Camelia,
I have checked the issue. Followings may help you.
1. About Cf: If you are using IS-875, then you must follow table:23 for Cf. Before PV Elite 2010 version this facility was not there in form of check box as said by Mandeep. You must follow value of Cf from table:23 of IS-875 Part-3 as same is higher than 0.7. Remember one thing mostly client's specifications are general.
2. About K2 : One thing you must understand that when you are using said IS Code without gust factor then value of K2 would be 0.9839 upto 10 m for Class-B, Category-2. If your geometry or client's requirement calls for gust factor consideration then check the box in PV Elite. Once you check the box then automatically it will read the value of K2 from table:33 as said by Mandeep because as per IS-875, Part-3 for gust factor method K2 value shall be from Table:33. So PV Elite is correct here.
3. About Clients Data: As I said above, mostly client's specifications are general. If you are designing without gust factor then table:2 is applicable for K2 and if you are designing with gust factor method then talbe:33 is applicable. If your Cf value from IS Code is coming higher than client's specified value then you need to follow the Code.
4. Different K2 which are not tabulated: PV Elite also interpolate values for different heights other than that tabulated in the values...
So you may not get exact values as tabulated in the IS Code.
5. Wind Loads Reduced by factor of 2: It is difficut to say that loads are reduced by factor of 2 just switching over from PV Elite 2009 to PV Elite 2010...If your gust factor check box was checked in 2009 version as well as in 2010 version then your loads would be increased with the tick on check box of "Compute Cf from table-23" as Cf is increasing form 0.7 to higher value. But Cf from table-23 is not taken then your PV Elite 2009 files is required to check the issue how loadings is reduced by a factor of 2.
Hope this clarifies your all queries.
Don't follow client's requirement blindly. Read it, think on the same and if required then ask them to change there inputs if same are conflicting with Code requirements and Code requirements are conservative.
Thanks.
Mukesh
www.theculminates.comM:+91-9428500192