Research On Calculation Of Bearing Capacity Of Bonded Steel Plate Reinforced Beam Based On The Influence Of Relative Slip Effect

The sticking steel plate reinforcement method is widely used in engineering practice because of its simple construction and good reinforcement effect.Among them,the bonding layer is a key factor to ensure that the original structure and the reinforced steel plate are cooperatively stressed.However,due to the difference in mechanical properties between the new and old materials,the relative slip effect between the bonding surfaces will inevitably occur in actual engineering,which will affect the reinforcement.The mechanical properties of the rear structure.For this reason,it is of practical significance to study the influence of the relative slip effect between the bonding surfaces of the bonded steel beams on the mechanical performance of the structure.This paper mainly studies the structural composite stiffness and the ultimate flexural bearing capacity calculation formula of the reinforced beam with steel plate under the influence of the relative slip effect between the bonding surfaces,and the relative sliding effect between the bonding surfaces on the strength of the strengthened structure.The research content is as follows:(1)On the basis of the current short-term stiffness calculation theory of concrete structures and related literature,the theoretical calculation formula for the structural composite stiffness and the ultimate flexural bearing capacity of the normal section of the bonded steel reinforced beam under the influence of the relative slip effect between the bonding surfaces is deduced.(2)Using the theoretical calculation formulas that have been derived,the calculation formulas for the composite stiffness and bearing capacity of the simply supported bonded steel reinforced beams under the forms of concentrated load,uniformly distributed load and symmetric concentrated load are given,and the calculation formulas are also given.Specific examples.From the theoretical formula and the results of the calculation example,it can be seen that the maximum composite stiffness of the simply supported bonded steel reinforced beam under the above three load forms occurs at the fulcrum section,and the minimum composite stiffness occurs at the mid-span section;it is caused by the relative slip effect.The additional bending moment of the structure is also the largest at the mid-span position.In addition,the composite stiffness of the bonded steel beams decreases with the increase of the external load,and the additional bending moment caused by the relative slip effect increases with the increase of the external load.(3)Establish two finite element models for steel-bonded reinforced beams considering and not considering the relative slip effect between the bonding surfaces.According to the corresponding finite element results,the cracking load,material stress,composite stiffness and normal section of the two are analyzed and compared.Variation characteristics of ultimate flexural capacity.From the above analysis,it can be seen that the relative slip effect reduces the cracking load,composite stiffness and ultimate flexural bearing capacity of the normal section of the structure;in addition,due to the relative slip effect,the compressive stress of the original concrete and the tension and compression steel The stress of the steel plate is higher than that without the relative slip effect;on the contrary,due to the relative slip effect,the reinforcing effect of the steel plate on the original structure is reduced,and the tensile characteristics of the steel plate are not fully exerted,resulting in a relatively non-relative tensile stress.The slip effect is small.