Research And Development Of CFRP Plates Tension Device For Strengthening Steel Structures

With the development of economic level and engineering technology, steel structuresin service are increasingly aging and damage, prolong their service life, strengthening andrepairing of steel structures is imperative. And replacement of damaged components willcause great waste, moreover will affect the normal use of structure, in addition, the steelstructure damage are locality and multiple features, structure appeared damage to retire isnot possible. Therefore, maximum use of existing resources, seeking efficient andeconomical reinforcement technology to repair of steel structure is extremely significanceof engineering field technical problem, at the same time, is also related to socialsustainable development. At present, prestressed reinforcement technology is one of themost effective method of reinforced concrete structures. Using prestressed CFRP plates tostrengthen and repair steel structures is a highly efficient, economic and practical method,and has a huge development prospect.The purpose of this paper are to research and development CFRP plates wedge-typeanchorage and its supporting fixed construction of prestressed tensioning device for steelstructures, and combine with the test verifies the practicability of the anchorage and theconstruction unit, put forward the feasible construction technology. This paper based onthe national natural science fund project “performance and intelligent monitoringtechnology research of prestressed CFRP plates reinforced steel structures”, the mainresearch contents and results were as follows:（1） In accordance with the design ideas of one anchor, two install, three tension,Using friction principle, design a set of CFRP plate wedge-type anchorage and itssupporting fixed construction of prestressed tensioning device for steel structures, and putforward the feasibility construction process.（2） Through to the force analysis of three stages of wedge-type anchorage, get thefollowing conclusions: Reasonable value of anchorage preload; After finished unloading,in order to ensure the preload clip does not rebound, anchorage can be self-locking, theangle of the jaw must be less than or equal to the friction angle between anchor plate andclip; In order to ensure plate will not occur slipping in the process of using, there shouldbe enough friction between CFRP plate and clip, suggest applying emery in the inside ofclip; Design the angle of clip is slightly larger than anchor plate, in order to avoid thehappening of "incision effect"; Reach the size calculation of anchorage parts, at the same time to meet the strength requirement σ₁-σ₃≤[σ]=σ_S/n; By statics analysis andstrength check, established the design theory basis of wedge-type anchorage.（3） Using parametric design, through finite element simulation of CFRP platewedge-type anchorage, the radial stress of stress in CFRP plate in anchorage zone wastaken as reference indicator, design change parameters include the length of anchorage,the angle of clip, the differential seat angle between anchor plate and clip andpre-tightening force, numerical analysis of internal stress distribution of anchorage wascarried out, and puts forward the reasonable value of the parameters, get a suitableanchorage size: the length of anchorage is100mm, the angle of clip is2.0°, thedifferential seat angle between anchor plate and clip is0.2°, prestressing force exerted onclip is200MPa.（4） Determines the each part size of anchorage, through the strength check, anchoragesatisfy the strength requirement.The proposed welding size of tensioning device waschecked weld calculation, the welding strength meet the requirements.Three CFRP plate-anchorage assembly parts were carried on the static load test, the ultimate load ofspecimens closed to the ultimate strength of CFRP plate, total strain of breakingelongation was close to CFRP plate, indicates that the design of the anchor has a reliableanchorage performance.CFRP plates wedge-type anchorage and its supporting fixed construction ofprestressed tensioning device for steel structures, through theoretical analysis andexperimental study, to achieve the successful grappling of CFRP plate anchorage, formedthe unique prestressed CFRP plate anchorage system.