Experimental Study On Constitutive Relation Of Eccentric Compression Rectangular Steel Tube Filled With Demolished Concrete Blocks

With the continuous progress of urbanization in China,construction waste is increasing,of which engineering waste concrete accounts for about 48.35% of construction waste,how green treatment of these waste concrete has become an urgent problem to be solved.It is necessary to waste a lot of concrete for the regeneration of concrete,and the disadvantages such as low strength and elastic modulus,shrinkage and creep,and poor mobility are also hindered.In order to solve this contradiction,this research group introduces the research of thin-walled steel pipe-recycled mixed concrete,which can give full play to the advantages of each material,high strength,good plasticity,fast construction speed,and eliminates the need for recycled aggregate Such as cumbersome procedures,save a lot of money and energy.In this paper,based on the research results of the research group,the constitutive relation and mechanical properties of the recycled concrete with eccentric compression rectangular steel tube are discussed by means of experimental study and numerical simulation.Based on the eccentricity,aspect ratio,steel content and mixing ratio,23 bias specimens and 3 axial compression specimens were designed.The results show that:(1)The composite concrete short columns with eccentric compression rectangular rectangle have good bearing performance and deformation ability,and the failure modes are similar to those of ordinary concrete-filled steel tubular short columns.The main factors of bearing capacity of regenerated mixed concrete short columns are eccentricity and steel content.The greater the eccentricity,the smaller the ultimate bearing capacity,the greater the steel content,the greater the ultimate bearing capacity,and the aspect ratio and the mixing ratio(3)The main factors influencing the ductility of the recycled concrete short columns are the eccentricity and aspect ratio,the eccentricity of the specimen has better deformation performance,the higher the aspect ratio,the extension of the specimen The effect of the worse,the steel content and the mixing ratio on the ductility of the specimen is limited.Based on the regression analysis of theoretical and experimental data,thecorrection coefficient of the effect of eccentricity on the tightening force is proposed.The coefficient is applied to the constitutive relation of the research group,and the stress-strain relation of the mixed concrete with eccentric compression is obtained Model,using the modified model for finite element calculation,found that the results consistent with the experimental results well.Choose typical specifications at home and abroad such as CECS159:2004、DBJ13-51-2003、ACI318-11、 AIJ-1997、BS5400-2005、EC4-2004 to calculate the eccentric compression ultimate bearing capacity of rectangular steel tube regenerative mixed concrete short column.The calculation results of DBJ are in good agreement with the measured data,and the data dispersion is small.It is suggested to use this procedure to calculate the ultimate bearing capacity of the recycled concrete columns with rectangular steel tubes.Finally,based on the theoretical analysis and experimental data regression analysis,the practical calculation formula of the ultimate bearing capacity of the recycled concrete columns with rectangular steel tube is presented.