Research On Plastic Controllable Steel Beam-column Joints For Precast Reinforced Concrete Structures

The precast concrete structure is a good form of structure due to its high efficiency of productivity,high quality of components,less construction waste and reservation of resource and energy.As the most important connecting components in the structure,the joints should have a better performance.But due to the current practice,in mechanical properties,most of the joints could not surpass the performance of cast-in-place concrete.Also,the plastic development could hardly be controlled,makes the joints often be the weak parts of the structure.Meanwhile,the ability of energy consumption and ductility of joints are poor.Therefore,to solve the existing problems,a steel joint based on mechanical connection was developed to provide plastic controllable characteristics and good energy dissipation capacity,and it was easy to install and detachable.And a high-performance fully assembled system was developed in this essay.Specifically included:The conceptual design of plastic controllable for new joints was proposed.Based on the principle of force of the new joints,the design partitions of the joint were determined.By analyzing the force model of the components in each partition,the construction scheme of the new joints was clarified.Through the application of mechanical bearing,the adequate shear bearing capacity was provided to ensure that the damage mode was beam end bending.And a kind of soft steel damper was developed,which provided stiffness under small earthquake and energy consumption under the big earthquake.Finally,the preliminary design formula of the new node was proposed,which provided theoretical guidance for the follow-up study of the new joints.To analysis the influence factors and to improve the property of the new joints,the influence factors of plastic control of new joints were studied,which considering the length height ratio and static moment of energy consumption beam.The influence factors on initial rigidity were studied to obtain the initial rigidity variation rule while changing the static moment of steel beam connection side plate,and the ratio of non-energy consumption beam length and energy consumption beam height.The energy consumption performance affecting factors were studied,which contains the effect of energy dissipation beam length,non – energy consumption support plate and energy consumption side plate thickness.Based on these,the improved design method of the new joints was proposed,and the performance of the new node was verified by finite element analysis.The reliability of the design method and the superiority of the new joints were also verified.The overall performance of the assembled concrete frame structure based on the new node was analyzed.In this paper,a fully assembled high-performance fabricated concrete frame structure was developed,based on the traditional fabricated concrete frame structure and the advantages of the new node.The bearing capacity,failure sequence,deformation characteristics,energy dissipation capacity and damage development of the structural system were analyzed.It was proved that the fully assembled frame structure based on the new node has better carrying capacity and ductility compared with the traditional precast frame structure system.The failure order was more reasonable,and the floor displacement and the displacement angle were reduced,and the main plastic development area can be precisely controlled at the beam end.The whole assembly frame structure is proved to be a better structure.