A 22m-level pre-tensioned broken-line prestressed double T-beam for bridge standardization

Abstract

The present invention relates to a standardized 22m-level pre-tensioned, folded-line prestressed double T-beam for bridges. The span of the double T-beam is no more than 22m. The double T-beam is an open section, including a top plate and two webs located below the top plate. Prestressed steel strands are arranged at the web positions, and the entire beam has a uniform cross-section, with cross-diaphragms only arranged at the beam ends, and no cross-diaphragms within the span. The double T-beam includes several beam types, all of which have the same top plate thickness. The web top width is a fixed value. According to different beam heights, the number of prestressed steel strands in the beam is adjusted to meet the requirements of different spans. The present invention has a simple structure and an open section, low material consumption, good economy, convenient construction, low construction difficulty, and good prefabrication quality. The web top width and top plate thickness are fixed values, and main beams of different beam heights can use the same template. Only the area below the web in the template needs to be filled. The modular and standardized main beam structure is conducive to industrial production, accelerates prefabrication speed, and reduces costs.

Description

Technical Field

[0001] The invention relates to the technical field of bridge structure design, in particular to a 22m-level pre-tensioned broken-line prestressed double T-beam used for bridge standardization. Background Art

[0002] In recent years, prefabricated, prestressed concrete beams with small and medium spans have been widely used in urban bridges due to their simple structure, well-defined loads, fast construction, low cost, and minimal impact on intersecting roads. Prefabricated, prestressed concrete hollow-core slabs (applicable for spans of 10-22 meters), T-beams (applicable for spans of 20-40 meters), and small box girders (applicable for spans of 25-40 meters) are all commonly used structural types for small and medium span bridges.

[0003] Hollow slabs and small box girders are closed sections, requiring core formwork during prefabrication. This places high demands on formwork construction techniques, and after prefabrication, the removal of the inner core formwork is difficult. Furthermore, the quality of the concrete pouring inside closed sections is difficult to control. Poor control of the core formwork can easily affect the quality of the beam and slab prefabrication, leading to numerous defects during the bridge's operation. During maintenance, inspectors struggle to reach the interior of the closed box, making maintenance and repairs difficult. External inspections of the bridge alone cannot reveal internal defects in the beams and slabs, and therefore cannot fully reflect the structure's actual operational status.

[0004] Hollow slabs and small box girders utilize double horizontal supports at their ends. After beam and slab erection, individual supports may become empty during operation due to factors such as construction precision and operational conditions. This emptying of a support increases the upper reaction force on adjacent supports, making them susceptible to crushing. This can also cause concrete cracking in components such as support pads and pier cap beams, leading to diagonal cracks in the webs.

[0005] According to research on previous engineering cases, the most common defects in small and medium-span prefabricated slab-girder bridges are cracks along the longitudinal hinge joints between the precast slab beams, leading to concrete spalling and water seepage in the hinge joints. This further develops into hinge joint failure, causing the single slab beam to be stressed and transverse cracks to appear at the lower edge of the bottom plate. These cracks continue to develop towards the web, forming U-shaped cracks. This defect is more prominent in sections where overweight and overloading are more serious.

[0006] Given the propensity for plate-girder bridges to develop defects after operation, and considering their full lifecycle, it was necessary to develop an open-section beam type that combines the advantages of hollow slabs and small box girders, such as reduced height and low economic indicators, with excellent durability, high prefabrication quality, and convenient construction. After thorough research, a standardized, pre-tensioned, 22m-long, double-T beam with a prestressed, zigzag shape was designed and developed for bridge applications. Summary of the Invention

[0007] The purpose of the present invention is to design and develop a 22m-level pre-tensioned broken-line prestressed double T-beam for bridge standardization, which has the advantages of hollow slab and small box beam bottom height, low economic indicators, etc., and has the advantages of safety, reliability, good durability, good prefabrication quality, adaptability to industrial production and convenient construction.

[0008] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: a standardized 22m-level pre-tensioned broken-line prestressed double T-beam for bridges, the span of the double T-beam is not greater than 22m, and is characterized in that: the double T-beam is an open section, including a top plate and two T-shaped webs located below the top plate, and prestressed steel strands are arranged at the web position, and the entire beam has a uniform cross-section, only cross-partials are arranged at the beam ends, and there are no cross-partials within the span; the double T-beam includes at least one of several beam types, and the top plate thickness of all beam types is the same; the web top width is a fixed value, and the beam width and web spacing adopt modular dimensions according to the bridge width; the beam height and web thickness adopt modular dimensions according to the span; and according to the different beam heights, the number of prestressed steel strands in the beam is adjusted to meet the requirements of different spans.

[0009] Furthermore, the double T-beam includes six beam types, with a beam span of 10m~22m and a beam height of 0.55m~0.95m. The top width of the web of the 22m-level double T-beam is 380~390mm; the side of the web is sloped, slightly narrowing from top to bottom, the slope of the side of the web is 3%~5%, the web spacing is 1m~1.5m, the top plate thickness is 180~220mm, and the chamfer of the bottom of the web is 20mm×20mm~35mm×35mm.

[0010] According to a specific embodiment of the present invention, the six beam types are: the first beam type is 10m span and 0.55m beam height; the second beam type is 13m span and 0.65m beam height; the third beam type is 16m span and 0.85m beam height; the fourth beam type is 18m span and 0.85m beam height; the fifth beam type is 20m span and 0.95m beam height, and the sixth beam type is 22m span and 0.95m beam height; the prestressed steel strands of the double T beam are arranged in a manner combining broken lines and straight lines, and the starting point of the steel strand bending is the same position, located 1.5~3.5m on both sides of the center of the beam length direction; the prestressed steel strands in the web of double T beams of different spans adopt the same transverse arrangement form, and a plurality of Prestressed steel strands are arranged in rows, with 3 prestressed steel strands arranged in the center of the bottom row, with a horizontal spacing of 50~53mm between the strands; no more than 5 prestressed steel strands are arranged in the center of the top row, and 5 prestressed steel strands are arranged in the center of each middle row, with a horizontal spacing of 50~53mm between the strands and a vertical spacing of 50~53mm. Bridges with different spans have different numbers of vertical rows of prestressed steel strands, but the horizontal and vertical spacings are unified; except for the bottom row, the prestressed steel strands in the middle of the remaining rows of the web are bent at the bending starting point, and the horizontal spacing of the steel strands at the support section is 50~53mm, and the vertical spacing of the prestressed steel strands is 80~100mm; the prestressed steel strands in the top row are flush with the bottom surface of the top plate, and the prestressed steel strands in the bottom row and the prestressed steel strands on both sides of the remaining rows are not bent.

[0011] Furthermore, the double T-beam bridge deck is connected by cast-in-place joints, the steel bars between adjacent precast beams at the joints are connected by welding or overlapping, the connecting steel bars are in the form of straight bars or circular bars, and the corresponding cast-in-place concrete is made of ultra-high performance concrete materials or ordinary concrete materials.

[0012] Furthermore, the first beam type is selected for spans below 10m, the second beam type is selected for spans between 10 and 13m, the third beam type is selected for spans between 13 and 16m, the fourth beam type is selected for spans between 16 and 18m, the fifth beam type is selected for spans between 18 and 20m, and the sixth beam type is selected for spans between 20 and 22m.

[0013] The present invention has obvious technical features through the characteristics of the above scheme: First, the structure is simple, and it is an open cross-section, with low material consumption, good economy, convenient construction, low construction difficulty, and good prefabrication quality; second, the top width of the web is a fixed value, and main beams with different beam heights can use the same template, and only the lower end area of ​​the web in the template needs to be filled; third, the main beam structure is modular and standardized, which is conducive to industrial production, speeds up prefabrication speed, and reduces costs; fourth, there is no cross-partition in the span, which is convenient for component prefabrication and on-site installation and construction, and reduces the number of processes; fifth, the shear force and torque in the beam end area are large, the stress is complex, and the structural stress is very unfavorable. The current conventional treatment method is to increase the beam end section (increase the beam height or thicken the web) and add cross-partitions between spans. In order to ensure the double T beam has an equal cross-section and no cross-partitions between spans, the present invention adopts a method of bending part of the steel bundles to increase the compressive stress on the upper edge of the cross-section in the beam end area, reduce the shear stress in the web, and ensure structural safety. The prestressed steel strands of this invention utilize a combination of straight and broken lines to ensure structural safety under the coupled forces of bending, shear, and torsion. The starting points of the strand bends are located at the same location, facilitating the installation of diverters. Sixth, two webs are provided, ensuring excellent stability during transportation and hoisting, preventing tipping. Seventh, the double-T beams have an open cross-section, making them accessible, inspectable, and repairable, facilitating maintenance. Eighth, double-T beams with spans of 10m or less can be pre-tensioned using either broken or straight lines, depending on the project scale. The added straight line arrangement allows double-T beams with spans of 10m or less to be pre-stressed using the long-line method, allowing two beams to be produced using a 22m double-T beam formwork, saving formwork costs and reducing project costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the elevation view of the first type of beam with broken line prestressing.

[0015] Figure 2 This is the elevation view of the second type of beam with broken line prestressing.

[0016] Figure 3 This is the elevation view of the third type of beam with broken line prestressing.

[0017] Figure 4 This is the elevation view of the fourth type of beam with broken line prestressing.

[0018] Figure 5 This is the elevation drawing of the fifth type of beam with broken line prestressing.

[0019] Figure 6 This is the elevation drawing of the sixth type of beam with broken line prestressing.

[0020] Figure 7 This is the cross-sectional view of the first type of beam with broken line prestressing.

[0021] Figure 8 This is the cross-sectional view of the second type of beam with broken line prestressing.

[0022] Figure 9 This is the cross-sectional view of the third type of beam with broken line prestressing.

[0023] Figure 10 This is the cross-sectional view of the fourth type of beam with broken line prestressing.

[0024] Figure 11 This is the cross-sectional view of the fifth type of beam with broken line prestressing.

[0025] Figure 12 This is the cross-sectional view of the sixth type of beam with broken line prestressing.

[0026] The figure includes: 1-top plate, 2-web plate, 3-diaphragm, 4-prestressed tendon, 5-bend starting point. DETAILED DESCRIPTION

[0027] A 22m-class pre-tensioned, broken-line prestressed double-T beam for standardized bridges, involving small and medium-span double-T beams with a span L of 5 to 22m. The specific embodiment span is selected according to the Shanghai Building Standard Design "Pre-tensioned Prestressed Concrete Hollow Slab (Bridge)" (DBJT08-101-2015). The standard drawings include 10m, 13m, 16m, 18m, 20m, and 22m. The span covers the commonly used spans of small and medium-sized bridges and adopts a standardized design, thereby forming a series of standard sections, which are suitable for factory construction and meet the development requirements of industrialization. At the same time, different spans correspond to different beam heights, 10m span 0.55m beam height, 13m span 0.65m beam height, 16m span 0.85m beam height, 18m span 0.85m beam height, 20m span 0.95m beam height, 22m span 0.95m beam height. The middle span can be selected by taking the upper limit. This type of span selection can adapt to various beam heights of existing hollow slab beam replacement projects.

[0028] The beam structure is an open section, consisting of a top plate and two webs. Cross diaphragms are only set at the ends of the beam. There are no cross diaphragms within the span, and prestressed steel strands are set in the webs.

[0029] Through calculation and solid beam tests, the top plate thickness h of double T beams of different spans is selected to be in the range of 180~220mm, preferably 200mm, and the web spacing B is in the range of 1m~1.5m, preferably 1.25m. Through standardized design, the prefabricated formwork of double T beams of different spans is universal, which improves construction efficiency, saves formwork cost, is suitable for mass production, meets the requirements of industrial development, and can adapt to all bridge widths of existing urban bridges and highway bridges by adjusting the length of the prefabricated beam cantilever.

[0030] The web of this double-T beam utilizes an inclined web, with the side slope ensuring a demolding slope of 3% to 5%. The same demolding slope is consistently used for different spans and beam heights. In a specific embodiment, a slope of 3% is selected. Only one set of formwork is required to prefabricate all spans of a 22m-class double-T beam. This system is well suited to a prefabricated formwork system for prefabricating prestressed double-T beams using the prestressing method. This eliminates the need for disassembly and assembly of formwork during beam production, allowing the beam to be lifted immediately after tensioning. This improves prefabricated beam production efficiency, improves formwork life, and reduces project costs. The bottom chamfer of the web is 35×35 mm. Test beams have verified that this dimension ensures that the concrete at the end of the prefabricated component is not prone to chipping or chipping during lifting and use, while also ensuring space for the support steel plates.

[0031] To meet standardized design requirements, the top width of the web of double T-beams with different spans and beam heights is fixed, and the bottom width of the web is changed according to the selected demoulding slope. Only one set of formwork is needed to prefabricate all span bridges of the 22m-level double T-beam, which can better adapt to a supporting formwork system for prefabricating prestressed double T-beams using the folded line pretensioning method. In a specific embodiment, the top width b1 of the web is selected to be 385mm. Test beams have shown that this size can ensure both the safety and durability of the structure. At the same time, the appropriate double T web width makes the transportation and installation of the double T-beams convenient, and conventional equipment is used for hoisting, resulting in high construction efficiency.

[0032] For double-T beams of varying spans and heights, prestressing tendons are added or removed to accommodate the load requirements of the beams, while maintaining fixed top plate thickness, web top width, and web spacing. For beams with spans of 10-22m, the prestressing tendons are arranged using a combination of broken and straight lines. The bending origin is located at the same position, 1.5-3.5m (preferably 2m) to either side of the beam's longitudinal center. This allows for bending of prestressed tendons for double-T beams of varying spans using the same formwork. The prestressing tendons within the webs of double-T beams of varying spans adopt the same transverse arrangement: three tendons are arranged centrally in the bottom row at mid-span, with a transverse spacing of t=52.5mm. Five tendons are arranged centrally in the second row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm. The number of vertical rows of prestressed tendons varies between bridges of varying spans, but the transverse and vertical spacing is uniform. In the support section, excluding the bottom row, the three central prestressing tendons in the remaining rows of the web are bent at the starting point. The transverse spacing of the tendons is t = 52.5 mm, and the top row of tendons is flush with the bottom surface of the top plate. The vertical spacing of the tendons is s1 = 80 mm and s2 = 100 mm. This spacing ensures safe tensioning of the tendons with tool anchors while ensuring adequate working space during tensioning. Furthermore, the compact arrangement efficiently utilizes the tensile strength of the tendons, conserves concrete, and reduces project costs.

[0033] like Figure 1 and Figure 7 As shown, for the first type of beam, a broken line prestressed steel strand is used. The span of the first type of beam is L=10m, the beam height is H=0.55m, the web top width b1 is selected as 385mm, the beam top plate thickness h is 0.2m, the web spacing B is 1.25m, the top plate thickness h=200mm, the web bottom chamfer is 35mm×35mm, prestressed steel strands are set in the web, and three rows of prestressed steel strands are set in the middle and lower part of the mid-span web. Three prestressed steel strands are set in the middle of the top and bottom rows, and one in the middle row is set. There are 5 prestressed steel strands, 3 of which are in the middle and correspond to the 3 in the bottom row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm; the 3 central prestressed steel strands in the top row and the middle row are bent at the bending starting point 5, which is 2m on both sides of the center of the beam length. The transverse spacing of the prestressed steel strands at the support section is t=52.5mm, and the vertical spacing of the prestressed steel strands is the first vertical spacing s1=100mm. The prestressed steel strands in the first row are flush with the bottom surface of the top plate; the rest are linear prestressed steel strands; the first beam type also includes two linear steel strands flush with the bottom surface of the top plate, which are arranged at the mid-span web position corresponding to the two outer sides of the 5 prestressed steel strands in the middle row.

[0034] like Figure 2 and Figure 8 As shown, for the second type of beam, a broken line prestressed steel strand is used. The span of the second type of beam is L = 13m, the beam height is H = 0.65m, the web top width b1 is selected as 385mm, the beam top plate thickness h is 0.2m, the web spacing B is 1.25m, the top plate thickness h = 200mm, the web bottom chamfer is 35mm × 35mm, prestressed steel strands are set in the web, and four rows of prestressed steel strands are set in the middle and lower part of the mid-span web, of which 3 prestressed steel strands are set in the middle of the bottom row, 5 prestressed steel strands are set in the top three rows, and 3 in the middle of the 5 prestressed steel strands are set. The first prestressed steel strands correspond to the three prestressed steel strands in the bottom row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm; the three central prestressed steel strands in the upper three rows are bent at the bending starting point 5, which is 2m on both sides of the center of the beam length. The transverse spacing of the prestressed steel strands at the support section is t=52.5mm, and the vertical spacing of the prestressed steel strands in the first and second rows is the first vertical spacing s1=100mm, and the vertical spacing of the prestressed steel strands in the second and third rows is the second vertical spacing s2=80mm. The prestressed steel strands in the first row are flush with the bottom surface of the top plate; the rest are linear prestressed steel strands.

[0035] like Figure 3 and Figure 9As shown, for the third type of beam, a broken line prestressed steel strand is used. The span of the third type of beam is L=16m, the beam height is H=0.85m, the web top width b1 is selected as 385mm, the beam top plate thickness h is 0.2m, the web spacing B is 1.25m, the top plate thickness h=200mm, the web bottom chamfer is 35mm×35mm, prestressed steel strands are set in the web, and four rows of prestressed steel strands are set in the middle and lower part of the mid-span web, of which 3 prestressed steel strands are set in the middle of the bottom row and the top row, 5 prestressed steel strands are set in the middle of the two middle rows, and the middle of the 5 prestressed steel strands is set. The three prestressed steel strands correspond to the three prestressed steel strands in the bottom row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm. The three central prestressed steel strands in the top row and the two middle rows are bent at the bending starting point 5, which is 2m on both sides of the center of the beam length. The transverse spacing of the prestressed steel strands at the support section is t=52.5mm. The vertical spacing of the prestressed steel strands in the first and second rows is the first vertical spacing s1=100mm, and the vertical spacing of the prestressed steel strands in the second and third rows is the second vertical spacing s2=80mm. The prestressed steel strands in the first row are flush with the bottom surface of the top plate. The rest are linear prestressed steel strands.

[0036] like Figure 4 and Figure 10 As shown, for the fourth type of beam, a broken line prestressed steel strand is used. The span of the fourth type of beam is L=18m, the beam height is H=0.85m, the web top width b1 is selected as 385mm, the beam top plate thickness h is 0.2m, the web spacing B is 1.25m, the top plate thickness h=200mm, the web bottom chamfer is 35mm×35mm, prestressed steel strands are arranged in the web, and five rows of prestressed steel strands are arranged in the middle and lower part of the mid-span web, of which three prestressed steel strands are arranged in the middle of the bottom row, two prestressed steel strands are arranged in the top row, and the two prestressed steel strands in the top row correspond to the outer two of the three prestressed steel strands in the bottom plate, and five prestressed steel strands are arranged in the middle of the three middle rows. Prestressed steel strands: the 3 middle ones of the 5 prestressed steel strands correspond to the 3 prestressed steel strands in the bottom row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm; the 2 prestressed steel strands in the top row and the 3 middle ones in the middle three rows are bent at the bending starting point 5, which is 2m on both sides of the center of the beam length direction. The transverse spacing of the prestressed steel strands at the support section is t=52.5mm, the vertical spacing of the first and second rows of prestressed steel strands is the first vertical spacing s1=100mm, the vertical spacing of the second and third rows of prestressed steel strands is the second vertical spacing s2=80mm, the vertical spacing of the third and fourth rows of prestressed steel strands is the first vertical spacing s1=100mm, and the first row of prestressed steel strands is flush with the bottom surface of the top plate; the rest are linear prestressed steel strands.

[0037] like Figure 5 and Figure 11As shown, for the fifth type of beam, a broken line prestressed steel strand is used. The span of the fifth type of beam is L=20m, the beam height is H=0.95m, the web top width b1 is selected as 385mm, the beam top plate thickness h is 0.2m, the web spacing B is 1.25m, the top plate thickness h=200mm, the web bottom chamfer is 35mm×35mm, prestressed steel strands are set in the web, and five rows of prestressed steel strands are set in the middle and lower part of the mid-span web, of which 3 prestressed steel strands are set in the middle of the bottom row and the top row, 5 prestressed steel strands are set in the middle of the three middle rows, and the middle of the 5 prestressed steel strands The 3 prestressed steel tendons correspond to the 3 prestressed steel tendons in the bottom row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm. The 3 central prestressed steel tendons in the top row and the middle three rows are bent at the bending starting point 5, which is 2m on both sides of the center of the beam length. The transverse spacing of the prestressed steel tendons at the support section is t=52.5mm. The vertical spacing of the prestressed steel tendons in the first and second rows is the first vertical spacing s1=100mm, the vertical spacing of the prestressed steel tendons in the second and third rows is the second vertical spacing s2=80mm, and the vertical spacing of the prestressed steel tendons in the third and fourth rows is the first vertical spacing s1=100mm. The prestressed steel tendons in the first row are flush with the bottom surface of the top plate. The rest are linear prestressed steel tendons.

[0038] like Figure 6 and Figure 12 As shown, for the sixth type of beam, a broken line prestressed steel strand is used. The span of the sixth type of beam is L=22m, the beam height is H=0.95m, the web top width b1 is selected as 385mm, the beam top plate thickness h is 0.2m, the web spacing B is 1.25m, the top plate thickness h=200mm, the web bottom chamfer is 35mm×35mm, prestressed steel strands are set in the web, and five rows of prestressed steel strands are set in the middle and lower part of the mid-span web, of which three prestressed steel strands are set in the middle of the bottom row, five prestressed steel strands are set in the middle of the top four rows, and the middle of the five prestressed steel strands are set in the middle. The three prestressed steel tendons correspond to the three prestressed steel tendons in the bottom row, with a transverse spacing of t=52.5mm and a vertical spacing of s=52.5mm. The three central prestressed steel tendons in the upper four rows are bent at the bending starting point 5, which is 2m on both sides of the center of the beam length. The transverse spacing of the prestressed steel tendons at the support section is t=52.5mm. The vertical spacing of the prestressed steel tendons in the first and second rows is the first vertical spacing s1=100mm, the vertical spacing of the prestressed steel tendons in the second and third rows is the second vertical spacing s2=80mm, and the vertical spacing of the prestressed steel tendons in the third and fourth rows is the first vertical spacing s1=100mm. The prestressed steel tendons in the first row are flush with the bottom surface of the top plate. The rest are linear prestressed steel tendons.

Claims

1. A standardized 22m-grade pre-tensioned, folded-line prestressed double-T beam for bridges, wherein the span of the double-T beam is no greater than 22m, and wherein: The double T-beam is an open cross-section, including a top plate and two T-shaped webs located below the top plate, and prestressed steel strands are arranged at the web position. The entire beam has a uniform cross-section, with cross-partials only arranged at the beam ends, and no cross-partials within the span; the double T-beam includes at least one of several beam types, and the top plate thickness of all beam types is the same; the web top width is a fixed value, and the beam width and web spacing adopt modular dimensions according to the bridge width; the beam height and web thickness adopt modular dimensions according to the span; and according to the different beam heights, the number of prestressed steel strands in the beam is adjusted to meet the requirements of different spans.

2. A 22m-class pre-tensioned prestressed double T-beam for bridge standardization as claimed in claim 1, characterized in that The double T-beams include six types of beams, with a beam span of 10m~22m and a beam height of 0.55m~0.95m. The 22m-level pre-tensioned broken-line prestressed double T-beams have a web top width of 380~390mm; the web side is sloped, slightly narrowing from top to bottom, the slope of the web side is 3%~5%, the web spacing is 1m~1.5m, the top plate thickness is 180~220mm, and the web bottom chamfer is 20mm×20mm~35mm×35mm.

3. A 22m-class pre-tensioned prestressed double T-beam for bridge standardization as claimed in claim 2, characterized in that The six beam types are: the first beam type has a span of 10m and a beam height of 0.55m; the second beam type has a span of 13m and a beam height of 0.65m; the third beam type has a span of 16m and a beam height of 0.85m; the fourth beam type has a span of 18m and a beam height of 0.85m; the fifth beam type has a span of 20m and a beam height of 0.95m, and the sixth beam type has a span of 22m and a beam height of 0.95m; the prestressed steel strands of the double T beams are arranged in a combination of broken lines and straight lines, with the bending starting points of the steel strands at the same position, 1.5 to 3.5m on both sides of the center of the beam length; the prestressed steel strands in the webs of double T beams of different spans adopt the same transverse arrangement, and several rows of prestressed steel strands are provided in the middle and lower part of the web of the mid-span section. , where 3 prestressed steel strands are arranged in the center of the bottom row, with a transverse spacing of 50~53mm between the strands; no more than 5 prestressed steel strands are arranged in the center of the top row; 5 prestressed steel strands are arranged in the center of each middle row, with a transverse spacing of 50~53mm between the strands and a vertical spacing of 50~53mm. Bridges with different spans have different numbers of vertical rows of prestressed steel strands, but the transverse and vertical spacings are unified; except for the bottom row, the prestressed steel strands in the middle of the remaining rows of the web are bent at the bending starting point, and the transverse spacing of the steel strands at the support section is 50~53mm, and the vertical spacing of the prestressed steel strands is 80~100mm. The prestressed steel strands in the top row are flush with the bottom surface of the top plate, and the prestressed steel strands in the bottom row and the prestressed steel strands on both sides of the remaining rows are not bent.

4. A 22m-class pre-tensioned prestressed double T-beam for bridge standardization as claimed in claim 1, characterized in that The double T-beam bridge deck is connected by cast-in-place joints. The steel bars between adjacent precast beams at the joints are connected by welding or overlapping. The connecting steel bars are in the form of straight bars or circular bars. The corresponding cast-in-place concrete uses ultra-high performance concrete materials or ordinary concrete materials.

5. The 22m-level pre-tensioned folded-line prestressed double-T beam for bridge standardization according to claim 1, characterized in that: One of the six beam types is selected according to the span. Among them, the first beam type is selected for a span of less than 10m, the second beam type is selected for a span of 10-13m, the third beam type is selected for a span of 13-16m, the fourth beam type is selected for a span of 16-18m, the fifth beam type is selected for a span of 18-20m, and the sixth beam type is selected for a span of 20-22m.

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