Method for repairing local crack of concrete beam by using shallow embedded shape memory alloy wire

A memory alloy wire and concrete beam technology, which is applied to bridges, bridge parts, bridge materials, etc., can solve the problems of large damage to concrete beams, narrow space, and large loss of prestress, so as to avoid construction difficulties, reduce labor costs, and reduce construction costs. simple effect

Inactive Publication Date: 2019-09-20
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] (1) Large loss of prestress
For example, when strengthening the longitudinal cracks in the hollow slab or the cracks in the web of the box girder, due to the small size of the structure perpendicular to the direction of the local cracks, the prestressed material required for reinforcement is short, and the prestress loss caused by mechanical tension is large, so it is difficult to apply effective prestressing to the structure. stress
[0005] (2) The installation of prestressed anchors will cause great damage to concrete beams
[0006] (3) The space at the local cracks may be narrow, and the construction of tensioning equipment is difficult

Method used

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  • Method for repairing local crack of concrete beam by using shallow embedded shape memory alloy wire
  • Method for repairing local crack of concrete beam by using shallow embedded shape memory alloy wire
  • Method for repairing local crack of concrete beam by using shallow embedded shape memory alloy wire

Examples

Experimental program
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Effect test

Embodiment 1

[0046] This embodiment provides a method for repairing local cracks in concrete beams with shallow-buried shape memory alloy wires. The specific steps are:

[0047] 100 Grooving: Cut off a certain thickness of the original concrete protective layer at the position where the concrete beam has local cracks, so as to complete the groove within the depth range of the concrete protective layer.

[0048] 200-tension alloy: It is necessary to stretch the alloy to produce a certain pre-strain.

[0049] 300 embedded alloy: the nickel-titanium-niobium shape memory alloy that has been stretched, and the titanium-niobium shape memory alloy is anchored with a flat anchor at the anchoring end.

[0050] 400 Injecting the bonding material: inject the bonding material into the groove.

[0051] 500 thermally actuated alloy: After the bonding material reaches the expected strength, the shape memory alloy is energized and thermally excited to generate a restoring force, and the anchoring force o...

Embodiment 2

[0059] This embodiment further introduces the flat anchor in Example 1. The flat anchor includes an anchor block, several headless hexagon socket screws, threading channels, and screw holes; the anchor block is a hexahedron, along the long axis There is a threading hole in the center, and several staggered screw holes with internal threads are opened on the two sides along the width direction of the anchor block. The depth of the screw hole reaches the threading hole. Thread matching, shape memory alloy for small diameter wire. After passing the shape memory alloy wire through the threading hole, respectively screw the headless hexagon socket head cap screws into the screw holes on both sides of the anchor block, and then tighten and anchor. The flat anchorage has small size, large anchoring force, little damage to concrete structures, effectively solves the anchoring problem of small-diameter shape memory alloy wires, has simple structure, easy installation, and low cost, and...

Embodiment 3

[0061] Usually, after the shape memory alloy wire is embedded in the cracked concrete beam and heated and excited, it is necessary to observe the achieved reinforcement effect. This embodiment provides a device for observing the reinforcement effect, including a loading system and an upper support system; the loading system It includes a lever, a rotating shaft, a balance object, a support column, a bearing plate and a loading object; the lever includes a steel pipe and a steel plate, a balance object is suspended at one end of the steel plate, the other end of the steel plate is connected with one end of the steel pipe, and a load bearing is suspended at the other end of the steel pipe. The loading plate is placed on the loading plate; there is a notch a on the upper surface of the steel plate, the bottom of the rotating shaft is rotatably connected to the notch a, a force sensor is placed on the top of the rotating shaft, and a notch b is opened on the lower surface of the ste...

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Abstract

The invention discloses a method for repairing a local crack of a concrete beam by using a shallow embedded shape memory alloy wire. The method for repairing the local crack of the concrete beam by using the shallow embedded shape memory alloy wire comprises the steps of 1) forming a groove in the concrete beam with the local crack within a protective layer depth range; 2) embedding a shape memory alloy after being stretched to generate pre-strain into the groove; 3) injecting a bonding material into the groove; 4) electrifying and heating the shape memory alloy; and after cooling, using permanent return stress to apply prestress to the concrete beam; and 5) recovering a concrete protective layer to finish reinforcing. According to the method for repairing the local crack of the concrete beam by using the shallow embedded shape memory alloy wire, in the case of not changing the appearance of an original structure, the shape memory alloy is driven to generate the permanent return force as the pre-stress to act upon the local crack of the concrete beam through thermal excitation on the shape memory alloy so that the stress state of the local crack of the concrete beam is improved and the local crack is reduced or closed; and therefore, the bearing capacity and durability of the structure are improved; and meanwhile, limitations such as low pre-stress, difficult anchorage device mounting and poor aesthetic property of a traditional active reinforcing method are avoided.

Description

technical field [0001] The invention belongs to the technical field of bridge engineering, and in particular relates to a method for repairing local cracks in concrete beams with shallow-buried shape-memory alloy wires. Background technique [0002] According to the data from the website of the Ministry of Transport, the number of dangerous bridges in my country accounted for about 13% of the total number of bridges in 2015, and bridge disease problems have become increasingly prominent, and local cracking of reinforced concrete beams is an important part of bridge disease problems. Concrete beams with cracks will cause degradation of the performance of concrete and steel bars, and cracks in critical areas may even affect the safety of bridge structures. Therefore, strengthening the partially cracked concrete beams has become an urgent problem to be solved. [0003] Existing reinforcement methods for concrete beams include passive reinforcement methods and active reinforcem...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E01D22/00E01D19/00E01D101/24
CPCE01D19/00E01D22/00E01D2101/24
Inventor 潘盛山惠华星张迪苏小菊乐锐
Owner DALIAN UNIV OF TECH
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