Civil Engineering/stuctures modes


Dear Sir,

     As I understand(please correct me If I am wrong) natural frequency of a structure is the frequency at which it starts vibrating, when disturbed, and the corresponding shapes of its vibration are called modes,
Now in practical in order to get the natural frequency of a structure it should be disturbed, what is the reference of this disturbing force taken as,
Now modes are the shapes/ pattern in which the structure responds to the disturbance. What is the meaning of first mode, second mode, third mode, are they,  the successive response patterns of the structure to the same single disturbing force.

Example:  when I disturbe a object(say a starched thread or a hand held scale) its first distinguishing shape of vibration(i.e First mode), then as it decay, its second most distinguishing pattern of vibration as second mode and so on.


Dear Faisal

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Babak Esmailzadeh Hakimi


I can answer questions in Structural Engineering, Earthquake Engineering, Project Management and Project Control topics!


I am experienced in the area of earthquake engineering in electrical power industry, i.e. Lifeline Earthquake Engineering. My focus has been on structural seismic design of power installations. Recently I have got involved in project management in the category of constructional engineering.

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Bs degree in Civil Engineering from Ferdowsi University ,1988, Mashhad Iran, Ms degree in Earthquake Engineering, Sharif University of Technology, 1993, Tehran, Iran

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