| In order to realize my country's land and sea overall planning,accelerate the construction of a strong marine nation,and promote the rapid development of island engineering construction,fiber reinforced composite(FRP)reinforced full coral concrete has become a research hotspot for island reef infrastructure.However,the current research on FRP-reinforced all-coral concrete mainly focuses on the bonding properties of FRP-reinforced coral-coral concrete and the flexural properties of FRP-reinforced coral-reinforced concrete.The experimental research on the shear behavior of FRP-reinforced coral-reinforced concrete is extremely lacking.The existing FRP reinforced concrete specifications do not consider the influence factors of the shear-span ratio,and the specification does not clearly specify the design of the lightweight aggregate coral concrete,which makes the FRP reinforced coral concrete be subject to certain restrictions when used in actual engineering design.Therefore,in this paper,CFRP(Carbon Fiber Reinforced Polymer,CFRP)reinforcement with better comprehensive performance is selected to make CFRP reinforced all-coral concrete beams,considering different shear span ratios and coupling rate factors,the shear performance is studied and tested with steel bars.Beam for comparison.The main research contents and test results are as follows:(1)Shearing performance of 10 CFRP tendon full coral concrete beams with web reinforcement,2 CFRP tendon full coral concrete beams without web reinforcement,1reinforced steel hoop full coral concrete beam and 1 reinforced CFRP stirrup full coral concrete beam Test to study the difference in shear performance under different shear span ratios and different coupling ratios.The main contents of the measurement include: cracking load,ultimate shear bearing capacity,deflection of mid-span and loading point,width of concrete crack at the height of diagonal crack and longitudinal reinforcement,strain of stirrup and tensile longitudinal reinforcement in shear span.(2)The shear properties of CFRP reinforced coral concrete beams with different shear span ratios(?=0.95,1.50,2.0)and different hoop ratios(0.251%,0.377%,0.628%)were analyzed.The results showed that the shear capacity of the test beams was significantly affected by the shear span ratio,and the shear capacity of the test beams decreased with the increase of the shear span ratio.With the increase of stirrup ratio,the shear capacity of the test beam increases,but the increase is not obvious.All coral concrete beams with different shear span ratio and different hoop ratio have similar failure morphology characteristics with ordinary concrete before the slip failure,and the failure mode can be subdivided into baroclinic failure after the slip,shear failure after the slip and post-slip cable-stayed failure after the slip,but generally speaking,the slip failure.(3)The longitudinal bar strain and stirrup strain were analyzed,and it was found that the maximum strain of CFRP bar was close to 8000,and its high tensile strength was not fully exerted.The maximum tensile strain of carbon fiber stirrups is close to 5000,and the stirrups only gradually emerge after the middle loading,but the general strain is within 1000,and the strength utilization ratio and shear contribution of CFRP stirrups are also low.In the reinforcement test beam,the effect of the hoop is obvious,and the hoop basically reaches the yield strain during the failure,while the CFRP stirrup strain is far from the ultimate strain.(4)Based on China's FRP code GB50608-2010,considering the influence of shear-span ratio,the shear-span-ratio influence coefficient is introduced to modify the calculation formula of shear strength of FRP all-coral concrete,and the calculation results are compared with those of other codes The results show that the modified formula has good applicability,and can provide a reference for the design of the CFRP reinforced all-coral concrete structure in the future. |
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