www.sefindia.org

[er.saurabhrshah]

Hello everybody, I recently checked the earthquake forces in staad by manual method and found that the earthquake forces generated by staad pro v8i are exactly half of what it should be.

After trial and error, I found that while we are giving parameters for earthquake it asks us for damping ration in percentage (Which should be 5% for concrete usually) but instead in calculations it takes 500% damping and as per IS 1893 Part 1:2002
If the damping value exceeds 30% earthquake forces are to be reduced to half.

So, for correct earthquake forces instead of 5% we need to give 0.05% in parameters for damping ratio and then all the forces are correct.


If same problem is being encountered by SEFI members then please specify or if i am doing something wrong then also please comment.

[rehan_nayeem]

Hi Saurabh

Yes the damping ratio in staad has to be given as DM 0.05.

Regards,
Rehan

[P.K.Mallick]

This is a problem in STAAD PRO 2007 also. The damping ratio has to be 0.05 both in STAAD PRO V8I and STAAD PRO 2007.