Hello aspirant,

Well to get a seat in NITs, you have to first clear the required cutoff as per your category. The 2019 JEE Main cutoff for ST category is 44.33 perecntile, where as you have got 85.63 percentile. So as per the rules you are JEE Main qualified. Now to get seat in NITs, you have to attend the JoSAA counselling process. Since you have given JEE Main paper 2, so I have listed the NITs which have B.Arch course along with the closing rank for previous year for ST category - 

• NIT Jaipur : 498 (Home State), 51 (Other State)
• NIT Bhopal : 439 (Home State), 139 (Other State)
• NIT Calicut : 229 (Home State), 84 (Other State)
• NIT Hamirpur : 486 (Home State), 122 (Other State)
• NIT Patna : 560 (Home State), 170 (Other State)
• NIT Raipur : 478 (Home State), 159 (Other State)
• NIT Rourkella : 47 (Home State), 111 (Other State)
• NIT Tiruchirappalli :  596 (Home State), 42 (Other State)
• NIT Nagpur : 57 (Home State), 119 (Other State)

Note : The above mentioned cutoffs are 2018 JEE Main paper 2 cutoffs. 

You can go through this link and checkout the details regarding JoSAA counselling : https://engineering.careers360.com/articles/josaa-counselling

Hope you get your choice of college. Good Luck !!!!