Six-degree-of-freedom ground-motion measurement

1994 ◽  
Vol 84 (5) ◽  
pp. 1665-1669
Author(s):  
Robert L. Nigbor
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Rotational Velocity ◽  
Free Field ◽  
Degree Of Freedom ◽  
Digital Data ◽  
Vertical Acceleration ◽  
Data Logger ◽  
Six Degree Of Freedom ◽  
Strong Ground

Abstract True six-degree-of-freedom (6DOF) measurement of free-field strong ground motion has been accomplished using a prototype 6DOF accelerograph system. This system consists of a traditional triaxial translational accelerometer, three new rotational velocity sensors, and a digital data logger. Rotational and translational ground motions at a single free-field location were measured successfully during the recent NPE event, a very large (1 kton) chemical explosion. Peak vertical acceleration at the near-field measurement site exceeded 1g for this event; the peak measured rotational velocity was 2.2°/sec. Earthquake strong-ground-motion measurements are currently in progress.

Empirical Attenuation Equations for Vertical Ground Motion in Turkey

2004 ◽  
Vol 20 (3) ◽  
pp. 853-882 ◽  
Author(s):  
Erol Kalkan ◽  
Polat Gülkan
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Strong Dependence ◽  
Strong Motion ◽  
Vertical Acceleration ◽  
Data Set ◽  
Attenuation Relationships ◽  
Geological Conditions ◽  
Ground Motion Records ◽  
Strong Ground

In the aftermath of two destructive urban earthquakes in 1999 in Turkey, empirical models of strong motion attenuation relationships that have been previously developed for North American and European earthquakes have been utilized in a number of national seismic hazard studies. However, comparison of empirical evidence and estimates present significant differences. For that reason, a data set created from a suite of 100 vertical strong ground motion records from 47 national earthquakes that occurred between 1976 and 2002 has been used to develop attenuation relationships for strong ground motion in Turkey. A consistent set of empirical attenuation relationships was derived for predicting vertical peak and pseudo-absolute vertical acceleration spectral ordinates in terms of magnitude, source-to-site distance, and local geological conditions. The study manifests the strong dependence of vertical to horizontal (V/H) acceleration ratio on spectral periods and relatively weaker dependence on site geology, magnitude, and distance. The V/H ratio is found to be particularly significant at the higher frequency end of the spectrum, reaching values as high as 0.9 at short distances on soil sites. The largest long-period spectral ratios are observed to occur on rock sites where they can reach values in excess of 0.5. These results raise misgivings concerning the practice of assigning the V/H ratio a standard value of two-thirds. Hence, nonconservatism of this value at short periods and its conservatism at long periods underline the need for its revision, at least for practice in Turkey.

scholarly journals A Numerical Study on Liquefaction Induced Settlements by Using PM4Sand Model

2021 ◽  
Vol 1203 (3) ◽  
pp. 032029
Author(s):  
Ozan Subasi ◽  
Serdar Koltuk ◽  
Merve Akbas ◽  
Recep Iyisan
Keyword(s):  
Finite Element ◽  
Ground Motion ◽  
Strong Ground Motion ◽  
Water Pressure ◽  
Free Field ◽  
Sudden Increase ◽  
Empirical Methods ◽  
Soil Layers ◽  
Semi Empirical ◽  
Strong Ground

Abstract Abstract: The destructive effects of earthquakes negatively affect many people's lives and cause a large number of lives and property losses. One of the most crucial factors that increase the destructive effects and structural damages of earthquakes is the deformations in the soil layers during strong ground motion. Especially liquefaction due to sudden increase in pore water pressure during strong ground motion in saturated sandy soils causes large deformations in the soil layers; hence leads to severe damage to the structures. Therefore, it is necessary to determine the liquefaction-induced deformations and settlements in the soil layers with high liquefaction potential. Following this purpose, three different two-dimensional fully saturated soil profiles with 35, 55, 75 % relative densities were created and carried out by using different strong ground motions for estimation of liquefaction-induced free field settlements. The finite element code "Plaxis 2D" and constitutive model "PM4Sand" were used in the analysis. The results of finite element (FE) analyses were compared with semi-empirical methods in the literature. The liquefaction state observed with pore pressure ratio (Ru) and safety factor (FS) is similar in numerical and empirical methods. The FE analyses have shown that the evaluation of free-field, liquefaction-induced settlements obtained from PM4Sand-Model have considerably lower settlement values than the semi-empirical methods. However, the semi-empirical method suggested by Cetin et al. (2009) and numerical analyses gave quite similar settlement results to each other. Moreover, there is no direct relationship between the liquefaction-induced settlements and the earthquake source properties in the numerical method. However, this is different for semi-empirical methods, and there is a relationship between strong ground motion features and liquefaction-induced settlements.

Nonlinear Dynamic Analysis of Pile Foundation Embedded in Sand Subjected to Strong Ground Motion Using Fiber Elements

2006 ◽  
Author(s):  
B. Asgarian ◽  
M. Boroumand ◽  
R. H. Soltani
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Interaction Analysis ◽  
Free Field ◽  
Nonlinear Dynamic Analysis ◽  
Offshore Structure ◽  
Structure Interaction ◽  
Pile Interaction ◽  
Fiber Element ◽  
Strong Ground

In this paper Fiber Element is used for modeling soil–pile interaction during earthquakes. In this model, both pile and surrounding soil are modeled using fiber elements. This model is developed using DRAIN–3DX software. In this method, behavior of soil is assign to fiber elements using p-y curves. In order to consider effects of free field soil on the motion, EERA and NERA software are used. In this paper pile behavior embedded in sandy soil subjected to strong ground motion were analyzed and compared with available experimental results. The model can be used for soil – pile – structure interaction analysis of jacket type offshore structure.

scholarly journals Experimental investigation of strong ground motion due to thrust fault earthquakes

2014 ◽  
Vol 119 (2) ◽  
pp. 1316-1336 ◽  
Author(s):  
Vahe Gabuchian ◽  
Ares J. Rosakis ◽  
Nadia Lapusta ◽  
David D. Oglesby
Keyword(s):  
Experimental Investigation ◽  
Ground Motion ◽  
Strong Ground Motion ◽  
Thrust Fault ◽  
Strong Ground
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