Bond and anchorage problems in advanced reinforced concrete systems with the use of high-strength materials

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This research deals with the bond and anchorage problems which arise in the development of advanced reinforced concrete building system with the use of high-strength concrete up to roughly 100 Mpa and high-strength reinforcing steel up to roughly 1000 Mpa. The main results of this research can be divided into four categories as in the followings.1. The influence of surface deformation of rebars on bond characteristics.Six types of configuration of rebars, three levels of concrete strength and three levels of lateral confinement against splitting action of rebars were combined as the test variables in pull-out tests of test bars having short embedded length of three times rib pitch. From these test results, the constitutive law of bond-slip including the effect of lateral stress and longitudinal crack width could be established.2. Bond splitting strength in R/C members with high-strength materials.Bond splitting failure tests were performed by the use of simply supported beam specimens with the emphasis on the effects of concrete strength, amount and arrangement of lateral rein-forcement, and development length. From the test results, the experimental equation which predicted the bond strength for extensive combinations of variables could be derived.3. Anchorage capacities of 90 degree hooked bars.Anchorage capacities of 90ﾟ hooks of high-strength bars were studied for a wide range of variables. A design equation which provided for many variables was proposed from the results.4. Bond deterioration of beam bars passing through joint region.A new test method which simulated the bond behavior of single beam bar in a joint was developed. From extensive test results, a bond design equation of bean bars in joints of week-beam and strong-column frames was proposed.