| The prefabricated reinforced concrete frame structure(PRCF)is one of the most common and widely used prefabricated structural systems.It has the advantages of high productivity,low labor cost,and short construction period,while offering reliable quality,low environmental pollution and sustainable development.Nevertheless,the poor connection reliability of PRCF was a challenging to satisfy the performance requirements under the action of earthquakes,resulting in limitation in the application in seismic areas.To effectively reduce the disaster of PRCF in earthquake areas and realize the easy-repair function of prefabricated frame structures,this paper has proposed a bending-shear decoupled artificial controllable plastic hinge(ACPH)connection to effectively to effectively promote the popularization and application of the green industrialized PRCF.The ACPH was composed of the energy dissipation system for bearing bending moment and the connection system for bearing shear force,which possessed the advantages of simple force transmission path,simple construction,and convenient installation and replacement.By coordinating the performance of ACPH and precast concrete members,ACPH entered the yield state firstly and concentrated the main damage of the structure,avoiding the damage or micro-damage of precast concrete members.This structure realized the structural damage mechanism and time sequence controllability to achieve the purpose of postearthquake recovery.Systematic experiments,theory and finite element analysis were carried out for exploring the mechanical mechanism of ACPH,synergistic working mechanism with ACPH and precast concrete members,and the seismic performance.The three levels of ACPH,beam-column joint with ACPH and frame with ACPH were explored in depth to offer the theoretical foundation for the promotion of this structure.The main research of this paper was as follows.(1)Artificial Controllable Plastic Hinge(ACPH):(1)The cyclic loading tests of three ACPH specimens were performed.The influence of the cross-section area of the energy-dissipating plate on the ACPH seismic performance were analyzed.The results indicated that the yield mode of ACPH was the compression yield of the energy dissipation plate,and the failure mode was the tearing failure in the weakened area of the energy dissipation plate to achieve the purpose of damage control;ACPH has symmetrical tensile and compressive loads,stable energy dissipation capacity,excellent rotational capacity and ductility;the bearing capacity of ACPH can be effectively changed by modifying the crosssection area size of the energy dissipation plate.(2)Based on the principle of maximizing the elastic range resistance of reinforced concrete beams and the minimum flexural bearing capacity of the ACPH position under the limit state of normal service,the calculation formula of the optimal position of the ACPH was proposed.(3)The refined finite element model(FEM)of ACPH was established by ABAQUS finite element software,and the influence of energy dissipation plate thickness,opening length,number of opening,pin pre-pressure and friction factor between lugs on the ACPH seismic performance was further explored.The results showed that the bearing capacity and energy-dissipation capacity of ACPH can be effectively improved by increasing the thickness of energy dissipation plate,the pin pre-pressure,and the friction factor between lugs.Besides,the region of stress concentration in energy dissipation plate can be effectively changed by the opening length and number of opening of energy dissipation plate.(4)Theoretical analysis of ACPH was conducted for the force mechanism and working process of ACPH components.Based on the component method,the deformation model and deformation calculation formula of ACPH were established,which considered the deformation effects of the bolt rod,the installation gap,the energy dissipation plate,the end plate of the energy dissipation and the installation clearance of bolts.Based on theory of thin plate with small deflection,the mechanical model of the energy dissipation plate was proposed considering the actual boundary conditions of ACPH,and the calculation formulas of yield stress and ultimate stress of energy dissipation thin plate were derived.Meanwhile,the calculation formula of the ACPH shear bearing capacity and the construction suggestions were provided.(2)Beam-column joint with artificial controllable plastic hinge(APHJ):(1)The cyclic loading tests of two precast beam-column joint with ACPH and one castin-place beam-column joint were performed.The experimental results revealed that the failure mode of APHJ was buckling deformation of energy dissipation plates,while only a few cracks appeared in precast concrete members,which realized the purpose of controllable damage location.The APHJ has symmetrical tensile and compressive loads,stable energy dissipation capacity,excellent rotational capacity and ductility.(2)The theoretical analysis was carried out on the force transfer mechanism and cooperation principle between ACPH and precast concrete members.The performance coordination mechanism between ACPH and precast concrete components was established,which introduced the deformation coordination coefficient,bearing capacity coordination coefficient and rotational stiffness coordination coefficient to coordinate the performance of ACPH and precast concrete members.This mechanism enabled the ACPH enter the yield state before the precast concrete beam,effectively achieving the controllability of structural damage location and time sequence.(3)The refined FEM of APHJ was established to investigate the influence of ACPH length,ACPH position,overall reinforcement ratio of beam section and longitudinal reinforcement ratio of beam section on the APHJ seismic performance.Moreover,the study mainly revealed the effect of the deformation coordination coefficient,bearing capacity coordination coefficient,and rotational stiffness coordination coefficient on the cooperation mechanism between ACPH and precast concrete members.The effectiveness of the performance coordination mechanism was verified,which provided a theoretical basis for the design of the ACPH structure.(3)Frame with Replaceable Artificial Controllable Plastic Hinge(APHF):(1)The low cyclic loading tests of two precast frames with ACPH and one cast-in-situ frame were completed.The results demonstrated that the frame failure mode with ACPH was beam hinge first and then column hinge,which achieved the purpose of controllable time sequence of structural damage;APHF has a full hysteresis curve,stable energy dissipation capacity,excellent rotation capacity and ductility.(2)The simplified model of APHF was constructed by Open SEEs,and the simulation results were in good agreement with the experimental results,while offering higher computational efficiency.Besides,a six-story frame with ACPH and a cast-in-place frame were established for nonlinear time history analysis.The parameters within top-floor displacement,interlayer displacement angle,the proportion of interlayer displacement angle,base shear,and proportion of base shear were emphatically analyzed.The analysis results showed that the base shear of the APHF was smaller,the interlayer displacement and the deformation distribution of nodes between layers were relatively uniform,which can effectively avoid the formation of the structure weak layer.The frame of ACPH was easy to deform,and the deformation was larger than that of cast-in-place structure.Therefore,it was essential to further analyze the influence of ACPH on the structure overall stiffness to avoid the deformation exceeding the specification limits.(3)Based on semi-stiffness theory,the relationship between APHF horizontal story drift,beam-column joint rotation angle and ACPH rotational stiffness was derived,and the influence coefficient of ACPH rotational stiffness on the overall stiffness of APHF was obtained.(4)Based on the aforementioned three levels of ACPH test,theoretical analysis and finite element analysis,the performance coordination seismic design method of the precast concrete frame with ACPH was proposed,and the design process,configuration suggestions,and design cases were given. |
