Determination of standard response spectra and effective peak. Introduction there are a large number of concrete gravity dams worldwide. Earthquake shaking generally occurs in all three directions. The peak ground acceleration pga at surface level was calculated for the entire south india for four different site classes. The 1997 nehrp recommended provisions for seismic regulations for new buildings 1997 nehrp provisions introduced seismic design procedure that is based on the explicit use of spectral response acceleration rather than the traditional peak ground acceleration andor peak ground velocity or zone factors. Rigorous analyses calculate displacement based on userspecified ground motions, while simplified analyses use empirical regression relationships to predict displacement based on ground motion parameters e. Response spectrum analysis software di simulazione comsol. Estimation of peak ground acceleration and spectral. In this case, we determine the spectral response of the ground motion for zgh station, and study his influence.
Design earthquake response spectrum affected by shallow. Traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration pga. How to calculate spectral acceleration design acceleration. Select the drift correction option and click ok to. May, 2011 use of single response spectrum shape for all site conditions is not appropriate 25. The site may be considered in one, two and three dimensions in order to analyze the ground response. The peak acceleration is the largest increase in velocity recorded by a particular station during an earthquake.
A new opensource software for strong ground motion data processing. Peak ground acceleration is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. It is the acceration ratio of the constant acceration branch to the peak ground acceleration. Determination of standard response spectra and effective. Each linear elastic response spectrum is associated with a. This can be measured at or specified for different oscillation frequencies and with different degrees of damping, although 5%. Site response analyses were performed to investigate the earthquake response of structures with shallow soil depth conditions in korea. The result is the artificial acceleration time history for a site in sleman district, yogyakarta, indonesia. Oct 29, 2018 the standard response spectra for type of soil considered is applied to building for the analysis in etabs 20 software. Factored deterministic acceleration value peak ground acceleration pga mce g peak ground acceleration fpga site amplification factor at pga pgam site modified peak ground acceleration ssrt probabilistic risktargeted ground motion 0. Peak ground acceleration pga is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. How to scale ground motion to desired pga such as 0. A response spectrum is used to provide the most descriptive representation of.
The shock response spectrum is the peak absolute acceleration response of each sdof system to the time history base input. The response spectra resulting from numerical analyses were compared with the design response spectra drs. Thus, in this case, effective peak acceleration in this period range is nearly numerically equal to actual peak acceleration. The seismic static coefficients are usually obtained from the seismic zone, which corresponds to a level of seismic acceleration. Ground motion history analysis, linear response spectrum analysis and fourier amplitude analysis and a module that. A free tool to generate curves for aashto lrfd bridge design specifications 2007 and aashto guide specification for lrfd seismic bridge design 2009 for locations in the continental united states. Feb 21, 2017 this lecture covers some of the basics about seismic building code and how ground motions are developed using the general procedure. The probabilistic maps depict peak horizontal ground acceleration and spectral response at 0. However, it is to be noted that there is high level of conservatism incorporated into prediction of liquefaction triggering, peak ground acceleration pga, earthquake magnitude m, and residual shear strength of liquefied soil. Select the acceleration option in the data type dropdown menu. The acceleration response spectrum of a ground motion is a relationship between the natural period of vibration of a sdof system and the maximum absolute acceleration that it experiences under the ground motion. The peak acceleration from the response spectrum is applied as a lateral force distributed along the pipe, and bending stresses and support reactions are calculated.
How to calculate soil spectral acceleration in specific damping. Peak acceleration an overview sciencedirect topics. The first data reported from an earthquake record is generally the peak ground acceleration pga which expresses the tip of the maximum spike of the acceleration ground motion figure 1. The spectral response accelerations are obtained from spectral response acceleration maps. Peak ground acceleration structural engineering general. Constant ductility inelastic acceleration response spectrum. The nonlinear response of the soil within the flexible sliding blocks can be taken account through the. Sep 26, 2018 the linear elastic response spectrum leresp for a response quantity acceleration, velocity, displacement, etc. The analysis parameters included the properties of soft soil deposits at 487 sites, input earthquake accelerations, and peak ground acceleration levels. First of all, the simplest way to scale earthquake acceleration is to divide every data of acceleration record by, for example 0. The earthquake ground motion and response spectra design for. An accelerogram can be integrated to obtain the time variations of the ground velocity and ground displacement. The standard response spectra for type of soil considered is applied to building for the analysis in etabs 20 software. The program also scales the suite such that the standard deviation fits the target standard deviation.
Safety of dam during and after an earthquake is an area of current concern in present work. Simplified design methods seismic slope stability analysis. Develop aashto acceleration response spectrum for rock type b spectrum for rock type b. Seismic hazard curves and uniform hazard response spectra for. Use of single response spectrum shape for all site conditions is not appropriate 25. The conception of effective peak acceleration epa related with response spectrum is more reasonable than the peak ground acceleration pga, as the latter lacks predictability in the nearfield, which is more important for high dams and its pulse peak with high frequencies is of little engineering significance to high dams. It well known that the deterministic dsha and probabilistic psha seismic hazard maps provide prediction of peak ground acceleration and ground motions for a specific site. Software for generation of spectrum compatible time history.
For peak ground acceleration, this dependence of amplification on ground motion level is illustrated by the relationship for soft soil developed by idriss 1991a shown in figure 38. Design response spectra are often provided in terms of the period, rather than the frequency. Procedures for estimating earthquake ground motions. Pga, where pga is the peak ground acceleration obtained from the ground motion mapsfrom the ground motion maps. Seismic response spectrum gui file exchange matlab central. Therefore, pga is often split into the horizontal and vertical components. An introduction to probabilistic seismic hazard analysis. The earthquake ground motion and response spectra design.
Response spectrum analysis software di simulazione. Peak ground acceleration pga is a measure of e arthquake acceleration on the ground. Peak ground acceleration jlnj structural 15 nov 16. Ceen 545 lecture 12 design ground motions from seismic. These lnsa values are normally distributed, which means that the nonlogarithmic sa values are lognormally distributed. A velocity response spectrum is a graph of velocity versus period.
Pga records the acceleration rate of change of speed of these movements, while peak ground velocity is the greatest speed rate of movement reached by the ground, and peak displacement is the distance moved. The resulting plot can then be used to pick off the response of any linear system, given its natural frequency of oscillation. Earthquake energy is dispersed in waves from the hypocentre, causing ground movement omnidirectionally but typically modelled horizontally in two directions and vertically. Seismic response, ansys, gravity dam, afghanistan 1. Fannie mae peak ground acceleration home client types fannie mae peak ground acceleration the 2014 update of the fannie mae multifamily selling and servicing guide for property needs assessments pna has been revised to include a determination of site seismic hazard using the 475year 10% in 50year peak ground acceleration. Openseismomatlab can calculate the following strong motion data processing output. This script aims to offer the shock response spectrum of an acceleration time history of an earthquake which is known. The estimation of peak groundmotion parameters from. Uniform hazard response spectrum uhrs at rock level for 5% damping and 10% and 2% probability of exceedance in 50years were also developed for all the grid points. The standard response spectrum for medium soil type and that can be given. Response spectrum curve generator for bridge design. However, since the response acceleration spectrum is asymptotic to peak acceleration for very short periods, some people have assumed that effective peak acceleration is 2. The linear elastic response spectrum leresp for a response quantity acceleration, velocity, displacement, etc. The acceleration response spectrum of a ground motion is a relationship between the natural period of vibration of a sdof system and the maximum absolute acceleration that it.
For 3d analysis two cities of afghanistan pga peak ground acceleration were selected 1 kabul by pga 48 %g 2 herat by pga 28% g result of static structural analysis 1 maximum equivalent stress a case 1. Pga is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a particular earthquake. Response spectrum analysis is a method for estimating structural responses to short, nondeterministic, transient dynamic events. What is spectral acceleration in structural analysis. Since one is the inverse of the other, the two graphs are just mirrored when plotting on a logarithmic scale. When the ground is shaking during an earthquake, it also experiences acceleration. Standard acceleration response spectra and effective peak ground accelerations are needed in the early stages of project development since they can be used as a starting point for preliminary seismic designs and evaluations and determining the need for more refined analyses. Peak ground acceleration pga is equal to the maximum ground acceleration that occurred. Response spectrum analysis by using etabs software youtube.
Apr 09, 2016 a velocity response spectrum is a graph of velocity versus period. The peak ground acceleration, duration, and frequency content of earthquake can be obtained from an accelerograms. Characteristics of spectral responses for a ground motion from. This section also explains the basis for the new peak ground acceleration pga maps in the 2009. The design response spectrum is the actual input to the response spectrum analysis. The dimensions are peak response g versus natural frequency hz. Statistically derived response spectra elastic design response spectra can be predicted in the same statistical manner as ground motion parameters such as peak ground acceleration or velocity. Spectral acceleration sa is a unit measured in g the acceleration due to earths gravity, equivalent to gforce that describes the maximum acceleration in an earthquake on an object specifically a damped, harmonic oscillator moving in one physical dimension. The map is based on the most recent usgs models for the conterminous u. Geotechnical data and soil column model for site located in the southern sharon and lod valley area zone 3, yehud area table 7. Spectral acceleration describes the maximum acceleration in an e arthquake on an object the spectral acceleration at different frequencies may be plotted to form a response spectrum. Therefore, it enables the user to calculate the peak ground acceleration pga and pseudo velocity.
Seismic response of concrete gravity dam in afghanistan. Construction of design response spectrum the chilean way. Seismic hazard curves and uniform hazard response spectra. The typical earthquake ground motion response spectrum represents an envelope of the peak responses of many singledegreeoffreedom sdof systems with different periods. The acceleration time history and response spectra design for certain site can be acquired using the seismic hazard analysis, amplification of ground motion quantity, and spectral matching in time domain. Fannie mae peak ground acceleration the 2014 update of the fannie mae multifamily selling and servicing guide for property needs assessments pna has been revised to include a determination of site seismic hazard using the 475year 10% in 50year peak ground acceleration. Earthquake hazard map showing peak ground accelerations having a 2 percent probability of being exceeded in 50 years, for a firm rock site. A plot of the peak value of a response quantity eg. The relationships between response spectrum peaks and peak ground motion parameters may also be useful in the selection of real time histories compatible with a smoothed design spectrum. Chapter 3 development of sitespecific response spectra. But that velocity is the maximum velocity that the structureor system will reach for each period.
Response spectra for the two horizontal components of the ground motion, the geometric mean of the response spectra, and the predicted mean for the given magnitude and distance using the prediction of abrahamson and silva. I would say that this is the ordinate on a response spectrum plot which gives the acceleration of a onedegreeoffreedom system with a certain natural period subjected to the ground motion represented by that response spectrum. Ground motion predictions models, such as the one used to make figure 1. It also plots the solution and stores them in a file allowing certain changes such as the acceleration unit. A response spectrum is a plot of the peak or steadystate response displacement, velocity or acceleration of a series of oscillators of varying natural frequency, that are forced into motion by the same base vibration or shock.
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