| Steel Reinforced Concrete not only has the advantages of high strength and good toughness of steel structure,but also can improve the utilization rate of concrete and reduce the waste of materials in practical engineering applications,so it has broad development prospects.In high-rise and long-span building structures,beam-column joints are the key parts connecting beams and columns,which play a very important role in the seismic performance of structures.Existing researches mainly focus on beam-column orthogonal joints,but there are few systematic researches on seismic performance of SRC beam-column skew joints at present,which makes the design without reliable basis and easily leads to structural safety hazards.Therefore,in this paper,numerical simulation and theoretical analysis are used to deeply study the mechanical properties and shear capacity calculation methods of SRC beam-column skew joints.The main research contents and achievements are as follows:(1)On the basis of summarizing the research results of domestic and foreign experts and scholars on SRC beam-column joints,the existing SRC beam-column plane joints are modeled and analyzed by finite element software,and the numerical simulation results are compared with the experimental results.The results show that the numerical simulation curves are in good agreement with the experimental curves,which verifies the accuracy and rationality of the modeling.(2)In order to realize the seismic design of the rigid concrete structure,aiming at the functional needs of the main structure of a comprehensive square,the SRC beam-column oblique edge joint is designed,and a SRC beam-column orthogonal edge joint is established at the same time.Under low cyclic loading,the mechanical properties of the specimens with two nodes are compared and analyzed from hysteretic curves and other aspects.The results show that after yielding,compared with SRC beam-column orthogonal edge joints,the bearing capacity of SRC beam-column diagonal edge joints decreases by about 20%,and the energy dissipation capacity decreases by about 8%.Therefore,the steel ratio can be increased with reference to this change range in design,so as to improve the bearing capacity and energy dissipation capacity of the structure.(3)The influence of axial compression ratio,concrete strength and column steel web thickness on the seismic performance of SRC beam-column diagonal joint is analyzed.The results show that the axial compression ratio and column steel web thickness are the main factors affecting the seismic performance of SRC beam-column diagonal joint during loading.It is suggested that the axial compression ratio should be controlled between 0.3 and 0.4 and the column steel web thickness should be controlled between 30 mm and 35 mm;However,in the later stage of loading,the concrete strength has little influence on the seismic performance of the structure.(4)The models of SRC beam-column skew middle joints and SRC beam-column orthogonal middle joints are established,and their mechanical properties under low cyclic loading are compared and analyzed.The results show that after yielding,compared with SRC beam-column orthogonal middle joints,SRC beam-column skew middle joints consume more energy,but their structural bearing capacity is about 15% lower.In order to ensure that the structural bearing capacity meets the design requirements,it can be strengthened with reference to this change range.(5)The influence of various parameters on the seismic performance of SRC beam-column skew middle joints is analyzed.The results show that when the axial compression ratio is 0.2～0.5,the bearing capacity and energy dissipation coefficient of the specimens are the largest and the ductility is the best when the axial compression ratio is 0.4.When the concrete strength is C40～C70,the loop stiffness and energy dissipation coefficient of the specimen gradually increase with the improvement of concrete strength grade.When the concrete strength is C60,the ductility of the specimen is the best,and it is suggested that the concrete strength should be C60.When the thickness of column steel web is25mm～40mm,the ductility and energy dissipation capacity of specimens with thickness of30 mm are the best,and it is suggested that the thickness of column steel web should be 30 mm.(6)Based on the research results of SRC beam-column skew joints under low cyclic loading,and referring to the current relevant codes,the calculation method of shear capacity of SRC beam-column skew joints is deeply studied by superposition method,and the calculation formula of shear capacity of SRC beam-column skew joints is derived,and the rationality of the formula is verified,which can be applied to the design of this kind of joints. |
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