Shear Behavior Of Concrete Structures Strengthened With Nsm Technology

With the aging of buildings,the use of functional changes,the existing structure of the reinforcement of the transformation has become the focus of attention.Fiber Reinforced Plastic is widely used in the reinforcement of concrete structures because of their light weight,high strength and convenient use.The Near-Surfaced Mounted has better effect in practical engineering because of its simple construction,less material consumption and better anchoring performance.Therefore,a large number of experimental studies have been carried out at home and abroad,but most of the researches are on the bond properties and flexural properties of concrete structures,and the research on the shear properties of concrete structures needs to be increased.The main research contents and corresponding conclusions of this paper are as follows:1.Based on the test of 8 reinforced concrete beams,the failure pattern,deflection and ultimate bearing capacity of shear behavior of concrete beams strengthened with NSM CFRP laminate are studied by using shear-span ratio,CFRP laminate embedding distance and CFRP laminate embedding angle,and so on,in this paper,the failure pattern,deflection and ultimate bearing capacity of reinforced concrete beams embedded with carbon fiber board after shear reinforcement are studied.The strain of steel bar,CFRP strain and the development law of oblique crack are studied and analyzed respectively.2.The NSM method is very effective for the reinforcement of reinforced concrete beams.The reinforced materials can work together with the members,and the bearing capacity of the strengthened members can be improved by 7% ~ 57%.The experimental results show that the oblique arrangement of the CFRP laminate can improve the bearing capacity of the members more than the vertical arrangement,and 45 °is the best embedding angle,which can effectively restrain the development of the inclined cracks.Reducing the spacing of CFRP laminate in a certain range can improve the shear capacity of the members,but if the spacing is not limited,the overreinforcement failure will occur easily.Therefore,the spacing cannot be reduced without limitation.The shear-span ratio has a greater influence on the shear capacity of the beam,and the larger the shear-span ratio,the higher the bearing capacity.By comparing with the control beam,the characteristics of the reinforced beam in shear performance are summarized,which provides a reference and basis for the later theoretical analysis.3.Based on the formula for calculating the shear capacity of reinforced concrete beams strengthened by external sticking method and truss-arch model,the formula for calculating the shear capacity of embedded reinforcement is proposed by modifying the reduction coefficient of the bond form.The calculated results are in good agreement with the experimental results.