Bond Behavior Between Concrete Confined By Stirrup And Steel Bars After Freezing-Thawing Cycles

Research on the durability of concrete and more and more attention by researchers at home and abroad,the frost resistance of concrete is an important indicator of durability,reinforced concrete structures in severe cold areas and non-cold areas suffered destruction of the freeze-thaw cycle,This damage is not only reflected in the destruction of the overall structural appearance,but also the damage to the internal structure.Once the degree of damage is increased,it will even cause an incalculable loss to the structure.The reason why the reinforced concrete structure can work stably is because the steel and concrete can maintain good adhesion performance.If the reinforced concrete overall structure can still maintain strong bonding performance after being subjected to freezing and thawing,the overall structure of the Frost resistance is strong.Therefore,it is necessary to study the bonding properties of concrete after freeze-thaw.This article mainly studies from the following aspects:1.The change of mass loss rate and relative dynamic elastic modulus of concrete with freeze-thaw cycles from 0 to 100 freeze-thaw specimens of C20 and C40 strengths with dimensions of 100mm×100mm×400mm was proposed.In accordance with the damage evaluation criteria of freeze-thaw damage mechanism,the change law of splitting tensile strength and compressive strength of cubic specimens with dimensions of 100mm×100mm×100mm cubes after freeze-thaw cycles from 0 to 100 freeze-thaw cycles was studied;2.The center pullout test was performed after 0 to 100 freeze-thaw cycles using two types of bonded specimens of light round steel bars and ribbed steel bars.The appearance changes and damage modes of the test pieces after freezing and thawing were analyzed,and the data were plotted based on the data obtained.The mean bond slip curves of the specimens of each group were used to study the relationship between bond strength,slippage,and freeze-thaw cycles.The effects of different reinforcing steel types,different concrete strengths,and different freezing and thawing times on the bonding performance were compared and analyzed;3.Calculate and formulate the formula of bond strength,and based on the experimental data of this experiment,fit and analysis deduced the calculation formula of bond strength between steel and concrete after freeze-thaw cycles,and provide a numerical reference for the subsequent study of bond strength.