Study On Mechanical Behavior Of Square Double Skin Steel Tube Short Columns Filled With Brick Particle Recycled Concrete

Recycled concrete-filled double-skin steel tube column was a new type composite structure which was discussed by professors at home and abroad in recent years.Recycled concrete can not only fundamentally solve the impact of construction waste on the environment,but also recycle construction waste,so that the problem of river sand,rock mining can be alleviated.Because recycled concrete has many defects,it has great resistance in practical engineering promotion.In recent years,steel pipe and recycled concrete were combined to offset for some defects of recycled concrete.They interact and complement each other.The brick granules recycled concrete-filled double-skin steel tube combination column,The brick granules recycled concrete-filled double-skin steel tube combination column,it was a kind of component which puts the inner and outer steel pipes into the interlayer of two steel pipes with recycled concrete,It has the advantages of simple joint connection,good seismic performance and lighter dead weight than ordinary concrete column.Based on this,this thesis firstly analyzed the mechanical properties of brick grain recycled concrete-filled double-skin steel tube square short column from both experimental and theoretical aspects,then studied the changes of mechanical properties of each specimen under different parameters,and studied the new component forms of brick grain recycled concrete-filled double-skin steel tube square short column.The research contents are as follows:(1)A monotonic axial loading test was carried out on brick grain recycled concrete-filled double-skin steel tube square short column.The changes of the specimens during the loading process and the final failure morphology of the specimens were observed by changing the replacement rate of recycled coarse aggregate,the loading eccentricity and the section type;base on the measured data,the relationship between the ultimate bearing capacity,load and specimen displacement and strain was obtained.At the same time,the influence of various parameters on the mechanical properties of specimens was analyzed by using the above experimental results.The experimental study findings: Specimen with built-in pipe combination of ordinary concrete specimen in this thesis the test of mechanical process,both the unloading process and destruction features,first external steel specimen submission,damage sites outside the steel pipe buckling phenomenon,buckling core parts of the recycled concrete crushing,all specimens were late showed good ductility;The increase of eccentricity and the replacement rate of recycled concrete with bricks has a negative effect on the bearing capacity of specimens.In addition,the eccentricity has a great negative effect on the bearing capacity,with a maximum reduction of 34.2%(2)On the basis of the test,the finite element modeling and analysis of the six test pieces were carried out,and finally the failure characteristics,stress change law,distribution pattern and bearing capacity performance of the components at different stages were presented.By comparison,the deformation characteristics and load-displacement curves of the simulation model and the measured results are basically consistent,which verifies the reliability of the finite element model presented in this thesis.Furthermore,in order to analyze the mechanical properties of recycled concrete-filled double-skin steel tube square short column in a more comprehensive way,the variation parameters of specimens were expanded,and finite element models with 12 different parameters were established for analysis and calculation.(3)Based on existing equation,using the method of effective width of square steel tube in local buckling of the negative influence of the specimen in this thesis,data regression analysis,The linear relationship between the improvement coefficient k of brick grain recycled concrete-filled double-skin steel tube square short column was obtained.Then this thesis determined the formula for calculating the axial bearing capacity of the square recycled concrete-filled double-skin steel tube short column.The influence coefficient of eccentricity on bearing capacity was introduced.The precision of the calculated expression meets the requirement,for similar component bearing capacity calculation in the project,it can provide some reference.