| The enhancement of construction industrialization made widely application of prefabricated structure in China.Compared to traditional cast-in-situ structure,prefabricated structure is representing the future benchmark construction which presents faster construction speed,better construction quality.And prefabricated construction could save more resources and contribute to environmental protection.Additionally,the connection and joints in prefabricated structure always act the most significant role in construction industrialization.Prefabricated beam-column joint is not only the essential area of force transmission,but also the weak part of the structure against earthquakes.Thus,it is of great significance to propose a prefabricated beam-column joint with brilliant seismic performance and statable connections to prevent major damage of the joints during earthquake.This paper aims to conduct experimental research on the seismic performance of precast prefabricated beam-column joints connected by 8.8 grade and 5.6 grade bolts under low-cycled reverse loading.The proposed prefabricated beam-column joint including T-shape beam and corbel column was connected by bolts and the proposed joints was recognized into semi-rigid joints according to their deformability.A Pseudo-test was carried out to analyze the seismic resistance performance of beam-column joints,including failure modes,hysteretic performance,bearing capacity degradation,stiffness degradation,ductility performance and energy dissipation capacity.The scatter diagram of load-displacement test was fitted and a skeleton curve of the restoring force model concerning this kind of joints was proposed to provide reference for elastoplastic seismic response analysis and structural dynamic test.Also,according to the layout of the experiment,the boundary condition and the loading system,a finite element model is established using ABAQUS.Furthermore,the correctness of the numerical simulation model is verified comparing to the experimental data.The conclusions are as follow on the basis of the paper research,experiment research and the finite element analysis.(1)The research progress of prefabricated concrete beam-column joints at domestic and abroad is reviewed,and the importance of prefabricated concrete structure technology to the development process of China is analyzed from the perspectives of the connection form,experimental research methods,and commonly used numerical simulation methods.(2)This paper proposed a novel prefabricated beam-column joints including T-shape beam and corbel column connected by bolts.A Pseudo-test was carried out to analyze the seismic resistance performance of beam-column joints and the experimental details including materials,experiment process,boundary condition,measurement plan,loading system was detected.(3)By analyzing the main experimental phenomenon and failure modes,we observe and write down the crack development,yielding and failure processes of the prefabricated concrete beam-column joints connected by 8.8 and 5.6 bolts: the hysteretic curves,overall bearing capacity curves,ductility coefficient,stiffness degradation,equivalent viscous damping coefficient curves and energy dissipating capacity curves.The results show that the precast prefabricated semi-rigid beam-column joints exhibited great seismic behavior.The hysteretic curves are plump and have obvious pinch segments.The overall bearing capacity curves and stiffness curves degrade slowly which show strong anti-lateral displacement ability.The beam-column joint connected by 5.6 grade bolts has better ductility ability and energy dissipating capacity than that connected by 8.8 grade bolts.(4)The load-displacement experiment data is scattered and a restoring force model based on the experiment data is established.The established restoring force model is in good agreement with the test value and can be used as the elastic-plastic response calculation of the bolted joint model.(5)The reliability of the prefabricated semi-rigid beam-column joints with 8.8and 5.6 bolt connections under low-cycle reverse loads is verified by finite element numerical simulation,and the equivalent plastic strain cloud diagram of the numerical model of the two specimens and the Mises stress of the bolts and steel plates were verified.We analyze the results of cloud diagrams,shear stress cloud diagrams in the core area as well as the joint stress state ratios.The results show that the results of the numerical simulation are in good agreement with the results of the experimental research.The numerical model can provide a reasonable calculation model for the engineering practice of prefabricated semi-rigid bolted beam-column joints.(6)Based on the results of full-scale tests and numerical simulations,the connecting bolts and the reinforced concrete in the core area of the joint are the main load-bearing parts.When the strength of the prefabricated beam and column components meets the requirements,the bolts can be replaced to complete the repair of the prefabricated joint after the earthquake disaster.The relevant conclusions and calculation models of the pseudo-static test of prefabricated concrete beam-column joints proposed in this paper can provide references for engineering seismic analysis,and we hope that the pseudo-dynamic test and vibration of such bolted joints will be connected in the following work.Figure 54 table 7 reference 74... |
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