Theoretical And Experimental Study Of CFRP Strengthening Bending Ultimate Bearing Capacity Of The Steel Member

As a kind of green building material,steel has been applied in a large number of bridges and buildings because of its light weight,convenient construction,good seismic resistance and flexible section selection.Caused by the influence of natural environment,the change of operation conditions and the increase of service life,more steel structures are faced with the need of reinforcement.In steel structure engineering,the ideal constructs under axial compression almost do not exist.As a result of the initial defects(including the uneven section,eccentricity of actual force and damage caused by the manufacture and transportation),most of the so-called axial compression constructs are bending constructs,so it is of particular importance to strengthen the steel constructs.The results show that the method of strengthening reinforced concrete structure with CFRP is more effective and the reinforcement of steel structure is also feasible.In order to discuss the effectiveness of strengthening different bending steel constructs with CFRP material,the following work has been done in this paper:(1)A comparative test of 40 steel members with different sections is carried out with CFRP sheets.Among them,10 are circular steel tubes,square steel tubes,angle steel and channel steel respectively.By considering the aspect ratio of each member,eccentricity,and the number of layers attached to CFRP cloth,the following factors are taken into account.The influence of these different factors on the ultimate bearing capacity of each member is studied.The results show that the ultimate bearing capacity of four kinds of cross-section members can be effectively increased by multi-layer CFRP cloth,and the increase range increases with the increase of the number of CFRP layers.(2)The finite element analysis of the test member is carried out,and the ultimate bearing capacity is solved by using ABAQUS software to model and calculate the stress,strain and displacement of the member under load.By comparing the results with the experimental results,we can see that the two results fit well,while the error is within areasonable range.The simulation results verify the correctness of the test results,which proved that the simulation model is suitable for the experimental research.(3)By giving the theoretical formula of the ultimate load of each constructs,the theoretical value of the ultimate load before and after the modification is compared with the experimental value and the simulated value.After the analysis of most of the modified theoretical values,it is found that the error between the theoretical value,the experimental value and the simulated value is reduced,that is,the modified theoretical formula can provide a better reference for the practical engineering.