Preparation method and bearing capacity calculation method of lightweight high-bearing-capacity composite bridge deck slab

Abstract

The invention relates to a bonding and riveting mixed connection light high-strength metal-FRP composite bridge deck slab and a bearing capacity calculation method thereof. The bridge deck is composed of an edge-covered metal plate and an FRP interlayer structure, and an FRP interlayer adopts a pultrusion process and comprises an epoxy hyperbolic web and a panel; the metal plate and the FRP are connected through the epoxy glue layer and the self-plugging rivet in an adhering and riveting mode, and reliable connection and buffering cooperative stress are achieved. According to the bonding and riveting mixed connection system, interface cracking and stripping under the repeated heavy load effect can be effectively restrained, and the overall structure and durability are remarkably improved. Through systematic optimization of structural configuration, connection form and key parameters, the bridge deck has the comprehensive advantages of light weight, high strength, bending resistance, shearing resistance, fatigue resistance, skid resistance, wear resistance, corrosion resistance and the like, the ultimate bearing capacity can reach 30 tons, the weight of the bridge deck is less than 1 / 3 of that of the same steel bridge deck, and the bridge deck is suitable for heavy-load and strong-dynamic-load working conditions, is convenient for prefabricated construction and quick replacement, and has a wide application prospect. And a traditional bridge deck system is efficiently replaced.

Description

Technical Field

[0001] This invention relates to the field of composite bridge deck preparation and load-bearing capacity analysis technology, specifically to a novel method for preparing lightweight, high-load-bearing metal-FRP composite bridge decks with adhesive-riveted fusion connection and calculating their load-bearing capacity. Background Technology

[0002] As a major component of the bridge deck system that directly bears vehicle loads, the bridge deck is one of the most susceptible to defects in beam bridges due to the combined effects of environmental erosion, overloading, and vehicle impacts. Traditional steel faces problems such as corrosion, metal fatigue, and excessive weight in engineering projects, and excessive weight of a single panel can also lead to low work efficiency and resource consumption.

[0003] Fiber-reinforced polymer (FRP) has the characteristics of high specific strength, specific stiffness, lightweight and high strength, corrosion resistance, fatigue resistance, simple maintenance and good designability. It can improve and solve the durability problems caused by traditional materials and is considered an ideal alternative material for achieving high performance and long service life.

[0004] However, FRP materials are limited in some bridge deck structure applications due to their low elastic modulus, which leads to large structural deformation. They are also prone to brittle failure under heavy loads and have defects such as poor surface wear resistance. In addition, existing connection methods have problems such as difficulty in disassembling and replacing bridge decks. Furthermore, the risk of metal-FRP adhesive joints coming unglued is also effectively reduced. In order to solve the above problems, there is an urgent need for a material to replace or partially replace steel in engineering applications.

[0005] Currently, FRP bridge decks and related structures are mainly used in pedestrian bridges and other light-load applications. Due to the constitutive properties of the material, the equivalent elastic modulus of commonly used FRP materials such as GFRP is typically between 25 and 40 GPa, resulting in low overall structural stiffness. The ratio of deflection to span is generally in the range of 1 / 50 to 1 / 100, which is insufficient to meet the current code requirements for vertical deformation of bridges. Specifically, the maximum vertical deflection of reinforced concrete bridges should not exceed 1 / 600 of the calculated span, and for steel bridges, it should not exceed 1 / 500. Therefore, existing FRP bridge deck systems often fail to meet deflection control requirements under normal use. Simultaneously, the overall load-bearing capacity of FRP bridge deck structures is relatively low. Existing research and engineering examples show that the ultimate bearing capacity at a single point during the span is typically no more than 10 kN, and the shear bearing capacity near the supports is generally no more than 20 kN, which is insufficient to meet the vehicle load requirements of conventional highway bridges. Therefore, even when traffic is permitted, it is mostly limited to light two-axle vehicles with a total weight not exceeding 2 tons, significantly restricting its application. Furthermore, the durability of conventional FRP materials and structures remains insufficient. Their resistance to ultraviolet radiation and environmental aging is weak; under prolonged sunlight and environmental conditions, discoloration typically begins on the material surface after 1-2 years of service, with the resin matrix deteriorating and even developing microcracks. With increasing service life, fiber exposure, interface degradation, and even fiber breakage gradually occur, affecting the overall structural performance and safety. Additionally, FRP materials are expensive; the cost of FRP bridge deck systems is significantly higher than traditional concrete or steel structures, approximately 13% higher than prestressed concrete bridges and 7% higher than steel beam bridges. Moreover, FRP has poor wear resistance. The resin matrix of FRP itself is relatively soft, often requiring an additional wear-resistant layer on the top surface of the bridge deck to resist wheel-load friction and delamination. Studies show that common FRP bridge deck wear layers may crack or delaminate in the early stages of service. A suitable wear-resistant coating is needed on the top layer of the FRP bridge deck to improve wear resistance under vehicle loads and prevent rapid degradation of the top layer due to soft resin exposure. Furthermore, thermal expansion mismatch and environmental factors can also lead to premature damage to the wear-resistant layer.

[0006] Therefore, the main advantages of metal-FRP composite structures as bridge decks lie not only in the synergistic effect of the metal and FRP to improve the structure's stiffness and ultimate bearing capacity, but also in their better economy and durability compared to all-FRP bridge decks. At the same time, compared to all-metal structures, the proposed concept can significantly reduce self-weight while ensuring sufficient load-bearing capacity. Furthermore, the stiffness of metal-FRP composite bridge deck structures is related to many factors such as load-bearing capacity, material properties, structural form, and connection mode. Currently, there are no mature and practical methods for measuring the stiffness, deformation, and load-bearing capacity of metal-FRP. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a metal-FRP composite bridge deck with adhesive and riveted connection and for calculating its load-bearing capacity.

[0008] To address the aforementioned technical problems, this invention provides a novel lightweight, high-load-bearing-capacity metal-FRP composite bridge deck with adhesive-riveted fusion connection, its molding process, and a method for enhancing its load-bearing capacity, comprising: The FRP sandwich structure is integrally formed by pultrusion process. The FRP sandwich structure includes an epoxy hyperbolic web and a fiber rectangular web, as well as an FRP upper panel above the epoxy hyperbolic web and an FRP lower panel below it; wherein, the curve equation of the specially designed hyperbolic web is shown in formula (1). Let be the real semi-axis length of the hyperbolic equation, b be the imaginary semi-axis length, B be the web thickness, and H be the web height. The cross-section of the epoxy hyperbolic web is shown in the attached figure. Figure 2 As shown, the web height-to-thickness ratio (H / B) of the FRP bridge deck ranges from 5 to 10. When the FRP bridge deck cavity is filled with polyurethane foam core, the web height-to-thickness ratio can be increased by about 10%. This optimized design significantly reduces stress concentration at the corners of the composite bridge deck. Finite element analysis and experimental results show that stress concentration can be reduced by more than 90%, thus avoiding failure of the composite bridge deck due to local stress concentration under heavy loads. Based on its stress mechanism, the stress and failure mode of the bridge deck is optimized, significantly improving the load-bearing capacity of the bridge deck. On the other hand, this hyperbolic optimized design significantly improves the utilization efficiency of fiber materials. With the same material usage, the bending moment of inertia of the cross section is increased through structural optimization, thereby significantly improving the bending stiffness and deformation resistance of the composite bridge deck. Through the optimization of the cross section, FRP composite bridge decks, which are not suitable for heavy loads, are made capable of withstanding heavy loads.

[0009]

[0010] The edging metal plate primarily serves two functions. First, it improves and optimizes the stress performance of each component of the composite bridge deck, fully utilizing the mechanical properties of each material. Through rational design of the edging metal plate, the position of the neutral axis of the composite bridge deck can be significantly optimized, increasing it by approximately 50% to 60%. This results in the lower fiber material having a strain 50% to 60% greater than the upper edging metal, allowing the fiber composite material to fully utilize its high allowable tensile strength (≥1500MPa) and high allowable tensile ductility (≥18000με), while simultaneously leveraging the high modulus (206~210GPa), high allowable compressive strength (≥350MPa), and low ultimate deformation (approximately 1500~2000με) of steel. Thus, by optimizing the position, structural form, and content of each component, the respective mechanical advantages of fiber composite materials and steel are fully utilized. Secondly, steel has excellent wear resistance, which is more than 100 times that of fiber composite materials under the same conditions, making it possible to use fiber composite bridge decks for heavy-duty wheeled and tracked vehicles.

[0011] Epoxy structural adhesive is uniformly applied to the contact surfaces of the edge-sealing metal plate and the FRP top panel to bond the two together. The thickness of the epoxy structural adhesive should be controlled between 0.1 and 1.0 mm. If the adhesive layer is too thick, it will reduce the bonding rigidity between the steel plate and the fiber composite top panel, affecting the transmission of influence between them; if the adhesive layer is too thin, it will affect the uniformity and flatness of the bonding between the steel plate and the fiber composite top panel, making it prone to delamination. Once moisture enters, it will cause rust and other damage, reducing its service life.

[0012] Blind rivets, which penetrate the edging metal plate and the FRP top panel, are used to rivet the two together, forming an adhesive-riveted fusion connection. The blind rivets, together with epoxy structural adhesive, ensure that the edging steel plate and the fiber composite top panel form a tight and strong whole, synergistically improving interfacial bonding strength and interfacial stress transfer performance. Theoretical analysis and experiments show that if the two components cannot form a whole due to weak bonding, two neutral axes will exist; if the bonding is strong, multiple components can form a whole, resulting in only one neutral axis. Compared to the case of two neutral axes due to weak bonding, the moment of inertia of the composite section with one neutral axis can be increased by more than 45%, thereby further improving its heavy load-bearing capacity and deformation resistance. In metal-FRP composite bridge decks bonded only with epoxy structural adhesive, under heavy load conditions, the large difference in elastic modulus between the metal and FRP materials leads to adhesive cracking when the bridge deck undergoes significant deformation. The addition of blind rivets effectively limits the relative deformation of the two materials, improving the overall integrity of the bridge deck. Generally, compared to commonly used epoxy structural adhesive bonding, adhesive-riveted connections can reduce deformation capacity by more than 45% and increase load-bearing capacity by more than 40%. Under heavy load conditions, this effectively reduces the risk of bridge deck delamination and improves the overall ultimate load-bearing capacity and deformation resistance of metal-FRP composite bridge decks.

[0013] Therefore, the epoxy hyperbolic web and the "adhesive riveting" interface process of epoxy structural adhesive + pop rivets proposed in this invention patent have not been reported in the literature and are the core technology of composite bridge deck.

[0014] Furthermore, the FRP upper and lower panels are made of a combination of fiber materials and epoxy resin. The fibers can be one or more of E-type alkali-free glass fiber, aramid fiber, carbon fiber, basalt fiber, etc., with a fiber content ranging from 65% to 75%. Among them, glass fiber composite bridge panels have generally average comprehensive mechanical properties but excellent cost performance; aramid fiber composite bridge panels have good toughness; carbon fiber composite bridge panels have high stiffness and strong resistance to deformation, but are more expensive; basalt fiber composite bridge panels have performance and price in between. The fiber composite bridge panels are manufactured through a unidirectional pultrusion process, using alkali-free glass fiber untwisted roving (8800 TEX) and continuous filament mat (CSM). The layup angle of the fibers is laid at 0°, ±45°, or 90° along the longitudinal direction on the surface of the FRP upper and lower panels to enhance their transverse tensile strength. The FRP upper and lower panels are one or more of aramid fiber, basalt fiber, carbon fiber, and glass fiber.

[0015] Furthermore, a foam core is filled between the FRP upper panel and the FRP lower panel to enhance local load-bearing capacity and resistance to deformation. In addition, the foam filling helps improve the stability of the epoxy hyperboloid web, allowing for a more appropriate increase in the aspect ratio of the front panel during design, thus improving the redundancy of the structural design.

[0016] Furthermore, under the same load-bearing capacity, the weight of a single 2000mm*750mm*70mm metal-FRP composite bridge deck is approximately 90~100kg, which is 1.2~1.5 times lower than conventional FRP bridge decks and 1.8~2.5 times lower than steel bridge decks.

[0017] Furthermore, the epoxy structural adhesive coating thickness is 0.1~1.0mm. If the adhesive layer is too thin, there will be uneven application of the structural adhesive between the metal plate and the FRP plate, and localized areas without adhesive, which not only affects stress transfer between the two interfaces but also poses a certain durability risk. If the adhesive layer is too thick, it will affect stress transfer between the metal plate and the FRP plate, leading to deformation inconsistencies. Through extensive experiments and theoretical research, an adhesive layer thickness within the range of 0.1~1.0mm results in a uniform adhesive layer at the interface and smooth stress transfer between the two interfaces.

[0018] Furthermore, the blind rivets are evenly arranged along the connection surface between the edge metal plate and the FRP upper panel, and the riveting sequence proceeds from the center outwards to both sides to avoid stress concentration and improve connection strength. Additionally, to enhance the anchoring capability of the blind rivets and prevent damage to the FRP plate, the blind rivets pass through a sleeve with a certain protrusion embedded in the FRP plate.

[0019] Furthermore, the edging metal plate has openings on both sides of its ends. Metal sleeves are welded to these openings and are used to insert high-strength bolts to fix the bridge deck to the bridge beam. Based on the friction coefficient between FRP and steel and the shear force they withstand, calculations and analysis show that a fixing hole is designed every 150-250 mm.

[0020] The lower end of the metal sleeve is provided with an end pad, which is bonded to the upper and lower FRP panels respectively with epoxy structural adhesive to buffer the load, reduce joint fatigue and prevent bolt loosening, thereby improving the overall connection performance between the composite bridge deck and the bridge.

[0021] Furthermore, metal tie rods are evenly arranged longitudinally at 500-800mm intervals along the bottom of the FRP lower panel. The inner side of the grooves of these metal tie rods is uniformly coated with epoxy structural adhesive and bonded to the FRP lower panel. They are then welded to the sides of the edging metal plate to enhance the lateral stiffness and deformation resistance of the bridge deck, further constraining the deformation of the metal plate and preventing its detachment from the FRP panel. Typically, the width of the metal strips is 30-150mm. Increasing the width of the metal-FRP composite bridge deck by adding these strips can reduce the deflection by more than 3%.

[0022] Furthermore, the edge-sealing metal plate can be an edge-sealing corrugated metal plate, and the FRP upper panel can be an FRP corrugated plate. The edge-sealing corrugated metal plate and the FRP corrugated plate are bonded together with epoxy structural adhesive and fixed together by driving in core-pulling rivets from the troughs.

[0023] This invention provides a method for preparing a lightweight, high-load-bearing metal-FRP composite bridge deck using adhesive-riveted fusion bonding. Based on the lightweight, high-load-bearing metal-FRP composite bridge deck using adhesive-riveted fusion bonding as described in any one of claims 1 to 9, the method includes the following steps: S1: Surface treatment Surface treatment of the edge-sealing metal plate: Use solvents such as xylene or acetone to remove oil stains from the surface of the edge-sealing metal plate, then remove weld slag and burrs from welds and other welding points to ensure a smooth and flat surface. Next, sandblast the edge-sealing metal plate to achieve the Sa2.5 rust removal standard using steel grit or quartz sand. For areas that cannot be sandblasted, use power tools for manual grinding to achieve the St3 standard, and apply a primer to improve adhesion. Finally, clean the surface of the edge-sealing metal plate with oil-free and water-free compressed air to remove residual dust and impurities. Surface treatment of FRP sandwich structure: The surface of the FRP sandwich structure is roughened by chiseling to enhance the bonding strength; then the surface of the FRP sandwich structure is wiped with industrial alcohol to remove the release agent and oil stains, ensuring that the bonding surface is clean.

[0024] S2: Hole Fitting and Positioning First, the edging metal plate and FRP sandwich structure are combined to ensure the accuracy of the hole position; then, holes are drilled in the edging metal plate and FRP sandwich structure using an electric drill, ensuring the hole position is accurate. After drilling, the holes are chamfered at 45° to ensure installation accuracy and avoid stress concentration.

[0025] S3: Installation of metal gaskets and end filler blocks Apply modified acrylic adhesive to the bottom of the rivet and install a sleeve-type metal washer with a boss on the bottom, ensuring that the washer fits tightly to prevent stress concentration from damaging the FRP sheet; fill the ends of the FRP sandwich structure with positioning blocks, and the position of the blocks should be strictly installed according to the positioning marks on the metal sleeve.

[0026] S4: Surface application and bonding of FRP sandwich structure The thickness of the adhesive layer should be controlled between 0.1 and 1.0 mm, using weight control. The structural adhesive should be evenly applied to the surface of the FRP upper panel. The operation time should be controlled within 40 minutes. The outdoor construction operation temperature should be above 5℃. Bonding surface treatment: Grind with a grinding wheel to achieve a metallic luster, ensuring a surface roughness of Ra3.2~12.5μm, while for FRP surfaces, Ra5~20μm is recommended. The grinding lines should be perpendicular to the direction of force on the metal material. Afterward, wipe clean with cotton wool soaked in acetone. FRP surfaces need to be ground to remove mold release agent and oil stains, and then wipe clean with cotton wool soaked in acetone. Structural adhesive preparation and application: Mix epoxy resin components A and B in a ratio of A:B=2:1, and stir evenly with an electric mixer to ensure thorough mixing. The amount prepared each time should be controlled between 6 and 10 kg. Apply the prepared epoxy structural adhesive evenly to the surface of the FRP upper panel, ensuring that the adhesive is thicker in the middle and thinner at the edges. Typically, the middle should be about 0.1 to 0.4 mm thicker than the edges. After application, lay the edge-sealing metal plate onto the surface of the FRP upper panel and apply pressure to allow the structural adhesive to overflow evenly.

[0027] S5: Rivet Fixing and Connection Use blind rivets to secure the edge metal plate and the FRP top panel to ensure a firm connection. Rivet installation: Use blind rivets to connect the edge metal plate to the FRP top panel. The rivet installation sequence should proceed from the middle to both sides and diagonally from the middle to both sides to avoid stress concentration and ensure even force distribution.

[0028] S6: Preload application and compaction Apply a preload of 200~250 N·m using high-strength bolts (usually M24) to compact the surface. Then flip the surface of the edge-sealing metal plate and the FRP top panel. The bolt preload, the weight of the FRP top panel, and the pulling force of the pop rivets will bond the surface of the edge-sealing metal plate and the surface of the FRP top panel together well, increasing the bonding area of ​​the structural adhesive.

[0029] S7: Metal tie rod installation and welding Apply epoxy structural adhesive evenly to the inner side of the U-shaped metal strip groove and attach it to the bottom surface of the FRP lower panel. Lay heat-insulating aluminum film at the welding position of the lower edge of the FRP to prevent the welding temperature from affecting the strength of the lower FRP and the adhesive. Then weld the metal strip to the edge of the edge-sealing metal plate to form the shape.

[0030] S8: Curing and Molding The structural adhesive on the surface of the edge-wrapped metal plate is heated and cured using a silicone heating tape. The curing time is 24 hours at room temperature or 4 hours at 60℃, which can achieve more than 95% of the adhesive strength, ultimately forming a metal-FRP composite bridge deck.

[0031] This invention provides a method for calculating the deflection and flexural stiffness D of a metal-FRP composite bridge deck. b and shear stiffness D s and flexural bearing capacity M u Equivalent model: Where, δ L / 2 δ represents the mid-span deflection at position L / 2. L / 4 Let P be the deflection at position L / 4, P be the concentrated load, L be the span, and D be the length of the span. b For the overall bending stiffness of the bridge deck, D s Let n be the overall shear stiffness of the bridge deck. Based on material properties and stress location, the entire cross-section is divided into n (n=3) parts: metal plate, colloid, and FRP plate (including upper and lower deck webs). Then, the bending stiffness and shear stiffness of the cross-section about the y-axis are respectively:

[0032]

[0033] In the formula, E x,S E x,A and E x,G These are the equivalent elastic moduli in the axial direction for the metal sheet, structural adhesive, and FRP sheet, respectively, which can be determined through force mechanics analysis or experiments; I y This represents the moment of inertia of each section about the y-axis. G xz Here, k is the shear modulus, and k is the shear coefficient of the cross-section, a parameter related to the cross-sectional shape; A w A represents the area of ​​the web portion of the FRP plate; A represents the total cross-sectional area of ​​the FRP plate.

[0034] The flexural bearing capacity is calculated using the following method: In the formula, M u For the ultimate bending bearing capacity, f S,u and f G,u These represent the yield strength of the metal sheet and the design strength of the FRP sheet, respectively; W S With W G The section modulus of the metal plate and the GFRP plate is given.

[0035] The above model can effectively predict the stress performance of metal-FRP composite bridge decks, providing a theoretical basis for engineering design and optimization, and further improving structural safety and economy.

[0036] The beneficial effects of this invention are: 1) The composite material bridge deck for heavy-duty vehicle passage provided by this invention has sufficient load-bearing capacity. The single-point ultimate bending capacity at mid-span of the 2000mm*750*70mm composite bridge deck can reach 300kN, and the shear capacity can reach more than 600kN, which is more than 15 times the corresponding load-bearing capacity of ordinary FRP bridge decks; 2) It has high stiffness characteristics, and its deformation ratio can meet the deformation requirements of steel beam and concrete bridge structures; 3) It has excellent fatigue performance. Indoor simulation tests show that after 2 million cycles of cyclic loading fatigue, its stiffness and ultimate bearing capacity do not show significant degradation; 4) The adhesive and riveting fusion connection method is reasonable and reliable, avoiding the risk of delamination under repeated heavy loads, which is beneficial for structures bearing large dynamic loads and can be used for heavy vehicle passage. In addition, it has a small span, is easy to transport, can be quickly installed and disassembled, and is lightweight and high-strength, non-slip and wear-resistant, resistant to punching and shearing, and has good resistance to corrosion and fatigue. It also has high mechanical properties such as high bending and shear resistance, which reduces the labor intensity of assembly operations, improves assembly efficiency, and realizes the replacement of traditional steel and concrete bridge decks. Attached Figure Description

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Figure 1 This is a schematic diagram of the cross-section of a metal-FRP composite bridge deck. Figure 2 This is a hyperbolic coordinate diagram of the web of a composite bridge deck. Figure 3 This is a plan view of a metal-FRP composite bridge deck. Figure 4 Detailed unfolded view of the metal-FRP composite bridge deck component; Figure 5 This is a perspective view of the elevation of a metal-FRP composite bridge deck. Figure 6 This is a schematic diagram of the elevation of an FRP mezzanine structure. Figure 7 This is a schematic diagram of the overall metal-FRP composite bridge deck. Figure 8 This is a schematic diagram of the connection between the end metal sleeve and the pad block; Figure 9 This is a perspective view of Embodiment 2 of the corrugated metal-FRP composite bridge deck; Figure 10 An exploded view of Example 2 of the corrugated metal-FRP composite bridge deck; Figure 11 This is a diagram showing the cross-sectional dimensions of the steel-GFRP composite bridge deck in Example 3. Figure 12 This is a schematic diagram of the loading points and measuring points layout in Example 3; Figure 13 The load-displacement curves from the static test results in Example 3; Figure 14 The load-strain curves from the static test results in Example 3; Figure 15 The load-displacement curves are shown for different cycles during the fatigue test in Example 3. Figure 16 This shows the variation of longitudinal strain of the steel plate and GFRP with the number of cycles during the fatigue test in Example 3.

[0039] In the picture: 1. Edge-sealed metal plate; 2. FRP top panel; 3. Epoxy structural adhesive; 4. Rectangular side web; 5. FRP bottom panel; 6. Epoxy hyperbolic web; 7. High-strength bolts; 8. End pads; 9. Metal sleeves; 10. Foam core; 11. FRP sandwich structure; 12. Nuts; 13. Blind rivets; 14. Metal tie rods; 15. Edge-sealed corrugated metal plate; 16. Sleeve-type metal pad with a boss at the bottom; 17. Metal beam; 18. FRP corrugated plate. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0041] Example 1: As Figure 1-8 As shown, a lightweight, high-load-bearing metal-FRP composite bridge deck with adhesive-riveted fusion connection according to the present invention includes: Edge-sealing metal plate 1; Edge-sealing metal plate 1 plays a framing role in the composite bridge deck, usually to improve the stability and load-bearing capacity of the overall structure. Using edge-sealing metal plate 1 can enhance the edge strength of the bridge deck and provide basic support for the installation of FRP sandwich structure 11.

[0042] FRP sandwich structure 11, with metal beam 17 installed, is integrally formed by pultrusion process. FRP sandwich structure 11 includes epoxy hyperbolic web 6 and rectangular side web 4, as well as FRP upper panel 2 above epoxy hyperbolic web 6 and FRP lower panel 5 below it. FRP upper panel 2 and FRP lower panel 5 are made of fiber and epoxy resin, with fiber content of 70%, and are made by unidirectional pultrusion process. The fibers are laid in longitudinal 0°, ±45° and 90° directions on the surface of FRP upper panel 2 and FRP lower panel 5 to enhance their transverse tensile strength. FRP upper panel 2 and FRP lower panel 5 are a combination of aramid fiber, basalt fiber, carbon fiber or glass fiber.

[0043] FRP sheets are made from fiber reinforced composite materials (FRP). The specific preparation process is as follows: untwisted fiber rovings are placed in a mold, modified epoxy resin curing agent is added, and then extrusion and curing are performed to form FRP pultruded profiles. FRP materials can be aramid fiber (AFRP), basalt fiber (BFRP), carbon fiber (CFRP), glass fiber (GFRP), etc., which have lightweight, high strength and good corrosion resistance.

[0044] The FRP sandwich structure 11 is integrally formed by pultrusion of the FRP upper panel 2, rectangular side web 4, epoxy hyperbolic web 6, and FRP lower panel 5, enhancing the integrity and strength of the structure. The FRP sandwich structure 11 is made of E-type alkali-free glass and epoxy resin through a pultrusion process, using E-type alkali-free glass fiber as the load-bearing fiber with a fiber content of 70% and a traction speed of 0.2m / min. Through a unidirectional pultrusion process, the fiber layup direction is basically longitudinal (along the length of the pipe), with angles of 0° and ±45°, and 8% of the fiber is laid in the 90° direction on the lower surface of the FRP upper panel 2 and the upper and lower surfaces of the lower panel. Laterally, it is constrained by the matrix and the surface chopped strand mat.

[0045] Epoxy structural adhesive 3 is uniformly applied to the contact surface between the edge-sealing metal plate 1 and the FRP upper panel 2 to bond the two together. The thickness of the epoxy structural adhesive 3 is 0.1~1.0mm, and the weight is controlled. The structural adhesive is uniformly applied to the surface of the FRP upper panel 2. The operation time should be controlled within 40 minutes, and the outdoor construction operation temperature should be above 5℃.

[0046] The edge-sealing metal plate 1 and the FRP upper panel 2 are bonded together with epoxy resin adhesive and fused together with pop rivets 13. The connection is firm and reliable. The bonded and fused connection can enhance the bonding strength between the metal and the FRP upper panel 2, improve the load-bearing capacity and resistance to deformation of the bridge deck structure, reduce the risk of delamination, better leverage the advantages of the two materials, enhance the synergistic effect between the materials, and improve the durability of the structure.

[0047] A blind rivet 13 penetrates the edge metal plate 1 and the FRP upper panel 2 to rivet the two together, forming an adhesive fusion connection. The blind rivet 13 is evenly arranged along the connection surface between the edge metal plate 1 and the FRP upper panel 2, and the riveting sequence is from the middle to both sides and from the middle to both sides in turn to avoid stress concentration and improve the connection strength.

[0048] The metal edging plate 1 and the FRP top panel 2 are bonded together with epoxy structural adhesive 3 and riveted with pop rivets 13. The connection is firm and reliable. The bonded and riveted connection can enhance the bonding strength between the metal and FRP, improve the load-bearing capacity and resistance to deformation of the bridge deck structure, reduce the risk of delamination, better leverage the advantages of the two materials, enhance the synergistic effect between the materials, and improve the durability of the structure.

[0049] The edge-sealing metal plate 1 has openings on both sides of its ends. The metal sleeve 9 is welded to the openings of the edge-sealing metal plate 1 and is used to pass through the high-strength bolts 7. The lower end of the metal sleeve 9 is provided with an end pad 8. The pad is bonded to the FRP upper panel 2 and FRP lower panel 5 respectively by epoxy structural adhesive 3 to buffer the load, reduce joint fatigue and prevent bolt loosening.

[0050] A hole is made on the surface of the edge-sealing metal plate 1, and a metal sleeve 9 is welded on it. An end pad 8 is placed under the metal sleeve 9. Epoxy structural adhesive is applied to the upper and lower surfaces of the end pad 8 and bonded to the lower surface of the FRP upper panel 2 and the upper surface of the FRP lower panel 5, respectively. After bonding, a pop rivet 13 is used to complete the bonding and riveting connection. High-strength bolts 7 are installed inside the metal sleeve 9 to connect and fix the composite bridge panel to the support. After the edge-sealing metal plate 1 and the metal sleeve 9 are welded, they are cooled to room temperature to avoid the high temperature generated by the metal welding affecting the FRP material. A hole is made at the end of the FRP upper panel 2 to facilitate the passage of the metal sleeve 9. The metal plate is bonded to the FRP pultruded profile and the adhesive layer is compacted to avoid leaving gaps that affect the bonding quality. After the bolts and metal washers 16 are installed, the nut 12 is tightened with a torque wrench to apply pressure. The applied torque is about 200~250 N·m, and it is advisable to let the adhesive no longer squeeze out. After constraint and pressure are completed, the overflowing adhesive is wiped off and left to stand at room temperature or heated for curing.

[0051] A foam core 10 is filled between the FRP upper panel 2 and the FRP lower panel 5 to enhance local load-bearing capacity and resistance to deformation.

[0052] Polyurethane foam is filled between the FRP upper panel 2 and the FRP lower panel 5 to improve the strength and deformation resistance of the bridge deck. It achieves a better local reinforcement effect with a small increase in weight, effectively improves the cracking of the FRP upper panel 2 and the buckling of the web in the direct wheel load area, and enhances the load-bearing capacity of the bridge deck. In addition, the foam core 10 presents a constrained state around the whole body, so that the FRP upper panel 2 and the FRP lower panel 5, as well as the epoxy hyperbolic web 6 and the rectangular side web 4, present a mutually reinforcing design effect with the foam core 10.

[0053] The bottom of the FRP lower panel 5 is provided with a metal tie rod 14. The inner side of the groove of the metal tie rod 14 is uniformly coated with epoxy structural adhesive 3 and bonded to the FRP lower panel 5. It is also connected to the side of the edge metal plate 1 by welding to enhance the lateral stiffness and deformation resistance of the bridge deck.

[0054] Example 2: Figure 9-10 The edge-sealing metal plate 1 can be an edge-sealing corrugated metal plate 15, and the FRP upper panel 2 can be an FRP corrugated plate 18. The edge-sealing corrugated metal plate 15 and the FRP corrugated plate 18 are bonded together with epoxy structural adhesive 3 and fixed by driving in the troughs with pop rivets 13.

[0055] A corrugated metal-FRP composite bridge deck replaces the edge metal plate 1 and the FRP top panel 2 with corrugated plates, including an edge corrugated metal plate 15 and an FRP corrugated plate 18. Both the edge corrugated metal plate 15 and the FRP corrugated plate 18 are made of corrugated plates for bonding. A pop rivet 13 is driven into the FRP corrugated plate 18 from the trough of the edge corrugated metal plate 15 and fixed. The corrugated plate can effectively prevent direct contact between the vehicle and the rivet, avoid wear and tear caused by repeated friction between the rivet and the heavy vehicle, and improve the wear resistance of the bridge deck surface. The corrugated plate increases the bonding area between the metal and FRP surfaces, improves the bonding strength between the two materials, and the use of the corrugated plate can improve the overall rigidity and anti-slip performance of the bridge deck.

[0056] Example 3: A high-strength steel-GFRP composite bridge deck, wherein the edging steel plate 1 is made of 3mm thick Q550 high-strength steel, and the GFRP panel is formed by pultrusion of 3.75mm upper and lower panels and 60mm high web plate 6. The steel plate and GFRP panel are bonded together by epoxy resin adhesive 3 and pop rivets 13. The end pads 8 are filled with PA66 nylon material.

[0057] A lightweight, high-load-bearing steel-GFRP composite bridge deck with adhesive and riveting connection, the dimensions of which are as follows: Figure 11-16 As shown, static and fatigue mechanical property tests were conducted to test its ultimate bearing capacity and mid-span displacement. A 200mm×600mm loading block was used to simulate the contact area of ​​a single heavy-duty wheel. The following results were obtained: the ultimate bearing capacity of the steel-GFRP composite bridge deck was 300.7kN, the ultimate deflection at mid-span was 77.4mm, and the longitudinal strain at mid-span of the GFRP plate was 7930.1με and the transverse strain was 1875.5με, which is consistent with the performance design in the claims. The neutral axis shifted upward, which well utilized the high tensile strain characteristics of FRP and the high compressive stiffness characteristics of steel.

[0058] Two million three-point bending fatigue tests were conducted under a single-point axle load of 100 kN. During the tests, no fatigue cracks or damage were observed in the bridge deck, and the strength and stiffness of the steel-GFRP bridge deck system did not decrease. With increasing loading cycles, the deflection and strain at the same load level changed very little. The deflection fluctuated between 18.66 mm and 20 mm, the longitudinal strain at the top of the steel plate was -950 με to -1078 με, and the longitudinal strain at the bottom of the GFRP plate was 2507.2 με to 3071.5 με. Based on theory and calculations, it can be reasonably determined that the system maintains sufficient fatigue strength and other mechanical properties under the design load.

[0059] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity, characterized in that, include: Edge-sealing metal plate (1); FRP sandwich structure (11), the FRP sandwich structure (11) is integrally formed by pultrusion process, the FRP sandwich structure (11) includes epoxy hyperbolic web (6) and rectangular side web (4), as well as FRP upper panel (2) located above epoxy hyperbolic web (6) and FRP lower panel (5) located below; epoxy structural adhesive (3), the epoxy structural adhesive is uniformly coated on the contact surface of edge-sealing metal plate (1) and FRP upper panel (2) for bonding the two and buffering the load-bearing capacity; blind rivet (13), the blind rivet (13) penetrates edge-sealing metal plate (1) and FRP upper panel (2) for riveting the two to form an adhesive-riveted fusion connection.

2. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claim 1, characterized in that, The FRP upper panel (2) and FRP lower panel (5) are made of fiber and epoxy resin, with fiber content between 65% and 78%, and are made by unidirectional pultrusion process. The fibers are laid crosswise in the longitudinal 0°, ±45° and transverse 90° directions on the FRP upper panel (2) and FRP lower panel (5) to simultaneously enhance their longitudinal and transverse comprehensive tensile strength and modulus. The FRP upper panel (2) and FRP lower panel (5) are one or more of aramid fiber, basalt fiber, carbon fiber or glass fiber. A foam core (10), such as polyurethane foam core, is filled between the FRP upper panel (2) and FRP lower panel (5) to enhance local load-bearing capacity and deformation resistance.

3. The lightweight, high-load-bearing composite bridge deck preparation method and its load-bearing capacity calculation method as described in claims 1-2, wherein the epoxy hyperbolic web shape is represented by the hyperbolic fiber web equation: in, a is the real semi-axis length of the hyperbolic equation, b is the imaginary semi-axis length, B is the web thickness, and H is the web height. The web height-to-thickness ratio H / B of FRP bridge deck is between 5 and 10. When the cavity of the FRP bridge deck is filled with polyurethane foam core, the web height-to-thickness ratio can be increased by about 10%, which can significantly reduce the stress concentration effect at the connection between the upper and lower decks and the web.

4. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claims 1-3, characterized in that, The epoxy structural adhesive (3) is coated with a thickness of 0.1 to 1.0 mm; the core-pulling rivets (13) are evenly arranged in a quincunx pattern along the connection surface between the edge metal plate (1) and the FRP upper panel (2), and the riveting sequence is from the middle to both sides.

5. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claims 1-4, characterized in that, The edge-sealing metal plate (1) has assembly holes on both sides of the end. The metal sleeve (9) is installed at the opening of the edge-sealing metal plate (1) by welding. The lower end of the metal sleeve (9) is provided with an end pad (8). The pad is bonded to the FRP upper panel (2) and FRP lower panel (5) respectively by epoxy structural adhesive to buffer the load, reduce joint fatigue and prevent bolt loosening. The high-strength bolt (7) fixes the composite bridge panel to the bridge structure through the metal sleeve (9).

6. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claims 1-5, characterized in that, The bottom of the FRP lower panel (5) is provided with a tie rod (14). The inner side of the groove of the metal tie rod (14) is evenly coated with epoxy structural adhesive and bonded to the FRP lower panel (5), and is tightly connected to the side of the edge metal plate (1) to enhance the lateral stiffness and deformation resistance of the bridge deck.

7. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claims 1-6, characterized in that, Provides a method for calculating the flexural stiffness D of metal-FRP composite bridge decks. b and shear stiffness D s Equivalent model and its calculation method, bending stiffness (D) of the section about the neutral (y) axis b ) and shear stiffness (D s They are respectively: D b =E x,S I y,S +E x,A I y,A +E x,G I y,G D s＝ G xz,S A S +G xz,A A A +kG xz,G A G k=A w / A G In the formula, P is the concentrated load, and E x,S E x,A and E x,G These are the equivalent elastic moduli in the axial direction for the metal sheet, structural adhesive, and FRP sheet, respectively; I y This represents the moment of inertia of each section about the y-axis. G xz Here, A is the shear modulus, and k is the shear coefficient of that section. w A represents the area of ​​the web portion of the FRP plate; A represents the total cross-sectional area of ​​the FRP plate.

8. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claims 1-7, characterized in that, An equivalent model and calculation method for calculating the ultimate flexural bearing capacity of metal-FRP composite bridge decks are provided: M u =f S,u W S +f G,u W G In the formula, M u For the ultimate bending capacity, f S,u and f G,u These represent the yield strength of the metal sheet and the design strength of the FRP sheet, respectively; W S With W G The section modulus of the metal plate and the GFRP plate is given.

9. The method for preparing a lightweight, high-load-bearing composite bridge deck and calculating its load-bearing capacity as described in claims 1-6, characterized in that the preparation process includes the following steps: S1 FRP board molding: The fiber is placed on the yarn rack, and the fiber is continuously drawn to the bundler by the traction device. The bundler is then impregnated with resin and extruded through a mold. After extrusion molding, it is cured at a high temperature of 100-150℃. Finally, it is cut according to the FRP size corresponding to the composite bridge panel. S2 Surface Treatment: Surface treatment of the edge-sealed metal plate (1): Use solvents such as xylene, alcohol or acetone to remove oil stains from the surface of the edge-sealed metal plate (1), then remove weld slag and burrs from welds and other welding points to ensure a smooth and flat surface. Next, sandblast the edge-sealed metal plate (1) to achieve the Sa2.5 level rust removal standard. Use metal sand or quartz sand for sandblasting. For areas that cannot be sandblasted, use power tools for manual grinding to achieve the St3 level standard, and apply primer to improve adhesion and rust prevention performance. Finally, use oil-free and water-free compressed air to clean the surface of the edge-sealed metal plate (1) to remove residual dirt. S3 FRP sandwich structure (11) surface treatment: First, the surface of each FRP is flattened, and the flatness is controlled within ±0.3mm and the perpendicularity of the line is controlled within ±0.2°. Then, the surface is treated by sandblasting process to control the surface roughness of the FRP sandwich structure (11) within the range of 50~150μm, which enhances the interface strength and does not affect the tensile, bending and shear strength of the FRP board itself. Then, the surface of the FRP sandwich structure (11) is wiped with solvent to remove the release agent and oil stains to ensure that the bonding surface is clean. S4 Assembly and Positioning: First, combine the edge-sealing metal plate (1) and the FRP sandwich structure (11) to ensure the precise fit of the hole positions; then, make holes in the edge-sealing metal plate (1) and the FRP sandwich structure (11) and ensure the hole positions are accurate. After the holes are made, the holes are chamfered at 45° to ensure installation accuracy and avoid stress concentration. S5 metal gasket (16) and end filler block installation Apply modified acrylic adhesive to the bottom of the rivet and install a sleeve-type metal washer (16) with a boss on the bottom to ensure that the washer fits tightly and prevent stress concentration; fill the end of the FRP sandwich structure (11) with positioning pads, and the position of the pads should be strictly installed according to the positioning marks of the metal sleeve (9); S6 FRP sandwich structure (11) Surface coating and bonding The thickness of the adhesive layer is controlled between 0.1 and 1.0 mm. The weight is controlled according to the density of the adhesive. The structural adhesive is evenly applied to the surface of the FRP upper panel (2). The operation time should be controlled within 40 minutes. The outdoor construction operation temperature should be above 5℃. Bonding surface treatment: Grind with a grinding wheel to achieve a metallic luster, ensuring a surface roughness of Ra3.2~12.5μm, while for FRP surfaces, Ra5~20μm is recommended. The grinding pattern should be at an angle of 85°~95° with the direction of force on the metal material, preferably perpendicular. Afterwards, wipe it clean. FRP surfaces need to be ground to remove mold release agent and oil stains. Adhesive preparation and application: Mix the epoxy resin components A and B in a ratio of A:B = 2:1 and stir evenly with an electric mixer to ensure that the adhesive is fully mixed; apply the prepared epoxy structural adhesive evenly to the surface of the FRP upper panel (2), ensuring that the middle is 0.2 to 0.4 mm thicker than the two sides. After application, lay the edge-sealing metal plate (1) on the surface of the FRP upper panel (2) and apply pressure to make the adhesive overflow evenly. S7 Rivet Fixing and Connection Use blind rivets (13) to fix the edge metal plate (1) and the FRP top panel (2) to ensure that the two are firmly connected; Rivet installation: Use blind rivets (13) to connect the edge metal plate (1) and the FRP top panel (2). The rivet installation sequence should be from the middle to both sides and from the middle to both sides diagonally to avoid stress concentration and ensure uniform force distribution. S8 Preload Application and Compaction Apply a pre-tightening force of 200-250 N·m with high-strength bolts (7) to compact the surface, then flip the surface of the edge-sealing metal plate (1) and the FRP upper panel (2), and firmly bond the surface of the edge-sealing metal plate (1) and the surface of the FRP upper panel (2) together with the bolt pre-tightening force, the self-weight of the FRP upper panel (2) and the pulling force of the core-pulling rivet (13), thereby increasing the bonding area of ​​the structural adhesive; S9 Metal Tie Strip (14) Installation and Connection Apply epoxy structural adhesive evenly to the inner side of the groove of the U-shaped metal strip (14) and stick it to the bottom surface of the FRP lower panel (5). Lay a heat insulation film at the welding position of the lower edge of the FRP to prevent the welding temperature from being too high and affecting the strength of the FRP and the adhesive. Then weld the metal strip (14) to the edge of the edge-sealing metal plate (1) to form a shape. S10 Curing and Molding The structural adhesive on the surface of the metal plate (1) is heated and cured using a silicone heating tape. The curing time at room temperature is 24 hours or 4 hours at 60℃, which can achieve more than 95% of the strength of the structural adhesive, and finally form a metal-FRP composite bridge panel.

Images