Experimental Research On Strengthening Eccentrically Compressed Steel Columns Encased With Reactive Powder Concrete Under Load

With the increasing proportion of steel structures in the construction field in the world,many steel structures in service have many hidden safety hazards due to the service environment,their own defects,load changes and other reasons,so there it is really essential to strengthen the defective steel structures.At present,there are many methods to strengthen steel structure.Among them,the increasing section reinforcement method is widely used.Common reinforced concrete wrapped steel is used for reinforcement.However,due to the existence of coarse aggregates,it is difficult to vibrate and thicken in the actual operation.The aggregate is difficult to distribute evenly,and ordinary reinforced concrete is restricted by the initial stress of the section steel,so it is difficult to achieve the ideal reinforcement effect.To address these shortcomings,the Reactive Powder Concrete（RPC）is used to carry out outsourcing reinforcement research on full-scale biased steel columns under load,and carries out corresponding theoretical analysis and derivation in this paper.The main research work is:（1）Six full-scale members with a cross-section of 250mm×350mm and a height of 2400 mm were designed to carry out the force and bias test of the RPC-clad steel column under load to observe the failure mode,crack development,disturbance change,strain law,etc.The results show that the use of RPC to strengthen the eccentrically compressed steel column can significantly increase its ultimate bearing capacity,and the ultimate bearing capacity raised in the wake of the increase of RPC strength,and decreases with the increase of eccentricity and initial load.（2）Using ANSYS finite element software to perform numerical simulation on each test column,using the life-and-death element method to truly simulate the initial loading of the member,and obtain the ultimate capacity,load-lateral displacement curve,and stress-strain curve of section steel and RPC,The stress cloud diagram and crack development diagram of the loading process are compared with the simulated value and the test result,and the reasult have shown to be in good agreement.And use finite element model to simulate another 30 components to explore the influence of other parameters on limit loads.（3）Comparing the existing reinforcement formulas,according to experimental phenomena and theoretical analysis,using concrete reinforcement steel structure as the calculation method,considering the strength reduction coefficient of outsourcing RPC,it is proposed that the outsourcing RPC strengthens the biased steel under load The calculation formula of the column is compared with the test results and numerical simulation results.The results show that the calculation formula of the formula in this paper is reasonable and can be used as a reference for actual reinforcement projects.