The OpenSees finite element platform (Open System for Earthquake Engineering Simulation) developed through the University of California Berkeley is the principal collaborative software identified by QuakeCoRE Technology Platform 4 for use in detailed seismic response modelling of individual infrastructure components. OpenSees was selected for this purpose due to its capabilities as an open-source platform for sequential and parallel analysis of both geotechnical and structural systems. OpenSees is one of the few tools available with all of these attributes, and due to this unique combination of features it meets all three of the underlying principles identified for QuakeCoRE Technology Platform 4: it is open-source, it is scalable (able to make use of HPC resources), and it is flexible (works for variety of problem types and able to work with other QuakeCoRE software modules).