Time period depends on stiffness of the column and if you are not modifying the stiffness after use of FRP the time period will be same.

I agree with Om Prakash sir. But the column will get strengthen after application of FRP and it increases the stiffness of column. If stiffness is increasing, the time period will reduce. But this is not happening If I apply FRP. Please calrify my question sir.

Thanks

Sai

I don't know which software you are using as most of the software's calculate stiffness on the basis of material property and dimensions. Whether you are considering effects of FRP on dimensions and material property and whether this effect is reflected in stiffness calculation in the software.

If that is happening you are bound to get different time.

You may get more information from the article attached

Thank you sir

I am using Open Sees software. I observed that the stiffness due to FRP is not taking in to consideration while calculating time period of column. The time period of column is mainly based on dimensions and elasticity of concrete.

Thank you

Sai

Respected professor

The response of retrofitted column under ground motion will be constant If time period of column is not changing after the application of FRP. This is what happening in my case.

In the other hand, If the column is strengthened due to application of FRP, the response of retrofitted column should reduce. I am not getting the logic. Please help me sir.

Thank you

Sai

The increse in ductility and confinement of concrete will result in to more capacity in absorbing energy and therefore time period of vibration must increase rather then decresing as per your statement above. You may read the conclusion of paper attached.

Additional references are available on this topic in large number but the attached one is quite useful.