A method and structure for reinforcing a corroded concrete beam

Abstract

The present invention discloses a method and structure for reinforcing a corroded concrete beam, which belongs to the technical field of repairing and reinforcing corroded concrete beams, and comprises the following steps: removing the corroded concrete layer of the concrete beam, exposing the corroded steel bars, and removing the rust from the corroded steel bars; implanting chemical bolts on the surface where the corroded concrete is removed, pouring a new concrete layer, and the chemical bolts penetrate the new concrete layer; pasting FRP plates on the surface of the new concrete layer, installing anchor steel fasteners with chemical bolts, and applying pre-pressure to the anchor steel fasteners with a torque wrench to complete the reinforcement of the corroded concrete beam. This method not only inhibits the premature peeling of the interface between FRP and concrete by applying pre-pressure, but also transmits pressure to the interface between new and old concrete through bolts to inhibit the separation of the interface, and the pinning action of the bolts also inhibits the peeling of the interface between new and old concrete, thereby further improving the reinforcement effect of the corroded beam.

Description

Technical Field

[0001] The invention belongs to the technical field of repairing and reinforcing corroded concrete beams, and in particular relates to a method and a structure for reinforcing corroded concrete beams. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Concrete bridges in coastal environments are subject to harsh corrosion environments and complex load forms, and their long-term service performance is insufficient, which seriously affects the safety performance and service life of the bridges. Among them, steel bar corrosion damage is the first factor affecting the durability of concrete. Concrete bridges are corroded by chloride ions, which causes the protective layer to rust and crack, further accelerating the corrosion of steel bars, seriously affecting the durability of concrete bridges. Domestic and foreign scholars have conducted a large number of experimental studies and computational analyses on the reinforcement and reinforcement of bridges, and found that fiber reinforced composite materials (Fiber Reinforced Polymer, referred to as FRP) are gradually being widely used in bridge reinforcement and reconstruction due to their light weight and high efficiency. When FRP is used to reinforce corroded concrete beams, in order to prevent the steel bars from continuing to rust after reinforcement, the usual practice is to remove the damaged concrete protective layer, derust the steel bars, and then re-pour the concrete and stick the FRP.

[0004] However, for coastal corroded concrete bridges, chloride corrosion and rust expansion cracking weaken the bonding between FRP and concrete interface and accelerate FRP peeling. At the same time, the peeling of concrete protective layer caused by rust expansion cracking leads to premature failure of FRP, significantly reducing the reliability and durability of FRP reinforcement. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method and a reinforcement structure for corroded concrete beams. The method is based on a hybrid-bonded FRP (HB-FRP) reinforcement method, which not only suppresses the premature peeling of the FRP and concrete interface by applying pre-pressure, but also transmits pressure to the new and old concrete interfaces through bolts to suppress the separation of the interfaces. The pinning action of the bolts also suppresses the peeling of the new and old concrete interfaces, thereby further improving the reinforcement effect of the corroded beams.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for reinforcing a corroded concrete beam, comprising the following steps:

[0008] The corroded concrete layer of the concrete beam is removed to expose the corroded steel bars, and the corroded steel bars are derusted;

[0009] Implant chemical bolts on the rusted concrete surface, pour a new concrete layer, and penetrate the new concrete layer;

[0010] Paste FRP plates on the surface of the new concrete layer, install anchor steel fasteners with chemical bolts, and apply pre-pressure to the anchor steel fasteners with a torque wrench to complete the reinforcement of the rusted concrete beam.

[0011] As a further technical solution, the rusted steel bars are derusted and then protected until a new concrete layer is poured.

[0012] As a further technical solution, the implantation process of the chemical bolt is:

[0013] After removing the rust from the concrete surface, locate the location for chemical bolt implantation and perform pre-drilling. After cleaning the hole, implant the chemical bolt into the pre-drilled hole using anchoring glue and maintain until the strength reaches the standard.

[0014] As a further technical solution, pre-drilling is performed upward from the bottom surface of the corroded concrete layer, with multiple holes drilled at intervals, and chemical bolts are implanted into the old concrete layer retained in the concrete beam.

[0015] As a further technical solution, the threads of the chemical bolts where the pre-pressure is applied are protected.

[0016] As a further technical solution, a new concrete layer will cover the exposed steel bars and replace the corroded concrete layer.

[0017] As a further technical solution, the pasting process of the FRP plate is as follows: wait for the new concrete layer to be cured until the strength reaches the standard, locate the FRP plate pasting position on the surface of the new concrete layer and perform roughening treatment, bond the FRP plate to the concrete surface through an adhesive, and cure until the strength reaches the standard.

[0018] As a further technical solution, the FRP plate is pasted at the bottom of the new concrete layer, and the chemical bolts pass through the FRP plate. After the chemical bolts are installed with anchor steel fasteners, the anchor steel fasteners are fitted with the FRP plate, and the chemical bolts are provided with nuts to fix the anchor steel fasteners.

[0019] In the second aspect, the present invention also provides a rusted concrete beam reinforcement structure, including a concrete layer, in which a plurality of longitudinal steel bars are arranged, and stirrups are connected between the longitudinal steel bars; an FRP plate is pasted to the bottom of the concrete layer, and chemical bolts are passed through the concrete layer, the chemical bolts pass through the new concrete layer and the FRP plate, and the chemical bolts are provided with anchor steel fasteners and nuts, the anchor steel fasteners are arranged in contact with the FRP plate, and the nuts lock the anchor steel fasteners.

[0020] As a further technical solution, the upper part of the concrete layer is the old concrete layer, and the lower part of the concrete layer is the new concrete layer. The stirrups and longitudinal steel bars located at the upper part are in the old concrete layer, and the stirrups and longitudinal steel bars located at the lower part are in the new concrete layer; the FRP plate is pasted to the bottom of the new concrete layer, and the top of the chemical bolt is placed in the old concrete layer.

[0021] The beneficial effects of the present invention are as follows:

[0022] Different from the traditional HB-FRP reinforcement mechanism, the reinforcement method of the present invention implants chemical bolts after removing the rusted concrete layer, and passes the chemical bolts through the new concrete layer and the FRP plate, and the chemical bolts anchor the steel fasteners to apply pre-pressure, which not only inhibits the premature peeling of the FRP and concrete interface by applying pre-pressure, but also transmits the pressure to the interface between the new and old concrete through the bolts, thereby inhibiting the separation of the interface.

[0023] The reinforcement method of the present invention connects the new and old concrete layers and the FRP plate through chemical bolts. The pinning action of the bolts also inhibits the peeling of the new and old concrete interfaces. It is an effective means to deal with the peeling of the protective layer and the FRP interface, and has good applicability in the reinforcement of coastal bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 is a schematic diagram of a corroded concrete beam reinforcement structure of the present invention;

[0026] Figure 2 is a top view schematic diagram of the anchoring steel fastener of the present invention;

[0027] Figure 3 It is a schematic diagram of the front view of the anchor steel fastener of the present invention;

[0028] Figure 4 It is a schematic diagram of the process of the method for reinforcing a corroded concrete beam of the present invention;

[0029] In the figure: the distances or sizes between parts are exaggerated to show the positions of the parts, and the schematic diagram is for illustration only;

[0030] Among them, 1 is stirrup, 2 is longitudinal steel bar, 3 is old concrete layer, 4 is new concrete layer, 5 is chemical bolt, 6 is FRP plate, 7 is anchor steel fastener, 8 is preload, and 9 is corroded concrete layer. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0032] As introduced in the background technology, for coastal corroded concrete bridges, when FRP is used to reinforce corroded concrete beams, chloride corrosion and rust expansion cracking weaken the bonding effect between the FRP and concrete interface and accelerate the FRP peeling; at the same time, the peeling of the concrete protective layer caused by rust expansion cracking leads to premature failure of FRP, significantly reducing the reliability and durability of FRP reinforcement.

[0033] In order to solve the above technical problems, the present invention proposes a method for reinforcing corroded concrete, which is based on a hybrid-bonded FRP (HB-FRP) reinforcement method. However, unlike traditional HB-FRP reinforcement, the method not only suppresses premature peeling of the FRP and concrete interface by applying pre-pressure, but also transmits pressure to the new and old concrete interfaces through bolts to suppress the separation of the interfaces. The pinning action of the bolts also suppresses the peeling of the new and old concrete interfaces, thereby further improving the reinforcement effect of the corroded beams.

[0034] In a typical embodiment of the present invention, Figure 3 As shown, a method for reinforcing a corroded concrete beam is proposed, and the components used for reinforcement in the process include chemical bolts 5, chemical adhesives, anchoring steel fasteners 7, and bolt matching nuts.

[0035] The lower part of the concrete layer of the corroded concrete beam is the corroded part, which is the corroded concrete layer 9, and the upper part of the concrete layer is the old concrete layer 3. A plurality of longitudinal steel bars 2 are arranged in the concrete layer, and stirrups 1 are connected between the longitudinal steel bars 2. The lower stirrups 1 and the longitudinal steel bars 2 are in the corroded concrete layer 9, and the surface of the steel bars will also rust.

[0036] The reinforcement process includes removing the rusted concrete layer 9, removing rust from the steel bars, pre-planting chemical bolts 5, pouring a new concrete layer 4, pasting the FRP plate 6, and applying pre-pressure to the new concrete layer 4 and the FRP plate 6 through the chemical bolts 5.

[0037] Specifically, the reinforcement method comprises the following steps:

[0038] Step (1): removing the corroded concrete layer 9 and removing rust from the steel bars;

[0039] The concrete layer at the corroded part of the concrete beam (i.e., the corroded concrete layer 9) is completely removed, and the corroded steel bars are completely exposed, including the longitudinal steel bars 2 and stirrups 1 located at the bottom of the concrete layer. On this basis, the corroded steel bars are derusted, and after derusting, the steel bars are protected until a new concrete layer is poured.

[0040] Step (2): pre-planting chemical bolts 5 and pouring a new concrete layer 4;

[0041] After removing the corroded concrete surface, locate the implantation position of the chemical bolt 5 and perform pre-drilling; after cleaning the hole, implant the chemical bolt 5 into the pre-drilled hole with the anchor glue and maintain it until the strength reaches the standard; protect the bolt thread at the pre-stressed part, support it with the formwork, and finally pour the new concrete layer 4, with the chemical bolt 5 penetrating the new concrete layer 4.

[0042] Step (3): Glue the FRP plate 6 and apply pre-pressure;

[0043] The new concrete layer 4 is cured until the strength reaches the standard, the surface of the new concrete layer 4 is roughened at the position where the FRP plate 6 is to be pasted, the FRP plate 6 is bonded to the concrete surface by an adhesive, and cured until the strength reaches the standard; the matching anchoring steel fasteners 7 and nuts are installed on the chemical bolts 5, and pre-pressure is applied to the anchoring steel fasteners 7 by a torque wrench, thereby applying pre-pressure to the FRP and concrete, and completing the reinforcement of the rusted concrete beam.

[0044] Among them, in step (2), pre-drilling is performed in the old concrete layer 3 at the bottom surface of the corroded concrete layer, the drilling direction is upward, and multiple holes are drilled at intervals; then the chemical bolts 5 are implanted in the corresponding pre-drilled holes.

[0045] In step (2), a new concrete layer 4 is poured at the bottom of the old concrete layer 3, covering the exposed steel bars therein, replacing the original rusted concrete layer 9.

[0046] In an optional embodiment, the chemical bolt 5 may be in the form of an inverted cone bolt.

[0047] In step (2), the chemical bolt 5 is implanted into the old concrete layer 3 retained by the concrete beam, and the hole is cleaned to prevent dust from affecting the adhesion. The thread of the chemical bolt 5 where the pre-pressure is applied is protected to prevent the thread from being covered during concrete pouring.

[0048] Among them, in step (3), the FRP plate 6 is pasted on the bottom of the new concrete layer 4, and the chemical bolt 5 passes through the FRP plate 6. After the chemical bolt 5 is installed with the anchor steel fastener 7, the anchor steel fastener 7 is fitted with the FRP plate 6, and the chemical bolt 5 is sleeved with a nut to fix the anchor steel fastener 7.

[0049] In another typical embodiment of the present invention, Figure 1-Figure 2 As shown, a corroded concrete beam reinforcement structure is proposed, which is a mechanical anchorage structure to suppress double interface debonding.

[0050] The reinforcement structure includes a concrete layer in which a plurality of longitudinal steel bars 2 ( Figure 1Only part of the longitudinal steel bars 2 are shown, and stirrups 1 are connected between the longitudinal steel bars 2; the upper part of the concrete layer is the old concrete layer 3, and the lower part of the concrete layer is the new concrete layer 4. The stirrups 1 and the longitudinal steel bars 2 located at the upper part are in the old concrete layer 3, and the stirrups 1 and the longitudinal steel bars 2 located at the lower part are in the new concrete layer 4.

[0051] The FRP plate 6 is pasted at the bottom of the concrete layer, specifically, the FRP plate 6 is pasted at the bottom of the new concrete layer 4; a chemical bolt 5 is inserted into the concrete layer, and the top of the chemical bolt 5 is placed in the old concrete layer 3. The chemical bolt 5 passes through the new concrete layer 4 and the FRP plate 6, and the chemical bolt 5 is provided with an anchoring steel fastener 7 and a nut. The anchoring steel fastener 7 is arranged close to the FRP plate 6, and the nut locks the anchoring steel fastener 7. The anchoring steel fastener 7 is plate-shaped, and a through hole is set in the anchoring steel fastener for the chemical bolt 5 to pass through. Two chemical bolts are inserted in the side direction of the concrete beam, and the two chemical bolts are connected by the same anchoring steel fastener. Therefore, in this embodiment, the anchoring steel fastener has two through holes.

[0052] The FRP plate 6 is provided with through holes for the chemical bolts 5 to pass through.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for reinforcing a corroded concrete beam, characterized in that: A corroded concrete beam reinforcement structure is adopted, comprising a concrete layer, a plurality of longitudinal steel bars are arranged in the concrete layer, and stirrups are connected between the longitudinal steel bars; an FRP plate is pasted and arranged at the bottom of the concrete layer, a chemical bolt is passed through the concrete layer, the chemical bolt passes through the new concrete layer and the FRP plate, and the chemical bolt is provided with an anchor steel fastener and a nut, the anchor steel fastener is arranged in contact with the FRP plate, and the nut locks the anchor steel fastener; The upper part of the concrete layer is the old concrete layer, the lower part of the concrete layer is the new concrete layer, the stirrups and longitudinal steel bars at the upper part are in the old concrete layer, and the stirrups and longitudinal steel bars at the lower part are in the new concrete layer; the FRP plate is pasted to the bottom of the new concrete layer, and the top of the chemical bolt is placed in the old concrete layer; The method for strengthening corroded concrete beams includes the following steps: The corroded concrete layer of the concrete beam is removed to expose the corroded steel bars, and the corroded steel bars are derusted; Implant chemical bolts on the rusted concrete surface, pour a new concrete layer, and penetrate the new concrete layer; The implantation process of chemical bolts is: After removing the rusted concrete surface, locate the implantation position of the chemical bolts and perform pre-drilling; after cleaning the channel, implant the chemical bolts into the pre-drilled holes through the anchor glue and maintain until the strength reaches the standard; paste the FRP plate on the surface of the new concrete layer, install the chemical bolts with anchor steel fasteners, paste the FRP plate on the bottom of the new concrete layer, and the chemical bolts pass through the FRP plate. After the chemical bolts are installed with the anchor steel fasteners, the anchor steel fasteners fit the FRP plate, and the chemical bolts are fixed with nuts; apply pre-pressure to the anchor steel fasteners with a torque wrench to complete the reinforcement of the rusted concrete beam; apply pre-pressure to suppress the premature peeling of the interface between FRP and concrete, and transmit the pressure to the interface between the new and old concrete through the bolts to suppress the separation of the interface; connect the new and old concrete layers and the FRP plate with chemical bolts, and the pinning effect of the bolts also suppresses the peeling of the interface between the new and old concrete.

2. The method for reinforcing a corroded concrete beam as claimed in claim 1, characterized in that: After derusting the corroded steel bars, they are protected until a new layer of concrete is poured.

3. The method for reinforcing a corroded concrete beam as claimed in claim 1, characterized in that: Pre-drill holes upward from the bottom surface of the removed rusted concrete layer, drill multiple holes at intervals, and implant chemical bolts into the old concrete layer retained in the concrete beam.

4. The method for reinforcing a corroded concrete beam as claimed in claim 1, characterized in that: The threads of chemical bolts where pre-pressure is applied are protected.

5. The method for reinforcing a corroded concrete beam as claimed in claim 1, characterized in that: The new concrete layer will cover the exposed steel bars and replace the rusted concrete layer.

6. The method for reinforcing a corroded concrete beam as claimed in claim 1, characterized in that: The pasting process of FRP board is as follows: wait until the new concrete layer is cured until the strength reaches the standard, locate the FRP board pasting position on the surface of the new concrete layer and perform roughening, bond the FRP board to the concrete surface through adhesive, and cure until the strength reaches the standard.

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