bridge 3d soil structure interaction methods...
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Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
Soil Structure Interaction using
midas Civil & midas GTS NX for
the Structural & Geotechnical Engineers
Bridge 3D Soil Structure Interaction
Methods Comparison
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
Contents
1. Introduction
2. Soil Structure Interaction Substructure Method
3. Ground Response Analysis for Calibration
4. Soil Structure Interaction Direct Method
5. Results Comparison Between SSI Methods
GTS NX
3
Soil Structure Interaction
SSI: The phenomenon in which the response of soil and movement of the structure influence each
other. When external forces, such as earthquakes, act on these systems, neither structural
displacements nor ground displacements are independent of each other. Unlike an above-ground
structure, the response of an underground structure subjected to an earthquake is mainly controlled
by the ground displacement. The ground displacement in turn is largely influenced by the dynamic
properties of the ground and its modeling method. The ground exhibits a complete nonlinear
behavior depending on the strains developed in the ground due to the dynamic load. It is therefore
important to closely examine the nonlinearity of the ground relative to strains.
GTS NX
4
Substructure Method Direct Method
Dynamic SSI
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
Soil Structure Interaction
by Substructure Method
GTS NXSubstructure/Indirect Method
The soil-structure interaction is reflected with soil spring data.
The soil spring data may be applied to the substructure-only model with the
superstructure load applied.
The soil spring data may be applied to the entire structure model with both the super
and substructure.
GTS NX
7
Initial Civil model dimensions
GTS NX
8
Add Soil Springs Supports
GTS NX
9
Time History Analysis Case
3
1
2
GTS NX
10
Results for TH in Civil using PY springs
Max Axial forces on structure (kN)
Max moments on structure (kN/m)
GTS NX
11
Results for TH in Civil using PY springs
Max displacements (cm)
Max Shear Forces (Kn)
GTS NXSubstructure/Indirect Method
The substructure-only approach:http://Northamerica.midasuser.com > Training > Review Courses
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
Soil Structure Interaction
by Direct Method
GTS NX
14
• Análisis Pushover de un marco tridimensional usado para diseño. Puede ser utilizado para concreto reforzado, acero
estructural y secciones compuestas de concreto-acero.
• Diseño basado en desempeño por FEMA, Eurocódigo 8 y Mampostería
Análisis Pushover para Mampostería
Definir materiales no lineales de rotulasEstado de Rótulas y Curva de Capacidad
Interaction with other software
GTS NXTools to check or verify mesh quality
GTS NX
To provide more reliable analysis results, GTS NX can automatically generate
hexahedral centered hybrid mesh. Hexahedral elements are the most stable for
stress and displacement results.
Hybrid Mesher
GTS NXExtensive Constitutive Model Data Base
GTS NX
18
GTS NX&
Civil
Linear Equivalent
Time History
Response Spectrum
Eigen Value
Dynamic Analysis
• Free Field
• Linear (Direct)
• Linear (Modal)
• Non linear (Direct)
• Non linear + SRM
• Liquefaction
• Moving Load
• 2D Linear Equivalent
GTS NX
19
Linear Equivalent 1D and 2D
Weathered
soil
Landfill
Colluvial
Weathered
rock
Class I
RockBed
Rock
2D Linear EquivalentFree FieldDynamic Curve
GTS NX
20
Linear EQ (Free Field)
Short Time History Function (2 sec Analysis)
Max acceleration (12 m/sec^2)
GTS NX
21
Linear EQ
Add embankment to soil layer
Short Time History Function (2 sec Analysis)
Max acceleration (14.3 m/sec^2)
Integrated Solver Optimized for the next generation 64-bit platform
Finite Element Solutions for Geotechnical Engineering
3D Time History Analysis
GTS NX
23
Use same dynamic curve and time
history function
Dynamic SSI
Free Field 1D
Linear Equivalent 2D
Time History 3D
GTS NX
24
Define 3D LTH Material (Ground Only)
GTS NX
25
2
3D LTH Loads and Boundaries (ground only)
1 45
6
3
GTS NX
26
3D Linear Time History Results (ground only)
Results for Linear Time History is within 5%. Max of 11.8 m/sec^22 sec Analysis*
3
GTS NX
27
3D Linear Time History Results
GTS NX
28
• Análisis Pushover de un marco tridimensional usado para diseño. Puede ser utilizado para concreto reforzado, acero
estructural y secciones compuestas de concreto-acero.
• Diseño basado en desempeño por FEMA, Eurocódigo 8 y Mampostería
Análisis Pushover para Mampostería
Definir materiales no lineales de rotulasEstado de Rótulas y Curva de Capacidad
Interaction with other software
GTS NX
29
3D SSI
GTS NX
30
Import model to GTS NX
1
3
2
GTS NX
31
Mesh CAD in 3D elements
GTS NX
32
3D SSI Results
Results for Time History is within 5%. Max of 14.2 m/sec^2
3
GTS NX
33
Dynamic results for imported bridge
Max Axial forces on structure
Max moments on structure
GTS NX
34
Results Comparison
GTS NX
35
Bridge with updated substructure
Max Acceleration
GTS NX
36
Max Shear Forces
Max Displacements
Results for Bridge with updated substructure
GTS NX
37
Results for Bridge with updated substructure
Max Axial forces on structure
Max moments on structure
GTS NX
38
Max Civil GTS NX Updated Base
Displacements (cm) 29 28 23
Axial Force (kN) 3,064 2,036 1,762
Moments Y (kN/m) 19,087 23,969 16,127
Shear Forces (kN) 2,032 5,838 2,404
• Midas Civil has internal PY curves in order to easily apply soil springs and run soil structure interaction through substructure method. For some soils, this is sufficient.
• Substructure Method cannot accurately capture the non linear behavior experienced by the foundation and surrounding ground during an earthquake.
• Midas GTS NX can import full structure from midas Civil to run SSI through Direct Method. However, since the ground is modeled in 3D, it must first be calibrated through comparison of ground response analysis like Free Field and Linear Equivalent.
Conclusion
GTS NX
39
Other SSI problems (Adjacent Structure consideration)
GTS NX
40
Initial Stage Excavation stage 1
Excavation stage 2 Final Excavation stage
Adjacent Structure consideration during excavation
GTS NX
41
Moments on tunnel Axial forces on rock bolts
Axial forces on bridge Moments on bridge
Adjacent Structure consideration during excavation
GTS NX
42
Thank You
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