Experimental Research On Mechanical Properties Of Axially Loaded Steel Columns Strengthened By Enclosed Reinforced Concrete While Under Load

Due to the influence of damage, various disasters, the environment and the using conditions, steel structure buildings has been caused by the structural damage that may not continue to play its function of the structure stably. The strengthening methods of axially loaded steel columns strengthened by enclosed reinforced concrete while under load has been widely used in all kinds of building structure reinforcement engineering, but, there is a lack of experimental research on the strengthening method. The value of the initial stress and the calculation method are different in the corresponding reinforcement method, and it has a hidden danger when it is applied to the practical engineering. In order to study the mechanism of force and failure patterns of axially loaded steel columns strengthened by enclosed reinforced concrete while under load, and in view of the problems in the existing steel structure reinforcement of the existing design methods, therefore, experimental study, theoretical analysis and calculation simulating are integrated in this article for the research of the axial compression.Firstly, seven reinforced steel columns and an un-reinforced steel column are designed, and the research on mechanism and failure mode, analysis on composite columns’ bearing capacity, deformation, strain distribution of steel, longitudinal reinforcement and concrete are studied through experiments. Comparison and analysis on the axially loaded steel columns strengthened by enclosed reinforced concrete while under load in different initial load size, concrete strength grade, the diameter of stirrup are carried out. The experimental results show that the bearing compressive capacity of composite columns increases with the increase of the diameter of stirrup and the strength of concrete, and the bearing compressive capacity of composite columns increases with the decrease of the initial load size; When the initial load is small, the bearing capacity and stiffness is improved obviously, but bearing capacity decreases with the increase of initial load significantly when the initial load is 0.5. This conclusion provides the basis for further research on the load carrying capacity of steel reinforced concrete columns under axial compression.On this basis, through the theoretical research, the design specification for the steel reinforced concrete structure and steel structure reinforcement procedures are analyzed, and then, referred to the calculation method of reinforced concrete structure, the calculation formula of bearing capacity is deduced for axially loaded steel columns strengthened by enclosed reinforced concrete while under load. The calculation results are compared with the test results, and the results show that the formula is simple, high reliability, so it can be used in practical engineering of the reinforcement technology.Finally, introducing element birth and death technology, the finite element model is established using ABAQUS. The method is verified by experiments, and the correctness of finite element simulation is verified. Analysis on the axially loaded steel columns strengthened by enclosed reinforced concrete while under load in different initial load size, concrete strength grade, the diameter of stirrup is carried out. The result shows that the initial load stress level indicator is not greater than 0.55, and the armored concrete reinforcing effect is obvious, so it can be used in practical reinforcement engineering of steel components widely. If the initial load stress level index is not more than 0.55, the reinforcement effect is obvious that it can be widely used in steel reinforcement engineering.In this paper, the key technical problems of steel reinforced concrete composite structures is used in reinforcement of steel structure, revealing the stress distribution law of different materials, which is a new breakthrough in the research of steel reinforced concrete composite structures. Therefore, the stress redistribution after reinforcement and the influence law of bearing capacity of reinforced steel column while under load is still a problem for the steel columns under axial compression.