Experimental Study On Shear Performance Of Steel Beams Wrapped By Reinforced RPC While Under Load

Steel has the advantages of light weight,high strength,good seismic performance,and can be used for many times.It has been widely used in various infrastructure projects.However,with the increase of service life,the structure continues to accumulate damage under the dual intervention of natural action and human factors,affecting the original use function.Under the strategic guidance of sustainable development,it is the most effective way to reinforce the existing steel structure.China’s code "Steel Structure Reinforcement Design Standard" mentioned a kind of external reinforced concrete method,the method of unique reinforcement on the basis of improving the bearing capacity of the original structure,greatly enhance the fire resistance and corrosion resistance of the steel structure,so it has been widely used in the field of reinforcement.In this paper,based on the design concept of outlining reinforced Concrete method,an outlining reinforced Concrete RPC method is proposed.In this method,a new material--Reactive Powder Concrete is used to replace ordinary Concrete in order to achieve better reinforcement effect.RPC has super high strength and good durability.With the deepening of research,the superiority of RPC material has been widely recognized by the engineering field.In this paper,considering the real stress conditions of the reinforced members in practical engineering,the mechanical performance of RPC steel girder with external reinforcement under secondary stress is analyzed and simulated.The results are as follows:(1)Seven full-scale RPC beams with external reinforcement and one pure steel beam with the same specification were designed to explore the influence of initial load ratio,RPC strength and section steel strength on the flexural performance of beams.The deflection deformation and fracture morphology of the specimens and the ultimate bearing capacity are recorded,the section steel,steel bar and the strain change of RPC are measured.The results show that the RPC outsourcing method can significantly enhance the bearing capacity and stiffness of the steel beam,and the change of bearing capacity is negatively correlated with the proportion of the initial load,and positively correlated with the RPC strength and the steel section strength.(2)On the basis of the experimental results,the simulation analysis of the beam shows that the calculation accuracy of the model is high,and the simulation results are similar to the experimental phenomena.Using the same modeling method,26 specimens were calculated,and the parameter expansion analysis was carried out to further explore the influence of three variables on the mechanical performance of the beam.(3)Refer to the design method of secondary stressed components in current codes and related literature,the calculation formula of flexural capacity of RPC encased with steel bars under secondary loading is established.The RPC strength reduction coefficient is introduced into the formula,and the reduction coefficient is given based on theoretical analysis and data fitting.The formula calculation is close to the experimental results,and the calculation results are small and conservative.