A bridge pier anti-collision device with GFRP wrapped with foamed aluminum

Abstract

The present invention belongs to the field of civil engineering, and specifically relates to a GFRP outer-wrapped foam aluminum bridge pier anti-collision device. The anti-collision device is composed of a plurality of assembled anti-collision blocks arranged on the outer periphery of the bottom of the concrete bridge pier. The anti-collision device composed of the anti-collision blocks is that each anti-collision block includes a GFRP hollow casing, a cover plate matched with the GFRP hollow casing, and foam aluminum assembled in the GFRP hollow casing through the outer casing barrel self-tightening technology; after assembly, the GFRP hollow casing applies prestress to the foam aluminum and realizes the centripetal constraint of the foam aluminum. The present invention utilizes the GFRP outer casing hollow casing to form a flexible skeleton to constrain the internal sandwich foam aluminum material, and the overall coordinated deformation can effectively disperse the vehicle impact energy. At the same time, the modular design concept is used to reduce material loss, simple to manufacture, convenient to carry, fast to assemble, and can be partially replaced and repaired when damaged. The present invention is applied to land circular bridge piers with vehicle impact protection requirements.

Description

Technical Field

[0001] The invention belongs to the field of civil engineering, and in particular relates to a bridge pier anti-collision device with GFRP wrapped with foamed aluminum. Background Art

[0002] With the development of society and economy, the transportation industry is becoming more and more prosperous, but various traffic accidents are increasing day by day. Among them, the accident of vehicle hitting bridge piers is the most common, and the probability of occurrence is rising year by year with the increase of urban overpasses and flyovers. This not only poses a certain threat to people's lives and safety, but also causes huge economic losses and adverse social impacts. It has become a top priority to take measures to alleviate the problem of bridge piers being damaged by vehicle collisions and protect the safety of people's lives and property. Therefore, it is particularly important to study the problem of vehicles hitting bridge piers.

[0003] To this end, many scholars at home and abroad have conducted research on the problem of vehicles colliding with bridge piers, and the bridge anti-collision theory has gradually matured. As the bridge anti-collision theory becomes more and more mature, many different types of bridge pier anti-collision devices have also emerged.

[0004] In the design of existing anti-collision devices, crushing structures are often used to absorb impact energy, and the special properties of foamed aluminum materials make it a new favorite for impact resistance. Foamed aluminum is a new type of material that is made by adding additives to pure aluminum or aluminum alloy and undergoing a foaming process. It has both metal and bubble characteristics. According to "Xu Dongfeng, Research on the Application of Foamed Aluminum Protective Devices on Bridges, Master's Thesis of Chongqing Jiaotong University, May 2006," the impact test of foamed aluminum materials pointed out that a unit volume of foamed aluminum can absorb at least 6 to 9J of energy. Compared with other materials, it not only absorbs more energy per unit volume, but also has a low density and a small volume, so foamed aluminum materials have now become an ideal material for absorbing impact loads in protective engineering. However, due to the low stiffness and strength of foam aluminum, the collision surface of the anti-collision device using a single foam aluminum material is very likely to produce discontinuous deformation and local damage to the material under high-speed collision, which is not conducive to the overall structure of the anti-collision device to absorb more energy. It is necessary to moderately increase the structural stiffness of the protective device and make the stiffness distribution of the device more uniform. Therefore, foam aluminum material is usually not suitable for use as a protective device alone. It is generally combined with high-strength and stiffness thin panels to form a sandwich structure. According to the experiment on carbon fiber reinforced composite material / foam aluminum sandwich structure in "Feng Huimin, Research on the Impact Resistance of CFRP / Foam Aluminum Sandwich Structure, Shenyang Ligong University, March 2019", it was found that compared with single foam aluminum material, fiber reinforced material (Fibreglass Reinforced Plastics, FRP) / foam aluminum sandwich structure has a certain improvement in impact resistance.

[0005] Although this type of sandwich structure has improved its impact resistance compared to single foam aluminum material, its impact resistance is still not ideal. There is a situation where the internal sandwich core is partially damaged in advance, and it is still difficult for them to work together stably and exert their respective mechanical advantages at the same time. If used as an anti-collision protection device for bridge piers, it still has great defects. Summary of the invention

[0006] The object of the present invention is to provide a bridge pier anti-collision device with GFRP coated with foamed aluminum.

[0007] The technical solution to achieve the purpose of the present invention is: a GFRP-coated foam aluminum bridge pier anti-collision device, the anti-collision device is composed of a plurality of assembled anti-collision blocks arranged on the outer periphery of the bottom of the concrete pier, the anti-collision device composed of the anti-collision blocks is that each anti-collision block includes a GFRP hollow casing, a cover plate matched with the GFRP hollow casing, and foam aluminum assembled in the GFRP hollow casing by the outer shell barrel self-tightening technology; after assembly, the GFRP hollow casing applies prestress to the foam aluminum and realizes the centripetal constraint of the foam aluminum.

[0008] Furthermore, the foamed aluminum assembled in the GFRP hollow casing by the shell barrel self-tightening technology is specifically:

[0009] Heat the GFRP hollow casing to 85-120°C, assemble the foam aluminum in the GFRP hollow casing, assemble the cover plate and cool naturally.

[0010] Furthermore, the GFRP hollow casing is made of a bottom plate, an inner plate, an outer plate, a left plate and a right plate. The inner plate is in an arc shape that matches the shape of the concrete pier, and the outer plate is in an arc shape. The thickness of the side plate of the GFRP hollow casing is not less than 20 mm and not more than 25 mm, and the deviation angle between the inner and outer edges of the side plate is 4 to 6%.

[0011] Furthermore, the left and right panels of the GFRP hollow casing are provided with identical rectangular connection slots, the outer panel is provided with an arc-shaped connection slot, and the corresponding positions of the cover plate are provided with connection keys of matching shapes; and after assembly, the outermost side of the cover plate has an outer edge protruding from the outer panel of the GFRP hollow casing.

[0012] Furthermore, the depth of the connection notch on the GFRP hollow casing is the same as the size of the connection key on the cover plate, which is 3 / 4 of the thickness of the cover plate.

[0013] Furthermore, trapezoidal protrusions and trapezoidal grooves are respectively provided on the side panels on both sides of the GFRP hollow casing of the anti-collision block, and adjacent anti-collision blocks are assembled by matching the trapezoidal protrusions and trapezoidal grooves, and the side walls are bonded by epoxy resin; the inner side panels of the anti-collision blocks are bonded to the outer surface of the concrete pier by epoxy resin glue; after the anti-collision blocks are assembled on the outer periphery of the concrete pier, epoxy resin glue is used to fix the outer edge of the cover plate to the ground or the pedestal.

[0014] Furthermore, after assembly, the height of the upper surface of the anti-collision device from the ground is 1.2±0.2m, and the height of the anti-collision device can be adjusted differently according to actual needs.

[0015] Furthermore, the foamed aluminum filled in the GFRP hollow casing is made of pure aluminum with a yield strength of 50-52 MPa, the pore size of the foamed aluminum is 1-2 mm, the relative density is 0.5-0.6, and the porosity of the foamed aluminum gradually increases from the outer plate to the inner plate.

[0016] Furthermore, the porosity of the foam aluminum gradually increases from the outer panel to the inner panel and is divided into three levels, namely 65%, 75%, and 85%.

[0017] Compared with the prior art, the present invention has the following significant advantages:

[0018] (1) The present invention is based on the principle of stress wave and energy conversion. By dissipating the energy of the combined anti-collision device in structure, deformation, crushing and destruction, it can effectively reduce the dynamic response of the collision impact on the bridge pier, reduce the damage to the bridge pier during the impact, and disperse the impact energy to the maximum extent.

[0019] (2) The present invention utilizes the principle of the self-tightening technology of the outer shell and barrel. By heating the outer shell GFRP casing as a whole and waiting for it to cool and shrink, a certain degree of prestress is applied to the internal sandwich material. This not only enables the two materials to fit closely together, but also effectively imposes a stronger centripetal constraint on the internal sandwich material. When the device is deformed by impact, the outer shell will drive the internal foam aluminum sandwich to deform as a whole, so that the device has the ability to work and exert mechanical properties together similar to reinforced concrete, thereby maximally avoiding local damage of the foam aluminum due to insufficient rigidity and thus losing material properties in advance, maximizing the overall participation of the foam aluminum sandwich in energy exchange, and maximizing the potential of the foam aluminum to resist impact.

[0020] (4) The internal core of the present invention adopts a density step-change design; specifically, the density of the internal core changes at intervals, gradually decreasing from the periphery to the inside, while the porosity increases, the damping performance is enhanced, and the energy absorption effect is better; when the outer shell of the device is impacted, the overall deformation of the foam aluminum with a density step-change inside is more regular than that of ordinary foam aluminum, and it can achieve better coordinated deformation, better coordinated work and better coordinated energy consumption with the outer shell, and the performance in all aspects is improved to a certain extent.

[0021] (5) The protective device can be prefabricated in the factory with reasonable quality and height, and is easy to manufacture and transport. The present invention is easy to install on site and does not require large-scale mechanical lifting. For existing buildings, the construction site occupies a small area and will not block traffic, thereby reducing labor, machinery and construction period costs.

[0022] (6) The present invention can be installed along the circumferential and vertical splicing of the bridge pier, and has a wide range of applications. It can protect the entire pier or part of the pier, and can be selected according to actual engineering needs.

[0023] (7) After the device of the present invention is hit, the degree of damage is visible and replacement and maintenance are convenient; minor damage is manifested as slight deformation of the GFRP shell, and no maintenance is required; severe damage is manifested as deformation, crushing, and destruction of the GFRP shell and the internal core, in which case only the damaged module needs to be replaced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a top view of the bridge pier anti-collision device of the present invention.

[0025] Figure 2 It is a schematic diagram of the cover plate of the present invention.

[0026] Figure 3 It is a schematic diagram of the GFRP hollow casing of the present invention.

[0027] Figure 4 It is a schematic diagram of the installation of the anti-collision device of the present invention.

[0028] Description of reference numerals:

[0029] 1-GFRP hollow casing, 2-foam aluminum, 3-cover plate, 4-connecting key, 5-concrete pier. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0031] A bridge pier anti-collision device with GFRP wrapped with foamed aluminum, such as Figure 1-4 As shown, it mainly includes: 1-GFRP hollow casing, 2-foam aluminum, 3-cover plate, 4-connecting key.

[0032] When manufactured in the factory, a mold is used to make a GFRP hollow casing 1, a cover plate 3 with a connection key 4, and the foam aluminum 2 is cut into the shape shown in the figure. The outer shell GFRP hollow casing is heated as a whole, and the foam aluminum is placed in it. After it cools and shrinks, the cover plate connection key is inserted into the notch of the GFRP hollow casing and fixed. At this point, an anti-collision block is completed. The internal filling foam aluminum material is made of pure aluminum with a yield strength of 50-52MPa, a pore size of 1-2mm, a relative density of 0.5-0.6, and is divided into three levels, with the porosity gradually increasing from the periphery to the inside, which are 65%, 75%, and 85% respectively.

[0033] The GFRP hollow shell and the internal foam aluminum are self-tightened and reinforced using the shell barrel self-tightening technology principle: the principle is that after the external GFRP hollow shell box is heated as a whole to 85-120°C, the GFRP shell material gradually expands outward according to the linear expansion coefficient of 68.5um / m°C of the glass fiber material. At this time, the internal sandwich material is placed in, and when the shell gradually cools and shrinks inward as a whole, it is hindered by the internal sandwich, which is equivalent to applying a certain degree of prestress, which has a strong restraining effect on the internal core.

[0034] At the construction site, when installing protective devices, the concrete surface of the pier should be polished, 1 to 2 mm of the surface layer should be removed, dust should be removed, and the concrete surface should be wiped clean with acetone to ensure that there is no oil, foreign matter, or dust on the concrete surface. The side of the anti-collision block close to the pier should be derusted, and the bonding operation should be carried out in accordance with the instructions of the steel adhesive product.

[0035] Then, turn the anti-collision block upside down, that is, place the cover plate downward, apply epoxy resin glue on the left and right sides of the anti-collision block and the side close to the bridge pier, lock the trapezoidal groove, and glue the remaining three anti-collision blocks to the outside of the bridge pier in turn. After the assembly is completed, the protruding part of the cover plate can be fixed to the ground or the pedestal with anchor bolts.

[0036] The anti-collision device adopts modular design, and can use four anti-collision blocks for full protection, with the best anti-collision effect. It can also use 1-3 anti-collision blocks for partial protection according to the actual situation. After the device of the present invention is hit, the degree of damage is visualized, and replacement and maintenance are convenient; its minor damage is manifested as slight deformation of the GFRP shell, and no maintenance is required; its severe damage is manifested as deformation, crushing, and destruction of the GFRP shell and the internal sandwich core, in which case only the damaged module can be replaced.

Claims

1. A bridge pier anti-collision device with GFRP wrapped with foamed aluminum, characterized in that: The anti-collision device is composed of a plurality of assembled anti-collision blocks arranged on the outer periphery of the bottom of a concrete bridge pier (5), wherein each anti-collision block comprises a GFRP hollow casing (1), a cover plate (3) matched with the GFRP hollow casing (1), and foam aluminum (2) assembled in the GFRP hollow casing (1) by means of an outer shell barrel self-tightening technology; after assembly, the GFRP hollow casing (1) applies prestress to the foam aluminum (2) and realizes centripetal constraint on the foam aluminum (2); The foamed aluminum (2) assembled in the GFRP hollow casing (1) by the shell barrel self-tightening technology is specifically: The GFRP hollow casing (1) is heated to 85-120°C, the foamed aluminum (2) is assembled in the GFRP hollow casing (1), and the cover plate (3) is assembled and then cooled naturally.

2. The bridge pier anti-collision device according to claim 1, characterized in that: The GFRP hollow casing (1) is made of a bottom plate, an inner plate, an outer plate, a left plate and a right plate. The inner plate is in an arc shape matching the outer shape of the concrete pier (5). The outer plate is in an arc shape. The thickness of the side plate of the GFRP hollow casing (1) is not less than 20 mm and not more than 25 mm. The deviation angle between the inner edge and the outer edge of the side plate is 4-6%.

3. The bridge pier anti-collision device according to claim 2, characterized in that: The left and right panels of the GFRP hollow casing (1) are provided with identical rectangular connection notches, the outer panels are provided with arc-shaped connection notches, and the corresponding positions of the cover plate (3) are provided with connection keys of matching shapes; and after assembly, the outermost side of the cover plate (3) has an outer edge protruding from the outer panel of the GFRP hollow casing (1).

4. The bridge pier anti-collision device according to claim 3, characterized in that: The depth of the connection notch on the GFRP hollow casing (1) is the same as the size of the connection key (4) on the cover plate, which is 3 / 4 of the thickness of the cover plate.

5. The bridge pier anti-collision device according to claim 4, characterized in that: Trapezoidal protrusions and trapezoidal grooves are respectively arranged on the side panels on both sides of the GFRP hollow casing (1) of the anti-collision block; adjacent anti-collision blocks are assembled by matching the trapezoidal protrusions and trapezoidal grooves, and the side walls are bonded by epoxy resin; the inner side panels of the anti-collision blocks are bonded to the outer surface of the concrete pier (5) by epoxy resin glue; after the anti-collision blocks are assembled on the outer periphery of the concrete pier (5), the outer edge of the cover plate is fixed to the ground or the pedestal by epoxy resin glue.

6. The bridge pier anti-collision device according to claim 5, characterized in that: After assembly, the upper surface of the anti-collision device is 1.2±0.2m above the ground.

7. The bridge pier anti-collision device according to claim 6, characterized in that: The foamed aluminum (2) filled in the GFRP hollow casing (1) is made of pure aluminum with a yield strength of 50-52 MPa, the pore size of the foamed aluminum is 1-2 mm, the relative density is 0.5-0.6, and the porosity of the foamed aluminum gradually increases from the outer plate to the inner plate.

8. The bridge pier anti-collision device according to claim 7, characterized in that: The porosity of the foam aluminum gradually increases from the outer panel to the inner panel and is divided into three levels, namely 65%, 75%, and 85%.

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