can I get seat in b.arch for 87 percentile

You haven't mentioned your Category or the State you belong to. Neverthless, going by the formula 100-87*112679/100 wherein 87 is your percentile and 112679 is the no.of Candidates who appeared for JEE Mains for January, your All India Rank would be approximately 14648. With this rank, a seat in Top Notch Colleges if you belong to General or OBC will be tad tough. You might have to appear for July session. Please visit our page for previous years cut offs : https://engineering.careers360.com/articles/jee-main-cutoff-for-b-arch-b-planning

Going by the formula, (100-87) x (112679/100) your approximate rank would be 14,648. Now if you are from general category, it would be difficult to to get seat in any NITs or SPAs as the cutoffs are usually high and all the seats get filled within 5000 rank almost. However, you can fill state level colleges for B.arch.Now if you are from any reserved category, then there are chances to get NITs. You can appear for the July session, and increase your marks. Try to score at least 98 percentile to get into the top colleges.
You can use our College Predictor tool to know where you have good chances-
http://engineering.careers360.com/jee-main-architecture-college-predictor