You have asked this repeatedly before as a question and two previous discussions on e.g. "How to find natural frequency of a bridge from vehicle induced vibrations?". You should not leave your own discussions and questions and start them again and again. I will not answer here because I gave a detailed answer of the moving contribution to mass and stiffness already at the first of your 2 discussions https://www.researchgate.net/post/Effect_of_mass_on_the_frequency

Mateen Ali, asking the same questions here repeatedly again is not a good habit. You don't give further details for a deeper discussion. Do you expect, somebody will snip the fingers and solve the problem for you? You are wasting peoples spare time.

Dear Faran,

I hope the following paper will help you answer your question.

Link: Article Experimental monitoring of bridge frequency evolution during...

Regards,

Pravin