Abstract: This paper firstly provides a short summary on the current research status on the numerical studying of low-ductility reinforced concrete (RC) frames and their related components, such as columns and joint subassemblages. Then detailed numerical modeling approaches of these key components using a truss model are provided and evaluated using several experiments. Finally, a numerical substructure method (NSM) developed in OpenSees is employed to build the detailed substructure model for analyzing a damaged RC frame subjected to Wenchuan Earthquake, and its aseismic performance and failure mode are studied in a detailed way according to the local performance. This study indicates that: the truss model performs well in simulating the nonlinear behaviors of columns and joints, especially to predict the brittle failures; numerical substructure method has great advantages, such as good numerical stability and applicable refined models, to study the performance of low-ductility RC structures; from the analytical results of damaged RC frame, it can be found that displacement or inter-story drift should not be the only criterion to evaluate the low-ductility structures, and instead the possible brittle failures must be considered in the aseismic analysis.