Research On Axial Compression Behavior Of Rectangular Concrete Short Columns Strengthened With Prestressed Angle Steel Plates

Due to the influence of human factors and the natural environment,many bridges built in the1970 s and 1980 s are damaged and aging,which can no longer meet the bearing requirements.If these bridges with potential safety hazards are comprehensively repaired,it will take a lot of time and labor cost to apply common reinforcement methods.Therefore,how to carry out efficient reinforcement is a key problem in practical engineering.The prestressed angle steel plate reinforcement technology described in this paper,as a new reinforcement technology,has the characteristics of simple construction and convenient operation,aiming at rapid repair of concrete column pier.At the same time,the method uses high-strength bolts to exert circumferential stress on the diagonal steel plate,so as to pre stress the internal concrete column and provide active restraint to the members,so as to improve the bearing capacity of the strengthened members.At present,in our country,the prestressed reinforcement technology has carried out a lot of research and practical engineering application,but how to optimize the complicated operation process and reinforcement device still needs to be discussed at this stage.In order to study the axial compression performance of rectangular section concrete short columns strengthened with prestressed angle steel plates,based on the existing theoretical basis and loading scheme,20 concrete short columns were tested under axial compression,and divided into one control group and three experimental groups according to the different prestress.The main purpose of this test is to study the influence of prestressed angle steel plate reinforcement on concrete short columns under axial compression.Three groups of prestress are set at the bolt connection between angle steel plates,which are 0,179.5mpa and 340 mpa respectively.In order to solve this problem,the finite element software is used for numerical analysis.In the numerical analysis,the influence of prestress,angle plate thickness and column section size on the axial bearing capacity of the strengthened column is considered.The results and conclusions are as follows(1)According to the test results,the bearing capacity of the rectangular section concrete short column strengthened by prestressed angle steel plate has been improved to a certain extent.Compared with the original column,the bearing capacity is improved by 30%-50%,and with the increase of the prestress on the angle steel plate,the axial bearing capacity of the component also increases.After reaching the ultimate load,the load displacement curve does not decline rapidly,but moves relatively gently downward The members strengthened by steel plate not only improve the bearing capacity,but also greatly enhance the ductility,and change the original brittle failure into plastic failure.However,with the increase of prestress,the increase of bearing capacity decreases gradually.It can be observed that there is an upper limit for the increase of prestress,and the axial bearing capacity and other properties of strengthened columns have been greatly improved.(2)In the elastic stage of loading,the curves of the control group and the experimental group are close,and the stress conditions of the two groups are the same.When loading to the plastic stage of concrete,the concrete of the reinforced column reaches the three-dimensional stress state.Compared with the control group,the curve is still rising,and the bearing capacity is improved.(3)Using the finite element software analysis,increasing the thickness of angle steel plate can improve the bearing capacity of reinforced members,and referring to the concrete-filled steel tubular column with similar structure type,there is also such strengthening effect;under the condition of other parameters unchanged,increasing the size of core concrete can also improve the bearing capacity to a certain extent,but the strengthening effect will gradually weaken,which also verifies the effectiveness of hooping effect theory(4)Combined with the mechanical characteristics of prestressed reinforced column and concrete-filled steel tube,this paper deduces the theoretical formula referring to the axial compression performance test of rectangular concrete short column strengthened with prestressed angle steel plate,and obtains a limit load formula with good agreement between data and results.