CN216196143U - Prefabricated assembled concrete scissors stair - Google Patents

Abstract

The utility model provides a prefabricated assembled concrete scissor stair which comprises a first straight stair and a second straight stair, wherein the first straight stair and the second straight stair are respectively fixed between a lower layer of stair beam and an upper layer of stair beam; the first straight-running stair comprises a first stair beam section and a second stair beam section, the lower end of the first stair beam section is fixed to the lower stair beam, the upper end of the second stair beam section is fixed to the upper stair beam, and the upper end of the first stair beam section and the lower end of the second stair beam section are both fixed to the middle stair beam; the second runs straight stair and includes ladder roof beam section I and ladder roof beam section II, and the lower extreme of ladder roof beam section I is fixed in upper ladder roof beam, and the upper end of ladder roof beam section II is fixed in lower floor's ladder roof beam, and the upper end of ladder roof beam section I and the lower extreme of ladder roof beam section II all are fixed in middle ladder roof beam. According to the utility model, the scissors stair is divided into two stair sections in the horizontal direction by arranging the middle stair beam, so that the weight of the scissors stair is greatly reduced, and the production, transportation, hoisting and installation of the prefabricated scissors stair step plates are facilitated.

Description

Prefabricated assembled concrete scissors stair

Technical Field

The utility model relates to the field of fabricated buildings, in particular to a prefabricated fabricated concrete shear stair.

Background

The fabricated building is a building which is formed by transferring a large amount of field operation work in the traditional construction mode to a factory, processing and manufacturing building components and accessories (such as floor slabs, wall slabs, stairs, balconies and the like) in the factory, transporting the components and accessories to a building construction site, and assembling and installing the components and the accessories on the site in a reliable connection mode. The assembly type building is a representative of a modern industrial production mode because of adopting standardized design, factory production, assembly construction, informatization management and intelligent application.

The assembly type building is one of the important directions for the development of building structures in China. The high-rise dwelling house has the advantage of plane standardization and is more suitable for the form of adopting the fabricated building. The scissors stairs are the most common stair form, and the prefabricated stair boards are produced according to the traditional conventional scissors stairs, and the weight of the prefabricated stair boards is about 4 tons or even heavier.

In the processes of production, transportation, hoisting, installation and the like, a common crane or vertical hoisting equipment cannot hoist the scissors stairs to produce the prefabricated step slabs; meanwhile, because the length-width ratio of the ladder plate is too large, cracks are easy to appear during hoisting; and the space between the staircases is limited, and the size of the stair boards is long, so that the installation is extremely difficult. The problems prevent the prefabricated assembled concrete scissor stairs from being popularized and applied in houses.

Disclosure of Invention

The utility model aims to provide a prefabricated assembled concrete scissors stair, which is characterized in that a middle ladder beam is arranged to divide the scissors stair into two ladder sections in the horizontal direction, so that the weight of the scissors stair is greatly reduced, and the production, transportation, hoisting and installation of the ladder plates of the prefabricated scissors stair are facilitated. In addition, the two terraces are divided, original tower crane equipment and the like are still used on the construction site, the situation that large-tonnage hoisting equipment is replaced due to the fact that the weight of a single prefabricated part is large is avoided, and construction cost is saved.

The technical scheme for realizing the purpose of the utility model is as follows:

a prefabricated assembled concrete scissor stair comprises a first straight running stair and a second straight running stair, wherein the first straight running stair and the second straight running stair are opposite in inclination direction, the first straight running stair and the second straight running stair are respectively communicated with an upper layer and a lower layer, the lower ends of the first straight running stair and the second straight running stair are respectively fixed on a lower layer of stair beam, and the upper ends of the first straight running stair and the second straight running stair are respectively fixed on an upper layer of stair beam;

the first straight-running stair comprises a first stair beam section and a second stair beam section, the lower end of the first stair beam section is fixed to a lower layer of stair beam, the upper end of the second stair beam section is fixed to an upper layer of stair beam, and the upper end of the first stair beam section and the lower end of the second stair beam section are both fixed to the middle stair beam;

the second runs straight stair and includes ladder roof beam section I and ladder roof beam section II, the lower extreme of ladder roof beam section I is fixed in upper ladder roof beam, the upper end of ladder roof beam section II is fixed in lower floor's ladder roof beam, the upper end of ladder roof beam section I with the lower extreme of ladder roof beam section II all is fixed in middle ladder roof beam.

In a possible implementation manner, the first ladder beam section, the second ladder beam section, the ladder beam section i and the ladder beam section ii are the same in width.

In one possible implementation, the span lengths of the first and second ladder beam sections are 1/2 span lengths of the first running straight stair;

the span length of the ladder beam section I and the ladder beam section II is 1/2 span length of the second straight running stair.

In a possible implementation mode, lower floor's ladder roof beam with upper ladder roof beam is one-way ear structure of choosing, first ladder roof beam section with ladder roof beam section I parallelly set firmly in the one-way ear structure of choosing of lower floor's ladder roof beam, second ladder roof beam section with ladder roof beam section II parallelly set firmly in the one-way ear structure of choosing of upper ladder roof beam.

In a possible implementation manner, the middle ladder beam is of a bidirectional non-through long ear picking structure, the first ladder beam section is fixedly arranged at one side part of the bidirectional non-through long ear picking structure, the ladder beam section i is fixedly arranged at the other side part of the bidirectional non-through long ear picking structure, and one side part and the other side part are symmetrical along the middle part of the bidirectional non-through long ear picking structure;

the second ladder beam section and the ladder beam section II are fixedly arranged in the middle of the bidirectional non-through long cantilever lug structure.

In one possible implementation manner, the lower end of the first ladder beam section and the lower end of the ladder beam section I are slidably supported on the lower ladder beam, and the upper end of the first ladder beam section and the upper end of the ladder beam section I are fixedly supported on the middle ladder beam;

the lower end of the second ladder beam section and the lower end of the ladder beam section II are slidably supported on the middle ladder beam, and the upper end of the second ladder beam section and the upper end of the ladder beam section II are fixedly supported on the upper ladder beam.

In a possible implementation manner, first filling layers are arranged between the first ladder beam section and the lower-layer ladder beam, between the first ladder beam section and the middle ladder beam, between the second ladder beam section and the upper-layer ladder beam, and between the second ladder beam section and the middle ladder beam;

between ladder roof beam section I and the lower floor's ladder roof beam between ladder roof beam section I and the middle ladder roof beam between ladder roof beam section II and the upper ladder roof beam between ladder roof beam section II and the middle ladder roof beam all be provided with the second filling layer.

In one possible implementation, the filling structure of the first filling layer is the same as the filling structure of the second filling layer.

In a possible implementation manner, the side surfaces of the first ladder beam section, the second ladder beam section, the ladder beam section I and the ladder beam section II are respectively provided with a plurality of lifting points for demolding;

first ladder beam section the second ladder beam section I with ladder beam section II is respectively marked time the surface and all is provided with a plurality of hoisting points for the installation.

In a possible implementation, the first ladder beam section, the second ladder beam section, the ladder beam section i and the ladder beam section ii are prefabricated members.

Compared with the prior art, the utility model has the beneficial effects that:

1. according to the utility model, the scissors stair is divided into two stair sections in the horizontal direction by arranging the middle stair beam, so that the weight of the scissors stair is greatly reduced, and the production, transportation, hoisting and installation of the prefabricated scissors stair step plates are facilitated. In addition, the two terraces are divided, original tower crane equipment and the like are still used on the construction site, the situation that large-tonnage hoisting equipment is replaced due to the fact that the weight of a single prefabricated part is large is avoided, and construction cost is saved.

2. According to the utility model, the scissors stair is divided into two stair sections in the horizontal direction by arranging the middle stair beam, the size of the prefabricated stair section is greatly reduced, the lifting and mounting difficulty of the stair sections is reduced in a narrow stair space, and the construction efficiency is improved.

Drawings

FIG. 1 is a first schematic view of a prefabricated concrete scissor stair provided by the utility model;

FIG. 2 is a second schematic view of the prefabricated concrete scissor stairs provided by the present invention;

FIG. 3 is a cross-sectional view A-A of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view B-B of FIGS. 1 and 2;

FIG. 5 is a schematic diagram of an example of a prefabricated concrete scissor stair application;

reference numerals: 1-a first straight stair; 11-a first ladder beam section; 12-a second ladder beam section; 2-the second straight stairs; 21-a ladder beam section I; 22-ladder beam section II; 3-middle ladder beam; 4-lower layer ladder beam; 5-upper ladder beam.

Detailed Description

The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that functional, methodological, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.

In the description of the present embodiments, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to a number of indicated technical features. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the utility model, the meaning of "a plurality" is two or more unless otherwise specified.

Stairways in the general sense include stairway sections, landings (landings and intermediate landings). The stair sections are the main use and bearing parts of the stair, are inclined components which are connected with two platforms with different elevations, and are composed of a plurality of continuous steps, and are commonly called stair sections or stair runs. The horizontal upper surface of the step is called a tread, and the vertical part of the tread is called a kickplate. The space between the stair sections and the platform is called a stair well, and the size of the stair well is determined according to the requirement of the supporting template during stair construction and the space size meeting the staircase. The platform is a horizontal part connecting the floor and the end part of the stair section, is mainly used for solving the problem of steering of the stair section, and enables people to have a buffer rest when going upstairs and downstairs. The middle platform is a platform positioned between two floors and has the functions of solving the turning of the stair sections and relieving fatigue. And the platform level with the floor level serves the function of buffering and distributing the flow of people from the building to the floors, called floor platform.

The problems of the existing concrete shear stairs are as follows: 1) the weight of a single stair plate of the concrete shear stair is too heavy, so that the production, transportation, hoisting, installation and other processes are difficult. The general crane or vertical hoisting equipment is difficult to meet the requirements, and the cost is increased if the tonnage is increased; 2) the length-width ratio of the stair treads of the scissors is too large, so that the stair treads are difficult to control during hoisting, cracks are easy to appear, the scissors need to be painted again at the later stage, and even the normal use of the stairs is affected when the scissors are serious; 3) the single step is too long in size and extremely difficult to install in a limited staircase space. The above conditions influence the construction efficiency, increase the cost and deviate from the original intention of the fabricated building.

The core of the embodiment of the utility model is that the scissors stair is horizontally split in advance in the production of the prefabricated stair, the thickness of the original stair section is reduced, the weight and the volume of a single stair section are greatly reduced, the traditional tower crane can be adopted for hoisting, the production, the transportation, the hoisting, the installation and the like are facilitated, and a good foundation is laid for the popularization and the application of the prefabricated assembled concrete scissors stair in a house.

Referring to fig. 1 and 2, an embodiment of the present invention provides a prefabricated assembly type concrete scissor stair, including a first straight running stair 1 and a second straight running stair 2, wherein the first straight running stair 1 and the second straight running stair 2 are opposite in inclination direction, the first straight running stair 1 and the second straight running stair 2 are respectively communicated with an upper layer and a lower layer, the lower ends of the first straight running stair 1 and the second straight running stair 2 are respectively fixed to a lower layer of stair beam 4, and the upper ends of the first straight running stair 1 and the second straight running stair 2 are respectively fixed to an upper layer of stair beam 5; the embodiment of the utility model provides a prefabricated assembled concrete scissor stair, which further comprises a middle ladder beam 3 arranged at the intersection of a first straight stair 1 and a second straight stair 2, wherein the first straight stair 1 comprises a first ladder beam section 11 and a second ladder beam section 12, the lower end of the first ladder beam section 11 is fixed on a lower ladder beam 4, the upper end of the second ladder beam section 12 is fixed on an upper ladder beam 5, and the upper end of the first ladder beam section 11 and the lower end of the second ladder beam section 12 are both fixed on the middle ladder beam 3; the second runs straight stair 2 and includes ladder beam section I21 and ladder beam section II 22, and the lower extreme of ladder beam section I21 is fixed in upper ladder beam 5, and the upper end of ladder beam section II 22 is fixed in lower floor's ladder beam 4, and the upper end of ladder beam section I21 and the lower extreme of ladder beam section II 22 all are fixed in middle ladder beam 3.

More specifically, in practical application, referring to fig. 2, the first straight stair 1 includes a first ladder beam section 11 and a second ladder beam section 12, wherein the lower end of the first ladder beam section 11 is fixed to the lower ladder beam 4 (the ladder beam on the lower floor), the upper end of the second ladder beam section 12 is fixed to the upper ladder beam 5 (the ladder beam on the floor), and the upper end of the first ladder beam section 11 and the lower end of the second ladder beam section 12 are both fixed to the middle ladder beam 3 between the floor and the lower floor; the second runs straight stair 2 and includes ladder roof beam section I21 and ladder roof beam section II 22, and the lower extreme of ladder roof beam section I21 is fixed in upper ladder roof beam 5 (the ladder roof beam on this layer), and the upper end of ladder roof beam section II 22 is fixed in lower floor's ladder roof beam 4 (the ladder roof beam on last layer), and the middle ladder roof beam 3 between this layer and the last layer is all fixed in to the upper end of ladder roof beam section I21 and the lower extreme of ladder roof beam section II 22.

Referring to fig. 3 and 4, the first ladder beam section 11, the second ladder beam section 12, the ladder beam section i 21 and the ladder beam section ii 22 according to the embodiment of the present invention have the same width.

With continued reference to fig. 3 and 4, the span lengths of the first and second ladder beam sections 11 and 12 of the embodiment of the present invention are 1/2 span lengths of the first running straight stair 1; the span lengths of the ladder beam section I21 and the ladder beam section II 22 are 1/2 span lengths of the second running straight stair 2.

In the specific application of the utility model, the lower-layer ladder beam 4 and the upper-layer ladder beam 5 are both of unidirectional ear-picking structures, the first ladder beam section 11 and the ladder beam section I21 are fixedly arranged on the unidirectional ear-picking structure of the lower-layer ladder beam 4 in parallel, and the second ladder beam section 12 and the ladder beam section II 22 are fixedly arranged on the unidirectional ear-picking structure of the upper-layer ladder beam 5 in parallel.

More specifically, the middle ladder beam 3 is preferably of a bidirectional non-through long ear-picking structure, the first ladder beam section 11 is fixedly arranged on one side part of the bidirectional non-through long ear-picking structure, the ladder beam section I21 is fixedly arranged on the other side part of the bidirectional non-through long ear-picking structure, and the one side part and the other side part are symmetrical along the middle part of the bidirectional non-through long ear-picking structure; the second ladder beam section 12 and the ladder beam section II 22 are fixedly arranged in the middle of the bidirectional non-through long cantilever lug structure.

More specifically, in practical application, the lower end of the first ladder beam section 11 and the lower end of the ladder beam section i 21 in the embodiment of the utility model are slidably supported on the lower ladder beam 4, and the upper end of the first ladder beam section 11 and the upper end of the ladder beam section i 21 are fixedly supported on the middle ladder beam 3; the lower extreme of second ladder beam section 12 and the lower extreme sliding support of ladder beam section II 22 are in centre ladder beam 3, and the upper end of second ladder beam section 12 and the upper end fixed support of ladder beam section II 22 are in upper ladder beam 5.

More specifically, in practical application, first filling layers are arranged between the first ladder beam section 11 and the lower ladder beam 4, between the first ladder beam section 11 and the middle ladder beam 3, between the second ladder beam section 12 and the upper ladder beam 5, and between the second ladder beam section 12 and the middle ladder beam 3; between ladder roof beam section I21 and the lower floor ladder roof beam 4, between ladder roof beam section I21 and middle ladder roof beam 3, between ladder roof beam section II 22 and the upper ladder roof beam 5, all be provided with the second filling layer between ladder roof beam section II 22 and middle ladder roof beam 3. Preferably, the filling structure of the first filling layer is the same as the filling structure of the second filling layer.

In practical application, the connection method between the lower ladder beam 4 and the first ladder beam section 11, between the upper ladder beam 5 and the second ladder beam section 12, between the ladder beam section i 21 and the lower ladder beam 4, and between the ladder beam section ii 22 and the upper ladder beam 5 in the embodiment of the utility model refers to page 27 of the national standard drawing set 15G 367-1. The connection method between the first ladder beam section 11 and the middle ladder beam 3, the connection method between the second ladder beam section 12 and the middle ladder beam 3, the connection method between the ladder beam section I21 and the middle ladder beam 3, and the connection method between the ladder beam section II 22 and the middle ladder beam 3 in the embodiment of the utility model refer to pages 27 of the national standard drawing set 15G 367-1.

In consideration of convenience in demolding and hoisting, the first ladder beam section 11, the second ladder beam section 12, the ladder beam section I21 and the ladder beam section II 22 are respectively provided with a plurality of demolding hoisting points on the side surfaces; the respective surface of marking time of first ladder beam section 11, second ladder beam section 12, ladder beam section I21 and ladder beam section II 22 all is provided with a plurality of hoisting points for the installation.

In order to improve the assembly rate of the concrete scissor stairs, the first ladder beam section 11, the second ladder beam section 12, the ladder beam section I21 and the ladder beam section II 22 are all prefabricated members.

Referring to fig. 5, taking a standard scissors stair with a floor height of 3m, a stair step width of 260mm and 18 steps as an example, a middle ladder beam 3 is additionally arranged at the intersection of the stairs, the scissors stair is horizontally split into two parts (DT 1-PC, DT2-PC, DT1(a) -PC and DT2(a) -PC), when the widths of the two side ladder boards are the same, the DT1-PC is the same as DT1(a) -PC, and the DT2-PC is the same as DT2(a) -PC), the calculated span length of the ladder section boards is reduced to 1/2 of the original span length, the board thickness and the reinforcing bars are both greatly reduced, and the corresponding weight and cost are also reduced.

Referring to fig. 5, the ladder beam (TL1) at the floor has one-way through long ears, and the middle ladder beam 3 (TL 2) has two-way non-through long ears. Pin key holes are reserved on the lifting lugs and the ladder beam. The lower ends of the prefabricated ladder boards (DT 1-PC and DT1(a) -PC) are slidably supported on the lifting lugs of the ladder beam (TL1) at the floor, and the upper ends of the prefabricated ladder boards are fixedly supported on the lifting lugs of the middle ladder beam 3 (TL 2); the lower ends of the prefabricated ladder boards (DT 2-PC and DT2(a) -PC) are slidably supported on the middle ladder beam 3 (TL 2), and the upper ends of the prefabricated ladder boards are fixedly supported on the lifting lugs of the ladder beam (TL1) at the floor.

It should be noted that a 30mm seam is reserved in the vertical direction for the prefabricated step plate and the lifting lug, a 20mm seam is reserved in the horizontal direction, and the prefabricated step plate and the lifting lug are filled with polyphenyl. In order to facilitate hoisting, 2 hoisting points for demoulding are arranged on the side surface of the prefabricated bench, and 4 hoisting points for installation are arranged on the tread. The middle ladder beam 3 is constructed in advance before the prefabricated ladder sections are installed.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.

It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (10)

1. A prefabricated assembled concrete scissor stair comprises a first straight running stair and a second straight running stair, wherein the first straight running stair and the second straight running stair are opposite in inclination direction, the first straight running stair and the second straight running stair are respectively communicated with an upper layer and a lower layer, the lower ends of the first straight running stair and the second straight running stair are respectively fixed on a lower layer of stair beam, and the upper ends of the first straight running stair and the second straight running stair are respectively fixed on an upper layer of stair beam; the first straight running stair and the second straight running stair are arranged at the intersection of the first straight running stair and the second straight running stair;

the first straight stair comprises a first ladder beam section and a second ladder beam section, the lower end of the first ladder beam section is fixed to the lower ladder beam, the upper end of the second ladder beam section is fixed to the upper ladder beam, and the upper end of the first ladder beam section and the lower end of the second ladder beam section are both fixed to the middle ladder beam;

the second runs straight stair and includes ladder roof beam section I and ladder roof beam section II, the lower extreme of ladder roof beam section I is fixed in upper ladder roof beam, the upper end of ladder roof beam section II is fixed in lower floor's ladder roof beam, the upper end of ladder roof beam section I with the lower extreme of ladder roof beam section II all is fixed in middle ladder roof beam.

2. The prefabricated assembled concrete scissor stair of claim 1, wherein the first ladder beam section, the second ladder beam section, the ladder beam section I and the ladder beam section II are all the same width.

3. The prefabricated assembled concrete scissor stair of claim 1 or 2, wherein the span length of the first and second ladder beam sections is 1/2 span length of the first running straight stair;

the span length of the ladder beam section I and the ladder beam section II is 1/2 span length of the second straight running stair.

4. The prefabricated assembled concrete scissor stair of claim 1, wherein the lower ladder beam and the upper ladder beam are both of unidirectional ear picking structures, the first ladder beam section and the ladder beam section I are fixedly arranged on the unidirectional ear picking structure of the lower ladder beam in parallel, and the second ladder beam section and the ladder beam section II are fixedly arranged on the unidirectional ear picking structure of the upper ladder beam in parallel.

5. The prefabricated assembled concrete scissor stair as claimed in claim 4, wherein the middle ladder beam is of a bidirectional non-through long lug structure, the first ladder beam section is fixedly arranged at one side part of the bidirectional non-through long lug structure, the ladder beam section I is fixedly arranged at the other side part of the bidirectional non-through long lug structure, and the one side part and the other side part are symmetrical along the middle part of the bidirectional non-through long lug structure;

the second ladder beam section and the ladder beam section II are fixedly arranged in the middle of the bidirectional non-through long cantilever lug structure.

6. The prefabricated assembled concrete scissor stair of claim 1, wherein the lower end of the first ladder beam section and the lower end of the ladder beam section I are slidably supported on a lower ladder beam, and the upper end of the first ladder beam section and the upper end of the ladder beam section I are fixedly supported on a middle ladder beam;

the lower end of the second ladder beam section and the lower end of the ladder beam section II are slidably supported on the middle ladder beam, and the upper end of the second ladder beam section and the upper end of the ladder beam section II are fixedly supported on the upper ladder beam.

7. The prefabricated assembled concrete scissor stair of claim 1, wherein a first filling layer is arranged between the first ladder beam section and the lower ladder beam, between the first ladder beam section and the middle ladder beam, between the second ladder beam section and the upper ladder beam, and between the second ladder beam section and the middle ladder beam;

between ladder roof beam section I and the lower floor's ladder roof beam between ladder roof beam section I and the middle ladder roof beam between ladder roof beam section II and the upper ladder roof beam between ladder roof beam section II and the middle ladder roof beam all be provided with the second filling layer.

8. The prefabricated concrete scissor stair of claim 7, wherein the filling structure of the first filling layer is the same as the filling structure of the second filling layer.

9. The prefabricated assembled concrete scissor stair of claim 1, wherein the first ladder beam section, the second ladder beam section, the ladder beam section I and the ladder beam section II are provided with a plurality of lifting points for demolding on respective side surfaces;

first ladder beam section the second ladder beam section I with ladder beam section II is respectively marked time the surface and all is provided with a plurality of hoisting points for the installation.

10. The prefabricated assembled concrete scissor stair of claim 1, wherein the first ladder beam section, the second ladder beam section, the ladder beam section I and the ladder beam section II are prefabricated parts.

Images