Experimental And Theoretical Research On Seismic Behavior Of Specially Shaped Co-Lumns Joints Reinforced By Steel Or X-shaped Reinforcement

The reinforcement concrete structure with specially shaped column, which possesses aseries of advantages such us satisfactory architectural functions, is applied more and morewidely in China. But the existence of weak parts of joints of specially shaped columns restrictsthe structure height and the range of structure with specially shaped columns. Steelreinforcement or X-shaped reinforcement to the weak part of joints with specially shapedcolumns is proposed and investigated. Moreover, the experiment and research foundation wereprovided for this structure, which is better to generalize further.The joint of specially shaped columns reinforced by steel or X-shaped reinforcement andwithout reinforcement in the core zone of joint were tested under low cyclic loading. Thedamage characteristic, stirrup strain, steel strain, web member strain, X-shaped reinforcementstrain and concrete strain variation in the core area of joint were compared.The results in termsof bearing capacity, displacement, ductility, hysteretic curve, rigidity degradation, energydissipation and cumulated damage were also compared. The test results show that steelreinforcement or X-shaped reinforcement is an effective measure for improving the seismicbehavior of specially shaped column joints in terms of decreased crack width, improved damagecharacteristic, increased deformation behavior, enhanced ductility and improved hystereticcharacteristic. In addition, steel reinforcement or X-shaped reinforcement in the joint core regionis an effective way to lighten the degree of cumulated damage. The seismic behavior andmechanics characteristic of joint reinforced by X-shaped reinforcement are better than that ofreinforced by steel reinforcement.The characteristics obtained from the specially shaped columnjoint with steel reinforcement or X-shaped reinforcement with better seismic performance can beused in engineering applications.On the basis of mechanical mechanism and design method, the shear property and the effectof reinforcement by steel or X-shaped reinforcement are considered, the shearing capacity formula of specially shaped columns joints reinforced by steel reinforcement or X-shapedreinforcement was proposed. It is shown that the shear capacity of joint reinforced by steelreinforcement or X-shaped reinforcement is also higher than that of without reinforcement. Thesteel reinforcement or X-shaped reinforcement has the function of reinforcement for the weakpart of joint with specially shaped columns. In addition, the test values are higher than calculatedvalue, which indicates that the formula is safe for design of specially shaped columns joins andwith slight high reliability.