Modeling soil-structure interaction (SSI) with lateral and rotational springs in OpenSees involves defining the properties and behavior of the springs to simulate the interaction between the soil and structure. Considering the large variation of stiffness across various deposits or within the same soil, its required to conduct site or lab-tests to estimate a reliable value of stiffness
(direct or coupled stiffness) under proper drainage condition.
An SSI study with an incorrect stiffness would spoil the purpose of the study. Further, the designer need to have a good estimate of strain levels to assume a suitable value of damping.
0:00 Target Explanations
3:42 Free Vibration and harmonic Impact Loading Opensees Code
22:00 Dynamic Analysis Opensees Code
Here's a step-by-step guide to help you get started:
Define the Model Geometry:
Set up your structural model (e.g., a building, bridge, etc.).
Define the nodes and elements for the structure.
Define Material Properties:
Define the materials for the structural elements.
Define the soil properties if necessary.
Create Springs for SSI:
You need to define springs at the base of the structure to simulate the soil-structure interaction.
Lateral and rotational springs can be created using zeroLength elements in OpenSees.
For soils exhibiting elastic or elastoplastic behavior, the stiffness and damping ratio can vary significantly. Here are some general estimates:
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Stiffness (k in N/m)
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Clay soils: Stiffness can range from 5 MPa to 20 MPa (MegaPascals, equivalent to N/m²).
Sandy soils: Stiffness can range from 10 MPa to 50 MPa.
Gravelly soils: Stiffness can range from 20 MPa to 100 MPa.
Stony soils: Stiffness can range from 200 MPa to 1500 MPa.
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Damping Ratio (ζ)
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Clay soils: Damping ratio typically ranges from 5% to 15%.
Sandy soils: Damping ratio typically ranges from 2% to 10%.
Gravelly soils: Damping ratio typically ranges from 1% to 5%.
Stony soils: Damping ratio typically ranges from 0.5% to 3%.
These values are approximate and can vary based on factors such as moisture content, compaction, and the presence of organic material. For accurate assessments, it's best to conduct site-specific geotechnical investigations.
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Report Text for Better Learning Soil-Structure Interaction for Building Structures
https://www.nehrp.gov/pdf/nistgcr12-917-21.pdf
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Download Content Link:
https://github.com/salardelavar/OPENSEES_SALAR/tree/main/SOIL_STRUCTURE_INTERACTION
SEISMIC PDF CODE:
https://github.com/salardelavar/OPENSEES_SALAR/blob/main/SOIL_STRUCTURE_INTERACTION/SEISMIC_LOADING/PDF_OPENSEES_SOIL_STRUCTURE_INTERACTION_COLUMN_SEISMIC.pdf
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Personal Website:
http://salardqashqai.blogfa.com/
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