Experimental Study On The Effect Of Reinforcement Ratio On The Mechanical Behavior Of Stainless Steel Reinforced Concrete Columns

Steel corrosion is a common durability problem of concrete structures.Steel corrosion not only affects the normal use of the structure,shortens the service life of the structure,but even directly endangers the safety of the structure.Stainless steel can fundamentally solve the problem of steel corrosion.In order to promote the application of the stainless steel,the experimental study on the mechanical behavior of stainless steel reinforced concrete columns was carried out in this paper,and the main experimental results are as follows:(1)The axial compression experiment of stainless steel reinforced concrete columns were carried out,and the effects of the ratio of longitudinal reinforcement and volume-stirrup ratio of stainless steel on the mechanical properties of axial compression specimens were analyzed.The test results showed that: The failure stage of stainless steel reinforced concrete columns under axial compression can be divided into three stages: linear elastic stage,elastic-plastic stage and failure stage.Under the same other conditions,with the increase of the ratio of longitudinal reinforcement and volume-stirrup ratio,the displacement and concrete strain of the specimen were decreased under the same load,and the bearing capacity of the specimen increased.When the volume-stirrup ratio was increased to a certain extent,the influence of volume-stirrup ratio on the longitudinal displacement and concrete strain was decreased.When the calculation formula of confined concrete compressive stress was used to calculate and analyze the bearing capacity of axially compressed columns,the error between calculated values and test values was small.In order to improve the safety of axially compressed columns,a modified formula for calculating the pressure of confined concrete with stainless steel was put forward in this paper.(2)The experiment of stainless steel reinforced concrete column under eccentric compression was carried out,and the effects of the ratio of longitudinal reinforcement,volume-stirrup ratio and eccentricity on the mechanical behavior of eccentrically compressed specimens were analyzed.The experiment results showedthat: The failure mode of stainless steel reinforced concrete columns under eccentrically load was basically the same as that of ordinary reinforced concrete columns.After the specimen reached the ultimate load,the tensile steel in the large eccentric compression member could reach yield.When the strain of the stainless steel on one side of the tension zone reached 0.002,the concrete was close to failure,but the stainless steel on one side of the compression zone did not yield.In the small eccentric compression member,the steel in the compression zone was yield,but the steel in the tension zone was not yield.For stainless steel reinforced concrete columns under large eccentric compression,the calculated results of the bearing capacity formula given by the code were in good agreement with the experimental results.For the stainless steel reinforced concrete columns damaged by small eccentric compression,due to the restraint of stirrups,the test load value was larger than the load value calculated by the current code.The calculation formula of small eccentric compression column was modified in this paper.The modified calculation results were in good agreement with the test results.(3)In this paper,the crack development law of stainless steel reinforced concrete columns under eccentric compression was analyzed,and the crack spacing and crack width of stainless steel reinforced concrete members under normal service conditions were discussed.The formula for calculating the average crack spacing of stainless steel reinforced concrete eccentrically loaded members was given.In the current code,the formula for calculating the maximum crack width of eccentrically loaded columns was too safe,and it was suggested that the influence of initial eccentricity should be taken into account.A modified formula for calculating the maximum crack width of stainless steel reinforced concrete eccentrically compressed members considering the influence of initial eccentricity was given in this paper.