Research On Seismic Performance Of PEC Column Composite Frame With Partial Self-centering Friction Damped Connection

The traditional frame structure realizes the overall energy consumption at the cost of the plastic damage of the main components.It often has a large residual deformation after the earthquake,and the repair cost is huge,which is equivalent to"uncollapsed ruins".How to control the residual deformation of the main components after the earthquake within the normal use requirements has become an urgent problem to be solved.Scholars at home and abroad have been inspired by prestressed concrete to improve component deformation,and have carried out a lot of theoretical and experimental research on self-resetting structure.The results show that the self-resetting structure can effectively control the residual deformation.However,in order to achieve its reset ability,the main components are restricted from maintaining elasticity,and the safety redundancy of the structure is correspondingly improved.It is only suitable for special fortification projects that require strict residual deformation after earthquakes.To this end,in order to further promote the application range of self-resetting structures in actual projects,based on the organic coordination of"self-resetting,energy consumption and safety redundancy",this research group proposed a partial self-resetting structure design concept,namely"primary restoring and friction energy-dissipation at design earthquake level,later partial restoring and yielding energy-dissipation of structural member at maximum considered earthquake level"At present,the related research focuses on the connection of nodes,and there are few comprehensive studies on the overall system of the frame.Combined with the research on the partial restoring connection of the research group,the test specimen of PEC column composite frame with restoring friction damped connection was taken as basic reference,design parameters as the penetrated bolts arrangement on flange of T stub,compression force of the column,the force of pre-tensioned bar and the force of friction bolts were considered to design 4 groups with 7 specimens by the use of the finite element software called“Abaqus”to simulate seismic performance.hysteretic loops,the restoring function and the energy dissipation were analyzed.The results and experiments complement each other and improve the research content.The results showed that the specimens had greater flexural stiffness result in the arrangement on the strong axis,the residual drift angle did not exceed 0.005 rad at design earthquake level,and it was still about 0.02rad at maximum considered earthquake level,with good reset performance and energy consumption capacity;the stiffness of the specimen with the weak axis is slightly lower,and the reset performance and energy consumption in the level stage of the mid-seismic action were not much different from the strong one,which showed that the structural treatment of the flange curling has solved the problem of the large difference in the two-way stiffness of the PEC.The pre-tension rod was arranged in the whole length,During the loading process,the deformation mode of the two ends of the pre-tension rod is opposite,and the stress was canceled,which reduced the local compression damage of beam,and had excellent reset performance.the hysteresis law of the experiment was basically the same as the simulation results,and there was only the difference between the force-transfer process of specimen,which showed the feasibility of the numerical simulation.The analytic results showed that all specimens can meet the two-stage performance design goal of"primary restoring and friction energy-dissipation at design earthquake level,later partial restoring and yielding energy-dissipation of structural member at maximum considered earthquake level"through the reasonable setting of the size of the oblong hole on the T-shaped friction plate.the force-transfer process of specimen was effected significantly by the penetrated bolts arrangement;axial compression of the column can increase the initial lateral stiffness and restoring function at design earthquake level,while its second-effect made the damage process and restoring degradation be accelerated at maximum considered earthquake level;friction bolt pre-tightening force had obvious influence on the mechanical process of self-resetting connection of specimens and seismic energy dissipation capacity.The increase of pre-tension rod force increased the initial stiffness of specimens;the pre-tension force of the pre-tensioned bar increasing or the pre-tension force of the friction bolt decreasing can increase ratio of M_a/M_b,correspondingly the restoring function was improved.When the residual drift angle of all models was not more than 0.0005 rad at design earthquake level,and it still not more than 0.015 rad at maximum considered earthquake level,the structure still had a certain reset capability.