This app was mentioned in 1 comment, with an average of 2.00 upvotes
Most of my work includes building planning and structural design of villas and apartment buildings up to 20 meters high. Here are two apps I use.
RCC Column Design - https://play.google.com/store/apps/details?id=com.ruksarkachchhi.columnsafetycalculator
RCC Slab Design - https://play.google.com/store/apps/details?id=com.flaminghawk.rccslabdesign