Study of restoring force model on beam-to-column assembled joint connected with partially unbounded bar
In order to study the seismic performance and restoring force character of beam-to-column assembled joint connected with partially unbounded bar,two high-performance precast frames were tested under low cyclic loading.The seismic performance indexes such as failure phenomenon,hysteresis performance,skeleton curve,ductility and deformation capacity of typical side-span beam-to-column assembled joints were studied and analyzed.According to the experimental results and theoretical analysis,the moment-rotation skeleton curve model of four-fold line joints was proposed,and the calculation method of each feature point was given.Based on the analysis of the characteristics of the test hysteresis curve,the restoring force hysteresis rule of the joint was constructed,and the restoring force model of the joint was formed with the skeleton curve.The results show that concrete damage in the joint area of the beam-to-column assembled joints is relatively light under limit state.The integral working state of the joints is good while the main yield concentrated on the connecting bar.A significant pinch phenomenon and obvious rotational deformation slip of moment-rotation hysteresis curves of the assembled joints indicates poor energy dissipation capacity.The ductility coefficients of the assembled joints are between 3.94 and 6.21,and the maximum rotation angles of the two frames are about 1/58 and 1/53.The ductility performance and deformation capacity of the assembled joints are good.The proposed joint moment-rotation skeleton curve model and restoring force hysteretic model are in good agreement with the test results.The established restoring force model can be used for the elastoplastic analysis of integral precast frame structure using this type of assembled joints.
partially unbounded barbeam-to-column assembled jointseismic performancehys-teresis curveskeleton curverestoring force model
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