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## Response of a line-like structure to a random load

version 3.0 (387 KB) by E. Cheynet

### E. Cheynet (view profile)

The time history of the displacement response of a line-like structure to Gaussian white noise is computed

Updated 31 Oct 2019

The submission contains:

- the function dynaResp_TD that computes the time history of the displacement response of a line-like structure to a given load.

- The function eigenModes.m used here to compute the mode shapes and eigenfrequency of a cantilever beam

- The file bridgeModalProperties.mat that loads the mode-shapes and eigenfrequency of a single span suspension bridge.

- 2 example files Example1.mlx and Example2.mlx

To keep the analysis as simple as possible, the structure has only one type of motion. No modal coupling is introduced and no added mass, stiffness or damping is included.

Any comments, suggestion or question is welcomed.

### Cite As

E. Cheynet (2020). Response of a line-like structure to a random load (https://www.mathworks.com/matlabcentral/fileexchange/66016-response-of-a-line-like-structure-to-a-random-load), MATLAB Central File Exchange. Retrieved .

E. Cheynet

### E. Cheynet (view profile)

Dear Maede,
Thank you for the feedback! The corresponding example file has been updated so that the model properties of the bridge are directly imported, without needing to call for the functions LysefjordBridge and eigenBridge. For your other comment, Ncoeff is the number of the coefficient for the from which are computed the mode shapes with the Galerkin method. These are neither the number of mode shapes nor the number of nodes, and this is why I use the variable name "Ncoeff". Ideally, Ncoeff should be much larger than the number of the highest mode. if Nyy is equal to Ncoeff in other submissions, it may be a coincidence. The absence of "t" in the function dYdT is indeed unnecessary (for the present case) and I have thus simplified the function. Note that in the updated submission, zetaStruct (the structural modal damping ratios) is also defined in a simpler way for the sake of clarity.

Maede Zolanvari

### Maede Zolanvari (view profile)

I found some bugs. First, I guess you forgot to include the LysefjordBridge and eigenBridge. However, they can be found easily through your other submissions, so no big deal :) Second, I guess the input of the eigenBridge(geometry,Ncoeff ), must be Nnodes (which is equal to Nyy in other submissions), rather than Ncoef. I don't think we need any Ncoef parameter here.
Another thing I wanted to mention is that in "dYdT" funstion, input "t" is not being used at all, not even in "Fun" or calculating the "k_i's," then why adding it as an input?
In Lysefjord.m, I think it's better to add "zetaStruct" as "Bridge.zetaStruct."
That's all I found for now. Keep the good work :)