Experimentali Study On Axial Compression Of Concrete Columns Strengthened With Prestressed Steel Strand And Wrapped Steel

Due to the influence of natural environment or man-made use,many building components are exposed to damage and aging,which cannot meet structural functional requirements.Therefore,the problem of effective reinforcement of damaged aging components is receiving more and more attention.As a new type of reinforcement,prestressed reinforcement technology improves the reinforcement mechanism of passive restraint in the previous reinforcement technology.Prestressing is used to provide active restraint to the component.While optimizing the force performance of the component,it also increases the use of the restraint device.At present,relevant researches have been carried out on prestressed reinforcement technology at home and abroad,but the reinforcement method and prestressing application device still need to be improved.Based on the research s-tatus of reinforcement technology,this paper proposes a prestressed steel strand-outer steel composite reinforcement method,and in order to accurately control the application of steel strand prestress,a set of steel strand prestressing device is designed.In this paper,the experimental study on the axial compression performance of prestressed steel strand-wrapped steel composite reinforced concrete columns is carried out.Five sets of reinforced concrete columns were designed,one of which was reinforced concrete standard column,one set was horizontal wire-wound reinforcement member,and the other three groups were composite reinforcement members with steel strand prestress of 1kN,2kN and 3kN respectively.The test results show that the bearing capacity of reinforced concrete columns strengthened by pre-stressed steel strands and clad steel is greatly increased,and with the increase of prestress,the bearing capacity of reinforced concrete columns is obviously improved.The results show that the lateral constraint of composite reinforcement can effectively delay the emergence and development of cracks,and improve the brittle failure of members to a great extent,and the load-displacement decline of members after failure is also relatively smooth.In addition,the stress and strain of stirrups,angle steel and concrete are analyzed,and the failure mechanism of members is studied.The finite element analysis software is used to model and analyze the test process,and the result of the finite element is in good agreement with the test results.The stress change of steel strand,angle steel and concrete is analyzed.The results show that the prestressed steel strands are in the elastic stage at the initial stage of axial compression,and the internal force changes linearly.Together with the angle steel,the lateral deformation of the concrete columns is effectively limited.under the constraint of composite reinforcement,the core concrete area of the concrete column section expands with the increase of the prestress,which improves the bearing capacity of the original component and improves the mechanical performance of the component.In this paper,the multi-parameter optimization analysis of the composite reinforcement is carried out,and the restraint effect of different angle steel types under different prestressing forces is studied.The results show that the increasing amplitude of the bearing capacity of the member increases with the increase of the limb length of the angle steel.The influence of angle steel on bearing capacity is greater,on the contrary,the change of prestressing force of steel strands weakens the influence on bearing capacity of members,and angle steel becomes the main force part of composite reinforcement device.However,in practical engineering,because of considering the cost problem,the influence of angle steel on the bearing capacity of members is weakened.Angle steel type selection should be based on the actual engineering selection.Through the experimental study of prestressed steel stranded steel-reinforced composite concrete columns,the constitutive relationship curves of the confined concrete are proposed,and the axial compression of the prestressed steel strand-outer steel composite reinforced concrete column is derived.The calculation formula of bearing capacity can provide reference for related reinforcement proj ects.