Abstract
In the preceding paper which was reported in Transaction of A.I.J. No. 55, Feb. 1957, the author showed conclusively that the final failures of composite beams ware seriously affected by the capacity of inner steel beams. In these tests, beams which had held rich steel beams compared with the volume of concrete were used. Experimental and analytical studies reported in this paper have been shown in the case of beams having poor steel beams. These were small model tests. Both series A with 6 simple beams having steel beams and reinforcing bars and series B including 12 restrained beams failed in shear. The studies have shown conclusively: (1) The maximum loads of beams with poor steel beams and the deformation for the maximum loads were both similar to those of equivalent reinforced concrete beams. (2) In respect of the expression of the ultimate strengths for such beams as in preceding paper which failures had been accompanied with large deformation and serious damage of "web concrete" the author analysed again. Hereby, it was shown that the expression might be appricable for the load carrying capacity of beams with poor steel beams which raised large deformation after maximum loads and formation of serious cracks of "web concrete". (3) It was found that the final tenacity of beams, that is say, the energy absorbed at the collapse of structural members must be affected by the inner steel beams. Therefore, if the rich steel members were used, the composite structure might be most appropriate for earthquake proofing construction of high buildings.
