Study On Axial Compression Performance And Bearing Capacity Calculation Of Composite Spiral Hoop Reinforced Steel Pipe Concrete Square Column

The current research status of restrained concrete shows that circular spiral hoop reinforcement has better restraint capacity among many forms of hoop distribution,but its application in rectangular cross-section columns still has limitations and less research.While in actual engineering,concrete columns with square cross-section are more common,and at the same time,in view of the weak restraint capacity of square steel pipe concrete columns compared with round steel pipe concrete columns,this paper proposes to add composite spiral hoop reinforcement in the interior of steel pipe concrete square columns to impose high restraint on the core concrete in order to solve the problem of larger bearing capacity and ductility demand of concrete square columns.The composite spiral hoop reinforcement steel pipe concrete square column has better bearing capacity and ductility performance,especially in high intensity fortification areas has great potential,therefore,this type of square column has wide application prospects in building structures.Based on this,this paper combines experimental research,finite element analysis and theoretical analysis to explore the axial compression performance of composite spiral hoop steel pipe concrete square column and propose its axial compression load capacity calculation formula,the main work is as follows:1.Collect relevant axial compression tests of single spiral hoop steel pipe concrete square columns to study the strength and ductility properties of this type of column,and discuss the influence of various influencing factors on its axial compression mechanical properties;use the finite element analysis software ABAQUS modeling to numerically analyze the test specimens,and conduct comparative analysis with the test results for their load-displacement curves,concrete section stresses,hoop stresses,steel tube stresses,etc.To verify the reasonableness of the proposed finite element model and related parameters.The results show that the load carrying capacity of concrete square column with built-in spiral hoop reinforcement is better than that of concrete square column without built-in hoop reinforcement;the load carrying capacity and ductility coefficient of concrete square column with single spiral hoop reinforcement increase gradually as the volume hoop ratio increases.2.Numerical simulations were conducted on the axial compression performance of the five-spiral hoop steel pipe concrete square column to explore the characteristics of its loaddisplacement curve in four stages,and to analyze the effects of concrete strength,steel tube thickness,spiral hoop spacing,spiral hoop strength,spiral hoop diameter,member length to slenderness ratio and other factors on its axial compression performance.The results of the study show that: compared with the single-spiral hoop arrangement,the five-spiral hoop arrangement has stronger restraint on the core concrete,and the bearing capacity and ductility performance of the specimens are better;with the increase of concrete strength,the increase of steel pipe thickness,the decrease of hoop spacing,the increase of hoop strength,the increase of hoop diameter and the decrease of column length to slenderness ratio,the bearing capacity and ductility of the five-spiral hoop steel pipe concrete square column will The load bearing capacity and ductility of five-spiral hoop steel pipe concrete square column will be improved to different degrees.3.Analyze the restraint mechanism of the composite spiral hoop reinforced steel pipe concrete square column,combine the double shear unified strength theory and superposition principle to propose the formula for calculating the axial compression load capacity of the composite spiral hoop reinforced steel pipe concrete square column,and compare it with the test and numerical simulation results.The results show that the formula proposed in this paper can be applied to the calculation of axial compression load capacity of composite spiral hoop reinforced steel pipe concrete square column.