| Factory production and field assembly is the only way to industrialization of the building. Usually the connection of the assemblage structure system hasn’t enough reliability to satisfy the requirement of carrying cyclic loading and resist progressive collapse. The prestress technology in this paper is applied to the joints of the prefabricated concrete structures, in which the prestressed reinforcements shall be passed through the beam-column connections and then be stretched so as to make them form integrate joints and continuous frames that can improve the seismic performance and robustness greatly and be applied widely in the earthquake area.Based on the pseudo-dynamic and pseudo-static experimental study of the single-span three-story prestressed fabricated concrete frame, this paper studies a lot of seismic performance such as dynamic performance, carrying capacity, hysteretic behavior, displacement ductility, energy dissipation and etc. Nonlinear static analysis and elasto-plastic time-history analysis are undertaken by using finite element analysis software for the test frame to discuss the seismic performance further. Numerical simulation of the Tie Method and the Alternate Path Method are employed for the two-span three-story prestressed fabricated concrete frame to explore the performance and mechanism of resisting progressive collapse. The main content and results are as follows.Based on pseudo-dynamic experimental study of the prestressed fabricated concrete frame, this paper investigates the displacement history curves, restoring force history curves and restoring force vs. inter story drift curves of the frame as well as inter story drift and rotation of frame and story shear under different experimental cases. The research includes the seismic performance of dynamic performance, deformation performance, stiffness degradation and etc. The maximal inter story displacement angle of frame arrives 1/368 under the experimental case of the peak acceleration of seismic wave at 102gal, which has no damage in small earthquake. The maximal inter story displacement angle of frame arrives 1/137 under the experimental case of the peak acceleration of seismic wave at 204gal, which is repairable under moderate earthquake.Based on pseudo static experimental study of the prestressed fabricated concrete frame, this paper discusses the story shear-displacement hysteretic curve of frame and the moment- rotation hysteretic curves at both ends of the beams. The research includes the seismic performance of carrying capacity, hysteretic behavior, displacement ductility, energy dissipation and etc. The plastic hinge first appears at the beam end and stiffness degradation doesn’t greatly appear at the column, which indicates the post-tensioned prestressed fabricated concrete frame is a "strong column weak beam" structure. The ultimate displacement angle of the first story is 1/42, the second story is 1/47, and the third story is 1/67, which cannot be destroyed when suffered rare earthquake. The story shear-displacement hysteretic curve of the first and second story of the frame is plentiful, and the equivalent viscous damping coefficient he of the last load cycle is between 0.065 and 0.087. That means the frame has good energy dissipation capability. The composite section at beam ends has good rotation capability and ductility ability, whose ductility coefficients is between 3.64 and 5.62. The residual deformation rate of every story arrives between 0.138 and 0.307 at the ultimate state, which shows that the frame has nice deformation recovery capability. Before the frame destroyed, beam plastic hinge can rotate fully, so the prestressed fabricated concrete frame is a "strong column weak beam" structure. The frame joints under the pre-pressure and the axial compression are in the biaxial compression state, which can satisfy the requirement of the strong nodes in the seismic design.Nonlinear static analysis is executed by SAP2000 for the test frame and then the base shear-top displacement curve is obtained. Comparing the measured value with the calculated value, the absolute error is 17.7% at positive loading and 1.4% at reverse loading. The general pattern and order of plastic hinge appeared can be gotten during the process of Pushover. The plastic hinge appears firstly at the beam end of frame bottom, then at the beam end of frame top, and finally at the bottom of the column. That shows the test frame with the whole yield mechanism in failure mode has excellent seismic performance.Linear time-history analysis is undertaken through MIDAS/Gen for the test frame and then the displacement history curves is gotten. Comparing the tested displacement with the calculated displacement is to validate the feasibility of the method utilized. With the same seismic wave as utilized in the pseudo-dynamic experiment and the adjusted peak acceleration, nonlinear time-history analysis is employed for the frame and then the displacement reaction is obtained. When the frame destroyed, the hinges of the beam end are in the state of Level-4, the hinges of column bottom are in the state of Level-5, and the ductility coefficients is more than 4. That prove the prestessed fabricated frame is a "strong column weak beam" structure with good ductility ability and comparative energy dissipation capability.Numerical simulation of the Tie Method and the Alternate Path Method are employed under different failure cases for the prestressed fabricated concrete frame to explore the performance and mechanism of resisting progressive collapse. It indicates that the residual structure of the simulated frame has considerable stability and strong ability of resisting progressive collapse except the top side column destroyed. Because of the prestressed reinforcement, when the side column damaged, the frame can resist progressive collapse with beam mechanism at the range of small deformation, while the frame cannot resist progressive collapse with suspending mechanism at the range of large deformation. When the interior column damaged, the frame can always resist progressive collapse with suspending mechanism or beam mechanism. |
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