600kgf/cm^2級高強度コンクリートを用いたRC柱の実用せん断設計式(B.一般論文,開学20周年記念特集号)

In Japan, to realize construction of super high-rise and lightweight reinforced concrete buildings, the synthetic research project on ultra-high strength reinforced concrete structures has carried out under the leadership of the Ministry of Construction. A study on the shear strength of high strength reinforced concrete columns was conducted by the authors as a link in the chain of the project. Thirty column specimens using high strength concrete of 48MPa～120MPa grade and high strength longitudinal reinforcing bars of 700MPa～1000MPa grade and transverse reinforcing bars of 345MPa～1300MPa grade were tested. The variables investigated were the quantity and yield stress of transverse reinforcement and the level of axial load. Failure modes, crack observation, and strain distributions of transverse reinforcement are described. Diagonal tension cracking load using elastic theory, and ultimate shear strength obtained by plastic theory were compared with test results. The conclusions are follows; 1. A method is presented for calculation of ultimate shear strength to high strength concrete columns, based on the plastic theory, which gave a fair estimation of test result. The presented ultimate shear strength are functions of the factor of effective compressive strength of concrete; V_C and an upper limit of the yield stress of transverse reinforcement; V_S 2. The diagonal tension cracking load of high strength reinforced concrete columns can be estimated by using the elasticity. 3. The factor of an upper limit of the yield stress of transverse reinforcement ; V_S were estimated by the distribution of the maximum stress of transverse reinforcements on the ultimate shear strength stage. 4. Substituting ultimate shear strength from experiments and the factor of V_S estimated from experiments into calculation of shear strength based on the plastic theory, the factor of effective compressive strength of concrete ; V_C were estimated