Reinforcing method for concrete structure based on gradient releasing prestress

Abstract

The invention discloses a reinforcing method for a concrete structure based on gradient releasing prestress. The reinforcing method comprises the following steps: S1, embedding a tensioned prestress fiber reinforced composite material (FRP) batten into a prefabricated slot of a reinforced concrete structure, wherein the prestress FRP batten and a concrete beam are bonded by means of a bonder within an appointed range; S2, releasing part of or all prestress after the bonder is cured and then filling two sides of a section of a prestress releasing end part of the FRP batten with the bonder of acertain length for curing according to a design structure of an actual need; and S3, releasing residual prestress after the newly filled bonder is cured, and filling the newly bonding end part with the bonder to form a bonding section as an anchorage device. The reinforcing method has the advantages of being simple in structure, convenient to construct, good in effect and the like.

Description

Technical field [0001] The present invention mainly relates to the field of civil engineering and traffic engineering, and particularly refers to a method for strengthening the surface layer of a concrete structure based on gradient release and tensioning prestressed with prestressed FRP. Background technique [0002] Fiber-reinforced composite material (FRP), as a new structural repair and reinforcement material, 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 strength utilization and material strain lagging of ordinary FRP reinforcement by applying prestress to FRP-strengthened reinforced concrete beams, that is, pre-applying a certain prestress to FRP to make it force in advance, and then The surface of the structure is bonded with a continuous fiber reinforced polymer composite (FRP) with a binder such as resin. [0003] On the one hand, from the perspective of ...

AI Technical Summary

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

Images