this basic form. Earthquake analysis and design of simple structures and.
Selecting and scaling earthquake ground motions for. Strongmotion processing steps in the automated workflow are clearly defined, and use a set of customizable parametersspecified in a configuration fileto generate cosmos v1 acceleration with mean removed, v2 baselinecorrected and filtered acceleration, velocity and displacement, and v3 response spectra, fourier spectra and intensity. 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. Selection and scaling of real earthquake accelerograms to. A response spectra analysis may be performed after the dynamic analysis to obtain forces, stresses and deflections. Practical guidelines to select and scale earthquake records for nonlinear response history analysis of structures by erol kalkan and anil k. A computerbased environment for processing and selection.
Fullcolor reports are available free of charge as a pdf. It includes capabilities for modification, correction, scaling, truncation and baseline correction of earthquake records and it can calculate a variety of strong motion parameters arias intensity, elastic and inelastic response spectra, acceleration, velocity, displacement and forcedisplacement response histories. Presented in partial fulfillment of the requirements. Included within the group based on response quantities are the spectrum intensity and the mean fourier amplitude. 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. A survey of techniques for predicting earthquake ground. The remaining geometric term, br5 ln, is thus the only term used by boore et al. Earthquake source scaling and selfsimilarity estimation. For the degree of master of applied science civil engineering at. World conference on earthquake engineering october 1217, 2008, beijing, china scaling of earthquake accelerograms for nonlinear dynamic analyses to match the earthquake design spectra y. Jul 10, 2016 etabs 2015 advanced tutorial deals with the response spectrum analysis which is a method of seismic analysis considered for irregular or tall buildings.
Scaling methods, which allow the generation of frs corresponding to new ground. Ground motion scaling in time domain in this approach, recorded motion is simply scaled up or down uniformly to best match the target spectrum within a period range of interest, without changing the frequency content. Army corps of engineers, vicksburg, mississippi, usa. This rigorous method of analysis requires selection and scaling of ground motions appropriate to design hazard levels. Chopra report peer 201510 structural behavior of columnbent cap beambox girder systems in reinforced concrete bridges subjected to gravity and seismic load, part. Acceleration, velocity and displacement spectra and ductility demand for simqke generated records trapezoidal intensity envelope with earthquake rise time2. A computerbased environment for processing and selection of. Equivalent lateral force for an earthquake is defined as a set of lateral force which will produce the same peak response as that obtained by dynamic analysis of structures. The peer reports series comprises stateoftheart research in earthquake engineering and related fields by the more than 150 expert members of the peer universities consortium. In general, the response spectra analysis procedure is based on the assumption that the dynamic response of a structural model can be approximated as a summation of the responses of the independent dynamic modes of the model. Introduction the most direct description of an earthquake motion in time domain is provided by accelerograms that are recorded by instruments called strong motion accelerographs. A scaling method for generating floor response spectra.
Scaled accelerograms and equivalent response spectra. Oct 10, 2008 vanmarcke eh 1979 representation of earthquake ground motion. Visual comparison of actual, target, and matching spectrum. Earthquake source scaling and selfsimilarity estimation from. Earthquake ground motions for performing response history analysis. Most studies on inelastic response spectra have focused on the selection of the elasticperfectly plastic material behavior, on taking into account the effects of the duration of the motion and on scaling methods 6, 7, 8, 9. Openseismomatlab is an innovative opensource software for strong ground motion data processing, written in matlab. An evaluation of scaling methods for earthquake response. The primary objective of this task was to develop guidance for selecting, generating, and scaling earthquake ground motions for effective use in performing response history analyses for use in performancebased seismic engineering. Rspmatch software developed by abrahamson 1992 list of candidate earthquake records used for rspmatch. Earthquake design spectra given a earthquake ground acceleration, there is no difficulty to compute response using newmarks method as the previous example. All are relatively new so there is very little in the way of a track record with any of them. Damping scaling factors for vertical elastic response. Significance of ground motion scaling parameters on amplitude.
Brief history of computation of earthquake response spectra. Such spectra are usually provided by the architectengineer or seismic structural analyst of the building. Seismic analysis is a subset of structural analysis and is the calculation of the response of a building or nonbuilding structure to earthquakes. In the context of seismic analysis of structures, various earthquake inputs may be required depending upon the nature of analysis being carried out.
The software implements an elastoplastic bilinear kinematic hardening constitutive model and uses a stateoftheart single step single solve time integration algorithm featuring exceptional speed, robustness and accuracy. Attenuation and scaling of response spectra are essentially eliminated gupta and trifunac, 1988a, 1990a, 1990b, 1991a, 1991b. The response spectrum rather than seismological parameters. The earthquake ground motion and response spectra design for. The equivalence is restricted to a single mode of vibration.
The soil behavior is modeled assuming that both the shear modulus and the damping ratio vary with the shear strain amplitude. It is part of the process of structural design, earthquake engineering or structural assessment and retrofit see structural engineering in regions where earthquakes are prevalent. A new computerbased platform has been proposed whose novelty consists in modeling the local site effects of the ground motion propagation using a hybrid approach based on an equivalent linear model. Response spectra for elastic, elastoplastic, and bilinear hysteretic systems for wide ranges of damping and ductility were used in the statistical study. The influence of local soil conditions is treated in section 2. Therefore, we can generate a response spectrum for that earthquake. The current emphasis of the series is on performancebased engineering of lifelines and building structures. Such spectra are called instructure response spectra or floor response spectra. A thesis in the department of building, civil and environmental engineering.
If the equipment is located at a higher floor of a building, then the response spectra for the earthquake motion at that floor are used in the analysis. The results show that a three parameter system of spectrum intensities, computed within low, medium, and high frequency regions, may provide a better means of scaling earthquake response spectra. Etabs 2015 advanced tutorial deals with the response spectrum analysis which is a method of seismic analysis considered for irregular or tall buildings. If you are looking for software to compute the scale factor appropriate to obtain a match to a target response spectrum, good options. It is part of the process of structural design, earthquake engineering or structural assessment and retrofit see structural engineering in regions where earthquakes are prevalent as seen in the figure, a building has the potential to wave back. Methods of ground motion scaling of earthquake time histories. Scaling methods, which allow the generation of frs corresponding to new ground response spectra grs by multiplying existing frs with appropriate scaling factors rather than by performing reanalyses of the structure, are efficient and economical approaches. In the 1982 eeri monograph on earthquake design and spectra, newmark and hall describe how they developed an idealized seismic response spectrum based on a range of response spectra generated for available earthquake records. Over the past four or five decades many advances have been made in earthquake groundmotion prediction and a variety of procedures have been proposed. Hence, etabs assumes that the response spectrum functions are unitless and that the scale factor converts them into the appropriate units. Significant reductions in dispersion may be realized if elastic spectra are normalized by the spectrum intensities rather than the peak ground motions. Due to its opensource nature, the software can be easily extended or modi. Matching spectrum in figure 14 is acquired based on multiplying between response spectra figure and scaling factor a 2. Earthquake response spectrum free software download.
A displacement response spectrum is the plot of maximum displacement of a single degree of freedom system sdof to a particular ground motion as. Smooth response spectrum real spectrum has somewhat irregular shape with local peaks and valleys for design purpose, local peaks and valleys should be ignored since natural period cannot be calculated with that much accuracy. So, the hysteretic behavior of the soil is described using the shear. Response spectra are very useful tools of earthquake engineering for analyzing the performance of structures and equipment in earthquakes, since many behave principally as simple oscillators also known as single degree of freedom systems. Selecting and scaling earthquake ground motions for performing responsehistory analyses, nist gcr 1191715 conference paper january 2012 with 710 reads how we measure reads. We are interested in the maximum relative displacement, velocity, and total accelerations. The earthquake ground motion and response spectra design. Selection, scaling and simulation of input ground motion for. Sep 10, 20 equivalent lateral force for an earthquake is defined as a set of lateral force which will produce the same peak response as that obtained by dynamic analysis of structures. This makes the estimates of more realistic nonlinear response difficult.
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