gts nx 2015(v1.1)_release note

Release NoteRelease NoteProduct 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 2. Analysis1. Pre Processing

1.1 Load Table Import / Export

1.2 Artificial Earthquake Generator

1.3 Free Field Element (Infinite Element for Dynamic Analysis)

y

2.1 SAFETY FACTOR (Mohr Coulomb Criteria)

2.2 Material : von Mises - Nonlinear

2.3 Material : Modified UBCSAND

1.4 Inelastic Hinge 2.4 Material : Sekiguchi-Ohta(Inviscid)

2.5 Material : Sekiguchi-Ohta(Viscid)

2.6 Material : Generalized Hoek Brown

2 7 M t i l 2D O th t i (2D St t l El t)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-Drnevich2.10 Material : Modified Hardin Drnevich

2.11 Option : Estimate Initial Stress

2.12 Option : Stress-Nonlinear Time History Analysis

Integrated Solver Optimized for the next generation 64-bit platform

Finite Element Solutions for Geotechnical Engineering

GTSNX 2015 V1.1 Release NoteGTSNX 2015 Enhancement

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]

3 / 30


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.

( ) ( ) sin( )n n nn

z t I t A tω φ= +2( )RS ω n

1 ( )

( )( ) ( )( )

Ai i i

A

RSG G

RS

ωω ωω+

=

4 / 30

[Process of Artificial Earthquake Generation] [Design Spectral Data]


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.

Where, ωn = Frequency, An = Amplitude, Фn = Phase Angle,and I(t) = Envelope Function

[Equation for time history function]

I(t) Level Time

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

[Envelope Function]Rise Time

Total Time 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

5 / 30

[Add/Modify Artificial Earthquake]


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.

Freefield

Freefield

Main domain

Seismicwave

[Free field effect(O), Absorb reflection(O)][Schematic overview of Free Field Element]

Viscous Viscousboundary boundary

6 / 30

[Free field effect(X), Absorb reflection(X)] [Free field effect(X), Absorb reflection(O)]


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

[P t Oth F Fi ld] Free Field -Enables to simulate infinite ground boundary

Absorbent Boundary-Enables to eliminate reflection wave at the ground boundary

[Property > Other > Free Field]

[Create Free Field Element]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)

7 / 30

DOF (Degree of Freedom for damping)-Users can select specified DOF for damping effect


1. Pre Processing

1.3 Element > Free Field Element (Model Calibration)

Free field element can result in identical behavior with infinite ground model.

[None] [Free field]

[Infinite ground]

[Ground acceleration]

[ g ]

2.00

4.00

Time vs displacement

None

8 00

-6.00

-4.00

-2.00

0.00

0.05

0.

35

0.65

0.

95

1.25

1.

55

1.85

2.

15

2.45

2.

75

3.05

3.

35

3.65

3.

95

4.25

4.

55

4.85

Dis

plac

emen

t

Infiniteground

Free field

Viscousb d

8 / 30

-10.00

-8.00

time

boundary


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.

Load

Crack or local failure

Inelastic hinge

9 / 30

[Schematic overview of Inelastic Hinge]

[Hinge Properties]


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

( d) f ( b d) i d l 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][Hysteresis Model Type : Single Component]

10 / 30

[Hinge Components (Single/Multi)][Yield Surface Parameters] [Yield Surface Function]


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.

[Model Overview : Deep Excavation in 3D]

11 / 30

[Engineering Examples]

[Model Overview : Tunnel Excavation in 2D] [Plastic Status : Element Stresses] [Safety Factor (region for less than 1.2)]


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 beHardening 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)

`

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 I t i ‘0’ f Ki ti d b t ‘0 1’ f C bi d h d i

(0) (1 ) ( )y c y c y ph h eσ λ λ= + −

Isotropic, ‘0’ for Kinematic, and between ‘0~1’ for Combined hardening.

Initial yield surface

2σ

Isotropic hardening

Combined hardening

Initial yield surface

2σ

· 1σ· · 1σ

Kinematic hardening

12 / 30

g

[Yield surface for each hardening rule]


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 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.

'ne

e e tG ref

ref

p pG K p

p

+=

( )2 13(1 2 )

e eK Gνν

+=

−

`

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.

sin sin sinm m cvψ φ φ= −

21sin'sin 1

' sin

npp

p mm s G f s

ref p

G pK R

p p

φφ κ κφ

− Δ = Δ = − Δ

cvφ

he

ar

Str

ess

Dilative

Constant volume

1 3p p

sκ ε εΔ = Δ − Δ

tre

ss R

atio

/ 'pG p

Sh

Contractive

St

SκΔ

sin mφΔ

13 / 30

Mean Stress Maximum Plastic Shear Strain

[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.


2. Analysis

2.3 Material : Modified UBCSAND

Parameter Description Reference

P f R f PIn-situ horizontal stress at mid-

Pref Reference PressureIn situ horizontal stress at mid

level of soil layer

Elastic (Power Law)

Elastic shear modulus number Dimensionless

Elastic shear modulus exponent Dimensionless

eGK

n e p

Plastic / Shear

Peak Friction Angle Failure parameter as in MC model

Constant Volume Friction Angle -

C Cohesion Failure parameter as in MC model

cvφpφ

`

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

pGK

n p

fR increasing relative density

Post Liquefaction Calibration Factor Residual shear modulus

Soil Densification Calibration Factor Cyclic Behavior

Advanced parameters

fR

po s tF

densF

Pcut Plastic/Pressure Cutoff (Tensile Strength) -

Cap Bulk Modulus Number -

Plastic Cap Modulus Exponent -

OCR Over Consolidation RatioNormal stress / Pre-overburden

pBK

m p

14 / 30

OCR Over Consolidation Ratiopressure


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.

( ) 0.3331 6021.7 20.0e

GK N= × ×( )1 60G

0.0163ν =

0 030 34cvφ< <

`

( ) 21 60 0.003 100.0p e

G GK K N= × +

0.50.4

ne

np

==

( ) ( )( )

( ) ( ) ( )( )1 160 60

1 601 160 60

/10.0 15.0

15/10.0 max 0.0, 15.0

5

cv

p

cv

N N

NN N

φφ

φ

+ <

= − + + ≥

( ) 0.151 601.1fR N

−= ×

[Parameters and Equations for Calibration]

15 / 30


2. Analysis

2.3 Material : Modified UBCSAND (Model Calibration)

Test

Analysis

Test

Analysis

15

20

25

15

20

25

stre

ss [

kPa]

0

5

10

0 1 2 3 4 5 6 70

5

10

0 20 40 60 80 100 120

Sh

ear

s

`[Undrained DSS (Monotonic)]

0 1 2 3 4 5 6 7 0 20 40 60 80 100 120

Shear strain [%] Vertical Stress [kPa]

10

15Analysis

10

15

Test Soil densification

0

5

0 20 40 60 80 100 120 0

5

0 20 40 60 80 100 120

ear

stre

ss [

kPa]

-15

-10

-5

-15

-10

-5

Sh

e

Vertical Stress [kPa] Vertical Stress [kPa]

16 / 30

Vertical Stress [kPa] Vertical Stress [kPa]

[Undrained DSS (Cyclic)]


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 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

( )0 0 0

ln 01 1

pCC v

p qf

e p e M p

λ κ λ κ ε − −= + − = + + ( )0 0 0

ln 01 1

pSO v

pf

e p e M

λ κ λ κ η ε − −= + − = + + ( )

2

2 20 0 0

ln ln 1 01 1

pMCC v

p qf

e p e M M p

λ κ λ κ ε − −= + + − = + +

32

ij cij ij cij

c c

s s s s

p p p pη

= − −

( )0 0 0e p e p ( )0 0 0e p e

32

ij ijs s q

p p pη

= =

0 1K =

( )0 0 0p p

`

0K

q

[Sekiguchi-Ohta (Inviscid)] [Cam Clay]

cp′ p′

[Modified Cam Clay]

Soft Soil Creep Sekiguchi-Ohta(viscid)

Always plastic state Plastic state after yielding

[Yield Function : If K0=1, Original Cam Clay model is equal to Sekiguchi-Ohta model]

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.

17 / 30


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.

Parameter

Description Reference value

Non-Linear

λ Slope of normal consolidation line Cc / 2 303 / (1 + e )λ Slope of normal consolidation line Cc / 2.303 / (1 + e0)

κ Slope of over-consolidation lineCs / 2.303 / (1 + e0)

(Cc / 5 for a rough estimation)

6 x sinФ’ / (3-sinФ’)

`

M Slope of critical state line (Ф’ : Effective internal friction angle)

KOnc Ko for normal consolidation 1-sinφ’ (< 1)

Cap yield surface

OCR / PcOver Consolidation Ratio / Pre-overburden pressure

When entering both parameters,

Pc has the priority of usage

Tallow Allowable Tensile Stress * Note

* 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)

18 / 30

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.


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 + e )λ Slope of normal consolidation line Cc / 2.303 / (1 + e0)



6 x sinФ’ / (3-sinФ’)

`



Cap yield surface

OCR / PcOver Consolidation Ratio / Pre-overburden pressure

When entering both parameters, Pc has the priority of usage

Tallow Allowable Tensile Stress * Note( )log time

* Note : Time Dependent

Time Dependent

α Coefficient of secondary consolidation Cc / 20 for a rough estimation

Initial volumetric strain rate * Note0

0t

αν =

0νSecondaryPrimary

19 / 30

t0 Time when primary consolidation ends * Notestrain


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)

Input Parameters Remarks

Plastic index

Compression index

Parameter

Description Reference value

Non-Linear

λ Slope of normal consolidation line Cc / 2 303 / (1 + e )

pI

cC

Drainage distance Unit: cmλ Slope of normal consolidation line Cc / 2.303 / (1 + e0)



6 x sinФ’ / (3-sinФ’)0.434 cCλ =0.015 0.007 pIλ = +

H

sin 0.81 0.233log pIφ′ = −0 3.78 0.156e λ= +



Cap yield surface

p

( )2log 0.025 0.25 1 / minv pc I cm= − − ±OCR / Pc

Over Consolidation Ratio / Pre-overburden pressure

When entering both parameters, Pc has the priority of usage

Tallow Allowable Tensile Stress * Note( )90% 0.848vT =

Time Dependent

α Coefficient of secondary consolidation Cc / 20 for a rough estimation

Initial volumetric strain rate * Note0ν( )0 2 90%v vH T c

αν =

20 / 30

t0 Time when primary consolidation ends * Note


2. Analysis1 00

1.20

1%/min

Undrained triaxial compression and extension - Effect of strain rate

2.5 Material : Sekiguchi - Ohta (Model Calibration)

0.40

0.60

0.80

1.00 /

0.1%/min

0.01%/min

0.001%/min

0.0001%/min

Plastic

dispalcement

0.3325λ = 0.15κ =0 1.5e =

0 0.65ncK =0.364ν =

1.12M =

strain : 20% -0.40

-0.20

0.00

0.20

0.00 0.20 0.40 0.60 0.80 1.00 1.20 (Sxx

-Szz

)/p0

pressureTriaxial-

Compression

strain : 20%

1t : 2.0e1 min.

2t : 2.0e2 min. -1.00

-0.80

-0.60

p/p0

dispalcement

3t : 2.0e3 min.

4t : 2.0e4 min.

5t : 2.0e5 min. 0.60

0.80

1.00

1.20

1%/min

0.1%/min

0.01%/min

0.001%/min

0.0001%/min

Pl iTriaxial-

Extension

5 : . e .

0.00

0.20

0.40

-25 -20 -15 -10 -5 0 5 10 15 20 25

(Sxx

-Szz

)/p0

Plastic

Undrained strength : max2

xx zzσ σ−

-0.80

-0.60

-0.40

-0.20

Undrained strength depends on the rate of shearing in different ways on the i l d t i l id f h i

21 / 30

Sekiguchi, H. and Ohta, H., "Induced anisotropy and time dependency in clays", 9th ICSMFE, Tokyo, Constitutive equations of Soils, 1977, 229-238

-1.00

Axial strain

compressional and extensional sides of shearing.


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 All geological index was subsequently extended for weak rock masses.

Applicable for Strength Reduction Method (slope stability analysis)

100exp28 14b i

GSIm m

D

− = −

100exp9 3GSI

sD

− = −

( )/ /1 1

`

( )/15 20/31 12 6

GSIa e e− −= + −

1σ3σ−

( )a

bmf sσ σ σ σ

= − − − + ( )1 3 1

1 2 3

HB cici

f sσ σ σ σσ

σ σ σ

+

≥ ≥

2σ 3σtσ1σ−

22 / 30

[Yield Function] [Failure surface in principle stress plane]


2. Analysis

2.6 Material : Generalized Hoek-Brown (Review of model parameters, Geological Index (Hoek,1999))

[Uniaxial Compressive Strength]

`

[Geological Strength Index (GSI)]

[Guidelines for estimating Disturbance Factor (D) (0 ~ 1)

23 / 30

[Intact Rock Parameter]

[Guidelines for estimating Disturbance Factor (D), (0 1)


2. Analysis

2.6 Material : Generalized Hoek-Brown (Model Calibration)

The Shear Strength Reduction Method for the Generalized Hoek-Brown CriterionHammah, R.E., Yacoub, T.E. and Corkum, B.C.R i I T t ON C dRocscience Inc., Toronto, ON, CanadaCurran, J.H.Lassonde Institute, University of Toronto, Toronto, ON, Canada

[Reference F S 1 15][Reference - F.S. : 1.15]

[GTSNX - F.S. : 1.19]

24 / 30

[GTSNX F.S. : 1.19]


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.

1 21 1

12 21 12 2111 1111

12 2 2

01 1

0

E E

TE E

νν ν ν νσ ε α

ν

− − − Δ Δ

12 2 222 22 22

12 21 12 2112 12

12

01 1

0 0

E ET

G

νσ ε αν ν ν ν

τ γ

= − Δ − −

0Gτ γ

`[Stress-strain relation in 2D]

31 31 31

23 23 23

00G

G

τ γτ γ

=


25 / 30



2. Analysis

2.8 Hardening Soil (Enhancement in Modified Mohr Coulomb model: Review of model parameters)

Parameter Description Reference value (kN, m)

Improvement of Convergence in algorithms : Implicit Backward Euler Method

Additional (advanced) parameter to define allowable tensile strength.

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/ g

m Power for stress-level dependency of stiffness0.5 ≤ 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 100p

KNC Ko for normal consolidation 1-sinφ (< 1)

Dilatancy cut-off

Porosity Initial void ratio -

Porosity(Max) Maximum void ratio Porosity < Porosity(Max)y( ) y y( )

Cap yield surface

OCR / Pc Over Consolidation Ratio / Pre-overburden pressureWhen entering both parameters,

Pc has the priority of usage

α Cap Shape Factor (scale factor of preconsolidation stress) from KNC (Auto)

26 / 30

β Cap Hardening Parameter from Eoedref (Auto)

Tensile Strength

Tallow Allowable Tensile Strength * Note (Refer to Sekiguchi-Ohta model)


2. Analysis

2.9 Material : Modified Ramberg-Osgood

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.



Initial Shear ModulusoG

Reference Strain

Maximum Damping 0.05 (for soil), γ oG

βγ τ α τ τ= +

rγ

maxh

Shear OnlyCheck : Consider shear modulus for each direction separately (Gxy, Gyz, Gzx)Uncheck : Consider equivalent shear modulus (Geq)

γ

oG ( )1 1,τ γ

Skeleton Curve

max

max

2 2,2 r o

h

h G

βπβ απ γ

= = −

u 1.5E+02

GTS NX

τ

oG

Skeleton Curve

m

k

c

m

0.0E+00

5.0E+01

1.0E+02

-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8

Fo

rce

Civil

Dyna2E

Hysteresis Curve

c

-1.5E+02

-1.0E+02

-5.0E+01

27 / 30

[Modified Ramberg-Osgood model]

Deform

[Verification Example]

[Load] [System] [Results]


2. Analysis

2.10 Material : Modified Hardin-Drnevich

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.



G γG

Hysteresis curves are formulated on the basis of the Masing’s rule.

Initial Shear Modulus

Reference Strain

Shear OnlyCheck : Consider shear modulus for each direction separately (Gxy, Gyz, Gzx)U h k C id i l h d l (G )

γ

1

o

r

G γτγγ

=+

oG

rγ

Shear OnlyUncheck : Consider equivalent shear modulus (Geq)

oG ( )1 1,τ γ

Skeleton Curve8.0E+01

1.0E+02

GTS NX

Civil

D 2E

u

τ

oG

-2 0E+01

0.0E+00

2.0E+01

4.0E+01

6.0E+01

-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6

Fo

rce

Dyna2E

m

k

c

m

Hysteresis Curve

-1.0E+02

-8.0E+01

-6.0E+01

-4.0E+01

2.0E+01

Deform

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[Modified Hardin-Drnevich model]

[Verification Example]

[Load] [System] [Results]


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 groundestimating 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.

`[Without Initial Stress Option : Horizontal Displacement : 84mm]

[Engineering Example : Excavation and Backfill][With Initial Stress Option : Horizontal Displacement : 30mm]

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[With Initial Stress Option : Horizontal Displacement : 30mm]


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 stageNonlinear time history stage must be set at the final stage.

`

[Stage Set : Stress-Nonlinear Time History]

[Define construction stage]

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gts nx 2015(v1.1)_release note

Documents

element beam load

pre processing1

transient earthquake

computed spectral data

embedded design spectral

release notegtsnx

load table import export1

d st t