Study Of Spiral Steel Pipe Concrete Column On Axial Compressive Properties

Because of the full play of the characteristics of steel and concrete materials separately,concrete filled steel tube structure has been widely used in practical engineering.To solve the result of the limitation of welding process In tall buildings and high-rise buildings and The high budget In the low-rise buildings,More and more thin-walled concrete filled steel tube structure with diameter-thick ratio of more than 100 even bigger are used In engineering practice.As a result of the local buckling of Thin-walled concrete-filled steel tube under load,The performance of components is depressed.To improve the bearing performance,the research on structural measures is very necessary,in addition to determining its reasonable design methods.Thin-wall round steel tube concrete column with outer spiral rib and concrete outside the outer wall of steel pipe was put forward to suppress the local curved pipe wall in this paper,outsourcing concrete also can be used as protective layer of concrete to effectively protect pipe wall from the affection of chemical corrosion and temperature.On the basis of the setting of the outer spiral rib,in order to prevent outsourcing concrete fall off in advance,a new form of outsourcing concrete with steel was put forward to improve the overall performance of concrete-filled steel tube column.This study were processed and axially compressed three specimens including ordinary concrete filled steel tube column,spiral steel pipe concrete column and external screw reinforced concrete filled steel tubular column.The ABAQUS finite element simulation Involved three parameters of outer spiral rib pitch、width-to-thickness ratio of outer spiral rib and the cross section area ratio of core concrete and outsourcing concrete was carried out on the basis of experiment.The results of axial compression experiment show that:(1)Due to the outsourcing of concrete and steel tube wall can’t work well,outsourcing concrete and steel tube of concrete filled steel tube column with outer spiral separated under under small load,also failed to effectively provide strength.It’s axial compression bearing capacity is far lower than the same materials of ordinary concrete filled steel tubular specimens,while the ductility increase slightly.(2)Because of both impacts of the suppression of spiral rib to local buckling on the wall of the lateral and the improvement of reinforcement to the overall performance of outsourcing concrete.The axial compression bearing capacity and ductility of external screw reinforced concrete filled steel tubular column significantly improved.Finite element simulation experimental results show that:(1)Outer spiral rib pitch on has little influence on axial compression bearing capacity of the steel tube concrete specimen,but main influence on ductility.(2)The influence on width-to-thickness ratio of outer spiral rib is not very clear.(3)The cross section area ratio of core concrete and outsourcing concrete on strength of specimens was significantly positive correlation,that makes it clear that the impact of the outsourcing concrete mainly is protective layer,not improvement to strength.