STRAP is described as '(STRuctural Analysis Programs) is a Windows based suite of finite element static and dynamic analysis programs for buildings, bridges and other structures. It also includes modules for the design of steel sections (rolled and cold formed) and reinforced concrete (beams' and is an app. There are more than 25 alternatives to STRAP for Windows, Linux and Mac. The best STRAP alternative is Robot Structural Analysis Professional. It's not free, so if you're looking for a free alternative, you could try SkyCiv Structural 3D. Other great apps like STRAP are RISA-3D, Etabs, SAP2000 and GT Strudl.