Axial Compression Mechanical Performance Of T-Shaped Recycled Concrete-Filled Steel Ribbed Tubular Short Columns

With the wide application of high-rise structures,the special-shaped columns of reinforced concrete can be used to solve the exposure problem of ordinary square(rectangular)columns,but its vertical bearing capacity is low and the seismic performance is poor.At the same time,the rapid development of the construction industry,the generation of new buildings and the demolition of old buildings have produced a lot of construction waste,the accumulation of these has a certain impact on the use of urban land and living environment.Using T recycled concrete filled steel tube columns can overcome the shortcoming of ordinary special-shaped columns and well recycle construction waste.Due to the poor performance of recycled aggregates can be larger outer convex deformation under the condition of large bearing capacity,but the steel restriction for recycled concrete is mainly concentrated on limb Angle,we can set stiffening rib to slow the destruction of the recycled concrete core.therefore this essay carry out study for compressive mechanical properties and work mechanism of the ribbed T recycled concrete filled steel tube columns.The effect of the recycled aggregate substitution rate and the change of thickness of steel pipe on the mechanical properties of the specimens was studied by axial compression test which had 5 recycled concrete T-shaped steel tube short columns with asymmetric stiffeners.Based on the test,the numerical analysis method was used to study the influence of the asymmetric stiffening rib on the mechanical properties of T-shaped recycled concrete filled steel tube short columns,caculated the range of thinkness of steel pipe that asymmetric stiffening rib can effectively exert the restraint effect and the enhancement degree of bearing capacity compared with those without ribs.(1)With the increase of the recycled aggregate substitution,the core recycled concrete of the specimen is easy to be crushed and its bearing capacity is affected.The ultimate load of GR3-1 and GR3-2 are reduced by 9.82% and 14.67% respectively.The existence of stiffeners can partially constrain the outer convex deformation of steel tubes.(2)Increasing the thickness of steel pipe can improve the axial stiffness and bearing capacity of specimens.The ultimate load of specimens GR3-1 and GR4-1 is 24.41% and 44.82% higher than that of GR2-1 respectively.(3)The plane center of mass deviates from the center axis due to the uneven distribution of the stiffener and the offset is mainly related to the thinkness of steel pipe and the length of stiffener..(4)The asymmetrical ribbed cause the asymmetrical distribution of stress on the end face of the specimen and the asymmetrical phenomenon becomes more obvious with the increase of the thickness of steel pipe.The result of the center of mass migration is that the total stress on one side of the center of mass is less than that on the other side(small eccentric phenomenon).(5)The recycled aggregate substitution rate has a small influence on the strain distribution due to its influence on the performance of core recycled concrete.The change of thickness of steel pipe will affect the strain distribution of the specimen in the failure process.(6)When the steel pipe wall thickness is less than 3.5mm,the constraint capacity of the asymmetric stiffener can be effectively guaranteed.When the steel pipe wall thickness is 3.5mm to 3.75 mm,the constraint capacity of the asymmetric stiffener can be basically ignored.(7)The bearing capacity of ribbed specimens compared with that of unribbed increase with the increase of thickness of steel pipe,the increased range is greatly affected by the thinkness of steel pipe and recycled aggregate substitution rate,and the average is 9.14%.(8).Based on the influence of the thickness of steel pipe to the constraint effect in the numerical simulation,the formula of the stiffener’s bearing capacity was put forward,and based on the test results and calculation results,the formula of bearing capacity of T-shaped recycled concrete filled steel ribbed tubular short coclumn was proposed which considered the restraint of steel pipe and stiffener.