Release Notes - Midasadmin.midasuser.com/UploadFiles2/74/GTS NX 2015(v1.1)_Release Notes.pdf · 3 / 31 GTSNX 2015 Enhancements GTSNX 2015 V1.1 Release Notes 1. Pre Processing 1.1

Integrated Solver Optimized for the next generation 64-bit platform

Finite Element Solutions for Geotechnical Engineering

Release Notes 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

3 / 31

GTSNX 2015 V1.1 Release Notes GTSNX 2015 Enhancements

1. Pre Processing

1.1 Load Table Import / Export

Define or modify load through Excel like Load Table.

User 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 a time.

The following types of loads are available: Force, Moment, Pressure, Prescribed Displacement and Element Beam Load

Useful when the user has to manage (input and modify) large number of load sets at once

[Engineering Example: Pile-Raft Foundation]

4 / 31


1. Pre Processing

1.2 Dynamic Tools > Artificial Earthquake

Generate artificial earthquake data from the embedded design spectral data.

The 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]

5 / 31


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 the target. -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

6 / 31


1. Pre Processing

1.3 Element > Free Field Element (Infinite Element for Dynamic Analysis)

For seismic analysis, the user needs to model infinite ground to eliminate the boundary effect caused by reflection wave. Since it is not possible to model infinite ground, the user

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]

7 / 31


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, the user has to input more than 104. This value is multiplied by the model width (In case of 2D, this is plain strain thickness (unit width)). DOF (Degree of Freedom for damping) -User can select specified DOF for damping effect.

[Property > Other > Free Field]

8 / 31


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 of an infinite ground model.

9 / 31


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)

The 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]

10 / 31


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]

11 / 31


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.

User can identify 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 to 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]

12 / 31


`

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 represented using the von Mises yield criterion.

As a material yields, hardening defines the change in yield surface with plastic straining, which is classified into 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 Plasticity 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]

13 / 31


`

2. Analysis


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 with 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 the following relationship: 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, which 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.

14 / 31


`

2. Analysis


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

15 / 31


`

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]

16 / 31


`

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)]

17 / 31


`

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 must 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.

18 / 31


`

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

Nonlinear

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 does 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 iterative 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.

19 / 31


`

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




M Slope of critical state line 6 x sinФ’ / (3-sinФ’)

(Ф’: Effective internal friction angle)


Cap yield surface

OCR / Pc Over Consolidation Ratio / Pre-overburden pressure

When entering both parameters, Pc has the priority of usage


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

20 / 31


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.

The 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




M Slope of critical state line 6 x sinФ’ / (3-sinФ’)

(Ф’: Effective internal friction angle)


Cap yield surface

OCR / Pc Over Consolidation Ratio / Pre-overburden pressure

When entering both parameters, Pc has the priority of usage


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

21 / 31


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.

22 / 31


`

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 retains an 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]

23 / 31


`

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)

24 / 31


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]

25 / 31


`

2. Analysis

2.7 Material: 2D Orthotropic

Applicable to 2D element types such as Shell, Plane Stress and 2D Geogrid

User 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 significantly different stiffness in horizontal and vertical directions.

[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

26 / 31


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 (Recommended 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

27 / 31



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.


[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]

28 / 31



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.


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]

29 / 31


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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 performs 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]

30 / 31


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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

User can perform nonlinear dynamic analysis considering stress status of ground resulted from not only self weight but also from 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]

Documents

Release Notes - Midasadmin.midasuser.com/UploadFiles2/74/GTS NX 2015(v1.1)_Release Notes.pdf · 3 / 31 GTSNX 2015 Enhancements GTSNX 2015 V1.1 Release Notes 1. Pre Processing 1.1