Finite Element Analysis And Actual Engineering Research On Ferrule Effect In Outsourcing Angle Steel Reinforced Concrete Column

According to the statistics, the considerable urban construction of China has entered theaging stage by the end of2010, so quality problems have occurred frequently, of which aboutbillions of square meters need repairing and reinforcing in order to eliminate safety concerns.Undoubtedly, as the share of cost on reinforcement and reconstruction in current and futurewill be higher and higher, the building reinforcement industry will develop more and morequickly.Reinforced concrete column is one of the most basic force components of reinforcedconcrete structure, which carries the whole structure security; therefore, the study onmechanical performance of reinforced concrete column has a profound engineeringsignificance. Compared with other reinforcement methods, outsourcing angle steel reinforcedmethod has some significant advantages, for example, do not increase the weight ofcomponents; do not change the original design of the structure; the simple construction; a smallamount of work site; improving the bearing capacity significantly; bettering rigidity andductility of section; and limiting the rapid increase of the original component deflection. Atpresent, the technology of outsourcing steel reinforcement has made a lot of research results,however, the steel skeleton from angle steels and batten plates constrains the concretecolumns, so that the study on ferrule effect caused by the situation that the core concrete fromthe uniaxial stress state into a triaxial compressive stress state. Therefore, this paper studiesthe influence of outsourcing angle steel reinforced column by ferrule effect in the method ofnumerical analysis, analyses the mechanism of ferrule effect, and initially establish thebearing strength formulas of outsourcing angle steel reinforced column influenced by ferruleeffect.Firstly, the numerical analysis model of outsourcing angle steel reinforced concretecolumn has been established initially in this paper. Through numerical analysis, we cananalyze the production mechanism of ferrule effect, the effect of reinforced columns’properties of ferrule effect, three factors of stirrup diameter, angle steel’s thickness andspacing battens, the change of mechanical properties of reinforced columns, and the linksbetween these factors and ferrule effect to establish the bearing strength formulas ofoutsourcing angle steel reinforced column influenced by ferrule effect. There are someconclusions followed through research: influenced by ferrule effect of outsourcing angle steel reinforced columns, the ultimate bearing capacity of reinforced concrete columns has beenimproved significantly; concrete stress has been better-distributed; the ductility anddeformation capacity of reinforced columns has been improved, and the mechanicalproperties of compression members has been improved greatly; the stress of the end concretecolumns is much larger than that of the central, while the deformation near the middle of steelskeleton is the largest, so more attention should be paid during construction of pouringconcrete columns’ end and welding the central of the steel frame; with the increasing of theangle steel’s thickness and cross-sectional area, the decreasing of batten spacing, the steelskeleton shares more load bearing capacity, which makes bearing capacity improved and thehoop constraint of core concrete increased. At the same time, the displacement of concreteand angle steel decreases with a certain level, the stress of the angle steel also decreases, butthe rate of capacity’s improvement is not changed in a linear to the increasing rate ofthickness and the decreasing rate of batten spacing. In the three factors influenced by ferruleeffect studied in the paper, the thickness of angle steel and the batten spacing are the mainfactors.