Research On The Axial Compression And Seismic Performance Of High-strength Square Steel Tube Recycled Concrete Short Columns

In recent years,China's development is relatively vigorous in the field of construction,resulting in the consumption of a large number of commercial concrete,making the problem of resource shortage increasingly prominent.In addition,due to urbanization construction and frequent natural disasters,tens of thousands of construction wastes are generated,which are often disposed of by burial,which is also obvious for environmental pollution.In order to effectively solve the above problems,some scholars have proposed a new material concept of recycled concrete.Firstly,it can save natural aggregates and reduce the plunder of natural resources.Secondly,it can recycle waste concrete and maximize resource utilization.Considering that the mechanical properties of recycled concrete are worse than those of ordinary concrete,it is injected into steel pipes to form a steel pipe recycled concrete composite structure.The merits of this construction are:on the one hand,due to the restraint of the steel pipe,the recycled concrete is in three directions,the compressive strength is improved,and the creep and damage of recycled concrete are improved.On the other hand,the structure has a certain load-bearing capacity,which can replace the traditional reinforced concrete structure,saving steel tying,supporting,demoulding,etc.The cumbersome procedures are of great benefit to improving construction efficiency.Due to the different cross-sectional forms of the steel tube recycled concrete structure,the stress situation is also different.Although the square steel tube recycled concrete structure is not as high as the round steel tube recycled concrete structure,its characteristics such as greater cross-section bending stiffness,simpler joint structure and easy decoration have attracted wide attention from scholars.Therefore,this paper focuses on the mechanical properties of the the recycled concrete-filled high-strength steel tube(RCFHSST).Because the square steel tube concrete structure has limited bearing capacity and cannot meet the requirements of large-span and high-rise buildings,this paper replaces ordinary square steel pipes with high-strength square steel pipes.One side,RCFHSST can inherit the advantages of the former,on the other hand,it can greatly improve the bearing capacity and seismic performance of the component,and it can lower the section size of the component and the structural weight.Obtaining more space in large-span and high-rise buildings,and improving the use of buildings.At present,there are few reports on the research of the recycled concrete-filled highstrength steel tube short columns(RCFHSSTSC).Therefore,this paper stresses the nonlinear simulation research on the axial compression and seismic performance of the composite short column,and mainly completes the following work:Firstly,in this paper,through selecting reasonable unit type,high strength steel pipe and recycled concrete stress-strain relationship,contact interface,grid technology,and the corresponding boundary conditions and loading mode,modeling work for composite short column,and the related parameter has been carried on the detailed introduction,has certain scientific research and application value.Secondly,in this paper,the feasibility of the finite element model of the axial compression stub column is verified by the relevant test results,and the axial compression mechanism of the combined stub column is analyzed.In addition,the influence of the replacement rate of recycled concrete,the replacement rate of reclaimed coarse aggregate,the yield strength of high strength steel tube and the steel content ratio on the axial compression index of the 16 composite short column was studied.The results show that the replacement rate of recycled coarse aggregate has little effect on the axial compression performance of the composite column.However,the strength of recycled concrete,the yield strength of high strength steel tube and the steel content ratio have great influence on the bearing capacity of such members.Thirdly,in this paper,the simulation results were compared with the results of domestic and foreign code bearing capacity numeration equations based on the two theories,and the viability of axial compression design of RCFHSSTSC was obtained,and linear regression fitting was carried out for axial compression.The test results verify the correctness of the formula for calculating the capacity of short column.Fourthly,based on the verified finite element model,this paper carried out nonlinear simulation research on the seismic performance of 17 RCFHSSTSC.The influence of the replacement rate of reclaimed coarse aggregate,yield strength of high strength steel tube,steel content ratio and axial compression ratio on relevant seismic resistance indexes of composite short column was analyzed.The consequences show that the replacement rate of reclaimed coarse aggregate has no obvious effect on seismic performance of composite column.However,the yield strength,steel content and axial compression ratio of the high-strength steel tube have significant effects on the seismic performance of the composite column.