One-Dimensional Effective Stress Non-Masing Nonlinear Ground Response Analysis of IIT Guwahati

2017 ◽  
Vol 8 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Devdeep Basu ◽  
Arindam Dey ◽  
Shiv Shankar Kumar
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Response Analysis ◽  
Eastern Region ◽  
Seismic Zone ◽  
Ground Response ◽  
Accurate Identification ◽  
Ground Response Analysis ◽  
Soil Medium ◽  
One Dimensional

Ground response analysis (GRA) helps to assess the influence of the soil medium on the propagating shear waves and indicates about the characteristics of the waves reaching the ground surface from the bedrock level. Such a study becomes imperative for the urbanized alluvial banks of North-Eastern region of India, which is located in the highest seismic zone of the country. Conventionally, GRA is carried out based equivalent linear approach, which being a simplistic approach is unable to capture the nonlinear characteristics of saturated silty sands subjected to seismic shaking. This article presents the outcome of seismic one-dimensional nonlinear GRA of IIT Guwahati (located on a varying geology in the saturated alluvial banks of River Brahmaputra) considering pore-water pressure dissipation characteristics and non-Masing unload-reload criteria. Various ground response parameters obtained from the study helps in the accurate identification of the earthquake intensity based site amplification of the region expressed through a 2-D mapping.

scholarly journals Site Response Analysis of S2 Soil Deposits Focusing on the Effects of Liquefaction and Pore-Pressure Dissipation on the Ground Surface Response Spectrum

2021 ◽  
Author(s):  
Maria Anthi ◽  
NIKOS GEROLYMOS
Keyword(s):  
Wave Propagation ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Response Spectrum ◽  
Water Pressure ◽  
Ground Surface ◽  
Response Analysis ◽  
Soil Profiles ◽  
Ground Response ◽  
Ground Response Analysis

Abstract A numerical algorithm for executing non-linear ground response analysis of layered sites is developed, capable of reproducing liquefaction phenomena, considering the simultaneous dissipation of the excess pore water pressure through soil grains. Τhe wave propagation algorithm is based on the plasticity constitutive model for sand Ta-Ger expressed in a one dimensional p-q space form, which exhibits remarkable versatility in representing complex patterns of sand cyclic behavior, such as stiffness decay and decrease in strength due to build-up of pore-water pressure. Its calibration is based on shear modulus reduction and damping curves for drained loading conditions and liquefaction resistance curves for undrained conditions. A detailed presentation of the numerical model formulation is provided, indicating the numerical approach of the wave propagation and consolidation differential equations. The recorded seismic ground response of the Port Island array from Kobe 1995 earthquake is used as a benchmark for testing the validity of model predictions. The model is finally applied to estimate the elastic response spectra at the surface of soil profiles with liquefiable layers (ground type S2) as per EC8:2004. The investigation study involves the ground response analysis of diverse soil profiles, all including a liquefiable zone, excited with a suite of earthquake motions at their base. The acceleration time histories were extracted from the PEER Ground Motion Database having characteristics compatible with the NGA-estimated response spectrum at the bedrock and with key seismological parameters such as the earthquake magnitude Mw and horizontal distance from the fault RJB. Two different methods are applied regarding the selection of base excitations: Amplitude scaled records (to match a target response spectrum) and spectral matched records. From the results an idealized response spectrum is deduced in terms of the design spectrum parameters S, η, ΤΒ and TC. It is shown that the idealized ground surface response spectrum is marginally sensitive to method of base excitation selection.

scholarly journals Modelling Propagation of Stress Waves through Soil Medium for Ground Response Analysis

Engineering ◽  
2013 ◽  
Vol 05 (07) ◽  
pp. 611-621 ◽  
Author(s):  
Palaniyandi Kamatchi ◽  
Gunturi Venkata Ramana ◽  
Ashok Kumar Nagpal ◽  
Nagesh R. Iyer
Keyword(s):  
Stress Waves ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Soil Medium

Integration of Viscoplastic Effects in a One-Dimensional Constitutive Model for Ground Response Analysis

2020 ◽  
Author(s):  
Samuel Yniesta ◽  
Mallak Janati-Idrissi
Keyword(s):  
Strain Rate ◽  
Stress Component ◽  
Response Analysis ◽  
Shear Strain Rate ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Strain Rate Effects ◽  
One Dimensional ◽  
Rate Effects ◽  
Modulus Reduction

During an earthquake, strain-rate effects affect both the stiffness and damping behaviour of soils, yet existing constitutive models for ground response analysis are typically formulated within a rate-independent framework. In this paper, a one-dimensional viscoplastic stress-strain model is presented to introduce strain rate effects in ground response analysis. Its constitutive equations are based on a model that uses a cubic spline fit of the modulus reduction curve and a coordinate transformation technique to match any input modulus reduction and damping curve. A viscous stress component is added to model the effect of strain rate on the mechanical behaviour of soils using a single input parameter. The model is able to reproduce the linear increase in shear strength with the logarithm of shear strain rate, and allows to introduce viscous effects in 1D ground response analysis with control over damping and modulus reduction behaviour. The model is implemented in a software for ground response analysis and used to predict the results of a centrifuge test modeling one-dimensional wave propagation. The results show that the model predicts accurately the amplification and attenuation of shear waves, in a context where strain rates impact significantly the response of the model.

3D Ground Response Analysis of Simplified Kutch Basin by Spectral Element Method

2019 ◽  
Vol 14 (01) ◽  
pp. 2050003
Author(s):  
R. Vijaya ◽  
A. Boominathan ◽  
Ilario Mazzieri
Keyword(s):  
Three Dimensional ◽  
Spectral Element ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Soil Medium ◽  
Kutch Basin ◽  
Rectangular Basin ◽  
Basin Edge ◽  
Multiple Edges

The damage pattern observed during the 1819 Kutch earthquake and 2001 Bhuj earthquake of magnitude [Formula: see text] in India implied the significance of the effect of Kutch basin on seismic ground motion. In the present study, the Kutch rift basin is modeled as a simplified rectangular basin of size 150[Formula: see text]km [Formula: see text] 90[Formula: see text]km [Formula: see text] 1.5[Formula: see text]km. The shear wave velocity of the Kutch region varies from 300[Formula: see text]m/s at the surface to 800[Formula: see text]m/s at the depth of 60[Formula: see text]m. Three-dimensional ground response analysis is carried out for the simplified Kutch basin subjected to ricker wave, using the spectral element code SPEED. The soil medium is modeled through visco-elastic soil model, where the damping is represented by Quality factor. It is found out from the numerical analysis that maximum amplification of 3.6 times occurs at the corner of the basin where interference of waves reflected from multiple edges happen. The long period structures with fundamental period in the range of 1.5–2.5[Formula: see text]s located near the basin edge are found to be significantly affected by the basin effect.

scholarly journals One Dimensional Site Response Analysis of Liquefaction Potential along Coastal Area of Bengkulu City, Indonesia

2018 ◽  
Vol 20 (2) ◽  
pp. 57
Author(s):  
Lindung Zalbuin Mase
Keyword(s):  
Coastal Area ◽  
Pore Water Pressure ◽  
Site Response ◽  
Water Pressure ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Liquefaction Potential ◽  
Excess Pore Water Pressure ◽  
One Dimensional ◽  
Excess Pore

This paper presents one dimensional non-linear site response analysis of liquefaction potential caused by the 2000 and the 2007 earthquakes in coastal area of Bengkulu City, Bengkulu, Indonesia. Site investigations, including Standard Penetration Test (SPT) and shear wave velocity (VS) measurement, were conducted in three locations along the coastal area of Bengkulu City. Further, the site investigation data were used in simulation of one-dimensional non-linear site response analysis by applying the synthetic ground motions at bedrock. The results show that liquefaction could happen at 0 to 1.5 m deep. This was indicated by the excess pore water pressure ratio (ru) which exceeded one. At depth between 1.5 m and 20 m, the excess pore water pressure almost reached the initial effective stress decreasing the effective confinement pressure close to zero. The results also indicated that liquefaction is possible to occur in this depth range if a stronger earthquake occurs.

scholarly journals Preliminary Amplification Studies of Some Sites using Different Earthquake Motions

2020 ◽  
Vol 6 (10) ◽  
pp. 1906-1921
Author(s):  
Manish Bhutani ◽  
Sanjeev Naval
Keyword(s):  
Ground Motions ◽  
Ground Surface ◽  
Earthquake Hazard ◽  
Response Analysis ◽  
Seismic Zone ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Earthquake Resistant Design ◽  
Earthquake Resistant

Stability of infrastructure during earthquakes demands ground response analysis to be carried out for a particular region as the ground surface may suffer from amplified Peak Ground Acceleration (PGA) as compared to bedrock PGA causing instability. Many studies have been carried out the world over using different techniques but very few studies have been carried out for the northern part of India, Punjab situated at latitude of 31.326° N and longitude of 75.576° E, which is highly seismic and lies in seismic zone IV as per IS:1893-2016. In this paper 1-D equivalent non-linear ground response analysis has been conducted for sixteen sites of Jalandhar region, Punjab (India) by using five earthquake motions. Input ground motions are selected from the worldwide-recorded database based on the seismicity of the region. Based on the average SPT-N values, all the sites have been classified as per the guidelines of National Earthquake Hazard Reduction program (NEHRP). Shear modulus (G) was calculated using correlation between G and SPT–N Value. The ground surface PGA varies from 0.128 to 0.292 g for the sites of Jalandhar region with Amplification Factor values varying from 1.08 to 2.01. Hence the present study will be useful to the structural designers as an input towards suitable earthquake resistant design of structures for similar sites.

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