Nonlinear Time History with Slope Stabi tabili lity ty Coup oupled led Analys alysis is
Tutoria Tutoriall by Angel Angel Francisco Martinez Martinez Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Element Solution s f or Geotechnic Geotechnic al Engineering Engineering
Overview
GTS NX
STEP 01
Geometry Import
STEP 02
Import Materials
STEP 03
Mesh generation
STEP 04
Boundary Conditions
STEP 05
Dynamic Load Conditions
STEP 06
Eigenvalue Eigenvalue Analysis Analysis
STEP 07
TH + SRM Analysis Case
STEP 08
Perform analysis and check result
2
01 2D Slope
GTS NX
Overview • 2D nonlinear time history analysis
coupled with slope stability •Plane strain elements are used to
model ground condition. •Free Field boundary conditions used for time history analysis. •Ground Acceleration used as dynamic load.
For performing slope stability analysis using the finite element method (FEM), use higher order elements and triangle shaped elements.
1-3
02 Material for Soil
GTS NX
Name
Ground
Material
Isotropic Mohr-Coulomb
Model Type
General Elastic Modulus (E) (kN/m^2)
50,000
Poisson’s Ratio(v)
0.4
Unit Weight(r) (kN/m^3)
19
K0
1 Porous
Unit Weight(Saturated) (kN/m^3)
19 Non-Linear
Friction Angle
5
Cohesion (kN/m^2)
30
1-4
03 Property for Soil
GTS NX
Name
Ground
Property
2D
Model Type
Plain Strain
Material
Ground
1-5
Modeling Procedure
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solution s f or Geotechnic al Engineering
01 Create New Project
GTS NX
Procedure 1
Main Menu > New
2
Analysis Setting > Model
1
Type > 2D Set units to kN / m / sec 2
1-7
02 Geometry works (Create or Import from AutoCAD )
GTS NX
Procedure 1
Main Menu > Open
2
Select NTH with SRM > DXF> 1
Open 3
Select OK
2
3
1-8
03 Define Material / Property for Soil & Structures
GTS NX
Procedure • Import Materials and Properties
from finished file (Refer to Project
1
Overview > Material / Property).
1
Mesh > Prop. > Property Import All
1
1-9
04 Generate Mesh (2D Element)
GTS NX
Procedure 1
Mesh > Generate > 2D > Auto -
1
Area 2
Select Edge(s) > Select 6 edges highlighted in figure. 2
1
7
Input element Size : 1 3
4
2
(1m between two nodes)
8
Select Property : Ground 3
5
Input Mesh Set Name : Ground
6
Click on the ‘>>’ icon to open the Advanced Option Window
7
Select Triangle as Element Type
8
Activate Higher Order Elements
4
5
9 9
6
Click OK > OK
1-10
05 Define Free Field Boundary
GTS NX
Procedure 1 1
Mesh > Element > Free Field
2
Line: Select the left and right vertical edges of the mode’s boundary as shown in the image.
3
2
Create Free Field Property > Free field type: Line Width Factor : 10e15 3
4
Press Ok>OK 4
1-11
06 Define Boundary Condition (Ground)
GTS NX
Procedure 1
1
Static / Slope Analysis > Boundary > Constraint > Advanced
2
Select all the bottom nodes and the bottom free field as shown in the images.
3
Restrict DOF Tx and Ty 2
4
Press OK 3
4
1-12
06 Define Boundary Condition (Ground)
GTS NX
Procedure Mesh > Create > Other > Ground Surface Sprind Select mesh set
Press OK
1-13
07 Load Condition (Self Weight)
GTS NX
Procedure 1 1
Static / Slope Analysis > Load > Self Weight
2
Load Set Name : Self weight
2
1-14
08 Dynamic Load > Gravity Procedure
GTS NX 1
Create Dynamic Load Case for gravity to be considered in dynamic analysis 1
Dynamic Analysis > Load > Time Varying Static
2
Select load set and click ADD
3
Dynamic Load Set : gravity
4
Press OK
2
3
4
1-15
08 Dynamic Load > Ground Acceleration
GTS NX
1
Procedure Create Time History Load Funcition
1
for dynamic analysis 1
Dynamic Analysis > Load > Ground Acceleration
2
2
Activate X direction, Scale Factor: -1
5
and click in the icon to define the function 3 3
4
Click ADD Time Function 6
Click EARTHQUAKE to select
6
function from out data base 5
Select 1940 El Centro, 270 degree 6
6
4
Press OK, > OK > CLOSE > OK
2
3
4 6
1-16
09 Analysis Case
GTS NX
Procedure Create EigenValue Analysis Cases
1
1.
Analysis > Analysisi Case > General > Eigenvalue 3
2
2.
Activate Sets as shown
3
3.
Analysis Control > 30 Modes
4
4.
Press OK > OK
1
4 2
1-17
10 Perform Analysis and Check Results
GTS NX
Procedure 1
Analysis > Analysis > Perform
2
Select OK
1
2
1-18
11 Post Processing (Results)
GTS NX
Procedure 1*
After analysis, model view
1
will be converted to PostMode automatically, can back to Pre-Mode to change model information.
2
Results can be Viewed in table format. 3
Find the 2 highest mass participation modes and write down their corresponding periods. MODE 1: 1.2222 sec MODE 4: 0.7152 sec
1-19
12
Analysis Case (Nonlinear Time History + SRM ) GTS NX 3
Procedure Create Nonlinear Time History & SRM analysis Cases 3 1
1.
Analysis > General > Nonlinear Time History & SRM
2
2.
4 1
Ac tivate all sets 2
3
3.
4
Define Time Step
Name: time Time Duration: 2 sec Time Increment:: 0.02 sec Intermediate Output:: 10 Press Add > OK > CLOSE 4
4.
Analysis Control > Dynamic > Damping Method
-Select > Calculate from Modal
4
Damping > Period -Type in the 2 periods from Eigenvalue results -Damping Ratio : 0.05
6
-Press OK 5 5
5. Analysis Control > SRM -Time: 1.68 sec Press Add > OK
6
Press OK
1-20
13 Perform Analysis and Check Results
GTS NX
Procedure 1
Analysis > Analysis > Perform
2
Select Nonlinear Time History
1
with SRM 3
Select OK
2
3
1-21
14 Post Processing (Post mode)
GTS NX
Procedure
1
Inspect the FOS or the SRM analysis case. FOS: 1.01 SRM>Plane Strain Strains>EEquivalent
1
1-22
GTS NX
Thank you Angel Francisco Martinez
[email protected]
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