Secondary self-emergency anti-beam-falling device for bridge and protection method

Abstract

The invention discloses a secondary self-emergency anti-beam-falling device for a bridge and a protection method, and relates to the technical field of roads and bridges. The bridge pier anchor fixing part is fixedly connected to a bridge pier through an anchor bolt and hinged to the connecting support body through a hinge shaft, the steel strand restraining assembly is fixedly connected to the outer side wall of the connecting support body, the beam bottom anchor fixing part is fixedly connected to the bottom of a box beam body through an anchor bolt, and the steel sleeve is fixedly connected with the beam bottom anchor fixing part through a bolt. The metal rubber efficiency assembly is arranged in the steel sleeve, the steel strand restraining assembly is connected into the steel sleeve in a penetrating mode, and the steel strand restraining assembly and the metal rubber efficiency assembly are matched to form a buffering-restraining anti-seismic device. Beam end impact is effectively restrained, relative displacement is limited, and reliable beam falling prevention constraint is provided; and through cooperative work of the metal rubber efficiency assembly and the steel strand constraint assembly, multi-stage protection of the bridge body under the earthquake action is achieved, and the overall anti-seismic toughness of the bridge is improved.

Description

Technical Field

[0001] This invention belongs to the field of road and bridge technology, specifically relating to a secondary self-emergency anti-falling beam device and protection method for bridges. Background Technology

[0002] The problem of beams falling off a bridge can cause the superstructure to detach from the substructure, resulting in traffic disruption and severely impacting road capacity. During natural disasters such as earthquakes, fallen beams can obstruct rescue vehicle access, delaying rescue efforts and increasing the difficulty of rescue operations. Furthermore, fallen beams can damage the bridge structure. During a fall, the beams exert tremendous impact and collision forces on the piers, causing damage to the piers, abutments, and other substructures, potentially leading to the collapse of the entire bridge. In addition, repairs after a beam fall are extremely difficult; earthquake damage from fallen beams is often difficult to treat and reuse, resulting in very high costs and long repair times. Falling beams can also trigger other structural damage. They may break piers, damage the substructure, or even cause the entire bridge to collapse, leading to a chain reaction of damage to surrounding buildings and facilities. After a beam falls, the bridge structure is in an unstable state, posing a serious threat to pedestrians and vehicles.

[0003] To prevent bridge beams from falling off, anti-falling beam devices are currently used. Traditional anti-falling beam devices are mostly rigid connection devices such as connecting rods, chains, and steel strands, which reduce bridge displacement through instantaneous action. However, rigid connection anti-falling beam devices have the following drawbacks in use:

[0004] I. Rigidly connected anti-fall beam devices are subjected to enormous forces during earthquakes, which can lead to excessive localized instantaneous tension, causing localized damage to the bridge structure and even causing the anti-fall beam device to malfunction.

[0005] II. Bridge dampers effectively control the relative displacement between the bridge beam and the pier by dissipating seismic energy. However, under extreme seismic loading, if the relative displacement exceeds the damper's design limit displacement, the damper may fail due to structural damage. In this case, the structure's seismic response may increase, placing higher demands on subsequent anti-falling beam devices (such as seismic blocks and cables). If the displacement further exceeds the design protection capacity of the anti-falling beam system, the bridge beam risks detaching from its support position. Summary of the Invention

[0006] To address the problems mentioned in the background section, the present invention aims to provide a secondary self-emergency anti-falling beam device and protection method for bridges.

[0007] This invention discloses a secondary self-emerging anti-falling beam device for bridges, comprising a pier anchor, a connecting support body, a steel sleeve, a beam bottom anchor, a steel strand restraint assembly, and a metal-rubber performance assembly. The pier anchor is fixedly connected to the pier by anchor bolts and hinged to the connecting support body via a hinge shaft. A steel strand restraint assembly is fixedly connected to the outer wall of the connecting support body. The beam bottom anchor is fixedly connected to the bottom of the box girder by anchor bolts. The steel sleeve is fixedly connected to the beam bottom anchor by bolts. The metal-rubber performance assembly is disposed inside the steel sleeve, and the steel strand restraint assembly passes through the inside of the steel sleeve. The steel strand restraint assembly and the metal-rubber performance assembly cooperate to form a buffer-restraint anti-falling device. The vibration device includes a metal-rubber performance component comprising a metal-rubber body and loosely shaped metal-rubber blocks. The loosely shaped metal-rubber blocks cooperate with the metal-rubber body and are disposed within a steel sleeve. The metal-rubber body is fixedly connected to the limiting plate of the steel strand constraint component. When the steel sleeve moves horizontally away from the pier along with the box girder, the metal-rubber body arranged on the limiting plate is in close contact with the loosely shaped metal-rubber blocks, and the loosely shaped metal-rubber blocks are in a state of buffering and energy dissipation deformation. With continued lateral displacement, the loosely shaped metal-rubber blocks are further compressed, and the metal-rubber body is in a state of buffering and energy dissipation deformation. When the compression of the metal-rubber body and the loosely shaped metal-rubber blocks reaches its limit, the steel strand constraint component is in a state of tension.

[0008] As a preferred embodiment: the pier anchor fixing component includes a pier fixing plate and a pier ear plate; two pier ear plates are fixedly connected to the side wall of the pier fixing plate, the pier ear plates are provided with hinge holes, and the pier fixing plate is provided with anchor bolt fixing holes.

[0009] As a preferred embodiment: the connecting support body includes a connecting plate and a connecting lug plate; two connecting lug plates are fixedly connected to the side wall of the connecting plate, and hinge holes are provided on the connecting lug plates.

[0010] As a preferred embodiment: the steel sleeve includes a seamless steel pipe, a lower rib plate, a right steel plate, and a left steel plate; two lower rib plates are fixedly connected to the upper end of the seamless steel pipe, a right steel plate is welded to the right side wall of the seamless steel pipe, and the left side wall of the seamless steel pipe is fixedly connected to the left steel plate by bolts.

[0011] As a preferred embodiment, the right steel plate has a movable hole in the middle.

[0012] As a preferred embodiment: the beam bottom anchor includes a beam bottom fixing plate and upper ribs, with two upper ribs fixedly connected to the bottom of the beam bottom fixing plate.

[0013] As a preferred embodiment: the steel strand constraint assembly includes a steel strand, a right anchor head, a limiting plate, and a left anchor head; the right end of the steel strand is fixedly connected to the right anchor head, the left end of the steel strand is fixedly connected to the left anchor head, and the limiting plate is fixedly connected to the right side wall of the left anchor head, with the limiting plate being fixedly connected to the steel strand.

[0014] A secondary self-emergency anti-fall beam protection method for bridges, the specific steps of which are as follows:

[0015] Step 1: Normal use process: The secondary self-emergency anti-fall beam device does not participate in the operation, the box girder body can freely expand and contract, and the metal rubber body, loose metal rubber blocks and steel strands are in a non-stressed state;

[0016] Step 2: Level 1 protection activation process: The box girder begins to move laterally, causing the steel sleeve to move; the loose metal rubber block comes into contact with the metal rubber body, the loose metal rubber block deforms, and begins to buffer and dissipate energy;

[0017] Step 3: Secondary protection activation process: The box girder continues to move laterally, the loose metal rubber blocks are further compressed, and the metal rubber body begins to buffer and dissipate energy;

[0018] Step 4: Level 3 protection activation process: If the displacement continues to increase, the loose metal rubber block and the metal rubber body can no longer be compressed, the steel strands begin to be stretched, providing rigid constraints to prevent the beam from falling.

[0019] This invention installs a secondary self-emergency anti-fall beam device between the box girder and the pier. The height of the upper rib plate connected to the bottom of the beam is determined to ensure that the position of the central axis of the steel strand in the length direction is matched with the height of the bottom side of the box girder. After determining the height of the upper rib plate of the corresponding thickness, the top side of the steel sleeve is connected to the bottom fixing plate of the beam by bolts, and the other end is connected to the outer wall of the pier by the pier anchor fixing component.

[0020] Compared with existing technologies, the beneficial effects of this invention are: through a combined limiting and buffering working mechanism, it effectively suppresses beam end impact, restricts relative displacement, and provides reliable anti-fall beam restraint. Specific advantages include:

[0021] I. This invention achieves multi-level protection of the bridge beam under seismic loads through the synergistic operation of a metal-rubber performance component and a steel strand restraint component. It effectively dissipates seismic energy through dry friction and the deformation of the metal wire mesh. The metal-rubber performance component combines the mechanical properties of metal with the elastic characteristics of rubber, exhibiting excellent fatigue resistance and environmental adaptability. It maintains stable mechanical properties within a temperature range of -40℃ to 80℃, and is corrosion-resistant and anti-aging, making it suitable for long-term use in bridge engineering. This device not only possesses the traditional function of preventing beam collapse, but more importantly, it significantly reduces the structural seismic response and improves the overall seismic toughness of the bridge through the buffering and energy-dissipating characteristics of metal rubber.

[0022] II. When the steel sleeve moves horizontally away from the pier along with the box girder, the metal rubber body arranged on the limiting plate comes into close contact with the loose metal rubber block, and the loose metal rubber block begins to function; as the lateral displacement continues, the loose metal rubber block is further compressed, and the metal rubber begins to function; when the compression of the metal rubber body and the loose metal rubber block reaches its limit, the steel strands function; the configuration of the steel strands, the connection method, the density of the metal rubber and the suitable cross section can be determined according to the actual working conditions.

[0023] Third, this invention employs a dual-level protection mechanism that combines buffering and constraint, achieving graded response under seismic loading through the coordinated work of metal rubber and steel strands:

[0024] During the buffering phase, the metal rubber plays a dominant buffering role. The metal rubber body has variable stiffness characteristics, which reduces the impact force at the beam end through its elastic deformation and dry friction energy dissipation. After contact, the loose metal rubber block provides initial buffering; if the displacement continues, the metal rubber body provides a second level of buffering.

[0025] During the constraint phase, the steel strands play a dominant constraint role. When the displacement exceeds the set threshold, the steel strands begin to be under tension, providing strong tensile constraints. The steel strands are 1860 grade low-relaxation prestressed steel strands, which have high strength and durability, ensuring the reliable function of preventing beam fall. Attached Figure Description

[0026] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a structural schematic diagram of the bridge pier anchor fastener;

[0029] Figure 3 for Figure 2 The left view;

[0030] Figure 4 This is a schematic diagram of the structure connecting the support body;

[0031] Figure 5 for Figure 4 Top view;

[0032] Figure 6 This is the front view of the steel sleeve;

[0033] Figure 7 Right view of the connection between the seamless steel pipe and the lower rib plate;

[0034] Figure 8 This is a schematic diagram of the right steel plate structure;

[0035] Figure 9This is a schematic diagram of the structure of the left steel plate;

[0036] Figure 10 This is a structural schematic diagram of the bottom anchor fastener for the beam;

[0037] Figure 11 This is a structural schematic diagram of a steel strand restraint assembly;

[0038] Figure 12 A schematic diagram of a loosely packed metal-rubber block;

[0039] Figure 13 This is a schematic diagram of shear failure at the edge of concrete.

[0040] In the diagram: 1-Pier anchor fastener; 2-Connecting support body; 3-Steel sleeve; 4-Beam bottom anchor fastener; 5-Steel strand restraint assembly; 6-Metal rubber body; 7-Loose metal rubber block; 8-Box girder body; 9-Pier.

[0041] 1-1-Pier fixing plate; 1-2-Pier ear plate; 1-3-Anchor bolt fixing hole;

[0042] 2-1-Connecting support plate; 2-2-Connecting ear plate;

[0043] 3-1 Seamless steel pipe; 3-2 Lower rib plate; 3-3 Right steel plate; 3-4 Left steel plate;

[0044] 3-31-Modible hole;

[0045] 4-1-Beam bottom fixing plate; 4-2-Upper rib plate;

[0046] 5-1-Steel strand; 5-2-Right anchor head; 5-3-Limiting plate; 5-4-Left anchor head. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. The structures, proportions, sizes, etc., illustrated in the accompanying drawings are only for illustrative purposes and to enable those skilled in the art to understand and read the invention, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention.

[0048] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0049] Specific implementation method one: Combining Figures 1 to 13 The following technical solution is illustrated in this specific embodiment: it includes a pier anchor fastener 1, a connecting support body 2, a steel sleeve 3, a beam bottom anchor fastener 4, a steel strand restraint assembly 5, and a metal rubber performance assembly. The pier anchor fastener 1 is fixedly connected to the pier 9 by anchor bolts. The pier anchor fastener 1 is hinged to the connecting support body 2 by a hinge shaft. The steel strand restraint assembly 5 is fixedly connected to the outer wall of the connecting support body 2. The beam bottom anchor fastener 4 is fixedly connected to the bottom of the box girder 8 by anchor bolts. The steel sleeve 3 is fixedly connected to the beam bottom anchor fastener 4 by bolts. The steel sleeve 3 is equipped with a metal rubber performance assembly inside. The steel strand restraint assembly 5 passes through the inside of the steel sleeve 3. The steel strand restraint assembly 5 and the metal rubber performance assembly cooperate to form a buffer-restraint seismic device.

[0050] In a further preferred embodiment, the steel strand constraint assembly 5 in this specific embodiment includes a steel strand 5-1, a right anchor head 5-2, a limiting plate 5-3, and a left anchor head 5-4; the right end of the steel strand 5-1 is fixedly connected to the right anchor head 5-2, the left end of the steel strand 5-1 is fixedly connected to the left anchor head 5-4, the right side wall of the left anchor head 5-4 is fixedly connected to the limiting plate 5-3, the limiting plate 5-3 is fixedly connected to the steel strand 5-1, and the right side wall of the limiting plate 5-3 is fixed to the metal rubber body 6.

[0051] In a further preferred embodiment, the metal rubber performance component in this specific embodiment includes a metal rubber body 6 and a loose metal rubber block 7; the loose metal rubber block 7 cooperates with the metal rubber body 6, the loose metal rubber block 7 is disposed inside the steel sleeve 3, and the metal rubber body 6 is fixedly connected to the limiting plate 5-3 of the steel strand constraint component 5.

[0052] The working principle of this specific implementation is as follows: When the steel sleeve 3 moves horizontally away from the pier 9 along with the box girder 8, the metal rubber body 6 arranged on the limiting plate 5-3 comes into close contact with the loose metal rubber block 7, and the loose metal rubber block 7 begins to function; with continued lateral displacement, the loose metal rubber block 7 is further compressed, and the metal rubber body 6 begins to function; when the compression of the metal rubber body 6 and the loose metal rubber block 7 reaches its limit, the steel strand 5-1 functions, that is, the loose metal rubber block 7 is initially buffered, and with continued lateral displacement, the loose metal rubber block 7 is further compressed, and the metal rubber body 6 begins the energy dissipation buffering process. The above process can be determined according to the actual working conditions, including the steel strand configuration, connection method, metal rubber density, and suitable cross-section; this device adopts a two-stage protection method of buffering and constraint, and through the coordinated work of the metal rubber body 6, the loose metal rubber block 7, and the steel strand 5-1, it realizes a two-stage graded response process under seismic action, specifically:

[0053] First: Buffering stage. In this stage, the metal rubber plays a leading role. Specifically, the metal rubber body 6 has variable stiffness characteristics. Through its elastic deformation and dry friction energy dissipation, it reduces the impact force at the beam end. After contact, the loose metal rubber block 7 provides initial buffering. If the displacement continues, the metal rubber body 6 provides a second level of buffering.

[0054] Second: Constraint stage. In this stage, the steel strands play a leading role. Specifically, when the displacement exceeds the set threshold, steel strand 5-1 begins to be under tension, providing strong tensile constraints. Steel strand 5-1 is a 1860 grade low-relaxation prestressed steel strand with high strength and durability, ensuring the reliable function of preventing beam fall.

[0055] Specific Implementation Method Two: Combining Figures 1 to 12 The following describes a specific embodiment, which is a further limitation of the first embodiment. In this specific embodiment, the pier anchor fastener 1 is used to fix the pier 9, and the specific technical solution is as follows: The pier anchor fastener 1 includes a pier fixing plate 1-1 and a pier ear plate 1-2; two pier ear plates 1-2 are fixedly connected to the side wall of the pier fixing plate 1-1, and the pier ear plates 1-2 are provided with hinge holes. The pier fixing plate 1-1 is provided with anchor bolt fixing holes 1-3, and the pier fixing plate 1-1 is used to fix the pier to the side wall of the pier 9 by anchor bolts.

[0056] In this specific embodiment, the anchor bolt fixing hole 1-3 of the pier fixing plate 1-1 is used to pass through the anchor bolt to fix the pier fixing plate 1-1 on the side wall of the pier 9, while the pier ear plate 1-2 is used to be hinged to the connecting support body 2.

[0057] Specific implementation method three: Combining Figures 1 to 12The following is an illustration of this specific embodiment, which is a further limitation of embodiment one or two. In this specific embodiment, the connecting support body 2 is used to be hinged to the pier anchor fixing member 1, and the specific technical solution is as follows: The connecting support body 2 includes a connecting support plate 2-1 and a connecting ear plate 2-2; two connecting ear plates 2-2 are fixedly connected to the side wall of the connecting support plate 2-1, and the connecting ear plates 2-2 are provided with hinge holes.

[0058] In this specific embodiment, the connecting ear plate 2-2 and the pier ear plate 1-2 are hinged together by a hinge shaft, which facilitates the hinged connection between the connecting support body 2 and the pier anchor fixing member 1.

[0059] Specific implementation method four: Combination Figures 1 to 12 The illustration shows this specific embodiment, which is a further limitation of embodiment one, two, or three. This specific embodiment uses a steel sleeve 3 to fix it to the bottom anchor 4 of the beam, so that the metal rubber performance component and the steel strand restraint component 5 work together. The specific technical solution adopted is as follows: The steel sleeve 3 includes a seamless steel pipe 3-1, a lower rib plate 3-2, a right steel plate 3-3, and a left steel plate 3-4; two lower rib plates 3-2 are fixedly connected to the upper end of the seamless steel pipe 3-1, a right steel plate 3-3 is welded to the right side wall of the seamless steel pipe 3-1, and the left side wall of the seamless steel pipe 3-1 is fixedly connected to the left steel plate 3-4 by bolts; a movable hole 3-31 is opened in the middle of the right steel plate 3-3.

[0060] In this specific embodiment, the right steel plate 3-3 is welded to the seamless steel pipe 3-1 using a seamless welding method. The movable hole 3-31 of the right steel plate 3-3 enables the movement of the steel strand constraint component 5. At the same time, the lower rib plate 3-2 and the upper rib plate 4-2 of the beam bottom anchor fastener 4 are fixedly connected by bolts, which enables the steel sleeve 3 to be connected to the beam bottom anchor fastener 4.

[0061] Specific Implementation Method Five: Combining Figures 1 to 12 The following is an illustration of this specific embodiment, which is a further limitation of specific embodiments one, two, three or four. In this specific embodiment, the bottom anchor fastener 4 is convenient to be fixed at the bottom of the box girder body 8. The specific technical solution adopted is as follows: the bottom anchor fastener 4 includes a bottom fixing plate 4-1 and an upper rib plate 4-2. Two upper rib plates 4-2 are fixedly connected to the bottom of the bottom fixing plate 4-1.

[0062] In this specific embodiment, the bottom fixing plate 4-1 is fixedly connected to the bottom of the box girder 8 by anchor bolts, while the upper rib plate 4-2 and the lower rib plate 3-2 are fixed by bolts to facilitate connection with the steel sleeve 3.

[0063] A secondary self-emergency anti-fall beam protection method for bridges is as follows: When the steel sleeve 3 moves horizontally away from the pier 9 along with the box girder 8, the metal rubber body 6 arranged on the limiting plate 5-3 comes into close contact with the loose metal rubber block 7, and the loose metal rubber block 7 begins to function; with continued lateral displacement, the loose metal rubber block 7 is further compressed, and the metal rubber body 6 begins to function; when the compression of the metal rubber body 6 and the loose metal rubber block 7 reaches its limit, the steel strand 5-1 functions, realizing a graded response under seismic action.

[0064] Buffering Stage - Role of Metal Rubber: The metal rubber body 6 reduces the impact force at the beam end through its elastic deformation and dry friction energy dissipation. After contact, the loose metal rubber block 7 provides initial buffering; if the displacement continues, the metal rubber body 6 provides a second level of buffering.

[0065] Constraint Stage - Steel Strand Function: When the displacement exceeds the set threshold, the steel strand 5-1 begins to be under tension, providing strong tensile constraint.

[0066] The usage process of this specific implementation method:

[0067] 1. Normal use stage: The device does not participate in the work, the box girder 8 can freely expand and contract, and the metal rubber body 6, loose metal rubber block 7 and steel strand 5-1 are in a non-stressed state.

[0068] 2. Level 1 protection activation: The box girder 8 begins to move laterally, causing the steel sleeve 3 to move; the loose metal rubber block 7 comes into contact with the metal rubber body 6, and the loose metal rubber block 7 deforms, starting to buffer and dissipate energy.

[0069] 3. Secondary protection activation: The box girder 8 continues to move laterally, the loose metal rubber block 7 is further compressed, and the metal rubber body 6 begins to buffer and dissipate energy.

[0070] 4. Level 3 protection is activated. At this level, the displacement continues to increase. When the displacement continues to increase, the loose metal rubber block 7 and the metal rubber body 6 can no longer be compressed. The steel strand 5-1 begins to be under tension, providing rigid constraints to prevent the beam from falling.

[0071] The installation process of this specific embodiment is as follows: the device is installed between the box girder 8 and the pier 9. The height of the upper rib plate 4-2 connected to the bottom of the beam is determined. The position of the central axis of the steel strand 5-1 in the length direction is matched with the height of the bottom side of the box girder 8. After determining the height of the upper rib plate 4-2 with the corresponding thickness, the top side of the steel sleeve 3 is connected to the bottom fixing plate 4-1 of the beam by bolts, and the other end is connected to the outer wall of the pier 9 by the pier anchor fixing part 1.

[0072] In this specific embodiment, the device is installed as follows:

[0073] (1) Anchoring: Accurately position the pier anchor fixing part 1 and the beam bottom anchor fixing part 4, adjust them to the design elevation and position, and fix them after ensuring that the anchor bolts are vertical.

[0074] (2) Lifting and positioning: Lift the main body of the device as a whole, and align the tail connector with the anchor support.

[0075] (3) Connection and fixing: Install locking device to ensure reliable connection; check whether the steel strand 5-1 is in a free state without twisting or crossing.

[0076] (4) Inspection and debugging: After installation, check whether the device can slide without jamming within the designed free displacement range, and remove all transportation fixing devices.

[0077] The basic parameters in this specific embodiment are shown in Table 1-1. Different models of devices can be selected according to the actual bridge type and span. After determining the device model, in order to ensure that the device functions properly after installation, the bridge should be designed for anchorage according to the anchorage standard value. The specific requirements are: (1) the concrete substrate should be verified; (2) the tensile and shear strength of the connecting plate between the beam pier and the bottom of the beam should be verified; (3) the anchorage should not damage the internal steel reinforcement of the beam. In Table 1-1, each bundle of steel strands is 1860 grade Ф15.2 low relaxation prestressed steel strand.

[0078] Table 1-1 Basic Parameters of Anti-Beam Falling Device

[0079]

[0080] Example:

[0081] This embodiment takes a 20m small box girder as an example, and the self-weight of a single box girder is about 79t.

[0082] Then design seismic action:

[0083]

[0084] Therefore, each cable bears the design seismic load:

[0085]

[0086] By referring to the number of steel strand bundles in the anti-fall beam parameter table, the QXHRT-Ⅰ type anti-fall beam device can be selected.

[0087] The anchoring design in this embodiment is as follows:

[0088] I. Beam Bottom Anchorage Design:

[0089] To ensure that the connection area between the beam and the pier does not fail when the anti-falling beam device functions, calculations are required for the beam bottom anchorage zone and the pier anchorage zone. The design and calculations are performed with reference to the standards "Code for Design of Strengthening Concrete Structures" (GB50367-2013) and "Technical Specification for Post-Anchorage of Concrete Structures" (JGJ 145-2013). The following are the key calculation procedures and control points based on the technical specifications for post-anchorage of concrete structures:

[0090] In this embodiment, an expanded-base anchor bolt will be used for anchoring. The selected bolt is MS20 / 35×250, and the corresponding parameters are as follows:

[0091] Effective anchorage depth =250mm;

[0092] Drilling depth =265mm;

[0093] Drilling diameter =35mm;

[0094] Tensile design load =86.9KN;

[0095] Shear design load =123.1KN.

[0096] This embodiment proposes to use a group of anchors for connection, and the corresponding parameters are as follows:

[0097] Minimum margin ;

[0098] Critical margin ;

[0099] Minimum spacing of anchor groups ;

[0100] Critical Spacing ;

[0101] To ensure that the connection area between the beam and the pier does not fail when the anti-falling beam device functions, calculations are required for the beam bottom anchorage zone and the pier anchorage zone. The design and calculations are performed with reference to the standards "Code for Design of Strengthening Concrete Structures" (GB50367-2013) and "Technical Specification for Post-Anchorage of Concrete Structures" (JGJ 145-2013). The following are the key calculation procedures and control points based on the technical specifications for post-anchorage of concrete structures:

[0102] In this embodiment, an expanded-base anchor bolt will be used for anchoring. The selected bolt is MS20 / 35×250, and the corresponding parameters are as follows:

[0103] Effective anchorage depth =250mm;

[0104] Drilling depth =265mm;

[0105] Drilling diameter =35mm;

[0106] Tensile design load =86.9KN;

[0107] Shear design load =123.1KN.

[0108] This embodiment proposes to use a group of anchors for connection, and the corresponding parameters are as follows:

[0109] Minimum margin ;

[0110] Critical margin ;

[0111] Minimum spacing of anchor groups ;

[0112] Critical Spacing ;

[0113] The formula for calculating the design tensile force of a single anchor bolt in similar standards is as follows:

[0114] (1)

[0115] In the formula: —Design value of tensile force that the anchor bolt can withstand;

[0116] —Number of anchors in the group;

[0117] —Total tensile design value;

[0118] —Coefficient of uneven stress distribution on anchor bolts;

[0119] The formula for calculating the design shear force borne by a single anchor bolt in similar standards is as follows:

[0120] (2)

[0121] In the formula: —The maximum design shear force that the anchor bolt can withstand;

[0122] —Number of anchors in the group;

[0123] —Total shear force design value;

[0124] In this embodiment, the maximum seismic design force is used as the total shear force design value. Six bolts are planned for placement. The design tensile force borne by a single anchor bolt is as follows:

[0125]

[0126] The anchorage selected in this embodiment meets the following requirements: To ensure the safety, reliability, and durability of the anchorage area and prevent the failure of the entire anchorage system due to brittle fracture of the concrete substrate, the concrete substrate of the anchorage area should be verified. According to the "Code for Design of Strengthening Concrete Structures" (GB50367-2013), the bearing capacity verification of concrete should consider three failure modes: conical failure of concrete under tension, shear failure of concrete edges, and shear-pry failure.

[0127] (1.1) Edge shear failure check:

[0128] When anchor bolt groups are positioned close to the edge of a structural member and bear shear forces perpendicular to the edge, the shear force is primarily transferred to the concrete through the anchor bolts closest to the edge. Excessive shear force can cause a semi-conical or wedge-shaped concrete block to form at the member edge, leading to splitting or spalling. Referring to formula 16.3.6 in the "Code for Design of Strengthening Concrete Structures" (GB50367-2013), shear failure at the concrete edge is as follows... Figure 13 As shown:

[0129] (3)

[0130] (4)

[0131] In the formula: —Design value of shear bearing capacity of the concrete substrate for anchor bolt connections;

[0132] —Influence coefficient of edge distance ratio on shear bearing capacity;

[0133] —Influence coefficient of edge-to-thickness ratio on shear bearing capacity;

[0134] —The influence coefficient of the angle between the shear force and the axis perpendicular to the free side on the shear bearing capacity;

[0135] —Influence coefficient of load eccentricity on shear bearing capacity;

[0136] —Influence coefficient of reinforcement in the anchorage zone on shear capacity;

[0137] —Influence coefficient of anchor bolt edge distance and spacing on the shear bearing capacity of anchor bolts.

[0138] According to relevant regulations We set it to 1, since we don't consider the effect of eccentricity. The value is set to 1 because the reinforcement details in the anchorage zone are unclear. Taking a conservative value of 1, the calculation process for other relevant parameters is as follows:

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145] The calculation for shear failure at the concrete edge passed and meets the requirements.

[0146] (1.2) Shearing and prying verification:

[0147] Shear-pry failure is essentially a complex stress failure. The failure process involves the anchor bolt, under tensile force, strongly compressing the concrete in front of it at its root or the top of its expansion cone, creating a localized high-pressure stress zone. This, in turn, triggers a shallow but steep oblique fracture surface within the concrete, much like a pry bar. However, the code, when formulating the verification method, does not directly calculate the complex localized concrete bearing stress. Instead, it indirectly limits the design value of the anchor bolt steel's tensile bearing capacity through a test-based reduction factor, thus safely and easily covering this failure risk dominated by localized compression.

[0148] According to the "Code for Design of Strengthening Concrete Structures" (GB50367-2013), shear failure calculations are exempted when the selection and construction of anchor bolts meet specific requirements. This is because shear failure mainly occurs with short, thick expansion anchor bolts, those with thick anchor plates, or those with poor displacement control performance. Therefore, the code excludes the types of anchor bolts most prone to shear failure through mandatory clauses (such as Clauses 16.3.1, 16.4.3, and 16.4.4), and strictly regulates the embedment depth and spacing of selected mechanical and adhesive anchor bolts. Meeting these construction requirements means that the anchor bolts have sufficient embedment depth and a reasonable arrangement, guiding their stress mode towards deeper, more ductile concrete cone failure or anchor bolt steel yielding, rather than shallow brittle shear failure. According to the code, shear failure calculations are exempted in this case; only the construction requirements need to be met.

[0149] II. Pier Anchorage Design:

[0150] This embodiment proposes to use rebar anchoring technology, selecting four 25mm diameter HRB400 grade hot-rolled ribbed steel bars with a tensile strength design value of [missing value]. =295N / mm 2 Assuming Grade A adhesive is used, its design bond shear strength is... =4.5N / mm 2 .

[0151] In this embodiment, the formula for calculating the design tensile force of a single anchor bolt in similar specifications is as follows:

[0152] (5)

[0153] In the formula: —Design value of tensile force that the anchor bolt can withstand;

[0154] —Number of steel bars;

[0155] —Total tensile design value;

[0156] Using the maximum seismic design force as the total tensile design value, and assuming 4 reinforcing bars are to be installed, the tensile design value of a single reinforcing bar is:

[0157]

[0158] III. Rebar Installation Verification:

[0159] 3.1 Anchorage depth verification: Refer to formula 15.2.2-1 in the "Code for Design of Strengthening Concrete Structures" (GB50367-2013):

[0160] (6)

[0161] Assuming a 30mm concrete cover and 6mm stirrup diameter, according to relevant specifications... If we take 1.05, the calculation process is as follows:

[0162]

[0163] (7)

[0164] According to relevant regulations , , The calculation process is as follows:

[0165]

[0166] (8)

[0167] According to relevant regulations The calculation process is as follows:

[0168]

[0169] The design value for anchorage depth is 470mm.

[0170] 3.2 Construction Requirements:

[0171] Minimum spacing requirement: ;

[0172] Minimum margin requirement: ;

[0173] Minimum anchorage length requirement:

[0174] ;

[0175] Minimum concrete thickness requirement:

[0176] .

[0177] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0178] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A secondary self-emergency anti-falling beam device for bridges, characterized in that: The device includes a pier anchor (1), a connecting support body (2), a steel sleeve (3), a beam bottom anchor (4), a steel strand restraint assembly (5), and a metal rubber performance assembly. The pier anchor (1) is fixedly connected to the pier (9) by anchor bolts. The pier anchor (1) is hinged to the connecting support body (2) by a hinge shaft. The steel strand restraint assembly (5) is fixedly connected to the outer wall of the connecting support body (2). The beam bottom anchor (4) is fixedly connected to the bottom of the box girder (8) by anchor bolts. The steel sleeve (3) is fixedly connected to the beam bottom anchor (4) by bolts. The metal rubber performance assembly is provided inside the steel sleeve (3). The steel strand restraint assembly (5) passes through the inside of the steel sleeve (3). The steel strand restraint assembly (5) and the metal rubber performance assembly cooperate to form a buffer-restraint seismic device. The metal rubber performance assembly includes... The assembly includes a metal rubber body (6) and a loose metal rubber block (7). The loose metal rubber block (7) is matched with the metal rubber body (6). The loose metal rubber block (7) is set inside the steel sleeve (3). The metal rubber body (6) is fixedly connected to the limiting plate (5-3) of the steel strand constraint assembly (5). When the steel sleeve (3) moves horizontally away from the pier (9) along with the box girder (8), the metal rubber body (6) arranged on the limiting plate (5-3) is in close contact with the loose metal rubber block (7). The loose metal rubber block (7) is in a state of buffering and energy dissipation. As the lateral displacement continues, the loose metal rubber block (7) is further compressed, and the metal rubber body (6) is in a state of buffering and energy dissipation. When the compression of the metal rubber body (6) and the loose metal rubber block (7) reaches its limit, the steel strand constraint assembly (5) is in a state of tension.

2. The secondary self-emergency anti-falling beam device for bridges according to claim 1, characterized in that: The pier anchor fixing component (1) includes a pier fixing plate (1-1) and a pier ear plate (1-2); two pier ear plates (1-2) are fixedly connected to the side wall of the pier fixing plate (1-1), the pier ear plates (1-2) are provided with hinge holes, and the pier fixing plate (1-1) is provided with anchor bolt fixing holes (1-3).

3. The secondary self-emergency anti-falling beam device for bridges according to claim 1, characterized in that: The connecting support body (2) includes a connecting support plate (2-1) and a connecting ear plate (2-2); two connecting ear plates (2-2) are fixedly connected to the side wall of the connecting support plate (2-1), and hinge holes are provided on the connecting ear plates (2-2).

4. A secondary self-emergency anti-falling beam device for bridges according to claim 1, characterized in that: The steel sleeve (3) includes a seamless steel pipe (3-1), a lower rib plate (3-2), a right steel plate (3-3), and a left steel plate (3-4). The upper end of the seamless steel pipe (3-1) is fixedly connected to two lower rib plates (3-2), the right steel plate (3-3) is welded to the right side wall of the seamless steel pipe (3-1), and the left side wall of the seamless steel pipe (3-1) is fixedly connected to the left steel plate (3-4) by bolts.

5. A secondary self-emergency anti-falling beam device for bridges according to claim 4, characterized in that: The right steel plate (3-3) has a movable hole (3-31) in the middle.

6. A secondary self-emergency anti-falling beam device for bridges according to claim 1, characterized in that: The beam bottom anchor fastener (4) includes a beam bottom fixing plate (4-1) and an upper rib plate (4-2). The bottom of the beam bottom fixing plate (4-1) is fixedly connected to two upper rib plates (4-2).

7. A secondary self-emergency anti-falling beam device for bridges according to claim 1, characterized in that: The steel strand constraint assembly (5) includes a steel strand (5-1), a right anchor head (5-2), a limiting plate (5-3), and a left anchor head (5-4). The right end of the steel strand (5-1) is fixedly connected to the right anchor head (5-2), and the left end of the steel strand (5-1) is fixedly connected to the left anchor head (5-4). The limiting plate (5-3) is fixedly connected to the right side wall of the left anchor head (5-4), and the limiting plate (5-3) is fixedly connected to the steel strand (5-1).

8. A method for secondary self-emergency anti-falling beam protection for bridges, implemented using the secondary self-emergency anti-falling beam device for bridges as described in claims 1, 2, 3, 4, 5, 6, or 7, characterized in that: The specific steps for secondary self-emergency beam-fall protection are as follows: Step 1: Normal use process: The secondary self-emergency anti-fall beam device does not participate in the work, the box girder (8) expands and contracts freely, and the metal rubber body (6), loose metal rubber block (7) and steel strand (5-1) are in a non-stressed state; Step 2: Level 1 protection activation process: The box girder (8) begins to move laterally, which drives the steel sleeve (3) to move; the loose metal rubber block (7) comes into contact with the metal rubber body (6), the loose metal rubber block (7) deforms, and begins to buffer and dissipate energy; Step 3: Secondary protection activation process: The box girder (8) continues to move laterally, the loose metal rubber block (7) is further compressed, and the metal rubber body (6) begins to buffer and dissipate energy; Step 4: Level 3 protection activation process: If the displacement continues to increase, the loose metal rubber block (7) and the metal rubber body (6) cannot be further compressed, and the steel strand (5-1) begins to be stretched, providing rigid constraints to prevent the beam from falling.

9. A secondary self-emergency anti-fall beam protection method for bridges according to claim 8, characterized in that: The secondary self-emergency anti-fall beam device is installed between the box girder (8) and the pier (9). The height of the upper rib plate (4-2) connected to the bottom of the beam is determined. The position of the center axis of the steel strand (5-1) in the length direction is matched with the height of the bottom side of the box girder (8). After determining the height of the upper rib plate (4-2) of the corresponding thickness, the top side of the steel sleeve (3) is connected to the bottom fixing plate (4-1) of the beam by bolts, and the other end is connected to the outer wall of the pier (9) by the pier anchor fixing part (1).

Images