scholarly journals MODIFIED CAM-CLAY MODELS FOR DYNAMIC ANALYSIS OF GRANULAR METAMATERIALS IN EARTHQUAKE ENGINEERING

2021 ◽  
Vol 4 (3) ◽  
pp. 54-60
Author(s):  
S. Kuznecov ◽  
A. Al' Shemali
Keyword(s):  
Dynamic Analysis ◽  
Earthquake Engineering ◽  
Seismic Energy ◽  
Strength Parameter ◽  
Fe Model ◽  
Seismic Shear ◽  
Modified Cam Clay ◽  
Artificial Nature ◽  
Slab Foundation ◽  
Cam Clay

the problem of protecting buildings and structures from vibrations of natural and artificial nature is im-portant for modern construction. One of such modern methods of protection is seismic pads. The purpose of this work was to study the effect of adding a layer of granular metamaterial under a slab foundation on the vibration of a building under the influence of seismic shear waves (S-waves). To achieve this objective, the finite element method (FEM) was used in combination with Cam-Clay models. The FE model consists of a ten-story superstructure rested on the slab foundation, under which there is a layer of granular metamateri-als. 16 models were created taking into account changes in the values of these parameters (pad thickness; density; cohesion; critical state strength parameter (M); Young's modulus-Poisson's ratio). The dynamic analysis performed using the software package Abaqus/CAE showed the effectiveness of granular met-amaterials in their ability to dissipate seismic energy and significantly reduce vibration transmitted from the ground to the building.

scholarly journals DRUCKER-PRAGER MODELS FOR DYNAMIC ANALYSIS OF GRANULAR METAMATERIALS IN EARTHQUAKE ENGINEERING

2021 ◽  
Vol 4 (2) ◽  
pp. 5-11
Author(s):  
A.A. Al' Shemali A.A.
Keyword(s):  
Dynamic Analysis ◽  
Earthquake Engineering ◽  
Seismic Waves ◽  
Friction Angle ◽  
Fe Model ◽  
Element Analysis ◽  
Seismic Shear ◽  
The Finite Element Analysis ◽  
Modern Methods ◽  
Slab Foundation

Problem of developing methods for protecting buildings and structures from the vibrations transmitted to them from the soil under the action of seismic effects is extremely important to date. One of these modern methods is seismic pads. The purpose of this work was to study the effectiveness of adding a pad of granu-lar metamaterials under the foundation of the building to decrease influence of seismic shear waves. The Finite Element Analysis of Mohr-Coulomb models was used to achieve this goal. The FE model consists of a ten-story superstructure rested on the slab foundation, under which there is a layer of granular metamateri-als. The values of five variables that affect the mechanical properties of these metamaterials were analyzed (density – cohesion – internal friction angle – Young's modulus – Poisson's ratio) for two different pad thicknesses. The dynamic analysis performed using the software package Abaqus/CAE showed the effec-tiveness of the granular metamaterials in their ability to significantly reduce magnitudes of displacements, velocities and accelerations in the building compared to the same values in the absence of these metamateri-als. The analysis also revealed that among the studied variables, the cohesion is the parameter most influenc-ing the effectiveness of metamaterials in their ability to dissipate seismic waves, while no significant effect was observed for the other parameters

scholarly journals Applicability of a Three-Layer Model for the Dynamic Analysis of Ballasted Railway Tracks

Vibration ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 151-174
Author(s):  
André F. S. Rodrigues ◽  
Zuzana Dimitrovová
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Shear Stiffness ◽  
Shear Resistance ◽  
Railway Track ◽  
Fe Model ◽  
Inertial Effects ◽  
Layer Model ◽  
3D Finite Element

In this paper, the three-layer model of ballasted railway track with discrete supports is analyzed to access its applicability. The model is referred as the discrete support model and abbreviated by DSM. For calibration, a 3D finite element (FE) model is created and validated by experiments. Formulas available in the literature are analyzed and new formulas for identifying parameters of the DSM are derived and validated over the range of typical track properties. These formulas are determined by fitting the results of the DSM to the 3D FE model using metaheuristic optimization. In addition, the range of applicability of the DSM is established. The new formulas are presented as a simple computational engineering tool, allowing one to calculate all the data needed for the DSM by adopting the geometrical and basic mechanical properties of the track. It is demonstrated that the currently available formulas have to be adapted to include inertial effects of the dynamically activated part of the foundation and that the contribution of the shear stiffness, being determined by ballast and foundation properties, is essential. Based on this conclusion, all similar models that neglect the shear resistance of the model and inertial properties of the foundation are unable to reproduce the deflection shape of the rail in a general way.

scholarly journals An approach to quantify the influence of ground motion uncertainty on elastoplastic system acceleration in incremental dynamic analysis

2017 ◽  
Vol 20 (11) ◽  
pp. 1744-1756 ◽  
Author(s):  
Peng Deng ◽  
Shiling Pei ◽  
John W. van de Lindt ◽  
Hongyan Liu ◽  
Chao Zhang
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Structural Response ◽  
Incremental Dynamic Analysis ◽  
Degree Of Freedom ◽  
Maximum Acceleration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Performance Based Earthquake Engineering

Inclusion of ground motion–induced uncertainty in structural response evaluation is an essential component for performance-based earthquake engineering. In current practice, ground motion uncertainty is often represented in performance-based earthquake engineering analysis empirically through the use of one or more ground motion suites. How to quantitatively characterize ground motion–induced structural response uncertainty propagation at different seismic hazard levels has not been thoroughly studied to date. In this study, a procedure to quantify the influence of ground motion uncertainty on elastoplastic single-degree-of-freedom acceleration responses in an incremental dynamic analysis is proposed. By modeling the shape of the incremental dynamic analysis curves, the formula to calculate uncertainty in maximum acceleration responses of linear systems and elastoplastic single-degree-of-freedom systems is constructed. This closed-form calculation provided a quantitative way to establish statistical equivalency for different ground motion suites with regard to acceleration response in these simple systems. This equivalence was validated through a numerical experiment, in which an equivalent ground motion suite for an existing ground motion suite was constructed and shown to yield statistically similar acceleration responses to that of the existing ground motion suite at all intensity levels.

Compression and consolidation characteristics of structured natural clay

2004 ◽  
Vol 41 (6) ◽  
pp. 1250-1258 ◽  
Author(s):  
J -C Chai ◽  
N Miura ◽  
H -H Zhu ◽  
Yudhbir
Keyword(s):  
Numerical Analysis ◽  
Void Ratio ◽  
Natural Clay ◽  
Hardening Law ◽  
Modified Cam Clay ◽  
Calculated Load ◽  
Natural Clays ◽  
Consolidation Behavior ◽  
Better Than ◽  
Cam Clay

The compression and consolidation behavior of some structured natural clays are discussed. It is shown that for some structured natural clays, the relation between void ratio (e) and mean effective stress (p′) is more linear in a ln(e + ec) – ln(p′) plot (where ec is a soil parameter) than in an e – ln(p′) plot. It is proposed that for structured natural clay with a sensitivity value greater than 4, a linear ln(e + ec) – ln(p′) relation can be used in settlement and consolidation calculation. The effect of introducing a linear ln(e + ec) – ln(p′) relation on the calculated load–settlement curve and consolidation behavior of structured clays is discussed. The linear ln(e + ec) – ln(p′) relation was incorporated into the modified Cam–clay model by modifying the hardening law of the model. It is shown that using the linear ln(e + ec) – ln(p′) relation simulated the consolidation behavior of the structured natural clays better than using the linear e – ln(p′) relation.Key words: structured natural clay, compression, consolidation, constitutive model, numerical analysis.

A New Elasto-Plastic Critical State Model RU+MCC for Overconsolidated Soil

2016 ◽  
Vol 837 ◽  
pp. 68-74
Author(s):  
Rafal Uliniarz
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Small Strain ◽  
Computer Code ◽  
Constitutive Law ◽  
Isotropic Hardening ◽  
Loading Test ◽  
Modified Cam Clay ◽  
Soil Behaviour ◽  
Cam Clay

The paper presents a reasonably advanced constitutive law for soil – a hybrid of the Modified Cam Clay and a new RU development. The Modified Cam Clay model is an isotropic hardening elasto – plastic model originated by Burland in 1967 [1] within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The other one is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The RU+MCC model has been implemented in the FEM computer code Z_SOIL.pc. To test the influence of the small strain nonlinearity on soil – structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark a trial loading test of strip footing was used.

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