Several combinations of seismic coefficient and factor of safety as reported in works of the late professor h. Hence, it may be appropriate to scale up the seismic forces to obtain the same base shear as in case of seismic coefficient method. The seismic base shear force is a function of the seismic response coefficient and the effective seismic weight. E r e i i0 the square root of the above relationship is called reflection coefficient, r. Read seismic analysis and design of retaining walls. Seismic analysis and design of retaining walls, buried structures, slopes, and embankments explores analytical and design methods for the seismic design of retaining. Ye yincan et al, in marine geohazards in china, 2017. The wave phenomena occurring at a boundary between two layers are discussed, such as snells. The seismic stability of embankment dams may be evaluated by a relatively simple method, originally proposed by n. Trbs national cooperative highway research program nchrp report 611. Seismic reflection is the most widely used geophysical technique. Seismic coefficient method and response spectra method. Extended mononobeokabe method for seismic design of.
Instead of a radio signal, a seismic signal is sent out and whatever comes back is recorded. The results of this study are discussed in greater detail later. Seismic load was defined by lateral force method, modal response spectrum, nonlinear timehistory analysis and pushover analysis. Introduction to seismic method linkedin slideshare. Seismic analysis is a subset of structural analysis and is the calculation of the response of a building or nonbuilding structure to earthquakes. Chapter 7 retaining walls seismic analysis and design of. The c2 coefficient of fema 356 implies that inelastic displacement should increase for stiffness degrading. The earliest applications of the method primarily concerned the determination of the depth to bedrock beneath a soil cover. The other 4 methods of analysis are applicable to the sdc3 to sdc5. Modal response spectrum method means a method of dynamic analysis in which a given earthquake design spectrum is applied to a mathematical model of the structure and the response of several modes are. A new seismic design method called the response and limit strength calculation rlsc, which incorporates the effect of the soilstructure interaction, was. The methods include seismic coefficient method as recommended by is code and modal analysis using response spectrum method of is code in which the. 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. Na near source factor used in determination of ca in seismic.
R response modification factor for lateral force resisting system, shown in table a4. The seismic hazard maps are revised and have 7% probability of exceedance in 75 years. Horizontal andor vertical forces, which are calculated as products of the seismic coefficients kh, kv and the weight of the structures are applied to the structures as shown in figure 1. Reflection seismology or seismic reflection is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the earths subsurface from reflected seismic waves. Seismic attribute analysis can extract information from seismic data that is, otherwise, hidden in the data and have been used to identify prospects, ascertain depositional environments. Seismic reflection methods environmental geophysics us epa. Comparative study of static and dynamic seismic analysis. The design seismic coefficient and acceptable minimum factor of safety are often selected based on precedence. Horizontal seismic coefficient reduction slope stability.
Ambraseys and sarma 1967 used a similar approach, also using the shear slice method, to develop average seismic coefficients for earth dams. Dynamic analysis of multistory building using response. Instructional material complementing fema 451, design examples seismic load analysis 9 2 topic objectives selection of method of analysis description of analysis techniques modeling considerations system regularity load combinations other considerations drift computation and acceptance criteria pdelta effects. Pdf seismic coefficient method the seismic force to be resisted. The coefficient, and hence the expected ground accelerations are dependent on the seismic zone and soil profile type. Horizontal andor vertical forces, which are calculated. Factors that affect a structures seismic risk include. Pdf effect of vertical seismic coefficient in slope. Seismic attributes are the components of the seismic data, which are obtained by measurement, computation, and other methods from the seismic data. This method is based on idealization of the potential slide mass as a sliding block on an inclined plane which undergoes a history of. Linear seismic analysis is done for the building by static method seismic coefficient method and dynamic method response spectrum method using staadpro as per the is1893 2002part1. 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. Comparative study of seismic response for seismic coefficient and.
Key words continue on reveree aide if necessary mnd identify by block nuwnber. The static analysis procedure defined by the building code 1 will generally give the lowest seismic load and resultant seismic inertia stresses in the pipe and loads on the pipe supports if the f. Commonoffset seismic reflection method a technique for obtaining onefold reflection data is called the commonoffset method or commonoffset gather cog. It consists of applying a constant acceleration to the distributed weight of the system in each of the three directions. Explanatory examples on indian seismic code is 1893 iit kanpur. The seismic coefficients, cv and ca are measures of the expected ground acceleration at the site. The r factor, or response modification coefficient, results from simplifying the seismic design process so that linear elastic, static analysis can be used for most building designs. L 5 seismic method courtesy of exxonmobil seismic migration unmigrated image. Further, it is now possible to make an approximate but rational connection between the seismic coefficient that is used in a pseudostatic stability analysis and the expected amplitudes and duration of ground motion by working backwards through the method for computing displacements of slopes that was originally suggested by newmark 1965. Seismic design of buildings worked examples worked examples presented at the workshop ec 8. Seismic method including single channel seismic and multichannel seismic method is one of the most effective methods for the identification and prediction of submarine gas hydrate. Hence, besides the need for estimating k y via pseudostatic analyses, some of these displacementbased methods also include procedures for estimating the peak seismic coefficient, k hmax.
Measurement of seismicwave travel time is one of the most common geophysical method. Seismic load determination for residential decks introduction building. Cv velocitydependent seismic coefficient, shown in table a7. Negative values of the reflection coefficient indicate a phase change of 180 in the reflected wave. As a consequent, the horizontal seismic coefficient for design ranges from 0. F ah w where f horizontal seismic force to be resisted. Seismic energy sources, whether at the earths surface or in shallow boreholes, produce wave types known as. The static seismic analysis method is common in the seismic design of piping systems in all other industries fossil power, chemical, aboveground pipelines that follow the asce7 static seismic design method. Ca accelerationdependent seismic coefficient, shown in table a6. Application of modern seismic methods for geotechnical. The procedures outlined below are recommended for determination of seismic coefficient. It plays a key role in the discovery of submarine gas hydrate. Introduction and general considerations seismic reflection is the most widely used geophysical.
One is a stability method for repetitive static loads based on the seismic coefficient concept method a and the other is a stability method which considers the acceleration time history of the. Seismic coefficient method the seismic force to be resisted by bridge component shall be competed as follows. Bolton seed and his coworkers are listed in table 1. The method requires a controlled seismic source of energy, such as dynamite or tovex blast, a specialized air gun or a seismic vibrator, commonly known by the trademark. Depending on the location of the building site, identify the seismic zone and assign zone factor z use table 2 along with seismic zones map or annex of is1893 2002 step2. The method requires a controlled seismic source of energy, such as dynamite or tovex blast, a specialized air gun or a seismic vibrator, commonly known by the trademark name vibroseis. It can be used to derive important details about the geometry of structures and their physical properties. In the earth, seismic waves can propagate as longitudinal p or as shear s waves. The design seismic coefficient of the embedding foundation of. Basic principles of the seismic method tu delft ocw. Instructional material complementing fema 451, design examples seismic load analysis 9 17 1a, 1b stiffness soft story irregularity vertical structural irregularities irregularity 1a exists if stiffness of any story is less than 70% of the stiffness of the story above or less than 80% of the average stiffness of the three stories above. Mar 16, 2019 one is a stability method for repetitive static loads based on the seismic coefficient concept method a and the other is a stability method which considers the acceleration time history of the. Newmark, in cases where there is no threat of liquefaction or severe loss of shear strength under seismic shaking. Horizontal seismic coefficient reduction howardoark geotechnical 7 mar 09 00.
Selection of seismic coefficients for use in pseudostatic. Convolution use the sonic and density logs to compute an impedance log calculate the reflection coefficients convolve our pulse with the seismic reflectivity sum the individual wavelets to get the synthetic seismic trace seismic ties compare well data to seismic data. On the contrary, nowadays, these displacements play the lead role in modern performancebased design of such structures, or method b above. Major fields of application of seismic reflection include. A reliable design approach that you can use is the approach of bray et al. Basic principles of the seismic method in this chapter we introduce the basic notion of seismic waves. For free space, the onedimensional wave equation is derived. The timehistory analysis is represented by accelerograms. Seismic coefficient method considers all horizontal as well as vertical forces for calculation and analysis. Asce 7 determines the seismic base shear in a given direction and the lateral seismic design forces are then distributed to each floor according to an inverted triangular distribution. Simplified design methods seismic slope stability analysis. This method is based on idealization of the potential slide mass as a sliding block on an inclined plane which. This corresponds to a return period of approximately years.
Calculation of design seismic force by static analysis method. Compute the seismic weight of the building w as per clause 7. A seismic signal would travel to the seismic sensors. Mononobeokabe mo method is still employed as the first option to estimate lateral earth pressures during earthquakes by geotechnical engineers. V rb r a r h r w where, a rh r design seismic coefficient at. The importance coefficient takes a value between 0. Pdf seismic coefficient method the seismic force to be. A seismic signal is produced by hammering a piece of wood placed on ground with a hammer. Reflection seismology is similar to sonar and echolocation. The selection of appropriate seismic coefficient relies on both local code requirements and engineering judgement. Seismic coefficient method the seismic coefficient method is one of the static procedures for earthquake resistant design of structures.
Earthquake resistant design encyclopedia of life support. Seismic survey is the geophysical method, which is most closely related to rock and soil mass properties, since seismic wave velocity varies with the main mechanical properties, such as poissons ratios and others modules. Seismic exploration is divided into refraction and reflection surveys, depending on whether the predominant portion of the seismic waves travel is horizontal or vertical. The intensity of ground shaking and other earthquake effects the structure. Seismic analysis and design of retaining walls, buried structures, slopes, and embankments explores analytical and design methods for the seismic design of retaining walls, buried structures, slopes, and embankments.
It states that the angle of incidence is equal to the angle of reflection. T fundamental period of the structure tl longperiod transition period, given in asce 710 figure 22, which is the transition period between the velocity and. Seismic waves are pulses of strain energy that propagate in solids and fluids. In case of i0, the ratio of the reflected energy of pwave, e r, to the incident energy, e i, is given by. Considering some simple assumptions and using a closed form method, mo solves the equations of equilibrium and suggests seismic active and passive lateral earth pressures.
Therefore, the results are true in its assumption range only, and in many. The regional seismic coefficient takes a value between 0. The seismic coefficient method is one of the static procedures for earthquake resistant design of structures. They may be found in tables 16q and tables 16r of ubc code see image below respectively. Summary and application example fema 440 improvement of nonlinear static seismic analysis procedures 103 incycle degradation produces effects similar to p. This law is utilized in the seismic reflection method. Seismic coefficient method is a static method to evaluate and design an earthquake resistive structure.
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