| The large-scale SRC nuclear power plant of conventional island is mainly composed of the steam engine room and the deaerator room and auxiliary span,and the frame-bent structure is used in the nuclear power plant.For the limitation of the special technological and irregular structural arrangement,a variety of abnormal joints are ususlly formed with split-level,variable beams and columns and leaning beams in the the large-scale SRC nuclear power plant.The failure modes of SRC abnormal joints are different from those of conventional joints,and the mechanical mechanism is more complex,and scholars at home and abroad have less research on SRC abnormal joints.Therefore,there are profound theoretical significance and practical significance of Engineering for the construction of nuclear power plant in high earthquake intensity regions to study the mechanical characteristics and seismic behaviors of SRC abnormal joints.At present,the JGJ 138-2016 "code for design of composite structures" mainly focuses on the SRC conventional straight joints,and there are less provisions for the calculation methods and structural measures of SRC abnormal joints.In this paper,CAP1400 SRC frame-bent nuclear power plant has built in Shandong Rongcheng was taken as a prototype,and based on the experiment research on the whole structure model,and several kinds of SRC abnormal joints appeared in the whole structure were selected,and according to different parameters,quasi-static test for 15 SRC abnormal joint specimens in 1/4 scale of the prototype model were carried out to study the mechanical behavior,failure mode and seismic design method for SRC abnormal joints more comperhensive and deeply.The main research work and results are as follows:(1)Given different design parameters and design principle of "strong members,weak joints",8 interior joints and 4 exterior joints are designed.And based on the principle of "strong joints,weak members",3 leaning beam-column joints are designed.The effects of different factors on the bearing capacity and the deformation capacity of SRC abnormal joints specimens are illustrated by the quasi-static test.And the mechanical properties,failure modes,hysteresis performance,ductility and energy dissipation characteristics,bearing capacity and stiffness degradation laws of different types of SRC abnormal joints are revealed.The differences between the failure modes and the mechanics mechanism of the SRC abnormal joints and SRC conventional joints are compared.The results showed that: the hysteresis curve of these abnormal SRC joints is relatively full,which is between the inverse S-shape and the spindle shape,and has the characteristics of steel and reinforced concrete joints together.When the axial compression ratio is less than 0.5,the bearing capacity of the joints increases with the increase of axial compression ratio,while the ductility and energy dissipation gradually decreases,suggesting that the axial compression ratio should not be too large.For the interior joints with split level with two side,the bearing capacity of the joints increases with the increase of the split level height,while the ductility and energy dissipation decreases.For interior joints of variable beams with two side,the capacity decreases with the decrease of the one side beam section height,while the ductility and energy dissipation increases gradually,and it is suggested that small beam section height should not be less than 1/2 of big beam.For SRC abnormal exterior joints of variable column,with the decrease of the height of the upper column,the shear failure of the joints is gradually developed into plastic damage of the end of upper column,and the bearing capacity of the joints is reduced,it is suggested that the column section height should not be too small;For leaning joints,the larger the split angle of the beam,the wider the crack in the beam end and the smaller the bearing capacity of the joints,it is suggested that the split angle ? of the leaning beam-column joints should not be beyond 10?,when ? ?3?,it can be designed according to the same design method.However when 3?(27)? ?10?,the bearing capacity should be reduced by 5%.(2)Based on the research on characteristic of restoring force of SRC conventional joints,according to the experimental hysteresis curve and skeleton curve,restoring force model being applicable for SRC abnormal joints is proposed so as to provide a theoretical basis for improving the seismic behavior and analysis method of SRC joints.(3)By adopting the appropriate element type and constitutive relation for different materials,and meshing reasonably,Abaqus is used in establishing the finite element model of the SRC abnormal joints.Calculation and analysis are carried out by applying repeated load,the finite element analysis results and the experimental research results are in good agreement.Several finite element models were established considering more parameters by Abaqus to analysis.The results show that the shear capacity of the joints increases with the increase of the axial compression ratio and the dislocation height,but decreases with the decrease of the height of the beam section and the height of the upper column section.(4)Through experimental research and finite element analysis,according to the crack development and failure process of the SRC abnormal joints,the core area division method of different types of abnormal joints is proposed.And this paper also reveals the mechanics mechanism of different types of SRC abnormal joints.Analysis the contribution for bearing capacity from the components of SRC abnormal joints quantitatively,and calculation formula of shear and crack resistance bearing capacity for SRC abnormal joints of different types are put forward.(5)On the basis of the experimental research and combined with the existing research results,the design method and construction measures for SRC abnormal joints are proposed,which can be used as reference for designers and constructors. |
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