Male pipe combined construction steel truss girder bridge

Abstract

The invention discloses a male pipe combined construction steel truss girder bridge, and relates to the field of steel truss girder bridges, the male pipe combined construction steel truss girder bridge comprises a bridge deck slab and a cross beam arranged below the bridge deck slab, a plurality of web members are arranged between the cross beam and the bridge deck slab, the web members are located on the two sides of the cross beam, and the web members, the bridge deck slab and the cross beam jointly define a pipeline space used for containing a plurality of pipelines; wherein the pipeline space comprises a first pipeline space body and a second pipeline space body which are arranged in the bridge direction of the steel truss girder bridge, the first pipeline space body is located above the second pipeline space body, and a pipeline support used for containing pipelines is arranged between the first pipeline space body and the second pipeline space body. Multifunctional combined construction of the road and the pipeline is achieved, various traffic and municipal demands under the condition of river crossing, river crossing and other channel resource shortage conditions are met, the public pipe combined construction design can reduce the cost and resource occupation of independent construction of a pipeline bridge, meanwhile, the pipeline and the road are integrated in the same bridge structure, and the construction cost is reduced. And unified maintenance and management are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of steel truss bridges, and in particular to a public-private joint-construction steel truss bridge. Background Art

[0002] Steel truss bridges offer a strong spanning capacity and are suitable for the construction of multifunctional channels. They are often used for the integration of multiple transportation systems, such as highways, railways, and rail transit. With the increasing scarcity of cross-river and river passageway resources, the construction of multifunctional bridges has become a trend. With the advancement of society and the development of cities, there is a need to carry large-diameter pipelines, such as heat pipes, water pipes, and gas pipelines, across rivers. However, traditional steel truss bridges are designed for a single function, such as highway or railway transportation, and lack a multifunctional integrated design. When the need for pipelines to cross rivers arises, the construction of dedicated pipeline crossing channels is required, resulting in wasteful resources and inadequate space utilization. With the increasing scarcity of cross-river and river passageway resources, the construction of separate highway and pipeline bridges will consume more land resources and water space, increasing the impact on the ecological environment and increasing construction and operating costs. Summary of the Invention

[0003] The present application provides a public-management-co-construction steel truss bridge, which can solve the problem that the existing steel truss bridge has a single function such as road traffic or railway traffic and lacks multi-functional integrated technology.

[0004] An embodiment of the present application provides a steel truss bridge constructed with both public and private pipes, comprising: a bridge deck, and a crossbeam arranged below the bridge deck, a plurality of webs arranged between the crossbeam and the bridge deck, the webs being located on both sides of the crossbeam, the webs, the bridge deck and the crossbeam jointly forming a pipe space for accommodating a plurality of pipes; wherein the pipe space comprises a first pipe space and a second pipe space arranged along the bridge direction of the steel truss bridge, and the first pipe space is located above the second pipe space, and a pipe bracket for accommodating pipes is provided between the first pipe space and the second pipe space.

[0005] In combination with the above embodiments, in one implementation, the public-pipe combined steel truss bridge further includes: a plurality of pipe pedestals for placing pipes, the pipe pedestals being arranged on a side of the beam facing the pipe space, and / or the pipe pedestals being arranged on a side of the pipe support facing the bridge deck.

[0006] In combination with the above embodiment, in one implementation manner, the side of the pipeline base facing the pipeline is a smooth arc surface, and the curvature of the arc surface matches the curvature of the pipeline.

[0007] In combination with the above embodiments, in one implementation, the public-pipe combined steel truss bridge further includes: a track arranged on the side of the bridge deck facing the pipeline space, the end of the track facing the pipeline space is provided with a suspension beam that can slide along the length direction of the steel truss bridge, and the end of the suspension beam facing the pipeline space is provided with a lifting ring that can be slidably connected in a direction perpendicular to the length of the steel truss bridge and is used for lifting pipelines.

[0008] In combination with the above embodiments, in one implementation, the pipe support includes: a first pipe support, one end of the first pipe support is fixed to the middle end of the web member, and the other end of the first pipe support extends from the middle end of the web member to the pipe space; a second pipe support, the cross-sectional shape of the second pipe support in a direction perpendicular to the bridge direction of the steel truss bridge is "π"-shaped, wherein the bottom of the second pipe support is vertically arranged on the crossbeam.

[0009] In combination with the above embodiment, in one implementation manner, an oblique stiffening rib is provided at the bottom of the first pipe support, one end of the stiffening rib is fixedly connected to the web member, and the other end of the stiffening rib is fixedly connected to the bottom of the pipe support.

[0010] In combination with the above embodiments, in one implementation, the public-pipe combined steel truss bridge further includes: a plurality of maintenance platforms arranged on a side of the beam facing the pipeline space, and the orthographic projection of the first pipe support on the beam does not cover the maintenance platform.

[0011] In combination with the above embodiments, in one implementation manner, the public-pipe combined steel truss bridge further includes: an inspection walkway, which is fixedly connected to the end of the web member away from the pipeline space, and the inspection walkway and the crossbeam are located in the same horizontal plane.

[0012] In combination with the above embodiment, in one implementation manner, the maintenance walkway includes: a bottom plate and guardrails vertically arranged on both sides of the bottom plate, and the bottom plate and the crossbeam are located in the same horizontal plane.

[0013] The beneficial effects of the technical solutions provided in the embodiments of the present application include: The embodiment of the present application provides a steel truss bridge with a combined public and private construction, comprising: a bridge deck, and a crossbeam arranged below the bridge deck, a plurality of webs arranged between the crossbeam and the bridge deck, the webs being located on both sides of the crossbeam, and the webs, the bridge deck, and the crossbeam together enclosing a pipeline space for accommodating a plurality of pipelines. Thus, the embodiment of the present application realizes the multifunctional combined construction of roads and pipelines, meeting various transportation and municipal needs under the conditions of tight channel resources such as across rivers and across rivers. This design of combined public and private construction can reduce the cost and resource occupation of building a pipeline bridge separately. At the same time, the pipeline and the road are integrated into the same bridge structure, which is convenient for unified maintenance and management, reducing the cost and complexity of later maintenance. Furthermore, the pipeline space includes a first pipeline space and a second pipeline space arranged along the bridge direction of the steel truss bridge, and the first pipeline space is located above the second pipeline space, and a pipeline bracket for accommodating pipelines is provided between the first pipeline space and the second pipeline space. By designing the first pipeline space and the second pipeline space and placing the first pipeline space above the second pipeline space, a three-dimensional layered arrangement of the pipelines is achieved, thereby fully utilizing the vertical space of the steel truss bridge, avoiding excessive occupation of the pipelines in the horizontal direction, and improving space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 A schematic diagram of the cross-sectional structure of a public-pipeline combined steel truss bridge provided in an embodiment of the present application; Figure 2 A schematic diagram of the pipeline hoisting of a public-pipe combined steel truss bridge provided in an embodiment of the present application.

[0016] In the figure: 1. Bridge deck; 2. Crossbeam; 3. Web member; 4. Pipe support; 5. Pipe pedestal; 6. Track; 7. Lifting beam; 8. Lifting ring; 9. Maintenance platform; 10. Maintenance walkway; 11. Pipeline. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0018] Steel truss bridges offer a strong spanning capacity and are suitable for the construction of multifunctional channels. They are often used for the integration of multiple transportation systems, such as highways, railways, and rail transit. With the increasing scarcity of cross-river and river passageway resources, the construction of multifunctional bridges has become a trend. With the advancement of society and the development of cities, there is a need to carry large-diameter pipelines, such as heat pipes, water pipes, and gas pipelines, across rivers. However, traditional steel truss bridges are designed for a single function, such as highway or railway transportation, and lack a multifunctional integrated design. When the need for pipelines to cross rivers arises, the construction of dedicated pipeline crossing channels is required, resulting in wasteful resources and inadequate space utilization. With the increasing scarcity of cross-river and river passageway resources, the construction of separate highway and pipeline bridges will consume more land resources and water space, increasing the impact on the ecological environment and increasing construction and operating costs.

[0019] The present application provides a public-management-co-construction steel truss bridge, which can solve the problem that the existing steel truss bridge has a single function such as road traffic or railway traffic and lacks multi-functional integrated technology.

[0020] Figure 1 A schematic diagram of the cross-sectional structure of a public-pipeline combined steel truss bridge provided in an embodiment of the present application.

[0021] See also Figure 1 A public-pipe combined steel truss bridge provided in an embodiment of the present application includes: a bridge deck 1, and a crossbeam 2 arranged below the bridge deck 1, a plurality of webs 3 are arranged between the crossbeam 2 and the bridge deck 1, the webs 3 are located on both sides of the crossbeam 2, and the webs 3, the bridge deck 1 and the crossbeam 2 are jointly arranged to form a pipe space for accommodating multiple pipes 11; wherein the pipe space includes a first pipe space and a second pipe space arranged along the bridge direction of the steel truss bridge, and the first pipe space is located above the second pipe space, and a pipe bracket 4 for placing the pipes 11 is arranged between the first pipe space and the second pipe space.

[0022] Specifically, the bridge deck 1, the crossbeam 2 and the web member 3 are jointly enclosed to form a pipeline space, and the pipeline 11 can be placed in the pipeline space, so that the bridge structure and the pipeline space are organically combined, and the structure is compact. On the one hand, it can realize the multifunctional construction of the highway and the pipeline 11, and meet the various transportation and municipal needs in the case of tight channel resources such as cross-river and cross-river, reduce the cost and resource occupation of building a separate pipeline bridge, and on the other hand, will not interfere with the original highway traffic function of the bridge.

[0023] In this embodiment, crossbeam 2 can be a node beam. Node beams are located at the nodes of the main trusses, connecting the trusses to form a unified structure that bears loads together. They are a crucial component of the steel truss structure. In this solution, the node beams also support the pipeline and its associated structures, improving the efficiency of the structure.

[0024] Furthermore, the embodiment of the present application further divides the pipeline space into a first pipeline space and a second pipeline space. On the one hand, it can fully utilize the vertical space without increasing the area occupied by the bridge, greatly improving the utilization efficiency of channel resources. On the other hand, it can set a more reasonable pipeline arrangement method according to the diameter, pressure, temperature and other characteristics of different types of pipelines 11 (such as thermal pipelines, water pipelines, gas pipelines, etc.), thereby further ensuring the safe use of the pipeline 11.

[0025] In an embodiment of the present application, the public-pipe combined steel truss bridge also includes: a plurality of pipe pedestals 5 for placing pipes 11, the pipe pedestals 5 are arranged on the side of the beam 2 facing the pipe space, and / or, the pipe pedestals 5 are arranged on the side of the pipe support 4 facing the bridge deck 1.

[0026] Specifically, a pipe pedestal 5 is placed in both the first pipe space and the second pipe space, and each pipe 11 corresponds to a pipe pedestal 5. The pipe pedestal 5 can be arranged to extend along the bridge direction of the steel truss bridge, and the length of the pipe pedestal 5 is the same as the length of the corresponding pipe 11. This arrangement is suitable for scenarios with high support requirements for the pipe 11, such as large pipes 11 or pipes 11 that require continuous support. The pipe pedestal 5 can also be arranged so that a pipe 11 is supported by multiple spaced-apart pipe pedestals 5. This arrangement is suitable for smaller pipes 11 or pipes 11 with relatively low support requirements, thereby saving material and construction costs. The arrangement of the pipe pedestal 5 can provide a support point for the pipe 11, disperse the weight of the pipe 11, improve the stability of the pipe 11, and reduce the loss of the pipe 11.

[0027] In the embodiment of the present application, the side of the pipe base 5 facing the pipe 11 is a smooth arc surface, and the curvature of the arc surface matches the curvature of the pipe 11.

[0028] Specifically, the pipe pedestal 5 is a pedestal with an arc-shaped groove, which fits tightly against the outer surface of the pipe 11, increasing the contact area and improving the support stability of the pipe 11. In addition, a covering belt is arranged to connect the pipe 11 and the pipe pedestal 5 to fix the pipe 11. In some other embodiments of the present application, the pipe pedestal 5 can be adjusted to suit pipes 11 of different diameters and types, as long as it meets the installation requirements of various pipes 11, such as thermal pipes 11, water pipes 11, and gas pipes 11. The shape and size of the pipe pedestal 5 are not limited herein.

[0029] Figure 2 This is a schematic diagram of the hoisting of a pipe 11 of a public-pipe combined steel truss bridge provided in an embodiment of the present application.

[0030] See also Figure 2In an embodiment of the present application, the public-pipe combined steel truss bridge also includes: a track 6 arranged on the side of the bridge deck 1 facing the pipeline space, a suspension beam 7 that can slide along the length direction of the steel truss bridge is provided on the end of the track 6 facing the pipeline space, and a lifting ring 8 that can be slidably connected in a direction perpendicular to the length of the steel truss bridge and is used to lift the pipeline 11 is provided on the end of the suspension beam 7 facing the pipeline space.

[0031] Specifically, by reserving a longitudinal full-length track 6, a lifting beam 7 can slide along the longitudinal track 6. A laterally movable lifting ring 8 is mounted on the lifting beam 7. Using a lifting hook in conjunction with a wire rope and a winch, each pipeline 11 can be installed and replaced during later operations. Thus, through the rational design of the lifting equipment and operating procedures, new installations of pipelines 11 and replacements during operation and maintenance are facilitated.

[0032] In an embodiment of the present application, the pipe support 4 includes: a first pipe support, one end of the first pipe support is fixed to the middle end of the web 3, and the other end of the first pipe support extends from the middle end of the web 3 to the pipe space; a second pipe support, the cross-sectional shape of the second pipe support in the direction perpendicular to the bridge direction of the steel truss bridge is "π"-shaped, wherein the bottom of the second pipe support is vertically arranged on the crossbeam 2.

[0033] Specifically, the first pipe space and the second pipe space are divided by the arrangement of the pipe support 4, thereby improving the utilization rate of the pipe space. The other end of the first pipe support extends from the middle end of the web 3 to the pipe space, providing a building platform for the pipe 11 and the pipe pedestal 5. The second pipe support is used to place the top of the pipe 11 on the same horizontal plane as the first pipe support. Both the first pipe support and the second pipe support can be made of high-strength steel to ensure that they have sufficient strength and rigidity to withstand the weight and internal pressure of the pipe 11. Furthermore, the pipe arrangement in the embodiment of the present application can ensure that each pipe has sufficient space for assembly or disassembly.

[0034] In the embodiment of the present application, an oblique stiffening rib is provided at the bottom of the first pipe support, one end of the stiffening rib is fixedly connected to the web 3 , and the other end of the stiffening rib is fixedly connected to the bottom of the pipe support 4 .

[0035] Specifically, the oblique stiffening ribs can effectively disperse the load of the pipe support 4 and transfer it to the web member 3 and the entire bridge structure, thereby improving the bearing capacity of the first pipe support and further improving the overall safety of the pipe 11.

[0036] In the embodiment of the present application, the width of the top of the second pipe support for accommodating the pipe 11 is greater than the width of the first pipe support.

[0037] Specifically, in order to more stably support the pipe 11 located in the second pipe space, the first pipe support is only used to accommodate one pipe 11. Due to the "π"-shaped structure of the second pipe support, the second pipe support can provide a wider and more stable support surface, so that the second pipe support can accommodate multiple pipes 11.

[0038] In an embodiment of the present application, the public-pipe combined steel truss bridge further includes: a plurality of maintenance platforms 9 arranged on the side of the beam 2 facing the pipeline space, and the orthographic projection of the first pipeline support on the beam 2 does not cover the maintenance platform 9.

[0039] Specifically, since the cross-sectional shape of the second pipe support in the direction perpendicular to the bridge direction of the steel truss bridge is "π"-shaped, and there is a gap between the bottoms of the second pipe support, the maintenance platform 9 can also be set in the gap between the two support columns, providing a stable platform for maintenance personnel, making it convenient for maintenance personnel to install, maintain and replace the pipeline 11.

[0040] In an embodiment of the present application, the public-pipe combined steel truss bridge further includes: an inspection walkway 10, which is fixedly connected to the end of the web member 3 away from the pipeline space, and the inspection walkway 10 and the crossbeam 2 are located in the same horizontal plane.

[0041] Specifically, the maintenance walkway 10 includes a base plate and guardrails arranged vertically on both sides of the base plate. The base plate is located at the same horizontal plane as the crossbeam 2. The structural design of the maintenance walkway 10 enables it to adapt to a variety of maintenance tasks, including pipeline 11 inspection, bridge structure inspection, and electrical equipment maintenance, while ensuring the safety of maintenance personnel.

[0042] During the specific construction design process, the pipeline dead load can be calculated based on the number and type of pipelines. Specifically, this is calculated by calculating the dead weight of the pipelines and the dead weight of ancillary facilities (pipe supports 4, pipe pedestals 5, maintenance platforms 9, maintenance walkways 10, etc.), as well as the live loads (load of the medium transported by pipelines 11, longitudinal friction caused by temperature fluctuations, etc.). Furthermore, based on the overall highway route design, bridge span layout, highway technical standards, and the aforementioned pipeline loads, the width of the steel truss upper deck 1, main truss height, main truss spacing, inter-section length, and main truss cross-section are determined through structural calculations and economic comparisons. Finally, based on the determined main truss height and main truss spacing, the pipelines 11 can be arranged. If the required space for pipeline 11 placement and maintenance is met, the design is complete.

[0043] If the required space for duct 11 layout and maintenance is not met, the main truss height is fixed, the main truss spacing is increased, and the duct 11 layout is adjusted until the required space is met. The main truss spacing is fixed, the main truss height is increased, and the duct 11 layout is adjusted until the required space is met. The two aforementioned solutions are substituted back into the structural calculation, the main truss cross-sections are updated, and the more optimal solution is determined through economic comparison.

[0044] The embodiment of the present application provides a steel truss bridge with a combined public and private pipeline structure, comprising: a bridge deck 1, and a crossbeam 2 disposed below the bridge deck 1, with a plurality of web members 3 disposed between the crossbeam 2 and the bridge deck 1, the web members 3 being located on both sides of the crossbeam 2, and the web members 3, the bridge deck 1, and the crossbeam 2 collectively forming a pipeline space for accommodating a plurality of pipelines 11. Thus, the embodiment of the present application achieves the multifunctional combined construction of a highway and pipelines 11, meeting various transportation and municipal needs in situations where channel resources are scarce, such as across rivers and streams. This combined public and private pipeline design can reduce the cost and resource usage of constructing a separate pipeline bridge. At the same time, the pipelines 11 and the highway are integrated into the same bridge structure, facilitating unified maintenance and management, thereby reducing subsequent maintenance costs and management complexity. Furthermore, the pipeline space comprises a first pipeline space and a second pipeline space arranged along the bridge direction of the steel truss bridge, with the first pipeline space located above the second pipeline space, and a pipeline support 4 for accommodating the pipelines 11 is disposed between the first pipeline space and the second pipeline space. By designing the first pipe space and the second pipe space and placing the first pipe space above the second pipe space, a three-dimensional layered arrangement of the pipes 11 is achieved, thereby fully utilizing the vertical space of the steel truss bridge, avoiding excessive occupation of the pipes 11 in the horizontal direction, and improving space utilization.

[0045] In the description of this application, it should be noted that the terms "upper" and "lower" 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 this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0046] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0047] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A steel truss bridge built by public and public management, characterized in that: include: A bridge deck (1), and a crossbeam (2) arranged below the bridge deck (1), a plurality of web members (3) being arranged between the crossbeam (2) and the bridge deck (1), the web members (3) being located on both sides of the crossbeam (2), and the web members (3), the bridge deck (1) and the crossbeam (2) jointly enclosing a pipe space for accommodating a plurality of pipes (11); The pipeline space comprises a first pipeline space and a second pipeline space arranged along the bridge direction of the steel truss bridge, and the first pipeline space is located above the second pipeline space, and a pipeline support (4) for accommodating a pipeline (11) is provided between the first pipeline space and the second pipeline space.

2. The public-pipeline combined steel truss bridge according to claim 1, characterized in that: The public-administered jointly built steel truss bridge also includes: A plurality of pipe pedestals (5) for accommodating pipes (11), wherein the pipe pedestals (5) are arranged on a side of the crossbeam (2) facing the pipe space, and / or the pipe pedestals (5) are arranged on a side of the pipe support (4) facing the bridge deck (1).

3. The public-pipeline combined steel truss bridge according to claim 1, characterized in that: The public-administered jointly built steel truss bridge also includes: A track (6) is provided on the side of the bridge deck (1) facing the pipeline space, and a suspension beam (7) that can slide along the length direction of the steel truss bridge is provided at one end of the track (6) facing the pipeline space, and a suspension ring (8) that can be slidably connected in a direction perpendicular to the length of the steel truss bridge and is used to lift the pipeline (11) is provided at one end of the suspension beam (7) facing the pipeline space.

4. The public-pipeline combined steel truss bridge according to claim 1, characterized in that: The pipeline support (4) comprises: a first pipe support, one end of the first pipe support being fixed to the middle end of the web (3), and the other end of the first pipe support extending from the middle end of the web (3) to the pipe space; A second pipe support, wherein the cross-sectional shape of the second pipe support in a direction perpendicular to the bridge direction of the steel truss bridge is in a "π" shape, wherein the bottom of the second pipe support is arranged perpendicularly to the crossbeam (2).

5. The public-pipeline combined steel truss bridge according to claim 4, characterized in that: An oblique stiffening rib is provided at the bottom of the first pipe support, one end of the stiffening rib is fixedly connected to the web (3), and the other end of the stiffening rib is fixedly connected to the bottom of the pipe support (4).

6. The public-pipeline combined steel truss bridge according to claim 4, characterized in that: The public-administered jointly built steel truss bridge also includes: A plurality of maintenance platforms (9) are provided on a side of the crossbeam (2) facing the pipeline space, and the orthographic projection of the first pipeline support on the crossbeam (2) does not cover the maintenance platforms (9).

7. The public-pipeline combined steel truss bridge according to claim 1, characterized in that: The public-administered jointly built steel truss bridge also includes: An inspection walkway (10), wherein the inspection walkway (10) is fixedly connected to an end of the web member (3) away from the pipeline space, and the inspection walkway (10) and the crossbeam (2) are located in the same horizontal plane.

8. The public-pipeline combined steel truss bridge according to claim 7, characterized in that: The maintenance walkway (10) comprises: A bottom plate and guardrails vertically arranged on both sides of the bottom plate, wherein the bottom plate and the crossbeam (2) are located on the same horizontal plane.

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