Abstract: The seismic damage of reinforced concrete (RC) frame structures during earthquakes has indicated that the widely used RC frame structures are lack of sufficient redundancy under earthquake actions. The damage of RC columns in a RC frame leads to its serious damage even collapses during a strong earthquake. If few steel braces are installed, the RC frame will become multi-fortification with steel braces as its first yielding structure elements and RC frame structure elements will be protected and its damage will be delayed. As a result, its safety margin and collapse-resisting capacity will be improved. According to a RC frame structure with few shear walls, this paper proposed the new conception of a RC frame structure with few braces. A typical RC frame structure and 3 RC frame structures with different braces are studied to achieve the definition of a RC frame structure with few braces based on the overturning moment carried by a frame part. With few steel braces, the collapse-resistant capacities of a RC frame structure is proved through a collapse fragility analysis based on an incremental dynamic analysis (IDA).