Abstract
This paper is reports the results of tests on general properties of the composite structure which has been developed for earthquake proofing construction of high buildings in our country. In those tests 30 beams almost full sized were used and studied on failures of concrete forming the greater part of web construction of beams, which are characteristic of this structure. The results obtained are: (1) The behavior of beams prior to formation of diagonal cracks was similar to those of reinforced concrete beams. And the behavior after formation of diagonal cracks was also essentially equivallent to reinforced concrete. (2) The final failures were accompanied with large deformation and serions damage of "web concrete." The final deformation was about tentimes that of reinforced concrete beams failed in shear. Therefore, it might be said that inner steel beams made a remarkable contribution to final tenacity. (3) With respect to ultimate strength after such deformation of beams, it might be found that beams were seriously influenced by strength of inner steel beams and then ultimate strength of beams were presented by sum of capacities of the steel beam and the effect of surrounding concrete. (4) Regard to the relationship between the strength of composite beam and beam with equivalent reinforcing bars, there are some questions being left for further studies. These will be expected to a subsequent report.
