A Strengthening Method of Concrete Structure Based on Gradient Tensile Prestress

Abstract

The invention discloses a method for strengthening concrete beams based on gradient tension prestressing, the steps of which are as follows: step S1: inserting stretched prestressed fiber reinforced composite material (FRP) slats into prefabricated slots of the reinforced concrete structure Inside, make the prestressed FRP slab and the concrete beam form a bond through the adhesive within the specified range; step S2: release part or all of the prestress after the adhesive is cured, and then construct the FRP slab according to the actual demand Fill a certain length of adhesive on both sides of the prestressed stretched end section and maintain it; Step S3: After the newly filled adhesive is cured, release the remaining prestressed force, and fill in the new bonded end The adhesive forms the bonded segment as an anchor. The invention has the advantages of simple structure, convenient construction, good effect and the like.

Description

technical field [0001] The invention mainly relates to the field of civil engineering and traffic engineering, in particular to a method for reinforcing a surface layer embedded prestressed FRP based on a gradient prestressed concrete structure. Background technique [0002] As an emerging structural repair and reinforcement material, fiber reinforced composite (FRP) has been widely used in the construction of various structures such as bridge engineering. In recent years, scholars in the industry have solved the problems of low utilization rate of ordinary FRP reinforcement strength and material strain lag by applying prestress to FRP reinforced reinforced concrete beams. The surface of the structure is bonded with continuous fiber reinforced polymer composites (FRP) with adhesives such as resins. [0003] On the one hand, from the material point of view, applying prestress to the structure can give full play to the high-strength tensile properties of the FRP sheet; Perfo...

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Problems solved by technology

[0004] Although the above reinforcement methods organically combine the relative advantages of surface embedded steel reinforcement technology and prestressed external bond reinforcement technology, only adhesive glue and protective layer concrete cannot fully transfer the prestress in NSMFRP at the same time within a limited bond length. Stress and tensile shear stress caused by external loads, studies and applications have shown that in some cases, the reinforced structure is prone to tearing and peeling of the concrete protective layer at the end of the FRP bond, resulting in the reinforcement of the structure because the performance of the reinforcement material cannot be fully exerted. Early damage

This is because within the limited stress transfer length (usually 10-20cm) of the FRP bonding end, the concrete protective layer simultaneously bears the tensile and shear stress caused by the external load and the prestressed tension transfer, and the limited stress transfer length makes the tension The shear stress easily exceeds the strength of the concrete at the FRP bonded end protective layer, which causes the protective layer to be torn or even peeled off

Setting special FRP anchors or other end anchoring measures also has defects such as complicated process, increased cost, unsatisfactory anchoring effect, and durability risks, which cannot simultaneously meet the requirements of reducing stress concentration at the end of FRP and reducing the complexity of construction operations , these become urgent problems to be solved

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