Experiment Study In Anchorage Behavior Of Headed Reinforcement

The studies of headed reinforcement recently and the trend of product developing are introduced in this paper. We mainly investigate the anchorage property of headed reinforcement in reinforced concrete through three parts of research:98 pull-out tests was designed and finished. Based on measurement of ultimate load and slip deformation of specimens, factors which affect the anchorage behavior of headed reinforcement such as stirrup, cover, compressive strength of concrete, diameter of bars, embedded length etc are studied. Anchorage property of rebars with conventional 90°bent hooks or anchorage plate are compared.21 concrete prisms with headed reinforcements embedded in pull-out or push-out tests was designed and finished. For different embedded lengths of headed reinforcement, based on measurement of the un-balanced load on the anchorage plate, the load transfer mechanism and anchorage character of headed reinforcement are analyzed. The load distribution of bond and mechanical anchorage is studied. The theory and test base for production or design of anchorage plate are given.4 full-scale beam-column knee or exterior joint tests were designed. Joints for test contain bars with conventional 90°bent hooks or anchorage plate. Joint specimens will be under the cyclic load. Based on measurement of stress of longitudinal bars in different loading stages, shear deformation of core area of joint, envelope curve, the anti-seismic performance of these new joints which contain headed reinforcement will be investigated. Ductility and energy dissipation capacity of exterior joints which contains bars with 90°bent hooks or anchorage plate will be compared.The creative results are as follows:The anchorage property of headed reinforcement is studied systematically. Based on the test investigation, it can be concluded that the main factors which affect the anchorage behavior of headed bars are compressive strength of concrete and cover. The load added to the headed reinforcement consists of peak head bearing and reduced bond.Anchorage plate which includes a circle plate and a hexangular nut is originally used in this paper. Using this kind of anchorage plate, the anchorage property of bars is improved, the material for producing the anchorage plate is reduced and the installation will be easier.A few kinds of knee joint and exterior joint with new type of detail are presented. Based on the evaluation of the test results, it will be proved that if these kinds of new joints are feasible in civil engineering practice or not.According to the study of basic behavior, the conclusion is that headed reinforcement has the same or better anchorage property than bars with conventional 90°standard bent hooks. It is also proved that the use of headed reinforcement in place of bars with conventional 90°standard bent hooks is feasible.