OpenSees

A computational environment for structural and soil-structure analysis, developed originally for earthquake engineering research at UC Berkeley. Models are written as scripts rather than built in a graphical interface, and that is exactly its strength: nonlinear materials, fibre elements and time-history dynamic analysis at a level of control commercial tools do not offer. It is common in thesis work and academic research, and requires familiarity with Tcl or Python. Anyone willing to accept the learning curve gets research-grade analysis with no licence cost.