The Application Research On Axially Compressed Concrete Columns Strengthened With Wet Encased Steel

Strengthening method with wet encased steel is a kind of widely used traditional strengthening method in practical engineering. Strengthening method with wet encased steel greatly improves bearing capacity, ductility and stiffness, without any increase in section size circumstances, because angle steel and batten plate's confinement effect make core concrete in three-dimensional stress state. The paper has established reasonable and effective finite element model by comparative analysis, for simulating reinforced concrete structure of the actual stress state. Summaried the changes of different factors, these provide practical engineering application with theoretical basis. The main contents are as follows:Firstly, considering secondary bearing member of the new added part existing stress and strain of the hysteresis phenomenon, it puts forward the steel-encased utilization coefficient and stress level index of the equation through degree of reinforcement yielding to considering the effect of stress history.Secondly, considering angle steel and batten plate's confinement effect and different confinement index, it puts forward concrete strength's improvement coefficient calculation formula and the core concrete compressive strength calculation method.Thirdly, considering angle utilization coefficient and concrete improvement coefficient, it determines wet strengthening axial compression column bearing capacity calculation formula in different stress level circumstances. It validates the correctness of the bearing capacity calculation method, through the experiment data, theoretical calculation results has been compared.Fourthly, according to stress characteristics of wet encased steel strengthening axial compression column, the finite element model simulates the experimental model with the Von Mises yield criterion to determine the yield point and Ottosen model as failure criteria. Compared with simulated results,experimental values and theoretical values, the effectiveness of the finite element model are validated.Fifthly, ANSYS finite element model analyses several factors on influencing wet encased steel strengthening axial compression column ultimate bearing capacity, for example, angle type, spacing of batten plates and the effect of stress history. Generally speaking, spacing of batten plates greater influence on ultimate bearing capacity than angle type.