| The increasingly obvious drawbacks of traditional cast-in-place concrete structures have made the development of building assembly technology in China extremely urgent.The convenience,economy and environmental friendliness of prefabricated assembled structures have been proven in construction at home and abroad.However,the majority of assemblies are still predominantly wet work on site,and the degree of prefabrication is low,essentially not completely free from the disadvantages of cast-in-place,which is still somewhat different from the national concept of green development.In addition,the force performance of the connectors and nodes between the components is unclear,which restricts the development of assembled structures.Therefore,the study of the mechanical and seismic properties of nodes is a necessary condition for the development of pre-structured assemblies.Based on this,this paper proposes a new type of prefabricated assembled dry joints node(hereinafter referred to as dry joints)with pre-embedded H-beams in prefabricated columns as concealed cow legs and friction type high-strength bolts to connect angles and H-beams.The mechanical properties of this new dry joints were investigated by numerical analysis.The paper firstly verifies the feasibility of the analysis technique and the validity of the model parameters used in this paper based on the existing literature;secondly,a comparative analysis of the mechanical properties of dry joints and cast-in-place joints is carried out and the parameters affecting the mechanical properties of dry joints are analysed;finally,the dry joints are applied to frame structures and the seismic performance of dry joint frames and cast-in-place frames is investigated.The main research contents and conclusions of this paper are as follows.Firstly,by comparing the finite element analysis results with the experimental results,the feasibility of the numerical analysis method and the validity of the model parameters has been verified.It was found that the damage of cast-in-place nodes often occurred at the core of the node,while the dry nodes only experienced stress concentrations at the angle and the pre-drilled bolt holes on the concealed bull leg,and local yielding of the longitudinal bars at the root of the precast beam,while the precast columns and the connecting members did not experience yielding damage as a whole.The results of the above study show that the dry joint design connection method is feasible and meets the guideline of strong column and weak beam.The hysteresis performance,skeleton curve,ductility,energy dissipation,stiffness degradation and strength degradation of the two joints were analysed,and the hysteresis curves of both joints showed a full shuttle shape with good energy dissipation.Secondly,this paper considers the effects of concrete strength grade,axial pressure ratio,angle steel stiffening ribs and yield strength of reinforcement on the mechanical properties of new dry joints.The load-bearing capacity of the joints increases with the increase of the axial pressure ratio and then decreases.Thirdly,the dynamic response of the cast-in-place joint frame structure and the new dry joint frame structure under seismic loading was calculated and the seismic performance of the two joint frame structures was analysed.By comparing the stress nephogram,transverse relative displacement time curves of the two frame structures,it was found that the stress,displacement responses of the cast-in-place joint frame structure were greater than those of the new dry joint frame structure,indicating that the seismic performance of the new dry joint frame structure was better than that of the cast-in-place nodal frame structure.Finally,to summarise the full work,a comprehensive analysis of the mechanical and seismic performance of the new assembled framed beam-column connection joints has been presented,concluding that the hysteresis performance and energy dissipation capacity of the new rigid dry connection joints are basically equivalent to those of cast-in-place nodes,but their ductility is better and their load-bearing capacity degrades more slowly,and that the study can provide a theoretical basis for the promotion and application of the new nodes. |
