A system is developed for simulating the collapse behavior of reinforced concrete frame structures from seismic loading. The purpose for developing this system is that the whole process from elastic-plasticity to collapse is modeled in the analysis. Consequently, the collapse mode, the collapse duration, the distribution of the debris after collapse and other information can be obtained. The numerical analysis is based on the distinct element method. The element shape is assumed to be rectangular solid, which is based on the cross section of the structural members. The elements are connected by dummy springs. The impact action among concrete blocks after the connecting springs fail is taken into account by the impulse models of impact, which are derived from the results of the experiments and the numerical tests. A comparison between a shaking-table test and the analysis is presented, which shows that the results of the simulation are in good agreement with the results of the experiment.