Recently, it is easy to produce concrete with compressive strength more than 1 000 kgf/cm2 by use of silica fume. However, the mechanical properties of RC members using such ultra high strength concrete have not known sufficiently. The purpose of this study is to investigate experimentally and analytically the mechanical properties of ultra high strength concrete beams subjected to pure bending moment. As a result, the evaluation methods of flexural capacity and of minimum steel ratio of such beams are proposed, and it is confirmed that ρ/ ρb (ρ : tensile steel ratio, ρb : balanced steel ratio) is a main factor influencing the ductility of such members.
