Study On Flexural Behavior And Design Methods Of Stone Slabs Strengthened With Prefabricated CFRP-reinforced Plates

Serving as one of the important components in stone structures,stone slabs would experience brittle fracture when the flexural strength is reached.To improve the safety of stone structures,an innovative strengthening technique by using prefabricated CFRP-reinforced sheets is proposed in this research.Compared with other existing strengthening methods,the proposed technique has the advantages of convenient construction on site and little effect on the appearance of original members.To verify the feasibility of the strengthening technique and provide evidence for engineering applications,the flexural behavior and design method of stone slabs strengthened with prefabricated CFRP-reinforced stone sheets was investigated.Firstly,bonding tests were conducted to study the bond behavior between the CFRP-reinforced stone sheet and the stone slab in both the tangential and normal directions.Double shear tests were adopted to investigate the bond behavior in the tangential direction,and the failure modes included the interfacial shear failure,stone shear failure,and local crushing of the stone block.Uniaxial tension tests were used to study the bond behavior in the normal direction,and the failure modes included the interfacial tensile failure and fracture of stone blocks.The experimental resulted show that:(1)The failure mainly occurred in the stone block,indicating a strong interfacial bonding strength between the adhesive and the stone block;(2)The bond strength mainly depended on the strength of the stone,and the surface roughness of the stone had little influence on the bond strength;(3)The bonded area had little influence on the bond strength within the considered parameter scope..Secondly,the experimental study on the flexural behavior of stone slabs strengthened with prefabricated CFRP-reinforced stone sheets was carried out.The experimental parameters included the ratio of CFRP bars,the diameter of CFRP bar,the width of the strengthening sheets,and the strengthening method.The test results showed that:(1)The proposed strengthening technique effectively improved the failure mode of the bare stone slabs by enhancing the flexural bearing capacity and plastic deformation capacity.(2)Within a certain range of reinforcement ratio,a higher reinforcement ratio resulted in a larger bearing capacity of the strengthened stone slabs.(3)Increasing the width of the strengthening sheets could increase the cracking load of strengthened stone slabs.Meanwhile,a larger width of the strengthening sheet could more effectively anchor the CFRP bars and improve the bearing capacity of strengthened stone slab after cracking.(4)Under the same reinforcement ratio,a smaller diameter of the CFRP bar led to better the deformation performance of the strengthened stone slab.(5)During testing,favorable bond behavior was obtained between the strengthening sheet and the stone slab,and no interface failure was found.Thirdly,based on the assumption of plane section and theory of limit equilibrium.The flexural behavior of stone slabs strengthened with prefabricated CFRP-reinforced stone sheets is theoretically studied,and the formula to be used to calculate the cracking moment and ultimate moment of strengthened stone slabs were put forward.The formula were validated against experimental results and showed acceptable accuracy.Finally,finite element analysis on the stone slabs strengthened with prefabricated CFRP-reinforced stone sheets was carried out.The influential rule and degree of different parameters on the flexural behavior of strengthened stone slabs were further analyzed,and specification of the stone slabs strengthened with prefabricated CFRP-reinforced stone sheets for engineering application was proposed.