Research On Mechanical Properties Of Axially Loaded Steel Columns Reinforced By External Reinforced Concrete While In Service

In recent years,the proportion of steel structure used in the actual project gradually increased,a large number of old steel structures and the new steel structures which are short of carrying capacity needs to be reinforced,this makes the reinforcement of steel structures play an increasingly important role.Therefore,this paper researches the reinforcement of steel structure,mainly researches the mechanical properties of in-service steel columns strengthened by the external reinforced concrete,The research contents of this paper are as follows:Use characteristics of the mechanical properties of ordinary steel reinforced concrete as analogy to analyze in-service steel columns strengthened by the external reinforced concrete.Analyzes the influence of initial load,concrete strength,steel strength and effect of stirrups constraint on the bearing capacity size of in-service strengthened steel column.According to the theoretical analysis by using the superposition method,considers the interaction between components of factors and deduces the bearing capacity calculation formula of in-service strengthened steel column,and the experimental parameters into the calculation formula of bearing capacity,by comparing the calculated results with the experimental results.The results showed that when the initial load increases,the bearing capacity of in-service strengthened steel column decreases;when the concrete strength increases,the bearing capacity of in-service strengthened steel column increases;when increasing the internal steel strength increases,bearing capacity of in-service strengthened steel column increases;bearing capacity of in-service strengthened steel column increases with increasing of the effect of stirrups constraint.Establishes ABAQUS model matched with experiment,simulates all stress process of in-service strengthened steel column with birth and death unit,and gets the simulation results,compares the simulation results with the experiment results and calculation results,verify the finite element model is correct after the comparison.Uses ABAQUS to do more groups of finite element analysis that in-service strengthened steel columns with differentinitial loads,different concrete strength and different internal steel strength,based on the theoretical derivation and experiment further analyzes the different influence factors on bearing capacity of in-service strengthened steel column.Analyses the characteristics of recycled concrete and factors affecting its strength.According to the bearing capacity of in-service steel columns strengthened by the external reinforced concrete,analysis of the influencing factors of in-service steel columns strengthened by the external recycled reinforced concrete,and the influence factors were the initial load,concrete strength,steel strength and effect of stirrups constraint,and according to the above proposed the bearing capacity calculation method.The finite element model is built in the existing steel reinforced concrete columns strengthened with ABAQUS regeneration,change the replacement rate of recycled concrete so as to change the strength of concrete,the different substitution rate of recycled reinforced concrete on the bearing capacity of in-service strengthened steel column,according to the results can be found when the replacement rate is 50%,the bearing capacity that recycled reinforced concrete and reinforced concrete strengthen in-service steel is similar to each other.