Recent content by javimm

That's exactly was my initial toughts when I purposely left the third frequency out. As the model is way simplistic, I tought that the only frequency that I had to consider was the first as it was the one I imposed from the beginning. As you mentioned, I had some doubts if the third one could be...

AlephZero, thanks for the insight. The object of the problem is modelling a simplified version of the towers, obtaining their approximate physical properties (density, E, etc) knowing their dimensions and the period of the first mode. With that, a model of the tower can be made. More data is...

First and second natural frequency of the model is 0.1 Hz (T=10s). It's one of the imposed data of the exercise (see my previous post). Third mode is 0.571 Hz.

Yes, indeed. The tower is modeled as a simple cantilever beam, using the first normal mode of T=10 s in order to obtain the physical properties. No floors or columns are modeled, just the beam with a fictional material that makes the tower has the desired mass and first normal mode. It's a very...

Yes, sorry about that. As I said there was an error in the data I entered into the program. Now I've tested the areas and values directly in the software and they do match what they are supposed to be. - With constant acceleration, maximum deflection is 0.4 m - With linear acceleration, maximum...

I've found a typing error in my first and fifth posts that I'm going to correct. As you said, both areas are the same. I've checked the numbers I've used in the software and they seem to be correct, but there is a difference between the two deflections. I guess using these two assumptions can...

That's what's driving me crazy. In theory both solutions should lead to very similar results, but they don't and by a large margin. I spotted a mistake on my part using the software, and the deflection is not several meters, but they one is twice the other (see below). The area under the F-t...

That is caused by rounding error from converting the plane speed from km/h to m/s. It dooesn't change the result by much though.

The problem comes up as part of a final master's project in FEM analysis. The project consists in calculating the oscillation response of the World Trade Center towers after the plane impacts. The particular problem I'm having trouble is that I need to transform the plane impact of which mass...