Research On Flexural Performance Of Reinforced Concrete Structure Strengthened By Prestressed FRP Grid

With the continuous development of China’s civil engineering industry,the construction of new structures will gradually become saturated,the demand for reinforcement of structures will gradually increase,and the field of structural reinforcement will become an important part of the construction industry.As FRP reinforcement structure has good durability and good bearing capacity,FRP material is widely used in civil engineering.FRP grid has two-way fiber ribs,low stiffness,high strength,is a linear elastic material.It has better anti-stripping performance and fire resistance compared to FRP sheet.Prestressed FRP grid reinforcement technology can effectively improve the structural mechanical properties,give full play to the characteristics of high FRP grid,and further inhibit the structural deformation and crack propagation.The tensile and anchoring techniques of prestressed FRP grid are difficult in engineering.In view of this difficulty,the end anchorage and tensioning method are studied in this paper,and the prestressing test of 6 hollow slabs is used to verify the prestress FRP grid,the calculation method of the normal bearing capacity of prestressed FRP grid reinforced hollow slab(beam)is proposed.This paper mainly carried out the following work:(1)Through the theoretical calculation and numerical simulation,a variety of FRP grid clip type anchors are designed,and the grid grips are clamped by using anchor samples.The mechanical properties and anchorage efficiency are tested on the tensile testing machine.From the mechanical performance and economic point of view,it is concluded that the corrugated clip type anchor is a better scheme.Then we designed a set of prestressed FRP grid tension method,and completed the grid tension by using corrugated clip-type anchor.(2)The non-prestressed FRP grid,prestressed FRP grid and prestressed steel wire rope flexural reinforcement test were carried out on the six hollow slabs,and the failure characteristics and failure mechanism of the hollow plate were studied.The results show that the cracking load,the yield load and the ultimate bearing capacity of the prestressed FRP grid are increased by at least 50%,57%and 62%respectively,and the ductility decreases slightly.Compared with the non-prestressed FRP grid reinforcement plate,it is shown that the prestressed FRP grid reinforcement can improve the cracking load and effectively inhibit the development of cracks.The comparison of the FRP grid and the steel wire rope reinforced by equal strength and prestressing level shows that the prestressed FRP grid can improve the flexural capacity more effectively than the steel wire rope.(3)According to the test results,the calculation formula of the bearing capacity of the normal section of the prestressed FRP grid is deduced,and the theoretical calculation value is compared with the experimental value.The results show that the theoretical value of the calculated plate and the error of the test result are within reasonable limits,that means the theory calculation is in good agreement with the experimental results.