Bridge closure section prestress construction method

Abstract

The invention discloses a bridge closure section prestress construction method, and relates to the technical field of bridge closure section prestress construction.The bridge closure section prestress construction method comprises the steps that profile steel connecting structures are arranged at the two ends of a bridge closure section to serve as temporary connecting rigid supports; first stiff frameworks are arranged at the bottoms of the adjacent beam sections and the junctions of the top plates and the web plates for external supporting; the first temporary prestressing tendons are tensioned to lock beam bodies at the two ends of the bridge closure section; concrete of the bridge closure section is poured; and the temporary prestressing tendons are removed, the prestressed cables in the corresponding stages are tensioned, and prestressing construction of the bridge closure section is completed. Due to the adoption of the measures such as the profile steel connecting structure, the first stiff framework and the temporary prestressing tendons, the stability of the beam body in the construction process is improved, excessive deformation or displacement of the beam body is prevented, the concrete pouring quality is ensured, the stress loss in the tensioning process of the prestressing tendons is reduced, and the construction safety and reliability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of prestressed construction for bridge closure segments, and particularly to a prestressed construction method for bridge closure segments. Background Art

[0002] The prestressed construction technology for bridge closure segments plays an important role in the field of bridge construction. With the continuous development of bridge engineering, the requirements for the construction quality and safety of bridge closure segments are also getting higher and higher.

[0003] At present, the prestressed construction for bridge closure segments mainly adopts the on-site tensioning method. This method requires the installation of temporary anchorages at both ends of the bridge closure segment, and the prestressing tendons are stretched by hydraulic jacks and then anchored to the bridge structure to apply prestress.

[0004] However, on-site tensioning construction is easily interfered by environmental factors, with limited operation space, difficult operation for construction workers, many potential safety hazards, and it is difficult to control the construction accuracy. The anchorage position of the prestressing tendons is prone to deviation, resulting in stress loss. Summary of the Invention

[0005] The main object of the present invention is to propose a prestressed construction method for bridge closure segments, aiming to solve the technical problems of deviation of the anchorage position of prestressing tendons and stress loss in the prior art, thereby improving the overall quality and reliability of the construction of bridge closure segments.

[0006] To achieve the above object, the prestressed construction method for bridge closure segments proposed by the present invention includes:

[0007] Install a profiled steel connection structure at both ends of the bridge closure segment as a temporary connection rigid support;

[0008] Install a first stiffening skeleton for external support at the bottom of the adjacent beam segments of the bridge closure segment and at the junction of the top plate and the web;

[0009] Tension a first temporary prestressing tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure segment;

[0010] Pour the concrete of the bridge closure segment;

[0011] When the concrete of the bridge closure segment reaches the preset strength, release the temporary prestressing tendon to form a single-cantilever simply supported beam, and tension the prestressing cables at the corresponding stage to complete the prestressed construction of the bridge closure segment.

[0012] In an embodiment, before the step of pouring the concrete of the bridge closure segment, the prestressed construction method for bridge closure segments further includes:

[0013] Weld and fix the stiffening skeleton at one end of the bridge closure segment;

[0014] When the temperature is the lowest on the day of pouring concrete for the bridge closure segment, tension and then weld and fix the stiffening skeleton at the other end of the bridge closure segment.

[0015] In one embodiment, the step of pouring concrete for the bridge closure segment includes:

[0016] Pour the concrete for the bridge closure segment when the closure temperature is 10°C - 20°C.

[0017] In one embodiment, the preset strength is 100% of the designed strength of the concrete.

[0018] In one embodiment, the preset tensile force is 300 MPa.

[0019] In one embodiment, before the step of pouring concrete for the bridge closure segment, the prestressed construction method for the bridge closure segment further includes:

[0020] Use the hanging basket and hanger system for the construction of the pouring formwork. The outer formwork and bottom formwork of the pouring formwork adopt the hanging basket formwork, and the inner formwork of the pouring formwork adopts the steel pipe scaffold and bamboo plywood formwork.

[0021] In one embodiment, the step of setting the profiled steel connection structure at both ends of the bridge closure segment as the temporary connection rigid support includes:

[0022] Embed steel plates at the intersection of the top plate and web of the adjacent beam segments of the bridge closure segment to form the second stiffening skeleton;

[0023] Tension the second temporary prestressed tendon so that the second temporary prestressed tendon and the second stiffening skeleton are locked together;

[0024] Connect channel steels to the second stiffening skeleton to form the profiled steel connection structure;

[0025] Use the profiled steel connection structure as the temporary connection rigid support at both ends of the bridge closure segment.

[0026] In one embodiment, before the step of setting the profiled steel connection structure at both ends of the bridge closure segment as the temporary connection rigid support, the prestressed construction method for the bridge closure segment includes:

[0027] Detect and calibrate the plane position and elevation of the bridge closure segment.

[0028] In one embodiment, the step of tensioning the first temporary prestressed tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure segment includes:

[0029] Tension the first temporary prestressed tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure segment, and keep the elongation amounts at both ends of the bridge closure segment substantially the same, and measure the retraction amount of the first temporary prestressed tendon during the process of removing the jack.

[0030] In one embodiment, before the step of pouring the concrete of the bridge closure segment, the prestressed construction method for the bridge closure segment includes:

[0031] Add an expansion agent to the concrete.

[0032] The technical solution of the present invention effectively solves the technical problems of large environmental interference, limited operation space, and difficult construction accuracy control existing in traditional construction by setting a profiled steel connection structure as a temporary connection rigid support at both ends of the bridge closure segment, setting a first stiffening skeleton for external support at the bottom of the adjacent beam segments and at the junction of the top plate and the web, and tensioning the first temporary prestressed tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure segment. On this basis, pour the concrete of the bridge closure segment. When the concrete reaches the preset strength, release the temporary prestressed tendon to form a single-cantilever simply supported beam, and tension the prestressed cables at the corresponding stages to complete the prestressed construction of the bridge closure segment. Due to the adoption of measures such as the profiled steel connection structure, the first stiffening skeleton, and the temporary prestressed tendon, the stability of the beam body during the construction process is improved, the beam body is prevented from having excessive deformation or displacement, the quality of the concrete pouring is ensured, the stress loss during the tensioning process of the prestressed tendons is reduced, and the construction safety and reliability are improved. Brief Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0034] Figure 1 It is a schematic flow chart of an embodiment of the prestressed construction method for the bridge closure segment provided by the present invention;

[0035] Figure 2 It is a schematic flow chart of another embodiment of the prestressed construction method for the bridge closure segment provided by the present invention;

[0036] Figure 3 For Figure 1 It is a detailed schematic flow chart of an embodiment of step S10 in

[0037] The realization of the object of the present invention, the functional characteristics and advantages will be further described with reference to the embodiments and the drawings. Detailed implementation manners

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0040] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0041] Currently, the prestressed construction of the bridge closure section mainly adopts the on-site tensioning method. This method requires the installation of temporary anchors at both ends of the bridge closure section, and the prestressed tendons are stretched by hydraulic jacks and then anchored on the bridge structure to apply prestress.

[0042] However, on-site tensioning construction is easily interfered by environmental factors, with limited operation space, great difficulty for construction workers to operate, many potential safety hazards, and it is difficult to control the construction accuracy. The anchoring position of the prestressed tendons is prone to deviation, resulting in stress loss.

[0043] To solve this technical problem, the present invention proposes a prestressed construction method for the bridge closure section.

[0044] Please refer to Figure 1 , in an embodiment of the present invention, the prestressed construction method for the bridge closure section includes the following steps:

[0045] Step S10: Set steel connection structures at both ends of the bridge closure segment as temporary connection rigid supports;

[0046] Step S20: Set the first stiffening skeleton for external support at the bottom of the adjacent beam segments of the bridge closure segment and at the junctions of the top plate and web;

[0047] Step S30: Tension the first temporary prestressed tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure segment;

[0048] Step S40: Pour the concrete of the bridge closure segment;

[0049] Step S50: When the concrete of the bridge closure segment reaches the preset strength, release the temporary prestressed tendon to form a single-cantilever simply supported beam, and tension the prestressed cables at the corresponding stages to complete the prestressing construction of the bridge closure segment.

[0050] Specifically, in step S10, by setting the steel connection structures at both ends of the bridge closure segment, it can provide temporary rigid supports for subsequent construction. The steel connection structures have good strength and stability, can effectively bear the loads during the construction of the bridge closure segment, prevent the beam body from excessive deformation or displacement, and thus create favorable conditions for subsequent construction.

[0051] In step S20, by setting the first stiffening skeleton at the key positions of the adjacent beam segments of the bridge closure segment, it can further strengthen the support and restraint effects on the beam body. The first stiffening skeleton is arranged at the bottom of the beam body and at the junctions of the top plate and web, can effectively limit the deformation and displacement of the beam body, improve the overall stiffness and stability of the bridge closure segment, and provide reliable external support for subsequent construction.

[0052] In step S30, by pre-tensioning the first temporary prestressed tendon, it can form an effective locking effect between the beam bodies at both ends of the bridge closure segment, ensure that the beam body remains stable during construction, without relative displacement or dislocation problems, and create favorable conditions for pouring concrete.

[0053] In step S40, after completing the foregoing preparatory work, the pouring construction of the concrete of the bridge closure segment can be carried out. During the concrete pouring process, the steel connection structures, the first stiffening skeleton and the first temporary prestressed tendon work together to ensure that the beam body remains stable, without deformation or displacement, and guarantee the quality of concrete pouring.

[0054] In step S50, after the concrete reaches the preset strength, the first temporary prestressed tendon can be released, so that the closure segment of the bridge forms a single-cantilever simply supported beam. At this time, the closure segment of the bridge already has a certain self-bearing capacity and can withstand the bending moment and shear force generated by its own weight. On this basis, the prestressed cables are tensioned in stages to introduce permanent prestress, compensate for the shrinkage and creep effects of the concrete, improve the bearing capacity and service performance of the closure segment of the bridge, and finally complete the prestressing construction.

[0055] For ease of understanding, a specific embodiment is shown here:

[0056] According to the above steps, prestressing construction is carried out on the closure segment of the bridge: First, a temporary connection structure welded by steel section members is set at both ends of the closure segment of the bridge, and a stable and reliable support system is formed through high-strength bolts and welding. Then, multiple I-beams are longitudinally and transversely arranged at the bottom of the adjacent beam segments, and L-shaped steel is arranged at the junction of the top plate and the web to form the first stiffening skeleton for external support of the beam body. Next, the first temporary prestressed tendon is threaded into the temporary connection structure and tensioned in stages to the design tension by a jack to effectively lock the beam body. On this basis, pumped concrete is used to pour the closure segment of the bridge in layers. After the concrete strength reaches C50, the temporary prestress is released, the temporary connection structure and the stiffening skeleton are removed, and the permanent prestressed cables are tensioned to apply prestress to the closure segment of the bridge, completing the prestressing construction process.

[0057] In the technical solution provided by the present invention, by setting a steel section connection structure at both ends of the closure segment of the bridge as a temporary connection rigid support, and setting the first stiffening skeleton at the bottom of the adjacent beam segments and at the junction of the top plate and the web for external support, and tensioning the first temporary prestressed tendon with a preset tension to lock the beam bodies at both ends of the closure segment of the bridge, the technical problems of large environmental interference, limited operation space, and difficult construction accuracy control existing in traditional construction are effectively solved. On this basis, the concrete of the closure segment of the bridge is poured. When the concrete reaches the preset strength, the temporary prestressed tendon is released to form a single-cantilever simply supported beam, and the prestressed cables at the corresponding stage are tensioned to complete the prestressing construction of the closure segment of the bridge. Due to the adoption of measures such as the steel section connection structure, the first stiffening skeleton, and the temporary prestressed tendon, the stability of the beam body during the construction process is improved, the beam body is prevented from excessive deformation or displacement, the quality of concrete pouring is ensured, the stress loss during the tensioning process of the prestressed tendons is reduced, and the construction safety and reliability are improved.

[0058] Please continue to refer to Figure 1 and refer to Figure 2 In the embodiment of the present invention, before the step of pouring the concrete of the closure segment of the bridge, the prestressing construction method for the closure segment of the bridge further includes:

[0059] Step T10: Weld and fix the stiffening skeleton at one end of the bridge closure segment.

[0060] Step T20: When the temperature is the lowest on the day of pouring concrete for the bridge closure segment, tension and then weld and fix the stiffening skeleton at the other end of the bridge closure segment.

[0061] Specifically, in step T10, by welding and fixing the stiffening skeleton at one end of the bridge closure segment, the structural stability of this end can be ensured, providing a firm support point for subsequent construction. Welding, as a reliable connection method, can ensure a strong bond between the stiffening skeleton and the main structure of the bridge, which is crucial for subsequent construction safety and the stability of the overall structure.

[0062] In step T20, choosing to carry out the tensioning, welding and fixing of the stiffening skeleton at the other end when the temperature is the lowest is based on the principle of thermal expansion and contraction of materials. Tensioning at the lowest temperature can ensure that the tensile force will not exceed the design limit when the temperature rises subsequently, thus avoiding excessive structural stress caused by temperature changes. This practice optimizes the stress distribution of the entire structure and reduces the potential risks caused by temperature changes.

[0063] In the embodiment of the present invention, the step of pouring concrete for the bridge closure segment includes:

[0064] Step S41: Pour concrete for the bridge closure segment when the closure temperature is 10°C - 20°C.

[0065] Specifically, in step S41, choosing to pour concrete for the bridge closure segment under the condition that the closure temperature is 10°C - 20°C can ensure the quality and uniformity of the concrete setting and hardening process. Within this temperature range, the hydration heat reaction rate of the concrete is moderate, which will not affect the development of concrete strength due to too low temperature, nor cause too large a temperature gradient inside the concrete due to too high temperature, generating harmful temperature stress. By controlling the closure temperature, quality defects such as cracks, bleeding, and segregation of the concrete can be effectively avoided, ensuring the construction quality of the bridge closure segment.

[0066] During the pouring process, the method of pumping concrete is adopted to fill the concrete synchronously and evenly from both ends of the closure segment. The concrete mix ratio is specially designed to have good workability and fluidity, ensuring that it can fully fill the gaps in the steel bar skeleton and form a dense overall structure. The pouring process is carried out in a layered and block-by-block manner, with the pouring thickness of each layer of concrete controlled at 30 - 50 cm, and an internal vibrator is used for full vibration to promote the discharge of air bubbles inside the concrete and improve the density of the concrete.

[0067] After the initial setting of the concrete, the surface of the concrete is cured by means of sprinkling water or covering with plastic film, etc., to prevent the surface moisture from evaporating too quickly and causing shrinkage cracks. At the same time, according to the data collected by the sensors, the curing measures are adjusted to ensure that the temperature difference between the inside and outside of the concrete does not exceed the specified limit value. After 7 - 14 days of curing, when the concrete strength reaches the design requirements, the formwork and supports are removed, and the concrete pouring work of the bridge closure section is completed.

[0068] By pouring concrete under suitable temperature conditions and adopting curing measures, the construction quality of the concrete in the bridge closure section can be fundamentally guaranteed, avoiding problems such as concrete cracks and insufficient strength caused by temperature factors, and thus creating favorable conditions for the subsequent prestressing construction and improving the overall safety and durability of the bridge structure. This method overcomes the defect that the traditional on-site tensioning method is easily interfered by environmental factors. By optimizing the construction timing and technological process, the material performance is maximized, ensuring the reliability of construction accuracy and quality.

[0069] In the embodiment of the present invention, the preset strength is 100% of the design strength of the concrete.

[0070] Specifically, when the concrete strength reaches 100% of the design strength, its mechanical properties fully meet the design requirements and can reliably bear the huge tensile force and anchoring force generated during the tensioning of the prestressing tendons. The setting of this strength standard fully considers the particularity and complexity of the prestressing construction, providing a solid material foundation for ensuring construction safety and the overall performance of the bridge structure.

[0071] During the tensioning process, the synchronous jack is used for symmetric tensioning, with graded loading. Each level of load is maintained for 2 - 3 minutes, and a dynamometer is used to monitor the tension change of the prestressing tendons in real time to ensure that the tension force reaches the design value. After the tensioning is completed, the prestressing tendons are anchored in the anchorage area of the bridge structure, and measures such as grouting are adopted for anchorage protection to prevent the anchor fittings from loosening and rusting. Finally, according to the design requirements, the prestressing tendons are cut off and sealed at the ends, and the prestressing construction of the bridge closure section is completed.

[0072] By strictly controlling the strength of the concrete in the bridge closure section to ensure that it reaches 100% of the design strength, the safety and reliability of the prestressing construction can be fundamentally guaranteed. This approach overcomes the defects that the traditional on-site tensioning method is easily interfered by environmental factors and the construction accuracy is difficult to control. By optimizing the construction technology and quality control measures, the material performance is maximized, effectively avoiding problems such as the deviation of the anchorage position of the prestressing tendons and stress loss. At the same time, the reliable guarantee of the strength of the closure section concrete also provides a solid foundation for the long-term service performance and safety of the bridge structure.

[0073] In the embodiment of the present invention, the preset tension force is 300 MPa.

[0074] Specifically, a tensile stress level of 300 MPa can, while ensuring the strength safety reserve of the prestressed tendons, provide a sufficiently large compressive stress for the bridge closure section, effectively offset the tensile stress generated by the self-weight of the structure and external loads, and prevent cracks from appearing in the beam body. At the same time, this stress level is also coordinated with the yield strength of the prestressed tendons, ensuring that the prestressed tendons will not undergo permanent deformation or stress relaxation during the tensioning and anchoring processes within the elastic working range of the material, thereby guaranteeing the lasting effect of the prestress and the overall performance of the structure.

[0075] More specifically, in the construction preparation stage, first pass the prestressed tendons through the reserved duct holes at both ends of the closure section and anchor them at the ends. Then, install a dynamometer and a displacement sensor at both ends of the self-anchoring jack to monitor the changes in the tensile force and elongation in real time. Before the formal tensioning, conduct two trial pulls first to check the working state of the equipment and the elongation of the prestressed tendons, and adjust the tensioning parameters according to the test results.

[0076] During the formal tensioning, adopt a step-by-step loading method, with each step loading 50 kN and maintaining for 1 - 2 minutes for each step until the designed tensile force is reached. During the tensioning process, calculate the stress level of the prestressed tendons in real time by synchronizing the oil pressure and elongation of the jacks to ensure that it does not exceed the preset value of 300 MPa. If any abnormal situation is found, such as over-standard stress or insufficient elongation, immediately stop the tensioning, find out the reason and deal with it.

[0077] When the stress of the prestressed tendons stabilizes at 300 MPa, start the anchoring operation. Adopt a wedge-shaped clip anchor, and through multiple hammer blows, make the anchor wedge into the anchor backing plate to achieve a reliable connection between the prestressed tendons and the anchor. After the anchoring is completed, cut off the prestressed tendons from the jack using a stress-free cutting method, and use special tools for anchor head protection treatment to prevent the anchor from rusting and stress concentration.

[0078] By strictly controlling the tensile stress level of the prestressed tendons and maintaining it near the preset value of 300 MPa, the performance advantages of the prestressed materials can be maximally exerted, ensuring that the bridge closure section can maintain a good stress state and overall performance during long-term use. This refined construction control method effectively overcomes the defects of the traditional on-site tensioning method that is easily interfered by the environment and difficult to guarantee construction accuracy. By reasonably setting the prestress magnitude and coordinating the material strength and structural stress requirements, the safety, reliability, and durability of the prestress construction are ensured, laying a solid foundation for the long-term service of the bridge structure.

[0079] In the embodiment of the present invention, before the step of pouring the concrete of the bridge closure section, the prestressed construction method for the bridge closure section further includes:

[0080] Step E10: The casting formwork is constructed using a hanging basket and hanger system. The external formwork and bottom formwork of the casting formwork adopt hanging basket formwork, and the internal formwork of the casting formwork adopts steel pipe scaffolds and bamboo plywood formwork.

[0081] Specifically, in step E10, when constructing the casting formwork using a hanging basket and hanger system, the structural strength of the built part of the bridge can be fully utilized, reducing the dependence on ground and water supports, and improving the construction convenience and safety. The hanging basket formwork, as the external and bottom formwork, has the characteristics of light self-weight, large stiffness, convenient installation and disassembly, etc., and can effectively control the external dimensions and bottom linearity of the beam body, ensuring the quality of concrete casting. At the same time, using steel pipe scaffolds and bamboo plywood as the internal formwork can flexibly adapt to the internal structural form of the beam body, and provide sufficient formwork strength and stability through steel pipe supports, preventing deformation or displacement during the casting process. The reasonable combination of the internal and external formworks not only meets the special requirements of the bridge closure section construction, but also takes into account the construction efficiency and cost control.

[0082] More specifically, first, heavy hanging basket hangers are erected on both sides of the closure section of the beam. The steel truss structure is adopted, and stability is maintained through multi-point lifting and balancing weights. Profiled steel formwork is laid on the hanging basket hanger as the external and bottom formwork. The formwork size is prefabricated according to the beam section design, and the height covers the entire range of the closure section. The steel formwork adopts high-strength panels and profiled steel stiffeners, and is connected by high-strength bolts to form an integral and stable formwork system.

[0083] During the formwork installation process, measuring equipment such as laser rangefinders and total stations is used to monitor the position and verticality of the formwork in real time to ensure that it meets the design requirements. For dark positions and complex structural parts, lighting and remote video monitoring are adopted to timely discover and solve construction problems. At the same time, a release agent is applied to the formwork surface to prevent concrete adhesion, and a waterstop is set at the joint between the formwork and the already cast part to avoid slurry leakage and deformation.

[0084] Through the organic combination of the hanging basket hanger and the internal and external formwork systems, it not only meets the requirements of the bridge closure section construction for the formwork stiffness and strength, but also can flexibly cope with complex structural forms and construction conditions. This formwork construction method overcomes the defects of the large scaffold system and great environmental constraints in traditional in-situ construction, creating favorable conditions for subsequent steel bar binding, prestressed tendon layout and concrete casting, and improving the construction efficiency and quality control level. At the same time, the hanging basket hanger is reasonably used to share the load, reducing the disturbance to the surrounding environment.

[0085] Please continue to refer to Figure 1 and refer to Figure 3 In the embodiment of the present invention, the step of setting a profiled steel connection structure at both ends of the bridge closure section as a temporary connection rigid support includes:

[0086] Step S11: Embed steel plates at the intersection of the top plate and the web of the adjacent beam segments of the bridge closure segment to form a second stiffening framework.

[0087] Step S12: Tension the second temporary prestressing tendon so that the second temporary prestressing tendon and the second stiffening framework are locked together.

[0088] Step S13: Connect channel steels to the second stiffening framework to form the profiled steel connection structure.

[0089] Step S14: Use the profiled steel connection structure as the temporary connection rigid support at both ends of the bridge closure segment.

[0090] In the embodiment of the present invention, the step of setting a profiled steel connection structure at both ends of the bridge closure segment as a temporary connection rigid support includes:

[0091] Specifically, in step S11, by embedding steel plates at the intersection of the top plate and the web of the beam segment, a second stiffening framework is constructed, which provides a firm anchorage point for the prestressing tendon, enabling the tensile force to be evenly transmitted to the bridge structure, thereby improving the overall stability and load-bearing capacity of the structure.

[0092] In step S12, the second temporary prestressing tendon is tensioned to achieve a tight fit with the second stiffening framework, ensuring that the shape and dimensions of the structure remain stable during the construction process of the entire bridge closure segment, and effectively preventing deformation caused by uneven loading or environmental factors.

[0093] In step S13, by connecting channel steels to the second stiffening framework, a complete profiled steel connection structure is formed. This structure not only has high strength and good rigidity, but also can effectively disperse the stress concentration introduced by prestressing construction, enhancing the durability and reliability of the structure.

[0094] In step S14, the formed profiled steel connection structure is used as the temporary connection rigid support at both ends of the bridge closure segment, providing the necessary stability to support the important load-bearing tasks of the closure segment during construction and the initial use stage, and reducing the risks caused by construction errors or initial load changes.

[0095] In the embodiment of the present invention, before the step of setting a profiled steel connection structure at both ends of the bridge closure segment as a temporary connection rigid support, the prestressing construction method for the bridge closure segment includes:

[0096] Step P10: Detect and calibrate the plane position and elevation of the bridge closure segment.

[0097] Specifically, in step P10, by precisely detecting and calibrating the plane position and elevation of the bridge closure section, the deviation problem of the beam body caused by the construction errors or deformations in the previous stage can be timely detected and corrected, providing a reliable geometric positioning basis for the subsequent installation of the profiled steel connection structure and the prestress construction. The implementation of this step helps to improve the construction accuracy of the bridge closure section, reduce the additional stress caused by the deviation of the beam body, and thus ensure the mechanical properties and durability of the structure.

[0098] More specifically, first, a number of high-precision prisms are installed on the reference points at both ends of the bridge closure section. The total station is used to measure the angles and distances of the prisms from multiple directions to obtain the three-dimensional space coordinates of the closure section. At the same time, the GPS receiver is used to position the key points of the closure section, and centimeter-level position accuracy is obtained through differential technology. After sufficient measurement data is collected, it is imported into the computer for processing and analysis.

[0099] In the embodiment of the present invention, the step of tensioning the first temporary prestressed tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure section includes:

[0100] Step S31: Tension the first temporary prestressed tendon with a preset tensile force to lock the beam bodies at both ends of the bridge closure section, and keep the elongation amounts at both ends of the bridge closure section basically the same, and measure the retraction amount of the first temporary prestressed tendon during the process of jack retraction.

[0101] Specifically, in step S31, by applying a preset tensile force to the first temporary prestressed tendon, the relative positions of the beam bodies at both ends of the bridge closure section can be effectively locked, preventing the beam body from having longitudinal displacement or deflection during the subsequent construction process. At the same time, by precisely controlling the tensile force and elongation amount, it is ensured that the forces at both ends of the closure section are evenly distributed, avoiding additional stress and deformation caused by uneven prestress. Measuring the retraction amount of the prestressed tendon during the jack retraction process can timely master the prestress loss situation, providing a basis for the adjustment of the subsequent tensile force and ensuring the accuracy and reliability of the prestress construction.

[0102] More specifically, during the tensioning process, digital force gauges are installed at both ends of the jack to real-time monitor the magnitude of the tensile force, ensuring that it fluctuates within the allowable range. At the same time, high-precision displacement sensors are installed on the beam bodies at both ends of the closure section to measure the elongation amount of the beam body. By synchronizing the oil pressure and elongation amount of the jack, the tensioning process is dynamically controlled to ensure that the elongation amounts at both ends of the closure section are basically the same, with an error not exceeding 2 mm.

[0103] After the temporary prestressed tendons are tensioned in place, the hydraulic synchronous jack is used to retract the jack. While keeping the tensile force constant, the oil pressure of the jack is slowly released, so that the beam bodies at both ends of the closure segment gradually fit under the action of prestress. During the retraction process, the retraction amount of the first temporary prestressed tendon is measured by using the relative displacement between the jack travel meter and the steel strand punctuation, and the prestress loss value is calculated. When the retraction amount reaches the design allowable value, the retraction of the jack is stopped, and the steel strand is fixed by the anchor to complete the construction of the first temporary prestressed tendon.

[0104] By controlling the tensile force and elongation of the first temporary prestressed tendon and monitoring the retraction amount in real time, the defects that the traditional on-site tensioning method is easily interfered by the environment and it is difficult to ensure the construction accuracy can be effectively overcome, ensuring the reliable locking and stable stress of the beam bodies at both ends of the closure segment.

[0105] In the embodiment of the present invention, before the step of pouring the concrete of the bridge closure segment, the prestressed construction method of the bridge closure segment includes:

[0106] Step A10: Add an expansive agent to the concrete.

[0107] Specifically, in the step A10, by adding an expansive agent to the concrete, the volume change of the concrete during the hardening process can be effectively controlled, thereby reducing or eliminating the autogenous shrinkage of the concrete and improving the overall stability and durability of the concrete. The expansive agent generates a small amount of expansive pressure to compensate or over-compensate the autogenous shrinkage of the concrete, so that the concrete maintains a slightly expanded state during the hardening process, which helps to reduce the stress concentration inside the concrete, reduce the generation of cracks, and improve the compactness and crack resistance of the concrete. In addition, the use of the expansive agent also helps to improve the impermeability and frost resistance of the concrete, thereby enhancing the durability and safety of the structure.

[0108] More specifically, select suitable types and proportions of expansive agents. Usually, sulfoaluminate-based or calcium oxide-based expansive agents are selected. These expansive agents can generate a small amount of gas or expansive products during the hydration reaction process, thereby realizing the slight expansion of controlling the volume of the concrete. By adding an expansive agent to the concrete, the concrete of the bridge closure segment maintains good volume stability during the hardening process, effectively avoiding cracks and stress concentration caused by concrete shrinkage, and improving the overall safety and durability of the structure. In addition, the use of expansive concrete also improves the impermeability and frost resistance of the bridge closure segment, which is beneficial to improving the service life and durability of the bridge. By adding an expansive agent to optimize the performance of the concrete, not only the common stress loss and crack problems in traditional prestressed construction are solved, but also the construction quality and structural safety of the bridge closure segment are improved.

[0109] The above are only exemplary embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A prestressed construction method for a bridge closure section, characterized in that: The prestressed construction method for the bridge closure section comprises: A steel connection structure is provided at both ends of the bridge closure section as a temporary connection rigid support; A first rigid skeleton is arranged at the bottom of the adjacent beam sections of the bridge closure section and at the junction of the top plate and the web plate for external support; tensioning the first temporary prestressed tendon with a preset tensioning force to lock the two end beams of the closure section of the bridge; pouring concrete of the closure section of the bridge; When the concrete of the closing section of the bridge reaches a preset strength, the temporary prestressed tendons are released to form a single cantilever simply supported beam, and the prestressed cables of the corresponding stage are tensioned to complete the prestressed construction of the closing section of the bridge.

2. The prestressed construction method for the bridge closure section according to claim 1, characterized in that: Before the step of pouring concrete of the bridge closing section, the prestressed construction method of the bridge closing section further comprises: Welding and fixing the rigid frame at one end of the closure section of the bridge; When the temperature is lowest in the middle of the day when the concrete of the bridge closing section is poured, the rigid frame at the other end of the bridge closing section is tensioned and then welded to fix.

3. The prestressed construction method for the bridge closure section according to claim 1, characterized in that: The step of pouring concrete of the bridge closure section comprises: The concrete of the closing section of the bridge is poured when the closing temperature is 10°C-20°C.

4. The prestressed construction method for the bridge closure section according to claim 1, characterized in that: The preset strength is that the concrete reaches 100% of the design strength.

5. The prestressed construction method for the bridge closure section according to claim 1, characterized in that: The preset tension force is 300 MPa.

6. The prestressed construction method for the bridge closure section according to any one of claims 1 to 5, characterized in that: Before the step of pouring concrete of the bridge closing section, the prestressed construction method of the bridge closing section further comprises: A hanging basket hanger system is used for the construction of the casting formwork, wherein the outer formwork and the bottom formwork of the casting formwork adopt hanging basket formwork, and the inner formwork of the casting formwork adopts steel pipe scaffolding and bamboo plywood formwork.

7. The prestressed construction method for the bridge closure section according to any one of claims 1 to 5, characterized in that: The step of providing a steel connection structure at both ends of the bridge closure section as a temporary connection rigid support comprises: Embedding steel plates at the junction of the top plate and the web plate of the adjacent beam sections of the bridge closure section to form a second rigid skeleton; tensioning a second temporary prestressed tendon so that the second temporary prestressed tendon is locked together with the second rigid skeleton; Connecting channel steel to the second rigid skeleton to form the section steel connection structure; The steel connection structure is used as the temporary connection rigid support at both ends of the bridge closure section.

8. The prestressed construction method for the bridge closure section according to any one of claims 1 to 5, characterized in that: Before the step of arranging steel connection structures at both ends of the bridge closure section as temporary connection rigid supports, the prestressed construction method of the bridge closure section includes: The plane position and elevation of the closure section of the bridge are detected and calibrated.

9. The prestressed construction method for the bridge closure section according to any one of claims 1 to 5, characterized in that: The step of tensioning the first temporary prestressed tendon with a preset tensioning force to lock the two end beams of the bridge closure section comprises: The first temporary prestressed tendon is tensioned with a preset tensioning force to lock the two end beams of the bridge closure section, and the elongation at both ends of the bridge closure section is kept basically consistent, and the retraction of the first temporary prestressed tendon is measured during the top withdrawal process.

10. The prestressed construction method for the bridge closure section according to any one of claims 1 to 5, characterized in that: Before the step of pouring concrete of the bridge closing section, the prestressed construction method of the bridge closing section includes: An expansion agent is added to the concrete.

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