Anand23404
Mechanical
- Jan 31, 2012
- 17
I have a problem while designing a tank for Seismic Analysis as per API 650, 2013.
The tank is located in India hence the applicable code for Seismic is IS-1893 & Zone given is V. For zone V the value of z is 0.36.
My concern is how to calculate the values of Ai & Ac, where Ai is Impulsive design response spectrum acceleration coefficient & Ac is Convective design response spectrum acceleration coefficient?
Should I use the equation for Ai= z/2*I/R*Sa/g [IS 1893]?
Or do I have to use the equation which is given in Appendix E of API 650?
If API 650is to be followed, then how to calculate the values of Ss, S1 , SDS & SD1 in terms if IS 1893?
The value of Ai calculated as per IS 1893 becomes much less than the calculated value of Appendix E, which in turn affects on the seismic moment. Because of the increased seismic moment mechanical anchorage is required & also the maximum longitudinal shell compression stress [E.6.2.2.2 of API 650] at the bottom of shell exceeds the allowable stress [E.6.2.2.3 of API 650] which in turn needs to increase the thicknesses of shell courses.
Kindly guide me through the equations to consider.
Regards
