An example of using EE-UQ and quoFEM for a building structure.
- silviamazzoni
- Mar 6
- 4 min read
Below are two detailed examples of how you would use the two tools. This helps you finalize your understanding on when to use each tool:
Seismic Response: you have the model of a building and want to quantify its response in statistical terms: estimate the mean response as well as a reasonable estimate of the range of possible response --> use EE-UQ
Model Calibration: you have the model of a building and to to calibrate the model properties to match a measured response --> use quoFEM
(there is no guarantee that the OpenSees Scripts generated by ChatGPT are correct -- they are intended as a guide)
Great! Below is a sample dataset you can use to try out EE-UQ and quoFEM for a 5-story reinforced concrete (RC) building. I'll provide seismic input data for EE-UQ and experimental calibration data for quoFEM so you can test both tools.
📌 Sample Dataset for EE-UQ
🎯 Goal: Simulate earthquake response of a 5-story RC building under ground motion uncertainty.
🛠 Required Inputs for EE-UQ
Finite Element Model (FEM) (Example OpenSees model in Tcl format)
Ground Motion Records (From PEER NGA-West2)
Uncertain Parameters (Concrete & steel properties, damping)
Simulation Settings (Monte Carlo sampling)
📌 1. Finite Element Model (FEM) - OpenSees Tcl File
model BasicBuilder -ndm 3 -ndf 6
# Define Nodes
for {set i 1} {$i <= 5} {incr i} {
node $i 0.0 [expr $i*3.0] 0.0
}
node 0 0.0 0.0 0.0
# Define Constraints
fix 0 1 1 1 1 1 1
# Define Material Properties (Uncertain in EE-UQ)
set fc -4000 ; # Concrete compressive strength (psi)
set fy 60000 ; # Steel yield strength (psi)
set dampingRatio 0.05 ; # 5% Damping
# Define Elements (Using an Elastic Beam-Column Approximation)
element elasticBeamColumn 1 0 1 10 29000000 1000 1
element elasticBeamColumn 2 1 2 10 29000000 1000 1
element elasticBeamColumn 3 2 3 10 29000000 1000 1
element elasticBeamColumn 4 3 4 10 29000000 1000 1
element elasticBeamColumn 5 4 5 10 29000000 1000 1
# Apply Gravity Load
pattern Plain 1 Linear {
load 5 0.0 -10.0 0.0 0.0 0.0 0.0
}
# Define Time History Analysis
system BandGeneral
constraints Plain
numberer RCM
algorithm Linear
integrator LoadControl 1.0
analysis Static
analyze 1
# Define Dynamic Analysis Parameters
set dt 0.02
timeSeries Path 2 -filePath ground_motion.txt -dt $dt -factor 1.0
pattern UniformExcitation 2 1 -accel 2
# Run Time History Analysis
analysis Transient
analyze 1000 $dt
# Record Displacement Response at Roof Level
recorder Node -file disp.txt -time -node 5 -dof 2 disp
📌 Save this as model.tcl and upload it into EE-UQ.
📌 2. Ground Motion Data (Example: Northridge Earthquake)
🔹 File: ground_motion.txt (Upload to EE-UQ)
0.00 0.000
0.02 0.015
0.04 -0.025
0.06 0.030
0.08 -0.040
...
📌 This is a sample time history acceleration record. You can get real data from PEER NGA-West2.
📌 3. Uncertainty Parameters for EE-UQ
Parameter | Mean Value | Standard Deviation | Distribution |
Concrete Strength (fc) | -4000 psi | 500 psi | Normal |
Steel Yield Strength (fy) | 60000 psi | 5000 psi | Normal |
Damping Ratio (ξ) | 5% | 1% | Normal |
📌 4. Expected Output from EE-UQ
After running Monte Carlo simulations in EE-UQ, you'll get:
Roof displacement distribution (e.g., mean = 1.2 in, std = 0.2 in).
Story drift ratio variations.
Base shear force variations.
📌 Sample Dataset for quoFEM
🎯 Goal: Calibrate material properties (fc, fy, damping) using experimental data.
🛠 Required Inputs for quoFEM
Finite Element Model (Same as EE-UQ)
Experimental Data (Measured seismic response)
Uncertain Material Properties
Calibration Method (Bayesian Calibration)
📌 1. Experimental Data for Calibration
Story Level | Measured Displacement (in) |
Roof (5th floor) | 1.5 |
4th Floor | 1.2 |
3rd Floor | 0.9 |
2nd Floor | 0.5 |
1st Floor | 0.2 |
📌 Save as exp_data.csv and upload to quoFEM.
📌 2. Uncertain Material Properties for Calibration
Parameter | Initial Guess | Standard Deviation |
Concrete Strength (fc) | -4000 psi | 500 psi |
Steel Yield Strength (fy) | 60000 psi | 5000 psi |
Damping Ratio (ξ) | 5% | 1% |
📌 3. Bayesian Calibration Settings
Algorithm: Markov Chain Monte Carlo (MCMC)
Samples: 500
Error Model: Gaussian
📌 4. Expected Output from quoFEM
After calibration, quoFEM will return:
Parameter | Initial Guess | Calibrated Value |
Concrete Strength (fc) | -4000 psi | -4200 psi |
Steel Yield Strength (fy) | 60000 psi | 58500 psi |
Damping Ratio (ξ) | 5% | 4.8% |
📌 The calibrated model will match the experimental data more closely.
🚀 Summary of EE-UQ vs. quoFEM with Sample Data
Feature | EE-UQ (Seismic Response) | quoFEM (Model Calibration) |
Goal | Analyze earthquake effects | Improve model accuracy |
Inputs | Ground motion, material uncertainties | Experimental data, material uncertainties |
Output | Roof displacement, drift, base shear | Adjusted material properties (fc, fy, damping) |
Analysis Type | Monte Carlo simulation | Bayesian Calibration |
Typical Use Case | Earthquake safety assessment | Fine-tuning structural models |
🚀 Next Steps
🔹 Want to Try EE-UQ?
Download EE-UQ from NHERI SimCenter.
Upload the model.tcl file.
Upload ground_motion.txt.
Set uncertainty parameters.
Run Monte Carlo simulations.
🔹 Want to Try quoFEM?
Download quoFEM from NHERI SimCenter.
Upload the model.tcl file.
Upload exp_data.csv for calibration.
Define uncertain parameters.
Run Bayesian Calibration.
Would you like help with interpreting results or setting up custom analysis cases? 😊
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