I want to know why scaler multiple of 1.3 is used while doing calc with IS:1893-2005 in PV-elite:2009

The reason is that Indian seismic code instructs to consider the horizontal load in one direction plus 30 % of load in the other horizontal direction.

Since a vertical pressure vessel is symmetric, we apply a 1.3 multiplier for the seismic load to add in the effect of the other horizontal direction.

Sir,

As i have seen these load multiplier (1.3) affects seismic loads not wind loads as described by you above.If it is described in wind code then wind shear should increase not seismic base shear. This is my first aspect.But in pv-elite output it affect seismic shear.

My second aspect is that i have read the pv-elite manual of PV ELITE 2008 JANUARY issue, page no 172 and after rading that my understanding says that it can be used as to compare compressive allowable stresses of equipment but sesmic base shear should not increased by 30% i.e equipment foundation should not be designed 30% more load than actual base seismic shear.

In the conclusion of above i want to say that 1.3 factor may be used in combined loading analysis but semsmic shear should not increase.

Regards
Mukesh kalra

Hi Mukesh,

My apologies I meant to say Seismic code in my earlier post. If you go to 7.3.2.1 of IS 18993 (Part 4) 2005 (latest at this time) you can see the 0.3 for the other direction.

You also get 20% increase in the allowable for occasional loads such as wind and seismic.

Sir,

Now the thing is too diffrent.

Equation 7.3.2.1 IS applcable to partial safety factor for limit state design of reinforced concrete & prestressed concrete.

So for stacks is not applicable i.e if our column is chekning on 30 % increased earthquake loads it is not right. The equation given shall be applicable for rectangular or octagonal etc i.e non symmetrical shape structures. fOR THIS EARTHQAUKE EFFECT CAN BE ADDED IF EARGQUAKE FORCE NOT IN THE LINE OF 'X' 'Y' & Z DIRECTION THEN THIS SAFETY CONSIDERATION IS OK .

BUT FOR CIRCULAR COLUMN IT ALWAYS LIES ALONG THE RADIAL DIRECTION AS IT IS SYMMETRICAL SHAPE. For stack like structure we should refer section-2 refer page -13 of IS-1893 PART-4 (2005)

But for circular shape column it is not applicable, Plesae check once again. We are facing lot of ploblem . PLease revert back.

Mukesh Kalra

IN CONCLUSION OF ABOVE I WANT TO SAY THAT 1.3 SHOLD BE USED FOR NON SYMMETRICAL SHAPE BODIES. FOR EG. IF A RECTANGULAR SHAPE STRUCTURE IS AGAINST EARTHQUAKE FORCE ALONG THE DIAGONAL OF RECTANGLUAR FOR THAT CASE 1.3 FACTOR IS USED FOR SAFETY. BUT FOR STACK LIKE STRUCTURES , CIRCULAR COLUMN EARTHQUAKE FORCE ALWAYS ALONG RADIAL AXIS SO FOR THAT 1.3 SHOULD NOT CONSIDERED.

REGARDS
MUKESH KALRA

hello mandeep,

please reply us it should be used or not. Our company is a regular customer of PV ELITE & we are using in PV ELITE in many projects. Please revert back.

Mukesh,

We have been occupied. I need to investigate this. But, in PV Elite you can always override the 1.3 factor and put 1.

Mr. Kalra,

If you want to use factor 1, then you can use it by overriding its value. based on your knowledge of IS 1893.

If I will get time then I will reply you in detail for the above.

Thanks.

Mukesh Chopra
www.theculminates.com
M: +91-9428500192

Mr.Chopra

I think its not the matter of overriding of factor 1.3 . Actualy what the maater is in our projects there are so many columns of 1762000 kgs OF OPERATING WT. Now due to this 1.3 ,directly seismic load is increasing by 1.3 times. So just think how much affect of 30% in these higher opearting condition. wt.

Its not my wish to use 1. Its the matter of right kind of output which we are giving to civil to make foundation.

This is not my prediction . MANY PROPLE HAVING SAME THOUGHT ABOUT THIS.

So i request you once again please calrify this so we can move further in right direction.


THANKS
Mukesh kalra