Understanding the dynamic load factor (DLF)

[Tygra]

Homework Statement

What is it and how to calculate it

Relevant Equations

In post

Dear all,

I am currently going through the book called "Essentials of Structural Dynamics" and I have come to a parameter known as the Dynamic Load factor (DLF for short). I am having trouble understanding what this is and how you calculate it for a given problem.

What's confusing is there are different equations to calculate it. I have cut out the equations that are in the book for you to see.

So, I am hoping that someone could help me with this?

Many thanks in advance,

Tygra

 

[Lnewqban]

I am currently going through the book called "Essentials of Structural Dynamics" and I have come to a parameter known as the Dynamic Load factor (DLF for short). I am having trouble understanding what this is and how you calculate it for a given problem.

Dynamic load factor quantifies the ratio of the dynamic load to the static load.

Dynamic loads add to the static ones and induce oscillations or waves or abnormal deflections (greater than produced by static loads) in concrete and steel structures.

Experimental testing or analytical methods are usual methods to estimate how much stiffer or stronger a structure must be that it would for resisting static loads only.

Please, see:
https://en.wikipedia.org/wiki/Structural_dynamics

https://en.wikipedia.org/wiki/Dynamic_amplification_factor

https://en.wikipedia.org/wiki/Resonance

"A dynamic load can have a significantly larger effect than a static load of the same magnitude due to the structure's inability to respond quickly to the loading (by deflecting). The increase in the effect of a dynamic load is given by the dynamic amplification factor (DAF) or dynamic load factor (DLF)."

"The natural frequency of a system is dependent only on the stiffness of the structure and the mass which participates with the structure (including self-weight). It is not dependent on the load function.

It is useful to know the modal frequencies of a structure as it allows you to ensure that the frequency of any applied periodic loading will not coincide with a modal frequency and hence cause resonance, which leads to large oscillations."