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Beam strengthening
Prestressed CFRP laminate
Prestressed CFRP laminate reinforcement technology can be widely used in many reasons, such as concrete structure damage, steel corrosion, load lifting, standard improvement, improper design and construction, use of functional changes, and gradually become a sick bridge, dangerous bridge.
The project is located in Ring Road, Taiyuan. The overpass is 726M across. The net width of the deck is 16.2M and the superstructure is prestressed box girder. The bridge was built and opened to traffic in the 1990s. After the recent bridge testing, it is found that the bridge bearing capacity reserve has declined seriously, which has begun to threaten the normal service of the bridge. The emergency rescue project determined by the government should be dealt with immediately and the bridge deck should not be affected during the reinforcement period. Therefore, prestressed CFRP laminate reinforcement technology is adopted to complete the structural reinforcement.
(1) By prestressing carbon fiber laminate, it can maximize the high tensile strength of carbon fiber laminate. Its principle is similar to that of prestressed beam structure, because the pre-stress is applied in advance, the material has a certain initial strain. After the secondary stress, the deformation ability of carbon fiber and concrete can be improved to improve the quality and effect of reinforcement.
(2) By applying prestress, the bending moment can be generated. The decompression moment can offset a large part of the load in the early stage, enhance the bearing capacity of the structure in the later stage, significantly enhance the crack resistance of the structure, limit the occurrence of new cracks, improve the overall stiffness and strength of components, reduce the load-bearing deflection of components.
(3) The deformation of carbon fiber sheet comes from two aspects, one is the deformation caused by prestressing, the other is the deformation caused by external load. The shear deformation of adhesives which share the two parts of the deformation is distributed at both ends of the component and in the middle of the span, so that the shear deformation of the adhesives can be uniformly distributed and the brittle failure of the adhesives can be prevented.
(4) For the structure to be strengthened, it is necessary to arrange the reinforcement position reasonably according to the mechanical performance and installation space of the engineering structure. Carbon fiber laminate coated with special epoxy adhesive were pre-tensioned to repair the deformation and closed cracks. The carbon fiber laminate is then pasted to the position of the stress plate of the member to maximize the carrying capacity of the structure.
location and paying off
polish
drilling hole
grooving
repairing and leveling
planting anchor
installing bounding box
installing anchor block
fixing carbon fiber laminate
fixing jack and high strength anchor bolt
prestretching
applying epoxy resin
prestretching
removing the thread rod
tablet fixing
finished product protection
or you can see the video:
Prestressed CFRP laminate reinforcement technology can be widely used in many reasons, such as concrete structure damage, steel corrosion, load lifting, standard improvement, improper design and construction, use of functional changes, and gradually become a sick bridge, dangerous bridge. In order to prolong and enhance the service life and capacity of the bridge structure as far as possible, enhance the bearing capacity of the structure, so that the bridge structure can play a higher service requirements, it is necessary to reinforce and reinforce the above bridge. Considering the advantages of using prestressed carbon fiber sheet reinforcement technology, such as simple construction, low technical threshold and so on, only the construction personnel need to have a certain degree of prestressing technology. In addition, the construction process does not require large-scale mechanical equipment support, only the use of various small equipment, such as electric drill, water drill and Jack can be completed. During the bridge reinforcement construction period, because no closed traffic is needed, it will not affect the normal traffic of the bridge deck, and will not cause congestion pressure on the local traffic. In this paper, the case analysis is the main way to summarize the relevant technology of prestressed carbon fiber sheet reinforcement. Practice shows that the use of prestressed carbon fiber laminate reinforcement method at the bottom of the beam can significantly improve the bearing capacity of the bridge, and the construction technology is relatively high cost, it is worth further promotion and use.
