| Compared with the general rectangular column,the special-shaped column has different characteristics of force and section,so it is more complicated to study.In recent decades,special-shaped column frame structure has received more and more attention at home and abroad,because its reasonable structural layout and good architectural function not only add to the aesthetic of the building,but also contribute to the improvement of structural stability.However,the low bearing capacity,poor seismic performance and poor ductility limit the application of special-shaped column structure in seismic area.Compared with ordinary steel bars,high-strength steel bars reduce the amount of raw materials used and installed,and save manpower investment.Its good mechanical properties ensure the quality of the project,improve the overall structure strength,ductility,stability and seismic performance.It will be an important trend to construct high strength reinforced concrete structure with high reinforcement in the future.Reinforced concrete frame structure will produce large plastic deformation under earthquake action.Once plastic deformation occurs,the deformation is mainly concentrated in the plastic hinge region.Plastic hinge,as the main energy dissipation part of the structure,affects the deformation of the structure and changes the internal force of the structure.At the same time,the plastic hinge length is an important parameter of structural plastic design and ductility design,and also an important concept of seismic design.Since the 20 th century,scholars at home and abroad have done a lot of tests and studies in the field of plastic hinge,on which different plastic hinge length calculation formula and calculation methods have been obtained,but the research on plastic hinge length is basically related to the general rectangular section column and the research on special-shaped column is very little.In this paper,the influence of axial compression ratio,shear-span ratio,stirrup ratio and other factors on plastic hinge length and ductility performance of 600 MPa high-strength reinforced concrete ten-shaped column is analyzed by finite element simulation software,and stiffness degradation,energy dissipation and other aspects of the simulated hysteretic curve are analyzed,providing a basis for seismic design.The specific work schedule is as follows:(1)The ABAQUS finite element software was used to establish the high-strength reinforced concrete ten-shaped column model,and the finite element model was verified by the failure state,ductility index of curvature displacement and characteristic points,compared with the test results of reference in this paper.(2)Based on the verified finite element model,five groups of high-strength reinforced concrete ten-shaped columns with different factors were established and lowcycle reciprocating load tests were carried out to study the influence of different factors on the plastic hinge length of special-shaped columns.Origin software was used to draw a dot plot to compare the simulated value of PLASTIC hinge length of ABAQUS with the calculated value of the proposed formula,and multiple linear regression method was used to give the calculation formula of plastic hinge length in line with the model in this paper.(3)According to the displacement curvature relation of column,combined with the simulation results of plastic hinge length,yield displacement and limit displacement,three ductility indexes are calculated to analyze the ductility performance of column specimens and the influencing factors.Finally,through the hysteretic curve of the column model,the seismic performance of stiffness degradation,energy dissipation and other aspects is analyzed. |
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