All I can understand from your post is that you are doing a comparison between two codes for Saudi and trying to find out quantitative difference of base shear? Also, I believe you want someone to check your numbers?
Before you do that you need to understand the differences between UBC and IBC Seismic Design Philosophy; you aren't comparing apples to apples if you just compare numbers. There is a lot different between two codes. Both codes design to a different Maximum Considered Earthquake (MCE). Considering everything is constant, IBC will give you a higher base shear. Read the attached article:IBC and UBC Comparison.PDF
Use the method provided in code to identify your seismic response coefficients. Ss=Ground acceleration at short (0.2 second) period, which will allow you to determine Sms and subsequently Sds. Code outlines the procedure to calculate all these components. I don't know why are you calculating Ss like you did.
Documents attached are result output, and calculation is not attached. Without a calculation, no one knows how you came up with the numbers. My best advice to you, to check your numbers is to compare them with a solved example. You can't go wrong.
