Pre-tensioning prefabricated small box girder and construction method thereof

Abstract

The invention discloses a small box girder prefabricated through a pre-tensioning method and a construction method thereof, and the small box girder prefabricated through the pre-tensioning method comprises a bottom plate which extends in the first direction; the two web plates are connected to the two opposite sides of the bottom plate in the first direction respectively; the first prestressed part is arranged in the bottom plate in the first direction, the second prestressed part is arranged on the web plate in the direction forming a certain included angle with the first direction, the first end of the second prestressed part is located on the web plate, and the second end of the second prestressed part is located on the side, away from the web plate, of the bottom plate. According to the small box girder prefabricated through the pre-tensioning method, a prestressed pipeline does not need to be arranged, the machining procedure is simplified, the prestress loss caused by friction between a prestressing tendon and the prestressed pipeline is reduced, the structural durability of the small box girder is improved, and cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, in particular to a pre-tensioned prefabricated small box girder and a construction method thereof. Background Art

[0002] Prefabricated small box girders are widely used in highway bridges and urban bridges because they are prefabricated in factories, have reliable quality, short production and processing cycles, are easy to assemble at the construction site, have high safety, beautiful appearance, and strong durability.

[0003] In the prior art, prefabricated small box beams are formed by pre-tensioning, which has the following shortcomings in processing: 1. Prestressed pipes and special anchors need to be set up, and they cannot be reused, which increases the cost; 2. The setting of prestressed pipes makes it difficult to vibrate the concrete under the pipes. Insufficient vibration is prone to bubbles or voids, which affects the appearance and internal quality of the structure. At the same time, prestressed pipes are prone to damage and leakage, causing blockage, and it is difficult to clear the pipe blockage, which increases the construction cost and construction period; 3. The grouting of prestressed pipes is not dense, which is easy to cause the prestressed pipes to The existence of gaps between the steel bundles and the concrete may cause the steel strands to rust, or the prestressed steel bundles may not be grouted in time after tensioning, which may easily lead to the shrinkage of the prestressed tendons, further increasing the loss of prestress, which is detrimental to the durability of the box girder structure; 4. For the entire long prestressed bundle, it is difficult to ensure the uniform distribution of the prestressed steel bar tension during the tensioning process. On the curved long bundle pipe, the friction force generated by the contact between the prestressed steel bundle and the pipe wall may cause the prestress loss to be as high as 40%, and the effective prestress is greatly reduced, affecting the overall force-bearing performance of the structure, the structural safety of the beam and the service life. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a pre-stressed prefabricated small box girder, which does not require the provision of a prestressed pipe, simplifies the processing procedures, reduces the prestress loss caused by the friction between the prestressed bundle and the prestressed pipe, improves the structural durability of the prefabricated small box girder, and reduces the cost.

[0005] The present invention also aims to provide a construction method for the above-mentioned prestressed small box girder.

[0006] According to an embodiment of the first aspect of the present invention, a prestressed small box girder is provided by the prestressing method, comprising: a bottom plate, the bottom plate extending along a first direction; two webs, the two webs being respectively connected to two opposite sides of the bottom plate along the first direction; a first prestressed member and a second prestressed member, the first prestressed member being arranged in the bottom plate along the first direction, the second prestressed member being arranged in the web along a direction forming a certain angle with the first direction, and the first end being located on the web, and the second end being located on a side of the bottom plate away from the web.

[0007] According to the pre-stressing method of the present invention, the small box girder is prefabricated by arranging the second prestressed member on the web along a direction forming a certain angle with the first direction, and the first end of the second prestressed member is located on the web, and the second end is located on the side of the bottom plate away from the web. Compared with the curved setting of the prior art, the positioning of the prestressed member is simpler, the construction accuracy requirement is lower, and the line shape is easier to match the design coordinates, thereby improving production efficiency; at the same time, compared with the post-stressing method of the prior art, the pre-stressing method does not need to set up a prestressed pipe, thereby reducing the project cost and avoiding problems such as structural appearance and internal quality caused by the setting of the prestressed pipe; the prestressed members do not need to be tied into bundles and set in the prestressed pipe, and each prestressed member can fully contact with the concrete, so that the prestress in the small box girder is more evenly distributed, thereby optimizing the performance of the small box girder.

[0008] According to some embodiments of the present invention, along the first direction, the web is provided with at least one group of two symmetrical second prestressed members, and the second ends of the group of two symmetrical second prestressed members are respectively located on both sides of the center line of the web along the first direction.

[0009] According to some embodiments of the present invention, along a direction away from the web, the first prestressed member includes a first upper prestressed member, a first middle prestressed member, and a first lower prestressed member that are spaced apart; Along the width direction of the bottom plate, a plurality of the first upper prestressed member, the first middle prestressed member and the first lower prestressed member are respectively arranged at intervals.

[0010] According to some embodiments of the present invention, the ends of the first upper prestressed member and the first middle prestressed member are respectively provided with a first failure segment and a second failure segment, and the length l1 of the first failure segment is greater than the length l2 of the second failure segment.

[0011] According to some embodiments of the present invention, a first isolating member is sleeved on an outer surface of the first failure segment, and a first lubricating layer is provided between the first failure segment and the first isolating member.

[0012] According to some embodiments of the present invention, along the width direction of the web, the second prestressed member comprises a second upper prestressed member and a second lower prestressed member that are spaced apart; Along the width direction of the bottom plate, a plurality of the second upper prestressed members and a plurality of the second lower prestressed members are arranged at intervals.

[0013] According to some embodiments of the present invention, the angle between the second upper prestressed member and the first direction is α1, 5°<α1<20°; An included angle between the second lower prestressed member and the first direction is α2, 5°<α2<20°.

[0014] According to some embodiments of the present invention, α1=α2.

[0015] According to some embodiments of the present invention, the distance from the intersection of the second end of the second prestressed member and the bottom plate to the center line of the web along the first direction is l3, and the length of the bottom plate along the first direction is l4, wherein (1 / 6)l4<l3<(3 / 10)l4.

[0016] The construction method according to the second aspect of the present invention is applied to the prestressed small box girder in the above embodiment, comprising the following steps: Step 1: Arrange a first prestressed component and a second prestressed component in the bottom plate and the web respectively, and tension the first prestressed component and the second prestressed component; Step 2: Pour concrete into the base plate and web.

[0017] According to the construction method of the embodiment of the present invention, the construction cost is saved by adopting the pre-tensioning method in the above embodiment to prefabricate the small box beam.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic elevation diagram of a prefabricated small box girder according to an embodiment of the present invention; Figure 2 is a schematic diagram of the arrangement of prestressed members in a prefabricated small box girder according to an embodiment of the present invention; Figure 3 is a schematic diagram of a failure section in a prefabricated small box girder according to an embodiment of the present invention; Figure 4 yes Figure 1 Schematic diagram of the AA position in the middle; Figure 5 yes Figure 1 Schematic diagram of the middle BB; Figure 6 yes Figure 1 Schematic diagram at CC in the middle; Figure 7 yes Figure 1 Schematic diagram of DD in the figure.

[0020] Reference numerals: Prefabricated small box beam 100, Bottom plate 10, first prestressed member 11, first upper prestressed member 111, first middle prestressed member 112, first lower prestressed member 113, first failure section 114, first isolation member 114a, first lubricating layer 114b, second failure section 115, second isolation member 115a, second lubricating layer 115b, center line 12, Web 20 , second prestressed component 21 , second upper prestressed component 211 , second lower prestressed component 212 . DETAILED DESCRIPTION

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0022] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific processes and examples of materials, but those of ordinary skill in the art can be aware of the applicability of other processes and / or the use of other materials.

[0023] The following describes a pre-tensioned prefabricated small box girder 100 according to an embodiment of the present invention with reference to the accompanying drawings.

[0024] Reference Figure 1 , Figure 2 , Figure 4-Figure 7 The prestressed small box girder 100 according to the first embodiment of the present invention includes a bottom plate 10, two web plates 20, a first prestressed member 11 and a second prestressed member 21.

[0025] Reference Figure 1 The bottom plate 10 extends along a first direction. Exemplarily, the first direction may be a length direction of the bottom plate 10 .

[0026] Reference Figure 4-Figure 7 The two webs 20 are respectively connected to two opposite sides of the bottom plate 10 along the first direction to form a chamber with an opening at the top with the bottom plate 10. Exemplarily, the two webs 20 are located on the same side of the bottom plate 10 and are inclined in a direction away from each other, that is, the distance between one end of the two webs 20 connected to the bottom plate 10 is smaller than the distance between the other ends of the two webs 20.

[0027] In some embodiments, reference Figure 4-Figure 7 The prefabricated small box girder 100 further includes a top plate connected to the other ends of the two web plates 20 .

[0028] Reference Figure 1 and Figure 2 , the first prestressed member 11 is arranged in the base plate 10 along the first direction, which can provide prestress for the base plate 10 structure. The second prestressed member 21 is arranged on the web 20 along a direction that forms a certain angle with the first direction, that is, the second prestressed member 21 is arranged on the web 20 in a straight line. The first end of the second prestressed member 21 is located on the web 20, and the second end is located on the side of the base plate 10 away from the web 20. Compared with the curved setting of the prior art, the positioning of the prestressed member is simpler, the construction accuracy requirements are lower, and the linear shape is easier to match the design coordinates, thereby improving production efficiency. Exemplarily, the two ends of the second prestressed member 21 can be anchored to a structure such as a pedestal by anchors or the like.

[0029] The prestressed small box girder 100 of the present application does not require the installation of prestressed pipes, simplifies the processing procedures, reduces the prestress loss caused by the friction between the prestressed bundles and the prestressed pipes, improves the structural durability of the prefabricated small box girder 100, and reduces the cost.

[0030] Therefore, refer to Figure 1 , Figure 2 , Figure 4-Figure 7 According to the pre-stressed small box girder 100 of the present invention, the second prestressed member 21 is arranged on the web 20 along a direction forming a certain angle with the first direction, and the first end of the second prestressed member 21 is located on the web 20, and the second end is located on the side of the bottom plate 10 away from the web 20. Compared with the curved setting of the prior art, the positioning of the prestressed member is simpler, the construction accuracy requirement is lower, and the line shape is easier to match the design coordinates, thereby improving production efficiency; at the same time, compared with the post-stressed method of the prior art, the pre-stressed method does not require the setting of prestressed pipes, thereby reducing the project cost and avoiding problems such as structural appearance and internal quality caused by the setting of prestressed pipes; the prestressed members do not need to be bundled and arranged in the prestressed pipes, and each prestressed member can fully contact with the concrete, so that the prestress in the small box girder is more evenly distributed, thereby optimizing the performance of the small box girder.

[0031] In some embodiments, the second prestressed member 21 can be arranged at the end of the web 20 along the first direction, or at the top plate opposite to the web 20, or at the end of the web 20 along the first direction and at the top plate opposite to the web 20.

[0032] When the second prestressed member 21 is disposed at the end of the web 20 along the first direction, along the height direction of the prefabricated small box girder 100 , the first end of the second prestressed member 21 is located at an end of the web 20 away from the bottom plate 10 .

[0033] The first prestressed member 11 and the second prestressed member 21 may be prestressed steel bars or the like.

[0034] In some embodiments of the present invention, reference Figure 1 and Figure 2 Along the first direction, the web 20 is provided with at least one group of two symmetrical second prestressed members 21, and the second ends of the group of two symmetrical second prestressed members 21 are respectively located on both sides of the center line 12 of the web 20 along the first direction.

[0035] By arranging at least one set of two symmetrical second prestressed members 21 along the first direction, prestress can be provided at both ends of the beam body. The second ends of the two second prestressed members 21 are respectively located on both sides of the center line 12 of the web 20 along the first direction, so as to prevent the two prestressed members from crossing, facilitate arrangement, and keep the prestress on both sides of the center line 12 of the beam body along the first direction balanced.

[0036] It can be understood that since a group of two prestressed members are symmetrically arranged, that is, the distances between the second ends of the two prestressed members and the center line 12 of the web 20 along the first direction are the same, and the inclination angles of the two prestressed members are the same.

[0037] In some embodiments of the present invention, reference Figure 1 and Figure 4 Along the direction away from the web 20, the first prestressed member 11 includes a first upper prestressed member 111, a first middle prestressed member 112 and a first lower prestressed member 113 which are arranged at intervals; along the width direction of the bottom plate 10, a plurality of first upper prestressed members 111, first middle prestressed members 112 and first lower prestressed members 113 are respectively arranged at intervals.

[0038] Multiple layers of prestressed members are arranged in a direction away from the web 20 , and multiple prestressed members are arranged at intervals in each layer, thereby increasing the prestress of the bottom plate 10 .

[0039] It is understandable that the spacing between adjacent ones of the first upper prestressed member 111, the first middle prestressed member 112 and the first lower prestressed member 113 may be the same or different. Preferably, the spacing between the first upper prestressed member 111 and the first middle prestressed member 112, and the spacing between the first middle prestressed member 112 and the first lower prestressed member 113 are the same, so that the prestress of the bottom plate 10 along the thickness direction is relatively uniform.

[0040] Similarly, the plurality of first upper prestressed members 111 may be arranged at the same spacing or at different spacings. Preferably, the plurality of first upper prestressed members 111 are arranged at the same spacing. The plurality of first middle prestressed members 112 may be arranged at the same spacing or at different spacings. Preferably, the plurality of first middle prestressed members 112 are arranged at the same spacing. The plurality of first lower prestressed members 113 may be arranged at the same spacing or at different spacings. Preferably, the plurality of first lower prestressed members 113 are arranged at the same spacing.

[0041] The spacing between two adjacent first upper prestressed members 111, the spacing between two adjacent first middle prestressed members 112, and the spacing between two adjacent first lower prestressed members 113 may be the same, or two of them may be the same, or they may be different. Preferably, the spacing between two adjacent first upper prestressed members 111, the spacing between two adjacent first middle prestressed members 112, and the spacing between two adjacent first lower prestressed members 113 are all the same.

[0042] In some embodiments of the present invention, reference Figure 2 and Figure 3 The ends of the first upper prestressed member 111 and the first middle prestressed member 112 are respectively provided with a first failure section 114 and a second failure section 115 , and the length l1 of the first failure section 114 is greater than the length l2 of the second failure section 115 .

[0043] By respectively setting the first failure section 114 and the second failure section 115 at the ends of the first upper prestressed member 111 and the first middle prestressed member 112, and the length of the first failure section 114 is greater than the length of the second failure section 115, the small box girder has better bearing capacity and prestress.

[0044] Specifically, the first upper prestressed member 111 is provided with a first failure section 114 at both ends, and the first failure section 114 extends from the end to the middle of the first upper prestressed member 111; similarly, the first middle prestressed member 112 is provided with a second failure section 115 at both ends, and the second failure section 115 extends from the end to the middle of the first middle prestressed member 112.

[0045] The lengths of the first failure section 114 and the second failure section 115 can be set according to actual construction requirements to improve the bearing capacity and prestress of the small box girder.

[0046] In some embodiments of the present invention, reference Figure 2 and Figure 3 A first isolating member 114 a is sleeved on the outer surface of the first failure section 114 , and a first lubricating layer 114 b is provided between the first failure section 114 and the first isolating member 114 a .

[0047] By sleeved the first isolation piece 114a on the outer surface of the first failure section 114, when pouring concrete, the first isolation piece 114a contacts with the concrete and isolates the concrete from the first upper prestressed member 111. At the same time, a first lubricating layer 114b is arranged between the first failure section 114 and the first isolation piece 114a, so that when the first upper prestressed member 111 is pulled back, it moves relative to the first isolation piece 114a, thereby making the concrete of the first failure section 114 have no prestress.

[0048] Correspondingly, a second isolating member 115 a is sleeved on the outer surface of the second failure section 115 , and a second lubricating layer 115 b is provided between the second failure section 115 and the second isolating member 115 a .

[0049] In some embodiments, the first lubricating layer 114b and the second lubricating layer 115b may be lubricating oil, for example, butter, etc. The first isolating member 114a and the second isolating member 115a may be isolating tubes sleeved on the first upper prestressing member 111 and the first middle prestressing member 112, etc. Exemplarily, the first isolating member 114a and the second isolating member 115a may be hard plastic tubes or plastic films, etc.

[0050] In some embodiments of the present invention, reference Figure 2 and Figure 4 Along the width direction of the web 20, the second prestressed member 21 includes a second upper prestressed member 211 and a second lower prestressed member 212 that are spaced apart; along the width direction of the bottom plate 10, a plurality of second upper prestressed members 211 and second lower prestressed members 212 are spaced apart.

[0051] By arranging the second upper prestressed parts 211 and the second lower prestressed parts 212 at intervals along the width direction of the web 20, and arranging multiple second upper prestressed parts 211 and second lower prestressed parts 212 at intervals along the width direction of the bottom plate 10, the prestress of the beam body can be increased and the performance of the beam body structure can be ensured.

[0052] Specifically, the plurality of second upper prestressed members 211 may be arranged at the same spacing or at different spacings. Preferably, the plurality of second upper prestressed members 211 are arranged at the same spacing. The plurality of second lower prestressed members 212 may be arranged at the same spacing or at different spacings. Preferably, the plurality of second lower prestressed members 212 are arranged at the same spacing.

[0053] In some embodiments of the present invention, reference Figure 2 The angle between the second upper prestressed member 211 and the first direction is α1, 5°<α1<20°; the angle between the second lower prestressed member 212 and the first direction is α2, 5°<α2<20°.

[0054] By setting the included angles α1 and α2 between the second upper prestressed member 211 and the second lower prestressed member 212 and the first direction to 5°-20°, the second end of the second prestressed member can be close to the middle of the beam body, thereby ensuring the prestress of the beam body.

[0055] Specifically, the angle α1 between the second upper prestressed member 211 and the first direction can be 5°, 6°, 7°, 8°, 10°, 12°, 15°, 18°, 20°, etc. Similarly, the angle α1 between the second upper prestressed member 211 and the first direction can be 5°, 6°, 7°, 8°, 10°, 12°, 15°, 18°, 20°, etc.

[0056] In some embodiments of the present invention, reference Figure 2 , α1=α2.

[0057] By setting the included angles of the second upper prestressed member 211 and the second lower prestressed member 212 with the first direction to be the same, it is easy to set up and construct, which reduces the construction difficulty and improves the construction efficiency.

[0058] It is understandable that the angle between the second upper prestressed member 211 and the first direction and the angle between the second lower prestressed member 212 and the first direction can also be set to be different. At this time, in order to avoid the second upper prestressed member 211 and the second lower prestressed member 212 from crossing, the angle α1 between the second upper prestressed member 211 and the first direction should be smaller than the angle α2 between the second lower prestressed member 212 and the first direction, and the difference can be 3° to 5°.

[0059] In some embodiments of the present invention, reference Figure 1 The distance from the intersection of the second end of the second prestressed member 21 and the bottom plate 10 to the center line 12 of the web 20 along the first direction is l3, and the length of the bottom plate 10 along the first direction is l4, wherein (1 / 6)l4<l3<(3 / 10)l4.

[0060] By setting the distance l3 from the intersection of the second end of the second prestressed member 21 and the bottom plate 10 to the center line 12 of the web 20 along the first direction to (1 / 6)l4≤l3≤(3 / 10)l4, the performance of the beam is ensured and the construction and setting are convenient.

[0061] Specifically, l3 can be (1 / 6)l4, (1 / 5)l4, (1 / 4)l4, (7 / 30)l4, (4 / 15)l4, (3 / 10)l4, etc.

[0062] The construction method according to the second aspect of the present invention is applied to the prestressed small box girder 1001 in the above embodiment, and comprises the following steps: Step 1: respectively arrange a first prestressed member 11 and a second prestressed member 21 in the bottom plate 10 and the web 20, and tension the first prestressed member 11 and the second prestressed member 21; Both ends of the first prestressed member 11 can be anchored to a pedestal at the end of the prefabricated small box girder 100 through an anchor assembly. One end of the second prestressed member 21 located at the web 20 can be anchored to a pedestal at the end of the prefabricated small box girder 100 through an anchor assembly, and the other end can be anchored to a pedestal at the bottom of the small box girder.

[0063] The tensioning of the first prestressed member 11 and the second prestressed member 21 can be performed by a jack or the like.

[0064] Step 2: pouring concrete into the bottom plate 10 and the web plate 20 .

[0065] According to the construction method of the embodiment of the present invention, the construction cost is saved by adopting the pre-tensioning method in the above embodiment to prefabricate the small box beam 100.

[0066] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0067] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or means that the first feature is lower in level than the second feature.

[0069] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0070] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A pre-tensioned prefabricated small box girder, characterized in that: include: a bottom plate extending along a first direction; Two webs, the two webs are respectively connected to two opposite sides of the bottom plate along the first direction; A first prestressed member and a second prestressed member, wherein the first prestressed member is arranged in the base plate along the first direction, and the second prestressed member is arranged in the web along a direction forming a certain angle with the first direction, and the first end is located on the web, and the second end is located on the side of the base plate away from the web.

2. The prestressed small box girder according to claim 1 is characterized in that: Along the first direction, the web is provided with at least one group of two symmetrical second prestressed members, and the second ends of the group of two symmetrical second prestressed members are respectively located on both sides of the center line of the web along the first direction.

3. The prestressed small box girder according to claim 1 is characterized in that: Along the direction away from the web, the first prestressed member includes a first upper prestressed member, a first middle prestressed member and a first lower prestressed member which are arranged at intervals; Along the width direction of the bottom plate, a plurality of the first upper prestressed member, the first middle prestressed member and the first lower prestressed member are respectively arranged at intervals.

4. The prestressed small box girder according to claim 1, characterized in that: The ends of the first upper prestressed member and the first middle prestressed member are respectively provided with a first failure section and a second failure section, and the length l1 of the first failure section is greater than the length l2 of the second failure section.

5. The prestressed prefabricated small box girder according to claim 4 is characterized in that: A first isolating member is sleeved on the outer surface of the first failure segment, and a first lubricating layer is provided between the first failure segment and the first isolating member.

6. The prestressed small box girder according to claim 1, characterized in that: Along the width direction of the web, the second prestressed member includes a second upper prestressed member and a second lower prestressed member which are arranged at intervals; Along the width direction of the bottom plate, a plurality of the second upper prestressed members and a plurality of the second lower prestressed members are arranged at intervals.

7. The prestressed small box girder according to claim 6 is characterized in that: The angle between the second upper prestressed member and the first direction is α1, 5°<α1<20°; An included angle between the second lower prestressed member and the first direction is α2, 5°<α2<20°.

8. The prestressed small box girder according to claim 7 is characterized in that: α1=α2。 9. The prestressed small box girder according to claim 2, characterized in that: The distance from the intersection of the second end of the second prestressed member and the bottom plate to the center line of the web along the first direction is l3, and the length of the bottom plate along the first direction is l4, wherein (1 / 6)l4<l3<(3 / 10)l4.

10. A construction method, applied to the prestressed small box girder according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Arrange a first prestressed component and a second prestressed component in the bottom plate and the web respectively, and tension the first prestressed component and the second prestressed component; Step 2: Pour concrete into the base plate and web.

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