Experimental Study On Seismic Behavior Of Prefabricated Self-centering Frame Connection

Prefabricated self-centering structure system has the advantages of short construction period, less energy consumption and less environment pollution. In this system, the beams and columns suffer little or no damage after earthquake, the prestressed tendons ramain elastic all the time so that the connection can be pulled back to the original location after earthquake. In this paper, experimental and analytical studies were conducted to investigate the seismic behaviors of prefabricated self-centering frame connection.A test program consisting of 18 specimens in six groups was conducted to investigate the shear behavior of prefabricated self-centering frame connection joint. The effects of the axial force of prestressed bolt, the dimension of member connection interface, steel corbels on the shear behavior of prefabricated self-centering frame connection joint were studied. The formulae for calculating the shear strength of prefabricated self-centering frame connection joint were presented. The value of coefficient of friction was analyzed. The results showed that the shear strength of prefabricated self-centering frame connection joint was positively influenced by the axial force of prestressed screw but not obviously influenced by the dimension of member connection interface; the shear behavior of prefabricated self-centering frame connection joint is improved by using steel corbels.Based on the experimental studies on shear behavior of prefabricated self-centering frame connection joint, quasi-static tests on one monolithic specimen ad 4 self-centering specimens were carried outto study the seisimc behavior of prefabricated self-centering frame connection. The prefabricated self-centering frame connection has no corbels, and the shear strength is provied by the friction produced by the force of prestressed tendons. The factors considered in this paper were the ratio of Ms and Mpr, whether the special steel has unboned section or not, whether the special steel is symmetrical reinforced or not The results showed that:1. The beams and columns suffered little or no damage, and there were less or no cracks on the beam and the joint core area; 2.The prestressed tendons ramain elastic during the tests that guarantees pulling back the connection to the original location; 3. The more fullness hysteretic behavior curve and the more energy consumption by increasing the ratio of Ms and Mpr, but the bigger residual deformation. When Ms and Mpr is about 50%, the ductility and the energy consumption of each drift cycle can achieve the level of monolithic reinforced concrete connection basically; 4) whether the special steel has unboned section or not has less effect on the seisimc behavior of prefabricated self-centering frame connection; 5) The asymmetrical reinforcements have little influence on ductility and stiffness degradation.Three specimens were repaired and quasi-static tests on them were conducted to investigate the seisimc behaviors of prefabricated self-centering frame connection after repairing. The results showed that the damage states of repaired connection was coincided with unrepaired connection, the beam and column of repaired specimens exhibited little or no damage and the damage concentrated on the joint grout, the seismic behavior of prefabricated self-centering frame connection after repairing can achieve that of the original specimens.Finally, analyses on the flexural strength of prefabricated self-centering beam was conducted. The formulae of the cracking moment, yielding moment and the ultimate moment of prefabricated self-centering beam were developed. The predicted moments were compared with the experimental values. The results showed that the calculated values agreed well with the test results.