is thesis focuses on the behavior of the CD20 building system during an earthquake. In order to calculate the forces on the system, first a detailed model was constructed of the characteristic CD20 connection in Diana. This model was used to determine the stiffness of the connection. This stiffness was then transferred into a model of the whole building in SCIA engineer. Using a response spectrum analysis the behavior of the system could be determined. The system can withstand seismic loads up to a degree and with a minor adaptation it can withstand larger earthquakes as well.