Experimental Study On Axial Compression Of T-section Concrete Columns Strengthened By Carbon Fiber Sheets

Special-shaped column refers to a column with cross-shaped,L-shaped and T-shaped cross-sectional geometry,and the ratio of the cross-section leg length to leg thickness is less than 4.Compared with rectangular columns,the flexible cross-sectional form of special-shaped columns can make the column limbs and the wall evenly thick.It has the advantages of avoiding obvious edges and corners in the room,reducing the weight of the structure,and increasing the actual indoor area.At present,the research on the reinforcement of special-shaped cross-section concrete columns with Carbon Fiber Reinforced Polymer(CFRP)mostly adopts the full-wrap method,but there are not many researches on the reinforcement of special-shaped columns with CFRP cloth banners.In order to study the effect of CFRP cloth banner reinforcement on the performance of special-shaped columns,this paper uses CFRP cloth banner width and net spacing as variables.this paper carried out an experimental study on the mechanical properties of 9 short reinforced concrete columns with T-shaped cross-section under axial compression,one of them is an ordinary concrete column that is not constrained by CFRP cloth,the remaining 8 concrete columns are divided into two groups,each group contains 3 test columns with the same amount of CFRP cloth,but different widths and net spacing of CFRP cloth,and 1 column with CFRP cloth fully wrapped along the height of the column.At the second group of test pieces,the CFRP cloth at the corner of flange and web of the T-section column is anchored by angle steel.Through the static load test,the test data of the ultimate load capacity of the specimen,the failure mode of the member,and get the stress change of the material,the failure mechanism of concrete compression members strengthened with CFRP cloth is analyzed,and discussed the effects of factors such as the net spacing of CFRP cloth and the anchorage of angle steel on the mechanical properties of reinforced T-section concrete columns,summarized the synergistic performance of CFRP cloth,longitudinally stressed steel bar and concrete under the action of axial pressure.The results show that CFRP cloth are used to strengthen T-section concrete columns,when the consumption of CFRP cloth is same,the ultimate bearing capacity of T-section columns increases with the decrease of the CFRP cloth net spacing under the same conditions;Under axial pressure,use appropriate CFRP cloth anchoring measures at the corner of flange and web of the T-section column,can give full play to the strength of extension of the CFRP cloth and improve the ultimate bearing capacity of the members;T-section column strengthened with CFRP cloth,can on the basis of saving material for good reinforcement effect.On the basis of the experimental data,the finite element software ABAQUS was used to carry out the numerical simulation analysis of the T-shaped cross-section column,and the finite element simulation results that were in good agreement with the experimental results were obtained,which verified the accuracy of the model.At the same time,using CFRP cloth banner width,CFRP cloth wrapping layer number,concrete strength,steel bar diameter and CFRP cloth dosage as variables,the influence of different parameters on the bearing capacity of T-shaped column reinforced with CFRP cloth banner is analyzed.The results show that the amount of CFRP cloth and the width of the banner have a certain influence on the load-bearing capacity and deformation capacity of the simulated column;The ultimate bearing capacity of the simulated column increases with the increase of the concrete strength grade,and the increase is relatively large;Increasing the diameter of the stressed longitudinal bars can significantly improve the deformation capacity of the simulated column and increase its bearing capacity;The ultimate bearing capacity of the simulated column increases with the increase of the number of CFRP layers,but the increase will decrease.Based on the simulation results and the test results,a formula for the axial compressive bearing capacity of concrete columns with T-shaped cross-sections confined by CFRP cloth banners anchored by angle steels is put forward under the condition of different amounts of CFRP cloth.