This tutorial is also available for Matlab in:
echodemo TutorialBridgeModel

Tutorial for the graphical user interface
File -> New -> Tutorial -> Tutorial 6. Bridge Model (see also Import Tutorial)

Problem definition

In this tutorial the global sensitivity analysis is applied to a practical problem in structural engineering: a mechanical model of a long bridge.

The conceptual model is sketched below.

This model is interesting for several reasons, which makes it suitable for an example application of the total sensitivity analysis and their upper bounds. The conceptual model contains 123 uncertain parameters. All the uncertain parameters are considered to be uncorrelated. The bridge is subjected to a harmonic load with a frequency of 10 Hz, applied at the mid point of the 3rd bay. The aim of the analysis is to identify the parameters that affect the variance of the maximum displacement of any points of the bridge as well as the parameters that have negligible effects. It is important to note, that in order to avoid unrealistic values of the input parameters during the simulation, truncated normal distributions are used.

Input data

Random Variables

Heights h: normal distributed with mean $\mu=0.001 m$ and coefficient of variation 0.05.
Young's modulus E: normal distributed with mean $\mu = 21.0 GN/m^2$ and coefficient of variation 0.03.
Length l: normal distributed with mean $\mu=0.36 m$ and and coefficient of variation 0.05.
Stiffness k: normal distributed with mean $\mu=200 Nm$ m and and coefficient of variation 0.10.
Rotation stiffness w: normal distributed with mean $\mu=40 Nm/rad$ and and coefficient of variation 0.16.
Damping c: normal distributed with mean $\mu=0.4 m$ and and coefficient of variation 0.25.