Research On The Durability And Flexural Behavior Of Concrete Components With Hybrid Reinforcement Of GFRP Bars And Steel Bars

The reinforced concrete structure is the most widely used in the field of modern engineering.However,due to the problem of corrosion of the steel bars,the durability problems of the steel bars during the long-term use have gradually emerged,which has aroused more and more attention.Since the 1950 s and 1960 s,fiber-reinforced composite materials have gradually entered the field of vision.This material has been gradually recognized by the engineering community for its advantages of corrosion resistance,high strength,light weight,and electromagnetic resistance.Reinforced steel is used in practical civil engineering structures and has achieved good practical results,of which the most widely used composite fiber composite reinforcement is GFRP reinforcement.However,due to the small elastic modulus of GFRP,it is easy to produce lar ge deflections and cracks in concrete structures,resulting in greatly reduced structural rigidity.If the steel bars and GFRP bars are mixed and arranged in the concrete structure,the advantages of high strength and corrosion resistance of the GFRP bars and better integrity of the steel bars can be organically combined,and the bearing capacity of the reinforced concrete structures can be enhanced,while the retained steel bars can be solved.The large deflection and cracks of the structure due to brittleness are an ideal form of reinforcement.In order to study the durability and flexural performance of GFRP-reinforced reinforced concrete structures,this paper mainly studied the following:1.Using the concrete carbonization depth to reach the surface of the steel bar as a sign that the steel bar starts to rust,combined with the calculation formula of the mean depassivation time of the steel bar surface,the durability performance of the GFRP-steel bars reinforced concrete members arranged by six differe nt reinforcements is compared and analyzed.The best reinforcement form of reinforced concrete structures is proposed,the study shows that the rebar is located far away from the windward and corner areas.When GFRP bars are installed in other areas,the percentage of durability of the components can be increased by 119%.That is,the durable life can be extended by 1.19 times correspondingly.The percentage of sexual promotion is somewhere in between.2.Based on the characteristics of the service life prediction methods for plain concrete,steel bars and GFRP bars,the structure service life prediction method under the influence of concrete durability and GFRP to steel bars area ratio is discussed and the service life prediction model of hybrid reinforced concrete structure is proposed.3.Based on the calculation method of crack widths of FRP-reinforced concrete beams,the influence mechanism of the difference between the slabs and beams structure is discussed to the calculation of crack widths.The correction method of the parameters such as the average crack spacing lcr,the section internal force arm coefficient ? and the FRP bar strain nonuniformity coefficient ? are introduced,at the same time,the proposal to abolish the ?te is proposed,calculation formula of crack width for mixed-reinforced concrete slabs is corrected.Based on the semi-theoretical semi-empirical method and the experimental analysis results,the calculation formula for the deflection of reinforced concrete structures is derived.4.Based on the plane section assumption and the internal force balance conditions of the section,the formulas for the ultimate bending capacity of the normal section under the conditions of the cracking moment and the appropriate reinforcement failure of the concrete slab with reinforced-reinforcement reinforcement are deduced,and the flexural performance of the hybrid reinforcement structure was verified by experiments and finite element simulations.The measured values agreed well with the formulas,the research shows that under the condition that the overall reinforcement ratio of the components is the same,the traditional single steel bar reinforcement method has the lowest flexural bearing capacity,and the flexural bearing capacity of the hybrid reinforcement component increases with the increase of the area ratio of GFRP bars and steel bars.The flexural bearing capacity can be increased up to 52.7%,and when the GFRP ribs are all arranged inside the concrete,the flexural bearing capacity of the components reaches a maximum value.