Mechanical Performance Analysis Of Steel Reinforced Concrete Inclined Columns

The steel-concrete oblique column in the composite structure of the inward folding super high-rise building is a force-bearing member composed of cross-shaped steel,shear nails,concrete and steel cages.The strength of the connection between concrete and cross section steel determines the force and deformability of the component.Reasonable welding of a certain number of shear nails on the surface of the section steel can effectively inhibit the extension of the slippage of the section steel-concrete interface,and ensure that the section steel and the concrete are simultaneously stressed and deformed together.This paper mainly studies the mechanical performance of steel reinforced concrete oblique columns with shear nails and the optimization of cross-section design.The completed work and the conclusions obtained are as follows:(1)Numerical simulation of mechanical properties of group screw connectors.A numerical simulation model for the mechanical performance of multi-layer shear nails was established to analyze the load carrying capacity of the joint and the uneven force transmission within the group of nails.On this basis,it analyzed the reduction degree of the concrete strength grade and the number of shear nail layers on the bearing capacity and shear stiffness of the group nail connectors.As can be concluded,the average shear bearing capacity and shear stiffness of shear nails decreased by 26.08%and 74.9%when 15 layers of shear nails were arranged,and the effect of group nails had a great influence on the shear stiffness of shear nails.The further away from the center of the steel,the greater the load on the rock,and the load borne by the shear nail near the loading end is greater than the load borne by the shear nail near the free end.The average carrying capacity and stiffness of the rock are reduced by the increase in the number of nails and increased by the increase in the concrete strength quality,but it is less affected by the strength grade of concrete.(2)Analysis of the mechanical performance of steel reinforced concrete oblique columns with shear nails.Relying on the composite structure of a 168m super high-rise building,a numerical simulation model of steel reinforced concrete inclined columns with an inclination angle of 4° was established,and in-situ tests were carried out on the construction site to verify the calculation accuracy of the model.On this basis,the factors affecting the bearing capacity of the inclined column and the slip of the steel-concrete interface under vertical and horizontal loads are analyzed.There are the following conclusions:when the horizontal load loading direction is the same as the tilt direction,the greater the tilt angle of the inclined column,the smaller its shear bearing capacity.By introducing a reduction factor that is positively related to the inclination angle,the calculation formula for the shear bearing capacity in the relevant code is revised.The slip distribution at the steel-concrete interface is greatly affected by the diameter and vertical spacing of the shear nails.(3)Design optimization of steel reinforced concrete inclined columns.Based on the basic genetic algorithm,the elite strategy is embedded in the selection operation,and the dynamic mutation probability and the perturbation formula are embedded in the mutation operation to form an improved genetic algorithm.Taking the maximum bearing capacity of the inclined column,the minimum interface slip and the minimum engineering cost as the objective function,the design optimization of the section parameters of the steel reinforced concrete inclined column is carried out.There are the following conclusions that the improved genetic algorithm is better;the use of the improved genetic algorithm to optimize the section of the steel concrete oblique column can get lower cost,higher load-bearing capacity,and smaller interface slippage.