Release Note - CSPFea€¦ · GTSNX 2015 Enhancement GTSNX 2015 V1.1 Release Note 1. Pre Processing...
Transcript of Release Note - CSPFea€¦ · GTSNX 2015 Enhancement GTSNX 2015 V1.1 Release Note 1. Pre Processing...
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
Release Note Release Date : January. 2015
Product Ver. : GTSNX 2015 (v1.1)
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
Enhancements
1. Pre Processing
1.1 Load Table Import / Export
1.2 Artificial Earthquake Generator
1.3 Free Field Element (Infinite Element for Dynamic Analysis)
1.4 Inelastic Hinge
2. Analysis
2.1 SAFETY FACTOR (Mohr Coulomb Criteria)
2.2 Material : von Mises - Nonlinear
2.3 Material : Modified UBCSAND
2.4 Material : Sekiguchi-Ohta(Inviscid)
2.5 Material : Sekiguchi-Ohta(Viscid)
2.6 Material : Generalized Hoek Brown
2.7 Material : 2D Orthotropic (2D Structural Element)
2.8 Material : Enhancements in Hardening Soil
2.9 Material : Modified Ramberg-Osgood
2.10 Material : Modified Hardin-Drnevich
2.11 Option : Estimate Initial Stress
2.12 Option : Stress-Nonlinear Time History Analysis
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1. Pre Processing
1.1 Load Table Import / Export
Define or modify load through excel like Load Table.
Users can import load from excel and export defined load (position (node), magnitude and direction) to excel - Only one excel file can communicate with GTSNX at once
Following types of loads are available : Force, Moment, Pressure, Prescribed Displacement and Element Beam Load.
Useful when users have to manage (input and modify) large numbers of load sets at once.
[Engineering Example : Pile-Raft Foundation]
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1. Pre Processing
1.2 Dynamic Tools > Artificial Earthquake
Generate artificial earthquake data from the embedded design spectral data.
Following design spectral data are available in GTSNX.
[Process of Artificial Earthquake Generation]
Compute Response Spectrum
Iteration i ≥ Max. Iteration
Read Target Design Spectral Data
Compute PSD(Power Spectral Density) Function
Compute Acceleration
( ) ( ) sin( )n n n
n
z t I t A t Modify PSD2
1 ( )
( )( ) ( )
( )
Ai i i
A
RSG G
RS
Output Results
NO
YES
[Design Spectral Data]
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1. Pre Processing
1.2 Dynamic Tools > Artificial Earthquake
Envelope Function enables to generate transient earthquake data.
There are three types of envelope functions : Trapezoidal, Compound and Exponential. GTSNX supports Trapezoidal type.
[Envelope Function]
[Add/Modify Artificial Earthquake]
I(t)
Rise Time
Total Time
Level Time
Where, ωn = Frequency, An = Amplitude, Фn = Phase Angle, and I(t) = Envelope Function
[Equation for time history function]
Generate Options -Max Iterations : Maximum number of iterations to fit computed spectral data to target one. -Max. Acceleration : Maximum acceleration of artificial earthquake data -Damping Ratio : Damping ratio to calculate spectral data Generate Acceleration : Covert from response spectrum to acceleration data -Spectrum Graph : Check results based on spectral data -Acceleration Graph : Check results based on acceleration data
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1. Pre Processing
1.3 Element > Free Field Element (Infinite Element for Dynamic Analysis)
For the seismic analysis, users need to model infinite ground to eliminate the boundary effect caused by reflection wave. Since it is not possible to model infinite ground, users can
apply Free Field Element at the boundary.
Free Field Element enables to apply traction resulted from Free Field Analysis to the ground boundary and then, eliminate reflection wave using absorbent boundary condition.
Main domain
Free
field
Free
field
Seismic
wave
Viscous boundary
Viscous boundary
[Free field effect(X), Absorb reflection(X)] [Free field effect(X), Absorb reflection(O)]
[Free field effect(O), Absorb reflection(O)] [Schematic overview of Free Field Element]
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1. Pre Processing
1.3 Element > Free Field Element (Infinite Element for Dynamic Analysis)
Select free edges in 2D and free faces in 3D to define Free Field Elements
[Create Free Field Element]
Free Field -Enables to simulate infinite ground boundary Absorbent Boundary -Enables to eliminate reflection wave at the ground boundary Width Factor (Penalty parameter) -In order to minimize the size effect, users have to input more than 104. This value is multiplied by model width (In case of 2D, this is plain strain thickness (unit width)) DOF (Degree of Freedom for damping) -Users can select specified DOF for damping effect
[Property > Other > Free Field]
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1. Pre Processing
1.3 Element > Free Field Element (Model Calibration)
[None] [Free field]
[Infinite ground]
[Ground acceleration]
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
0.0
5
0.3
5
0.6
5
0.9
5
1.2
5
1.5
5
1.8
5
2.1
5
2.4
5
2.7
5
3.0
5
3.3
5
3.6
5
3.9
5
4.2
5
4.5
5
4.8
5
Dis
pla
cem
en
t
time
Time vs displacement
None
Infiniteground
Free field
Viscousboundary
Free field element can result in identical behavior with infinite ground model.
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1. Pre Processing
1.4 Element > Inelastic Hinge
Inelastic hinge can be applied to the structural elements to simulate crack or local (plastic) failure.
Applicable in Nonlinear Static and Time History Analysis as follows : Nonlinear, Construction Stage, Consolidation, Fully Coupled, SRM (Slope Stability)
Following properties are available to define inelastic hinge : Beam, Truss, Elastic Link and Point Spring.
Crack or local failure
[Schematic overview of Inelastic Hinge]
Inelastic hinge
Load
[Hinge Properties]
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1. Pre Processing
1.4 Element > Inelastic Hinge (Property & Components (Single / Multi)) Refer to Online Manual (F1) in detail...
Mesh >Prop./ Csys./ Func. > Hinge > Hinge Properties…
Mesh >Prop./ Csys./ Func. > Hinge > Hinge Components…
Hinge Type : Beam (Lumped / Distributed), Truss, Elastic Link, Point Spring Interaction : Single Component (None, P-M, P-M-M), Multi Component
Component : Location (Lumped), No. of Sections (Distributed), Hysteresis Model, Yield Surface Parameters / Function (P-M, P-M-M, Multi Component) Hysteresis Model Type: Single Component (…), Multi Component (Kinematic)
[Hinge Properties]
[Hinge Components (Single/Multi)] [Yield Surface Parameters] [Yield Surface Function]
[Hysteresis Model Type : Single Component]
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2. Analysis
2.1 Safety Result (Mohr - Coulomb criteria, Material > Isotropic > General Tab)
Cohesion , Friction Angle and Allowable tensile strength (optional) can be defined as the failure criteria.
Stress status of material for each construction stage can be represented by Factor of Safety based on Mohr-Coulomb failure criteria.
The ratio of generated stress to stress at failure for each element will be calculated automatically.
Users can figure out stable, potential failure and plastic failure area directly.
Check factor of safety for each element - (2D : Plain Strain Stresses > SAFETY FACTOR , 3D : Solid Stresses > SAFETY FACTOR)
In case that Safety Factor is less than 1(or 1.2), it can be identical with plastic failure region.
[Engineering Examples]
[Model Overview : Tunnel Excavation in 2D] [Plastic Status : Element Stresses] [Safety Factor (region for less than 1.2)]
[Model Overview : Deep Excavation in 3D]
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2. Analysis
2.2 Material : von Mises - Nonlinear
von Mises model is often used to define the behavior of ductile materials based on the yield stress.
Undrained strength of saturated soil can be appropriately presented using the von Mises yield criterion.
As a material yield, hardening defines the change of yield surface with plastic straining, which is classified in to the three types : Isotropic, Kinematic and Combined.
Appropriate for all types of materials, which exhibit Plastic Incompressibility.
Perfect Plastic: Specify Initial Uniaxial (tensile) Yield Stress Hardening Curve : Relation between plastic strain and stress(true stress) can be resulted from uniaxial compression / tensile test or shear test.
Stress Strain curve (optional) : Relation between strain and stress(true stress)
Hardening Rule: Isotropic, Kinematic and Combined (Isotropic + Kinematic) - Total increment of Plastic can be expressed by Isotropic and Kinematic Hardening as follows
- Combined hardening factor (λc, 0~1) represents the extent of hardening. ‘1’ for Isotropic, ‘0’ for Kinematic, and between ‘0~1’ for Combined hardening.
(0) (1 ) ( )y c y c y ph h e
·
Initial yield surface
1
2
Isotropic hardening
· ·
Combined hardening
Initial yield surface
1
2
Kinematic hardening
[Yield surface for each hardening rule]
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2. Analysis
2.3 Material : Modified UBCSAND
An effective stress model for predicting liquefaction behavior of sand under seismic loading.
GTSNX Liquefaction Model is extended to a full 3D implementation of the modified UBCSAND model using implicit method.
In elastic region, Nonlinear elastic behavior can be simulated, elastic modulus changes according to the effective pressure applied.
In plastic region, the behavior is defined by three types of yield functions : shear (shear hardening), compression (cap hardening), and pressure cut-off.
In case of shear hardening, soil densification effect can be taken into account by cyclic loading.
Elastic: Shear modulus is updated according to the effective pressure(p’) based on the following equation. - Allowable tensile stress (Pt) is calculated using cohesion and friction angle automatically. - Poisson’s ratio is constant and bulk modulus of elasticity will be determined by following relation. Plastic/Shear : Depending on the difference between mobilized friction angle(Фm) and constant volume friction angle(Фcv), shear induces plastic expansion or dilation is predicted. - The Plastic shear strain increment is related to the change in shear stress ratio assuming a hyperbolic relationship and can be expressed as follows.
'ne
e e tG ref
ref
p pG K p
p
2 1
3(1 2 )
e eK G
sin sin sinm m cv
cv
Mean Stress
Sh
ea
r S
tre
ss
Contractive
Dilative
Constant volume
21
1 3
sin'sin 1
' sin
npp
p mm s G f s
ref p
p p
s
G pK R
p p
Maximum Plastic Shear Strain
Str
ess R
atio
S
sin m
/ 'pG p
[Reference for UBCSAND model] Beaty, M. and Byrne, PM., “An effective stress model for predicting liquefaction behaviour of sand,” Geotechnical Special Publication 75(1), 1998, pp. 766-777.
Puebla, H., Byrne, PM., and Phillips, R., “Analysis of CANLEX liquefaction embankments: protype and centrifuge models,” Canadian Geotechnical Journal, 34, 1997, pp 641-657.
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2. Analysis
2.3 Material : Modified UBCSAND
Parameter Description Reference
Pref Reference Pressure In-situ horizontal stress at mid-
level of soil layer
Elastic (Power Law)
Elastic shear modulus number Dimensionless
Elastic shear modulus exponent Dimensionless
Plastic / Shear
Peak Friction Angle Failure parameter as in MC model
Constant Volume Friction Angle -
C Cohesion Failure parameter as in MC model
Plastic shear modulus number Dimensionless
Plastic shear modulus exponent Dimensionless
Failure ratio (qf / qa) 0.7~0.98 (< 1), decreases with
increasing relative density
Post Liquefaction Calibration Factor Residual shear modulus
Soil Densification Calibration Factor Cyclic Behavior
Advanced parameters
Pcut Plastic/Pressure Cutoff (Tensile Strength) -
Cap Bulk Modulus Number -
Plastic Cap Modulus Exponent -
OCR Over Consolidation Ratio Normal stress / Pre-overburden
pressure
e
GK
ne
cvp
p
GK
np
fR
postF
densF
p
BK
mp
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2. Analysis
2.3 Material : Modified UBCSAND (Model Calibration)
Monotonic and cyclic drained Direct Simple Shear (DSS) test (skeleton response).
Constant volume DSS test (undrained test)
Single Element test and Calibration using Standard Penetration Test (SPT) - ((N1)60 : Equivalent SPT blow count for clean sand.
0.333
1 6021.7 20.0e
GK N
0.0163
2
1 600.003 100.0p e
G GK K N
1 160 60
1 60
1 160 60
/10.0 15.0
15/10.0 max 0.0, 15.0
5
cv
p
cv
N N
NN N
0.15
1 601.1fR N
0 030 34cv
0.5
0.4
ne
np
[Parameters and Equations for Calibration]
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2. Analysis
2.3 Material : Modified UBCSAND (Model Calibration)
[Undrained DSS (Monotonic)]
0
5
10
15
20
25
0 1 2 3 4 5 6 7
Test
Analysis
0
5
10
15
20
25
0 20 40 60 80 100 120
Test
Analysis
Sh
ear
str
ess [
kP
a]
Shear strain [%] Vertical Stress [kPa]
-15
-10
-5
0
5
10
15
0 20 40 60 80 100 120
Analysis
-15
-10
-5
0
5
10
15
0 20 40 60 80 100 120
Test
Sh
ear
str
ess [
kP
a]
Vertical Stress [kPa] Vertical Stress [kPa]
Soil densification
[Undrained DSS (Cyclic)]
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Soft Soil Creep Sekiguchi-Ohta(viscid)
Always plastic state Plastic state after yielding
2. Analysis
2.4 Material : Sekiguchi - Ohta (Overview)
Critical state theory model which is similar to Modified Cam Clay model
Nonlinear stress-strain behavior in elastic region
Stress induced anisotropy - Ko dependent term in yield function : Always have to apply “Ko condition” for initial stress of ground (Ko Anisotropy is not applicable )
Time dependent behavior , Creep (Viscid type only)
- time variable in yield function which is similar to SSC (Soft Soil Creep) model, but based on different elasto-visco plastic theory
[Yield Function : If K0=1, Original Cam Clay model is equal to Sekiguchi-Ohta model]
3
2
ij cij ij cij
c c
s s s s
p p p p
0 0 0
ln 01 1
p
CC v
p qf
e p e M p
0 0 0
ln 01 1
p
SO v
pf
e p e M
3
2
ij ijs s q
p p p
0 1K
[Sekiguchi-Ohta (Inviscid)] [Cam Clay]
0K -line
cp p
qC.S.L
C.S.L
2
2 2
0 0 0
ln ln 1 01 1
p
MCC v
p qf
e p e M M p
[Modified Cam Clay]
1) These equations have a common term as their first term.
2) Second term in each equation represents the contribution
of dilatancy, the volume change caused by the change in
the ratio of shear stress to hydrostatic stress.
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2. Analysis
2.4 Material : Sekiguchi - Ohta (Inviscid)
Representative cohesive soil model that can consider the elasto-plastic behavior, but time-independent one.
The same background with Modified Cam Clay model , but can simulate irreversible dilatancy considering initial stress (Ko) of normally consolidated state.
Para
meter Description Reference value
Non-Linear
λ Slope of normal consolidation line Cc / 2.303 / (1 + e0)
κ Slope of over-consolidation line Cs / 2.303 / (1 + e0)
(Cc / 5 for a rough estimation)
M Slope of critical state line
6 x sinФ’ / (3-sinФ’)
(Ф’ : Effective internal
friction angle)
KOnc Ko for normal consolidation 1-sinφ’ (< 1)
Cap yield surface
OCR / Pc Over Consolidation Ratio /
Pre-overburden pressure
When entering both
parameters,
Pc has the priority of usage
Tallow Allowable Tensile Stress * Note
critical state line
q
P
M
isotropic normal consolidation line
critical state line
overconsolidation line
k
ln(1)ln P
V
* Note : Allowable Tensile Stress
This model fundamentally do not allow tensile stress in the failure criteria (stress-strain relationship). However, various conditions can generate tensile stress, such as the heaving
of neighboring ground due to embankment load during consolidation or uplift due to excavation. To overcome the material model limits and increase the applicability, analysis on
tensile stress within the 'allowable tensile stress' range can be conducted.
The size of the allowable tensile stress is not specified, and requires repeated analysis to input a larger value than the tensile stress created from the overburden load (embankment)
or failure behavior. However, when directly entering the pc (pre-consolidation load), the allowable tensile stress cannot surpass the pc value. When defining using the OCR, the pc
value is automatically calculated internally by considering the size of the input allowable tensile stress.
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2. Analysis
2.5 Material : Sekiguchi - Ohta (Viscid)
Representative cohesive soil model that can consider the elasto-visco plastic behavior, and time-dependent one like soft soil creep model
Parameter Description Reference value
Non-Linear
λ Slope of normal consolidation line Cc / 2.303 / (1 + e0)
κ Slope of over-consolidation line Cs / 2.303 / (1 + e0)
(Cc / 5 for a rough estimation)
M Slope of critical state line 6 x sinФ’ / (3-sinФ’)
(Ф’ : Effective internal friction angle)
KOnc Ko for normal consolidation 1-sinφ’ (< 1)
Cap yield surface
OCR / Pc Over Consolidation Ratio / Pre-overburden pressure
When entering both parameters, Pc has the priority of usage
Tallow Allowable Tensile Stress * Note
Time Dependent
α Coefficient of secondary consolidation Cc / 20 for a rough estimation
Initial volumetric strain rate * Note
t0 Time when primary consolidation ends * Note
0
0t
0
log time
strain
SecondaryPrimary
* Note : Time Dependent
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Input Parameters Remarks
Plastic index
Compression index
Drainage distance Unit: cm
2. Analysis
Sekiguchi Ohta model requires some material properties, which can be obtained by triaxial tests.
Following empirical relations can be used to estimate the additional soil parameters : Karibe Method
2.5 Material : Sekiguchi - Ohta (Review of soil parameters)
sin 0.81 0.233log pI
0 3.78 0.156e
2log 0.025 0.25 1 / minv pc I cm
Parameter
Description Reference value
Non-Linear
λ Slope of normal consolidation line Cc / 2.303 / (1 + e0)
κ Slope of over-consolidation line Cs / 2.303 / (1 + e0)
(Cc / 5 for a rough estimation)
M Slope of critical state line 6 x sinФ’ / (3-sinФ’)
(Ф’ : Effective internal friction angle)
KOnc Ko for normal consolidation 1-sinφ’ (< 1)
Cap yield surface
OCR / Pc Over Consolidation Ratio / Pre-overburden pressure
When entering both parameters, Pc has the priority of usage
Tallow Allowable Tensile Stress * Note
Time Dependent
α Coefficient of secondary consolidation Cc / 20 for a rough estimation
Initial volumetric strain rate * Note
t0 Time when primary consolidation ends * Note
0.434 cC 0.015 0.007 pI
0
0 2 90%v vH T c
90% 0.848vT
H
pI
cC
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2. Analysis
Undrained triaxial compression and extension - Effect of strain rate
2.5 Material : Sekiguchi - Ohta (Model Calibration)
pressure
dispalcement
dispalcement
Triaxial- Compression
Triaxial- Extension
0.3325 0.15
0 1.5e
0 0.65ncK
0.364
1.12M
strain : 20%
1t : 2.0e1 min.
2t : 2.0e2 min.
3t : 2.0e3 min.
4t : 2.0e4 min.
5t : 2.0e5 min.
Sekiguchi, H. and Ohta, H., "Induced anisotropy and time dependency in clays", 9th ICSMFE, Tokyo, Constitutive equations of Soils, 1977, 229-238
Undrained strength : max2
xx zz
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0.00 0.20 0.40 0.60 0.80 1.00 1.20 (Sxx
-Szz
)/p0
p/p0
1%/min
0.1%/min
0.01%/min
0.001%/min
0.0001%/min
Plastic
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
-25 -20 -15 -10 -5 0 5 10 15 20 25
(Sxx
-Szz
)/p0
Axial strain
1%/min
0.1%/min
0.01%/min
0.001%/min
0.0001%/min
Plastic
Undrained strength depends on the rate of shearing in different ways on the
compressional and extensional sides of shearing.
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2. Analysis
2.6 Material : Generalized Hoek-Brown
Representative model to simulate general rock behavior (stiffer and stronger than other types of soil).
Hoek-Brown model is isotropic linear elastic behavior.
Generalized Hoek-Brown is to link the empirical criterion to geological observations by means of one of the available rock mass classification schemes.
All geological index was subsequently extended for weak rock masses.
Applicable for Strength Reduction Method (slope stability analysis)
100exp
28 14b i
GSIm m
D
100exp
9 3
GSIs
D
/15 20/31 1
2 6
GSIa e e
1 3 1
1 2 3
a
bHB ci
ci
mf s
[Yield Function]
1
2 3t1
3
[Failure surface in principle stress plane]
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2. Analysis
2.6 Material : Generalized Hoek-Brown (Review of model parameters, Geological Index (Hoek,1999))
[Intact Rock Parameter]
[Geological Strength Index (GSI)]
[Uniaxial Compressive Strength]
[Guidelines for estimating Disturbance Factor (D), (0 ~ 1)
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2. Analysis
2.6 Material : Generalized Hoek-Brown (Model Calibration)
The Shear Strength Reduction Method for the Generalized Hoek-Brown Criterion Hammah, R.E., Yacoub, T.E. and Corkum, B.C.
Rocscience Inc., Toronto, ON, Canada
Curran, J.H.
Lassonde Institute, University of Toronto, Toronto, ON, Canada
[Reference - F.S. : 1.15]
[GTSNX - F.S. : 1.19]
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2. Analysis
2.7 Material : 2D Orthotropic
Applicable to 2D element type such as Shell, Plane Stress and 2D Geogrid.
Users can define different values of stiffness along each direction which is defined by the following parameters : E1, E2, V12, G12, G23, and G31.
Useful to define geometrically orthotropic with significant different stiffness in horizontal and vertical direction.
[Stress-strain relation in 2D]
[Engineering Examples]
1 21 1
12 21 12 21
11 1111
12 2 222 22 22
12 21 12 21
12 12
12
01 1
01 1
0 0
E E
TE E
T
G
31 31 31
23 23 23
0
0
G
G
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2. Analysis
2.8 Hardening Soil (Enhancement in Modified Mohr Coulomb model: Review of model parameters)
Parameter Description Reference value (kN, m)
Soil stiffness and failure
E50ref Secant stiffness in standard drained triaxial test Ei x (2 – Rf) /2 (Ei = Initial stiffness)
Eoedref Tangent stiffness for primary oedometer loading E50ref
Eurref Unload / reloading stiffness 3 x E50ref
m Power for stress-level dependency of stiffness 0.5 ≤ m ≤ 1 (0.5 for hard soil,
1 for soft soil)
C (Cinc) Effective cohesion (Increment of cohesion) Failure parameter as in MC model
φ Effective friction angle Failure parameter as in MC model
ψ Ultimate dilatancy angle 0 ≤ ψ ≤ φ
Advanced parameters (Recommend to use Reference value)
Rf Failure Ratio (qf / qa) 0.9 (< 1)
Pref Reference pressure 100
KNC Ko for normal consolidation 1-sinφ (< 1)
Dilatancy cut-off
Porosity Initial void ratio -
Porosity(Max) Maximum void ratio Porosity < Porosity(Max)
Cap yield surface
OCR / Pc Over Consolidation Ratio / Pre-overburden pressure When entering both parameters,
Pc has the priority of usage
α Cap Shape Factor (scale factor of preconsolidation stress) from KNC (Auto)
β Cap Hardening Parameter from Eoedref (Auto)
Tensile Strength
Tallow Allowable Tensile Strength * Note (Refer to Sekiguchi-Ohta model)
Improvement of Convergence in algorithms : Implicit Backward Euler Method
Additional (advanced) parameter to define allowable tensile strength.
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Parameter Description Reference
Initial Shear Modulus
Reference Strain
Maximum Damping 0.05 (for soil),
Shear Only Check : Consider shear modulus for each direction separately (Gxy, Gyz, Gzx) Uncheck : Consider equivalent shear modulus (Geq)
2. Analysis
2.9 Material : Modified Ramberg-Osgood
oG
oG
1 1,
Skeleton Curve
Hysteresis Curve
max
max
2 2,
2
o
r o
G
h
h G
oG
r
maxh
One of Hysteresis models for inelastic hinge, an extension was made to 2D and 3D solid elements.
Can be applied to simulate crack or local (plastic) failure.
Applicable in Nonlinear Static and Time History Analysis as follows : Nonlinear, Construction Stage, Consolidation, Fully Coupled, SRM (Slope Stability)
[Modified Ramberg-Osgood model]
m
k
c
m
u
-1.5E+02
-1.0E+02
-5.0E+01
0.0E+00
5.0E+01
1.0E+02
1.5E+02
-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8
Fo
rce
Deform
GTS NX
Civil
Dyna2E
[Verification Example]
[Load] [System] [Results]
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GTSNX 2015 V1.1 Release Note GTSNX 2015 Enhancement
Parameter Description Reference
Initial Shear Modulus
Reference Strain
Shear Only Check : Consider shear modulus for each direction separately (Gxy, Gyz, Gzx) Uncheck : Consider equivalent shear modulus (Geq)
2. Analysis
2.10 Material : Modified Hardin-Drnevich
oG
oG
1 1,
Skeleton Curve
Hysteresis Curve
1
o
r
G
oG
r
One of Hysteresis models for inelastic hinge, an extension was made to 2D and 3D solid elements.
Can be applied to simulate crack or local (plastic) failure.
Applicable in Nonlinear Static and Time History Analysis as follows : Nonlinear, Construction Stage, Consolidation, Fully Coupled, SRM (Slope Stability)
Hysteresis curves are formulated on the basis of the Masing’s rule.
[Modified Hardin-Drnevich model]
-1.0E+02
-8.0E+01
-6.0E+01
-4.0E+01
-2.0E+01
0.0E+00
2.0E+01
4.0E+01
6.0E+01
8.0E+01
1.0E+02
-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6
Fo
rce
Deform
GTS NX
Civil
Dyna2E
m
k
c
m
u
[Verification Example]
[Load] [System] [Results]
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GTSNX 2015 V1.1 Release Note GTSNX 2015 Enhancement
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2. Analysis
2.11 Analysis Option : Estimate Initial Stress of Activated Elements
* Note : Initial Stress for Activated Elements during construction
In order to calculate the initial stress of ground, GTSNX perform Linear Analysis even if nonlinear material is assigned to the elements. In this case, it can result in, sometimes, over-
estimating the soil behavior (large displacement). Initial Stress Options can eliminate this problem especially for newly activated elements which are to simulate a fill-up ground
such as backfill and embankment.
[Engineering Example : Excavation and Backfill]
[Without Initial Stress Option : Horizontal Displacement : 84mm]
[With Initial Stress Option : Horizontal Displacement : 30mm]
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GTSNX 2015 V1.1 Release Note GTSNX 2015 Enhancement
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2. Analysis
2.12 Construction Stage > Stress - Nonlinear Time History Analysis
* Note : Perform nonlinear dynamic analysis based on initial stress of ground resulted from construction stage analysis
Users can perform nonlinear dynamic analysis considering stress status of ground resulted from not only self weight but also construction stage (the history of stress).
Nonlinear time history stage must be set at the final stage.
[Stage Set : Stress-Nonlinear Time History]
[Define construction stage]