The authors designed 8 beams in accordance with the ultimate strength design and experimented them in the state of two multiple loadings. We measured strains and deflections of simply supported beams, and added consideration to them, defined the failure into three boundaries, which are bending, bending-shear (shear-bending), shear failure. The judgement by a/d of the failured boundary and by the theoretical equation of the ultimate bending moment nearly agreed with the results from the experiments, and then we calculated the tensile stresses of main steel bar and compared with the measured stresses.