| Under the action of earthquake,joint connection plays a crucial role in the seismic performance of prefabricated concrete structures,is a key element that affects the overall performance of prefabricated structures,and is a core issue in the seismic design of prefabricated structures.Therefore,investigating the seismic performance of prefabricated joints is particularly important for studying prefabricated structures.In this thesis,a connection form of steel joints suitable for pre-assembled reinforced concrete(PRC)columns with variable crosssection is proposed.By using numerical simulation methods such as quasi-static analysis and dynamic time-history analysis,the mechanical and seismic performance of prefabricated steel node connected frame columns are investigated,and the seismic behavior of the frame structure is analyzed.The details of study are as follows:(1)Using finite element general program ABAQUS,a refined model of frame columns connected with fabricated steel joints was established,and its reciprocating loading was simulated and compared with cast-in-place columns.The seismic performance of the new type of fabricated steel joints was evaluated,especially the impact of axial compression ratio on the failure form of columns with variable cross-section under reciprocating loading,as well as the seismic performance indicators such as ductility,stiffness degradation and energy dissipation capacity of joints.The results show that under low cycle reciprocating loading,the concrete at the bottom of the fabricated RC column collapses,while there is no significant plastic deformation in the steel joint area.The joint design is practical and feasible.The failure modes of fabricated RC columns and cast-in-situ columns are both typical bending failures.The development trend of the hysteretic curves of fabricated RC columns is the same as that of castin-situ columns,with their hysteretic curves showing a shuttle shape,full curves,and good energy consumption capacity.The displacement ductility coefficients of fabricated RC columns are all greater than 3,indicating that the new fabricated steel joint connection RC columns have good ductility and meet seismic requirements.Considering the bearing capacity and deformation capacity of column members comprehensively,the axial compression ratio is about 0.5,and the seismic performance of fabricated frame column members is good.(2)The refined model of fabricated steel joint connected RC columns was simulated under one-way pushover and eccentric loading,and the effect of axial compression ratio on the failure morphology and bearing capacity of column members under one-way pushover was analyzed.The failure morphology of steel joint connected RC columns under different eccentricities were investigated.The compression bending performance and overall performance of steel joint connected RC columns were studied,and compared with traditional cast-in-situ columns.The simulation results show that under the action of one-way push over load and eccentric load,there is no damage in the joint area of fabricated RC column members,which meets the design concept of nodes being stronger than components.Moreover,under the action of horizontal oneway load,the joint force transfer is reasonable,and the column members show good resistance to horizontal lateral forces.(3)According to the mechanical characteristics and hysteretic curve of the assembled RC column under reciprocating loading,the restoring force model of force and displacement is established.Based on the regression analysis of the simulation results using the data processing software Origin,a three fold skeleton curve model was proposed.On the basis of the three fold model,the hysteretic curve was analyzed,and the hysteretic criterion of the restoring force model suitable for this new type of assembled frame column joint was obtained.Therefore,the restoring force model of the new type of assembled RC column was established.The hysteretic curve calculated by using the restoring force model is compared with the hysteretic curve obtained by numerical simulation.The curve calculated by the restoring force model agrees well with the curve obtained by numerical analysis.The restoring force model established in this thesis can better reflect the hysteretic characteristics of the new fabricated RC column.(4)Based on the fabricated frame structure of a laboratory building,a multiscale technology is used to establish a frame model for the fabricated frame structure.The detailed nodes are refined models of fabricated steel joints connecting RC columns,and the macro models of the rest of the beam column components of the frame structure are established.Modal analysis and calculation were conducted for the multiscale model and macro beam element model of the frame structure.By comparing the vibration forms and natural frequencies of the two types of frame models,examined the dynamic performance of the frame structure,the dynamic characteristics of the frame were analyzed,and the accuracy of the multiscale model was tested.Time history analysis was conducted for two types of frame structures.By applying seismic action,time history curves of seismic response indicators such as structural acceleration,vertex displacement,and base shear force under different seismic waves were obtained.The computational accuracy of the multiscale model was investigated,and the seismic performance of frame structures under earthquake action was analyzed. |
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