Analysis Of Compressive Bearing Capacity Of Stainless Steel Reinforced Concrete Based On Micro-mechanics

The corrosion of steel bars in concrete is one of the main factors affecting the durability of concrete structures.Stainless steel materials are selectively applied in engineering construction due to excellent corrosion resistance.However,due to the fact that there is no uniform calculation formula for the bearing capacity of stainless steel reinforced concrete structures in China,the promotion and application of stainless steel reinforced concrete structures are limited to a certain extent.In this paper,the eccentric and axial compressive bearing capacity of stainless steel reinforced concrete columns were studied by using the meso-mechanics approach with the support of the National Natural Science Foundation of China(51679220,51309203).The main contents and results are as follows:(1)A mesoscopic numerical model of stainless steel reinforced concrete was established.The stainless steel reinforced concrete is regarded as a multiphase composite consisting of mortar matrix,coarse aggregate,stainless steel bar,interface phase(coarse aggregate-mortar matrix interface,steel bar-mortar bond layer).The parameter assignment method of steel-mortar matrix bonding layer material was studied,the influence of interface properties on bond strength was analyzed,and the recommended range of tensile strength of bonding layer was given.(2)The failure process and bearing capacity of stainless steel reinforced concrete columns under eccentric compression were analyzed.Using the established mesoscopic numerical model of stainless steel reinforced concrete,the eccentric compression test of stainless steel reinforced concrete was simulated.The effects of reinforcement ratio and eccentricity on the failure process and bearing capacity of the components were analyzed.The results show that: the calculated failure mode and bearing capacity of the specimen are in good agreement with the macroscopic test results;the strain distribution along the height of normal section is basically linear,conforming to the assumption of flat section;the reinforcement ratio and eccentricity have a great influence on the bearing capacity of stainless steel reinforced concrete columns,the bearing capacity increases with the increase of the reinforcement ratio and decreases with the increase of the eccentricity;with the increase of reinforcement ratio and eccentricity,the ductility of the column is better,and the load-nominal strain curve and load-steel strain curve tend to be flat with the increase of eccentricity.(3)The failure process and bearing capacity of stainless steel reinforced concrete columns under axial compression were analyzed.The axial compression test of stainless steel reinforced concrete was simulated,and the influence of slenderness ratio and section size on failure process of the member was studied.The axial compression test of stainless steel reinforced concrete was simulated.The influence of slenderness ratio and section size on failure process of component was studied.The results show that: with the decrease of slenderness ratio,the fracture zone transits from "X" shape to "V" shape distribution,and the initiation point of the main crack is not affected by slenderness ratio,and its extension direction is approximately with horizontal angle;with the increase of section size,the ductility of members decreases,and the gradient of load-nominal strain curve decreases,but the nominal axial compressive strength decreases more obviously,showing a significant size effect feature,which verifies that Ba?ant's size effect theory can be well applied to the analysis of nominal axial compres-sive strength.