Filling a steel tube with concrete strengthens flexural strength of a tube, but it also makes the tube brittle. To prevent steel tube failure due this brittleness, there are two kinds of reinforcement methods, i.e., putting reinforcement bars in Concrete Filled Steel Tubular (CFT) or welding semicircular steel around the tube on the outside. These two methods are evaluated by two types of experiments. First, the weight dropping test is carried out to damage the reinforced CFT, and then the static cantilever bending test is performed to measure the residual performance of the damaged CFT. Comparing with the result of non-reinforced CFT, the reinforcement effect concerning ductility is investigated.