Numerical analysis of kinematic response of single piles

2000 ◽  
Vol 37 (6) ◽  
pp. 1368-1382 ◽  
Author(s):  
Kevin J Bentley ◽  
M Hesham El Naggar
Keyword(s):  
Finite Element ◽  
Human Life ◽  
Free Field ◽  
Time History ◽  
Benchmark Problems ◽  
Soil Parameters ◽  
Nonlinear Behaviour ◽  
Pile Head ◽  
Element Mesh ◽  
Single Piles

Recent destructive earthquakes have highlighted the need for increased research into the revamping of design codes and building regulations to prevent further catastrophic losses in terms of human life and economic assets. The present study investigated the response of single piles to kinematic seismic loading using the three-dimensional finite element program ANSYS. The objectives of this study were (i) to develop a finite element model that can accurately model the kinematic soil–structure interaction of piles, accounting for the nonlinear behaviour of the soil, discontinuity conditions at the pile–soil interface, energy dissipation, and wave propagation; and (ii) to use the developed model to evaluate the kinematic interaction effects on the pile response with respect to the input ground motion. The static performance of the model was verified against exact available solutions for benchmark problems including piles in elastic and elastoplastic soils. The geostatic stresses were accounted for and radiating boundaries were provided to replicate actual field conditions. Earthquake excitation with a low predominant frequency was applied as an acceleration–time history at the base bedrock of the finite element mesh. To evaluate the effects of the kinematic loading, the responses of both the free-field soil (with no piles) and the pile head were compared. It was found that the effect of the response of piles in elastic soil was slightly amplified in terms of accelerations and Fourier amplitudes. However, for elastoplastic soil with separation allowed, the pile head response closely resembled the free-field response to the low-frequency seismic excitation and the range of pile and soil parameters considered in this study.Key words: numerical modelling, dynamic, lateral, piles, kinematic, seismic.

Implicit and Explicit Implementation of the Dynamic Relaxation Method for the Definition of Initial Equilibrium Configurations of Flexible Lines

2006 ◽  
Author(s):  
Danilo Machado Lawinscky da Silva ◽  
Breno Pinheiro Jacob ◽  
Marcos Vini´cius Rodrigues
Keyword(s):  
Finite Element ◽  
Equilibrium Configuration ◽  
Static Equilibrium ◽  
Element Approximation ◽  
Nonlinear Behaviour ◽  
Dynamic Relaxation ◽  
Mooring Lines ◽  
Element Mesh ◽  
Tangent Stiffness Matrix ◽  
Equilibrium Configurations

Recent activities in the offshore oil exploitation industry require new structural concepts employing flexible lines (both mooring lines and risers). Such systems present increasingly complex configurations, with dynamic nonlinear behaviour; therefore, the use of efficient numerical solution procedures, based on the Finite Element Method, becomes mandatory for their analysis. The usual analysis procedure for flexible lines by the FEM is based in the calculation of an initial, stable static equilibrium configuration in order to define the finite element mesh. Usually this configuration is obtained by the classic catenary equations. However, in more complex problems these equations cannot be applied. Therefore, the objective of this work is to present the use of a more general finite element approximation, associated to dynamic relaxation algorithms. Such algorithms can be started from arbitrary configurations, not necessarily in equilibrium. The resulting procedure is accurate, robust, and avoids numerical problems such as the ill-conditioning of the tangent stiffness matrix, allowing the static equilibrium configuration to be obtained in an efficient way.

The Research for the Technology of Inner Struck Pile and the Coefficient of Pile Endpoint Resistance

2012 ◽  
Vol 170-173 ◽  
pp. 335-338
Author(s):  
Xin Sheng Yin ◽  
Jing Wei Cai ◽  
Pang Feng Ba
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Small Area ◽  
New Technology ◽  
Friction Angle ◽  
Poisson's Ratio ◽  
Soil Parameters ◽  
Pile Head ◽  
Area Method ◽  
Finite Element Software

This document introduces a kind of new technology including testing pile, making pile, measuring pile----the technology of the inner struck pile. The mechanism for the inner struck piles and small area method for testing pile was explained. The coefficient of the pile endpoint resistance was calculated in different depth with the finite element software and it's variation was analyzed with different parameters' variation (cohesion, friction angle, elastic modulus, Poisson's ratio). The result shows that the value of the coefficients of the pile endpoint resistance reduces with the rising of the value of depth and the value is affected by the size of the pile head and the soil parameters.

scholarly journals Nonlinear Behaviour of Concrete Buttress Dams under High-Frequency Excitations Taking into Account Topographical Amplifications

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Roghayeh Abbasiverki ◽  
Richard Malm ◽  
Anders Ansell ◽  
Erik Nordström
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
High Frequency ◽  
Free Field ◽  
Low Frequency ◽  
Nonlinear Behaviour ◽  
One Dimensional ◽  
Field Modelling ◽  
Stream Direction ◽  
Modelling Approach

Concrete buttress dams could potentially be susceptible to high-frequency vibrations, especially in the cross-stream direction, due to their slender design. Previous studies have mainly focused on low-frequency vibrations in stream direction using a simplified foundation model with the massless method, which does not consider topographic amplifications. This paper therefore investigates the nonlinear behaviour of concrete buttress dams subjected to high-frequency excitations, considering cross-stream vibrations. For comparison, the effect of low-frequency excitations is also investigated. The influence of the irregular topography of the foundation surface on the amplification of seismic waves at the foundation surface and thus in the dam is considered by a rigorous method based on the domain-reduction method using the direct finite element method. The sensitivity of the calculated response of the dam to the free-field modelling approach is investigated by comparing the result with analyses using an analytical method based on one-dimensional wave propagation theory and a massless approach. Available deconvolution software is based on the one-dimensional shear wave propagation to transform the earthquake motion from the foundation surface to the corresponding input motion at depth. Here, a new deconvolution method for both shear and pressure wave propagation is developed based on an iterative time-domain procedure using a one-dimensional finite element column. The examples presented showed that topographic amplifications of high-frequency excitations have a significant impact on the response of this type of dam. Cross-stream vibrations reduced the safety of the dam due to the opening of the joints and the increasing stresses. The foundation modelling approach had a significant impact on the calculated response of the dam. The massless method produced unreliable results, especially for high-frequency excitations. The free-field modelling with the analytical method led to unreliable joint openings. It is therefore recommended to use an accurate approach for foundation modelling, especially in cases where nonlinearity is considered.

Response of guyed tower to irregular waves for linear and nonlinear behaviour of mooring cables

1985 ◽  
Vol 12 (1) ◽  
pp. 200-212 ◽  
Author(s):  
Momen A. Wishahy ◽  
M. Arockiasamy
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Time History ◽  
Element Model ◽  
Irregular Waves ◽  
Wave Forces ◽  
Beam Model ◽  
Nonlinear Behaviour ◽  
Irregular Wave ◽  
Linear And Nonlinear

The dynamic response of a guyed tower to irregular waves has been studied by the finite element method. Hydrodynamic interaction is taken into account by the added water mass concept, and the fundamental frequencies are determined using (i) a lumped-parameter two-dimensional beam model and (ii) a three-dimensional truss finite element model. The effect of the mooring guy lines is simulated using one-dimensional boundary elements. The example structure analyzed is the Exxon test guyed tower erected in water of 89.3 m depth in the Gulf of Mexico. The measured wave height – time history reported by Exxon is used to determine the wave forces. Irregular wave forces are computed using the linearized Morison's equation. The nonlinearity of the mooring system is computed using an iterative technique in which the cable configuration is corrected using successive solutions. The tower response in terms of offset-time history to wave forces is determined for both linear and nonlinear cable behaviour. The computed frequencies and the responses agree reasonably well with the available measured values. Key words: guyed tower, irregular wave forces, linear and nonlinear mooring cable stiffness, dynamic response.

An Eight-Node Hexahedral Finite Element with Rotational DOFs for Elastoplastic Applications

2019 ◽  
Vol 11 (1) ◽  
pp. 54-66
Author(s):  
Ayoub Ayadi ◽  
Kamel Meftah ◽  
Lakhdar Sedira ◽  
Hossam Djahara
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Plastic Zone ◽  
Displacement Vector ◽  
Small Strain ◽  
Benchmark Problems ◽  
Plasticity Model ◽  
Vector Approximation ◽  
Calculation Code

Abstract In this paper, the earlier formulation of the eight-node hexahedral SFR8 element is extended in order to analyze material nonlinearities. This element stems from the so-called Space Fiber Rotation (SFR) concept which considers virtual rotations of a nodal fiber within the element that enhances the displacement vector approximation. The resulting mathematical model of the proposed SFR8 element and the classical associative plasticity model are implemented into a Fortran calculation code to account for small strain elastoplastic problems. The performance of this element is assessed by means of a set of nonlinear benchmark problems in which the development of the plastic zone has been investigated. The accuracy of the obtained results is principally evaluated with some reference solutions.

scholarly journals Influence of finite element mesh size on the carrying capacity analysis of single-row ball slewing bearing

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110090
Author(s):  
Peiyu He ◽  
Qinrong Qian ◽  
Yun Wang ◽  
Hong Liu ◽  
Erkuo Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Carrying Capacity ◽  
Mesh Size ◽  
Finite Element Mesh ◽  
Fe Model ◽  
Element Mesh ◽  
Heavy Load ◽  
Slewing Bearing ◽  
Maximum Contact ◽  
Slewing Bearings

Slewing bearings are widely used in industry to provide rotary support and carry heavy load. The load-carrying capacity is one of the most important features of a slewing bearing, and needs to be calculated cautiously. This paper investigates the effect of mesh size on the finite element (FE) analysis of the carrying capacity of slewing bearings. A local finite element contact model of the slewing bearing is firstly established, and verified using Hertz contact theory. The optimal mesh size of finite element model under specified loads is determined by analyzing the maximum contact stress and the contact area. The overall FE model of the slewing bearing is established and strain tests were performed to verify the FE results. The effect of mesh size on the carrying capacity of the slewing bearing is investigated by analyzing the maximum contact load, deformation, and load distribution. This study of finite element mesh size verification provides an important guidance for the accuracy and efficiency of carrying capacity of slewing bearings.

Buckling characteristics of cut-out borne composite stiffened hyperbolic paraboloid shell panel

2021 ◽  
pp. 146442072110058
Author(s):  
Sarmila Sahoo
Keyword(s):  
Finite Element ◽  
Orientation Angle ◽  
Buckling Load ◽  
Benchmark Problems ◽  
Hyperbolic Paraboloid ◽  
Element Analysis ◽  
Load Effect ◽  
Global Buckling ◽  
Fiber Orientation Angle ◽  
Shell Panel

The present study investigates buckling characteristics of cut-out borne stiffened hyperbolic paraboloid shell panel made of laminated composites using finite element analysis to evaluate the governing differential equations of global buckling of the structure. The finite element code is validated by solving benchmark problems from literature. Different parametric variations are studied to find the optimum panel buckling load. Laminations, boundary conditions, depth of stiffener and arrangement of stiffeners are found to influence the panel buckling load. Effect of different parameters like cut-out size, shell width to thickness ratio, degree of orthotropy and fiber orientation angle of the composite layers on buckling load are also studied. Parametric and comparative studies are conducted to analyze the buckling strength of composite hyperbolic paraboloid shell panel with cut-out.

Finite Element Modeling of a Mechanically Stabilized Earth Trial Wall

2021 ◽  
pp. 036119812110164
Author(s):  
Andrew Lees ◽  
Michael Dobie
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Retaining Wall ◽  
Back Analysis ◽  
Soil Parameters ◽  
Failure Behavior ◽  
Valuable Insight ◽  
Deformation And Failure ◽  
First Case ◽  
Soil Shear Strength

Polymer geogrid reinforced soil retaining walls have become commonplace, with routine design generally carried out by limiting equilibrium methods. Finite element analysis (FEA) is becoming more widely used to assess the likely deformation behavior of these structures, although in many cases such analyses over-predict deformation compared with monitored structures. Back-analysis of unit tests and instrumented walls improves the techniques and models used in FEA to represent the soil fill, reinforcement and composite behavior caused by the stabilization effect of the geogrid apertures on the soil particles. This composite behavior is most representatively modeled as enhanced soil shear strength. The back-analysis of two test cases provides valuable insight into the benefits of this approach. In the first case, a unit cell was set up such that one side could yield thereby reaching the active earth pressure state. Using FEA a test without geogrid was modeled to help establish appropriate soil parameters. These parameters were then used to back-analyze a test with geogrid present. Simply using the tensile properties of the geogrid over-predicted the yield pressure but using an enhanced soil shear strength gave a satisfactory comparison with the measured result. In the second case a trial retaining wall was back-analyzed to investigate both deformation and failure, the failure induced by cutting the geogrid after construction using heated wires. The closest fit to the actual deformation and failure behavior was provided by using enhanced fill shear strength.

Optimization of a finite element mesh for plates subjected to in-plane patch loading

2019 ◽  
Vol 33 (3) ◽  
pp. 1185-1193 ◽  
Author(s):  
Ghania Ikhenazen ◽  
Messaoud Saidani ◽  
Madina Kilardj
Keyword(s):  
Finite Element ◽  
Finite Element Mesh ◽  
Element Mesh ◽  
Patch Loading
Sign in / Sign up

Export Citation Format

Share Document