Ground Response Analysis Research Articles

Site-specific ground motion simulation and seismic response analysis for microzonation of Nanded City, India

We study strong ground motion characteristics and ground response analysis of different sites in Nanded City, India. Synthetic strong ground motion records are obtained for two scenario earthquakes of magnitude M 5.2 and M 6.8 in southern Peninsular India using the finite fault model. Shear-wave velocity averaged over top 30 m of the soil is obtained from multichannel analysis of surface wave survey at 60 sites at depths of 20–50 m below the ground surface. The sites in different parts of the city are characterized by peak ground acceleration (PGA) at the surface and bedrock level, 5 % damped response spectra at the ground surface and the amplification factor defined as the ratio of ground motion at the surface to that at the bedrock. The area east to the lineament is characterized by low V S30 values (<200 m/s), probably associated with Godavari River basin sediments with alluvial deposits, composed of brown clay with intercalated bands of sand and gravel. A relatively high PGA value at the surface of about 0.24 g for the M 5.2 target event and hence high ground motion amplification indicative of major damage are observed at sites E-NE to the lineament in the area that are associated with the top soil column consisting of unconsolidated river basin sediments with very low V S30 values (<200 m/s). The amplification factor for the city ranges from 3 to 8 for the highest target event of magnitude M 6.8. There is a strong lateral variation in PGA values at the surface for the part of the city lying to the east of the lineament and parallel to its trend, where a relatively high amplification factor of 6–8 is found at a dominant frequency of 1.5–2.5 Hz, which can be considered as a significant zone of amplification and hence areas with high seismic hazard. The site-specific response spectra show that the peak of spectral acceleration for different sites occurs around 3 Hz. There is a large spatial variation of spectral acceleration at any given frequency for the city. For example, site nos. 9 and 50 are characterized by a peak in spectral acceleration of 0.55 and 0.9 g, respectively, at 3 Hz frequency.

Seismic analysis of laterally loaded pile under influence of vertical loading using finite element method

An efficient analytical approach using the finite element (FE) method, is proposed to calculate the bending moment and deflection response of a single pile under the combined influence of lateral and axial compressive loading during an earthquake, in both saturated and dry homogenous soil, and in a typical layered soil. Applying a pseudo-static method, seismic loads are calculated using the maximum horizontal acceleration (MHA) obtained from a seismic ground response analysis and a lateral load coefficient (a) for both liquefying and non-liquefying soils. It is observed that for a pile having l/d ratio 40 and embedded in dry dense sand, the normalized moment and displacement increase when the input motion becomes more severe, as expected. Further increasing of a from 0.1 to 0.3 leads to increase in the normalized moment and displacement from 0.033 to 0.042, and 0.009 to 0.035, respectively. The validity of the proposed FE based solution for estimating seismic response of pile is also assessed through dynamic centrifuge test results.

Investigation of the soil amplification factor in the Adapazari region

Turkey is located on the highly active Eurasian plate. A very active strike slip fault, the North Anatolian Fault Zone (NAFZ), crosses Turkey from east to west; earthquakes occurred on this fault on August 17, 1999 (Kocaeli) and November 12, 1999 (Duzce). Regional geology and subsoil conditions can significantly change the characteristics of ground motion. For this reason, determining soil amplification during an earthquake, especially for soft soils, is a very important topic for researchers. In this study, one dimensional ground response analyses were performed for selected Adapazari sites using the August 17, 1999 Kocaeli earthquake strong ground motion record with SHAKE2000 software. Soil characteristics and depth to engineering bedrock at the selected sites are different and the observed level of structural damage at these sites during the Kocaeli earthquake was also different. Calculated soil surface response spectrums at these sites were compared with the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. According to one dimensional ground response analyses, the calculated response spectra of the selected sites exceed the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. Calculations show that higher amplification ratios occur at higher periods due to soil behaviour. Results of this study indicate that local geological conditions may amplify ground motion at some periods and, due to this amplification, the calculated response spectra may exceed the recommended design spectra. Therefore, it is clear that local site conditions must be considered for earthquake-resistant engineering designs on soft alluvial soil deposits.

Site-Specific Seismic Ground Response Study for Nuclear Power Plants and Ports in Mumbai

AbstractThe importance of characterizing site-specific free-field surface motion of facilities of national and worldwide economic influence [like ports and nuclear power plants (NPPs)] is well-realized, especially in Mumbai, the most important commercial city in India, with 40% of its land reclaimed from the Arabian Sea. In the research reported in this paper, site-specific seismic hazard and one-dimensional (1D) equivalent linear ground response analysis (GRA) of important sites in Mumbai [Jawaharlal Nehru Port (JNPT), Mumbai Port, Bhabha Atomic Research Center (BARC), and Tarapur Atomic Power Station (TAPS)] are attempted. The seismicity of the research region is modeled through delineation of 31 fault sources with an earthquake database of the past 418 years (years 1594–2012). The epistemic uncertainty in hazard estimation is accounted by employing seven different ground motion prediction equations developed for worldwide shallow crustal intraplate environments. The probabilistic seismic hazard analysi...

Dynamic Characterization and Site Response Studies for an Offshore Site Based on Detailed Geotechnical Tests

The uniqueness of this paper is large amount of field test data and in addition laboratory test results on undisturbed soil samples, has been analyzed to capture the effect of local site condition and material properties of overlying soil on seismic ground motion characteristics. This study involves the seismic site characterization and ground response analysis of an offshore site in Western Yemen. From the results of field and laboratory tests, dynamic properties such as shear modulus and damping ratio for a very low to high strain levels was determined and site characterization was also carried out. Using seismic cone penetration test (SCPT) data a new correlation has been developed to predict the shear wave velocity. Synthetic ground motion was generated using Boore's stochastic modeling technique for ground response analysis and peak ground acceleration (PGA) was evaluated and presented in the paper. This paper also presents a site specific design response spectrum based on Eurocode, corresponding to 475 and 2500 year return period.

Seismic site characterization and ground response analysis for an offshore site

Seismic site characterization and ground response analysis for an offshore site

Discussion on “Implications of surface wave data measurement uncertainty on seismic ground response analysis” by Jakka et al.

The discussion deals with the effect of shear wave velocity uncertainties on 1D seismic ground response analysis. In particular, the paper refers to uncertainties deriving from the solution of the inverse problem in surface wave methods. We address some issues related to the evaluation of “equivalent” profiles from surface wave data, the inversion strategy and the numerical simulation of seismic site response. The pitfalls in the analyses point out the need for more refined studies to draw general conclusions on the subject.

Summarization on Deterministic Seismic Response Analysis of Soil Deposits

Seismic ground response analysis methods are categorised into linear, equivalent linear and non-linear methods that perform the analysis in the time or the frequency domain.The equivalent linear and the non-linear methods are two main methods of seismic response analysis for soil layers. The Equivalent linear method is the most common soil seismic response of a way to analyze in the current engineering practice. In recent years, the study on method of seismic response analysis of nonlinear soil layers is an important content in research domain of geotechnical earthquake engineering now. In this paper, these two methods’ basic principles are clarified briefly, Their developing courses and actualities are summarized. According to their basic principles and application practices, their merits and shortcomings are pointed out. The reasons why the merits and shortcomings appear are analyzed briefly.

Stochastic analysis of ground response using non-recursive algorithm

During an earthquake, the amplitudes of seismic wave may amplify significantly as it propagates through the soil layers near the ground surface. Analysis of site amplification potential is strongly influenced by the uncertainty associated to the definition of soil thickness and its properties. In this paper, the non-recursive algorithm is used in linear and nonlinear Hybrid Frequency Time Domain (HFTD) approaches for stochastic analysis of site amplification. The non-recursive algorithm causes time reduction of analysis that is the essential base of stochastic analysis. The selected soil stochastic parameters are shear wave velocity, density, damping and thickness. The results of sensitivity analysis also show that the damping ratio is the most effective parameter in PGA at ground surface. The stochastic peak ground acceleration, response spectrum and amplification factor at the ground surface are determined by the two approaches for four sites with different average shear wave velocities. Comparison of the results shows that the nonlinear HFTD approach predicts closer response to real recorded data with respect to linear HFTD.

Reply on “Implications of surface wave data measurement uncertainty on seismic ground response analysis”

We are thankful to Comina and Foti [1] (‘The Discussers’), who showed their interest in our research and raised some issues on our paper on the “Implications of surface wave data measurement uncertainty on seismic ground response analysis”. Their main concerns [1] are on the selection criteria that we adopted to select the equivalent profiles, requirement of multimodal inversion and the seismic response of those equivalent profiles. We have prepared here a detailed explanation on all the raised issues and it is shown that the variations in spectral parameters are not merely due to the so-called discrepancies raised by ‘The Discussers’.

Dynamic soil-structure interaction studies on 275m tall industrial chimney with openings

In this paper, a three dimensional soil-structure interaction (SSI) is numerically simulated using finite element method in order to analyse the foundation moments in annular raft of tall slender chimney structures incorporating the effect of openings in the structure and the effect of soil flexibility, when the structure-soil system is subjected to El Centro (1940) ground motion in time domain. The transient dynamic analysis is carried out using LS-DYNA software. The linear ground response analysis program ProShake has been adopted for obtaining the ground level excitation for different soil conditions, given the rock level excitation. The radial and tangential bending moments of annular raft foundation obtained from this SSI analysis have been compared with those obtained from conventional method according to the Indian standard code of practice, IS 11089:1984. It is observed that tangential and radial moments increase with the increase in flexibility of soil. The analysis results show that the natural frequency of chimney decreases with increase in supporting soil flexibility. Structural responses increase when the openings in the structure are also considered. The purpose of this paper is to propose the need for an accurate evaluation of the soilstructure interaction forces which govern the structural response.

Optimization of ground response analysis using wavelet-based transfer function technique

One of the most advanced classes of techniques for ground response analysis is based on the use of Transfer Functions. They represent the ratio of Fourier spectrum of amplitude motion at the free surface to the corresponding spectrum of the bedrock motion and they are applied in frequency domain usually by FFT method. However, Fourier spectrum only shows the dominant frequency in each time step and is unable to represent all frequency contents in every time step and this drawback leads to inaccurate results. In this research, this process is optimized by decomposing the input motion into different frequency sub-bands using Wavelet Multi-level Decomposition. Each component is then processed with transfer Function relating to the corresponding component frequency. Taking inverse FFT from all components, the ground motion can be recovered by summing up the results. The nonlinear behavior is approximated using an iterative procedure with nonlinear soil properties. The results of this procedure show better accuracy with respect to field observations than does the Conventional method. The proposed method can also be applied to other engineering disciplines with similar procedure.

Reply to comment on “Effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis”

Pettiti et al. (2014) commented on our study on the effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis. They showed in their analyses that non-uniqueness has negligible effect on Fourier amplification and response spectra, which is in disagreement to our earlier observations (Roy et al. in Nat Hazards 68:1141–1153, 2013). The apparent discrepancies are due to the differences in the definition of problem used in the ground response analyses. Pettiti et al. (2014) extended our original profiles to a depth of 60 m and then assumed the presence of high-impedance layer of velocity 1,240 m/s, irrespective of the half-space velocity obtained from the surface wave inversion. This resulted in similar kind of responses of all the profiles in spite of the differences in their shear wave velocity and thickness variations. Otherwise, the observations made by Roy et al. (Nat Hazards 68:1141–1153, 2013) confirm findings of previous studies on the same topic (e.g., Boaga et al. in J Geophys Eng 8:162–174, 2011).

Comment on “Effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis” by Roy et al.

We discuss a paper dealing with the effect of surface wave solution non-uniqueness on 1D seismic site response analysis. We address some issues on the numerical simulations of seismic site response, specifically the correct definition of input motion. If a consistent framework is adopted, the solution non-uniqueness has negligible effect in amplification and acceleration response spectra for the presented dataset, confirming previous studies on the same topic.

Verification of LSSRLI-1 Applicability on Soft Sites Using Exact Solution

LSSRLI-1 is an equivalent linear program which is used for seismic ground response analysis. Since the LSSRLI-1 was proposed by Xiaojun Li in 1989, it played very important role in seismic safety evaluation, solved the inputting problem for dynamic response analysis of structure. Some deficiency was found in the practice, especially when the layered site is soft. Linear exact solution is deduced in the frequency domain.based on the engineering wave theory. A program is compiled in the MATLAB environment, which is used to compare with the LSSRLI-1 results, including the ground response spectrum and the soil strain distribution.

Seismic response analysis of layered soils considering effect of surcharge mass using HFTD approach. Part II: Nonlinear HFTD and numerical examples

Studies of earthquakes over the last 50 years and the examination of dynamic soil behavior reveal that soil behavior is highly nonlinear and hysteretic even at small strains. Nonlinear behavior of soils during a seismic event has a predominant role in current site response analysis approaches. Common approaches to ground response analysis include linear, equivalent linear and nonlinear methods. These methods of ground response analysis may also be categorized into time domain and frequency domain concepts. Simplicity in developing analytical relations and accuracy in considering soils' dynamic properties dependency to loading frequency are benefits of frequency domain analysis. On the other hand, nonlinear methods are complicated and time consuming mainly because of their step by step integrations in time intervals. In part Ι of this paper, governing equations for seismic response analysis of surcharged and layered soils were developed using fundamental of wave propagation theory based on transfer function and boundary conditions. In this part, nonlinear seismic ground response is analyzed using extended HFTD method. The extended HFTD method benefits Newton-Raphson procedure which applies regular iterations and follows soils' fundamental stress-strain curve until convergence is achieved. The nonlinear HFTD approach developed here are applied to some examples presented in this part of the paper. Case studies are carried in which effects of some influencing parameters on the response are investigated. Results show that the current approach is sufficiently accurate, efficient, and fast converging. Discussions on the results obtained are presented throughout this part of the paper.

Seismic response analysis of layered soils considering effect of surcharge mass using HFTD approach. Part Ι: basic formulation and linear HFTD

Seismic ground response analysis is one of the most important issues in geotechnical earthquake engineering. Conventional seismic site response and free field analysis of layered soils does not consider the effect of surcharge mass which may be present on the top layer. Surcharge mass may develop extra inertial force to the soil and, hence, significantly affect on the results of seismic ground response analysis. Methods of analysis of ground response may also be categorized into time domain and frequency domain concepts. Simplicity in developing analytical relations and accuracy in considering soil dynamic properties dependency to loading frequency are benefits of frequency domain analysis. In this part of the paper, seismic ground response is analyzed using transfer function method for soil layers considering surcharge mass on the top layer. Equation of motion, wave equation, is solved using amended boundary conditions which effectively take the impact of surcharge mass into account. A computer program is developed by MATLAB software based on the solution method developed for wave equation. Layered soils subjected to earthquake loading were numerically studied and solved especially by the computer program developed in this research. Results obtained were compared with those given by DEEP SOIL computer program. Such comparison showed the accuracy of the program developed in this study. Also in this part, the effects of geometrical and mechanical properties of soil layers and especially the impact of surcharge mass on transfer function are investigated using the current approach and the program developed. The efficiency and accuracy of the method developed here is shown through some worked examples and through comparison of the results obtained here with those given by other approaches. Discussions on the results obtained are presented throughout in this part.

One-dimensional wave equation analyses for pile responses subjected to seismic horizontal ground motions

This paper presents a numerical one-dimensional wave equation analysis technique for piles and pile groups subjected to seismic horizontal ground motions in liquefiable zones. The so-called Earthquake Wave Equation Analysis for Piles (EQWEAP) procedure is introduced for piles subjected to horizontal earthquake excitations. Disregarding the effects of kinematic soil–pile interaction, the seismic responses of piles can be obtained by approximating the free-field ground response analysis, the ultimate earth pressure model, and the ground displacement profiles. The nonlinearities of the concrete piles were modeled using the approximate tri-linear moment–curvature relationships. A case study and application concerns were presented. Although the analysis is in one dimension, it is found to be effective and able to provide a rapid estimation in foundation design when seismic pile behaviors are of interest. The advantages of this analysis are the time efficiency of the seismic design of pile foundations and the relative simplicity of the analysis. In addition, it suggests alternative modeling for the dynamic analysis adopting the commonly known static models and/or methods.

Study on the Ground Response Analysis for Stiff Soil

In order to test the applicable of the seismic response analysis procedures SHAKE2000 and LSSRLI-1 for class ІІ site, 17 stations and 35 underground strong motion records of KiK-net are selected from Class ІІ site. 210 working conditions are used to verify the applicability of the two soil seismic response analysis programs at Class ІІ site. These two programs are used to calculate the selected working conditions, giving the peak acceleration of the ground, the shear strain and the ground acceleration response spectra. By analyzing the results of the two programs and the measured results to assess the degree of difference between the two methods and which program is closer to the real situation. Studies have shown that in class ІІ site, in most cases, the results of SHAKE2000 and LSSRLI-1 differ little. While comparing with the actual records, SHAKE2000 is closer to the strong motion records.

Three-Dimensional Nonlinear Seismic Ground Response Analysis of Local Site Effects for Estimating Seismic Behavior of Buried Pipelines

Damage to buried pipelines caused by local amplification of seismic ground motion in highly nonuniform grounds is not yet fully understood. The development of methods to evaluate the amplification of ground motion in complex ground structures is thus desirable. Here, we report large-scale nonlinear seismic ground response analysis using a 3D nonlinear finite element method (FEM) and attempt to reproduce observed seismic ground motion. We also discuss the strain amplification processes and their effects on buried pipelines in detail. The findings are expected to aid in improving the seismic resistance of buried pipelines.