STEEL COMPONENT FOR STRUCTURES TO REPLACE A PREDETERMINED AREA OF A REINFORCED CONCRETE COMPONENT INTENDED FOR LOAD-BEARING

Description

[0001] The present invention relates to steel components which can replace predetermined areas of reinforced concrete components intended for load-bearing, in particular reinforced concrete beams, and which can be designed to be less dense without loss of load-bearing capacity in order to create space for technical installation elements such as pipes, cables and ducts.

[0002] The aim of the general state of the art is to arrange technical installation elements within the structural plane rather than beneath a supporting structure. This avoids having to reduce the room height of a building for technical installations, or increase the room height if the room height remains the same. For this purpose, load-bearing webs must be provided with openings through which installation elements can be passed. However, the load-bearing capacity of webs is reduced if openings are placed too close together. For this reason, openings must be spaced far enough apart to ensure that the load-bearing capacity defined for the structure in question is not undercut.Based on pure double-T steel girders, the basic rule laid down, for example, in Guideline 015 (7 / 90) of the German Steel Construction Committee (DASt) applies: without particularly solid and rigid stiffeners between adjacent openings, the distance between them must be one and a half to two times the opening height to avoid having to make the webs opened in this way more extensive, thus counteracting the goal of not having to change the room or floor height. The same basic rule applies to the distances between the openings and the girder ends.

[0003] The published patent application DE 198 60 340 A1 already addresses the problem of the high installation density that should be enabled within the structural plane. It proposes a composite beam for buildings with a web for absorbing shear forces and with web openings for the passage of installation elements. The web openings are formed in a predetermined area of ​​the beam where comparatively low shear forces act relative to the entire beam. In uniformly loaded single-span beams, such an area is usually located centrally within the entire beam, since the shear forces within a beam decrease from its ends toward the center, while the load due to the global moment is strongest in the center.In the case of multi-span beams, particularly those with different spans or uneven loading, other conditions may prevail, although suitable areas with relatively low shear forces can regularly be identified there too.

[0004] The composite girder proposed in DE 198 60 340 A1 has the disadvantage that the predetermined area in which relatively low shear forces act is bordered by areas of the composite girder in which greater shear forces act. Typically, such a composite girder runs across the entire area to be underpinned. Accordingly, the entire composite girder, i.e. both the areas exposed to high shear forces and the area provided with web openings, is made of steel, with a one-piece compression flange running across the entire length of the girder above the web openings, with the disadvantage of increased quantities of steel to be installed and correspondingly high costs. The task therefore arises of providing the function of the aforementioned composite girder of the prior art and at the same time significantly reducing the proportion of steel to be installed.A composite beam is also disclosed in published patent application US 2011 / 0265422 A1, which describes a method for producing a composite beam using steel T-beams. This involves a double T-beam whose web is cut into two T-beams along the beam's alignment, with the cuts alternating above and below the centerline and alternating between them using an oblique connecting cut. The T-beams thus obtained have recesses and can be formed using formwork concrete, which is placed between vertical stiffeners attached to the ends of the T-beam, to enclose the T-beam only to the extent that the recesses are not completely covered by concrete, and the resulting recesses are available for the passage of installation lines.The disadvantage here is that the concrete recesses must be spaced apart for structural reasons, and the beam must first be constructed from various components, some made of steel and some of concrete. Against this background, the task also included constructing a steel component through which installation lines could be routed without the laborious addition of formwork concrete, allowing for a low construction height, thus keeping the required floor height as low as possible for a given room height, and allowing for easy installation.

[0005] The object is achieved by means of a steel component according to claim 1 and a supporting structure according to claim 12, wherein advantageous embodiments arise from the respective subclaims. to limit the steel component by the concrete of the reinforced concrete component in the longitudinal direction of the recess beam up to these surfaces. If several such surfaces are present on the recess beam, typically on its end faces, the largest of them is initially considered the connection surface; if the size is the same, the surface that is closer to the beam opening is considered. Nevertheless, connection means projecting longitudinally beyond these surfaces or their planes or arranged on them can be present as parts of the steel component and are encased in concrete for connection purposes.The distance between a support opening and an adjacent connecting surface is defined for each of the connecting surfaces as the shortest distance between the respective connecting surface and the nearest support opening, the height of which is determined as its greatest extent between the top and bottom of the recess support parallel to the shortest connecting distance between its top and bottom.

[0006] A steel fixture for buildings is proposed for replacing predetermined areas of reinforced concrete components intended for load-bearing, in particular reinforced concrete beams, which comprises a recess beam having two longitudinally spaced-apart connection surfaces, each with a top, bottom, front and back side that is different from the connection surfaces, as well as one or more support openings in the recess beam leading from the front to the back for the passage of installation elements, the distance between the openings and the adjacent connection surface being less than their respective height between the top and bottom sides. For example, with regard to a beam-shaped recess beam, the connection surfaces are therefore arranged on the end faces of such a beam, while the ceiling to be underpinned rests directly or indirectly on the top side. As a rule, the respective sides are flat.However, they can also have curves, protrusions, or indentations. For example, in special cases, the cross-section of the recess beam could also be circular; the designated sides would then be the corresponding circular arcs. The connecting surfaces of the recess beam are not the same as the ends that determine the length of the steel fixture. Rather, the term connecting surface refers to those surfaces of the recess beam that are intended to determine the length of the concrete-free area of ​​the supporting structure made of reinforced concrete components.

[0007] The goal of saving steel as a support material can be more easily achieved using the proposed steel component by defining at least one support opening at its underside edge by one of the broad sides of a steel strip. As the word "-band" already suggests, the steel strip has a cross-section that is wider than it is high, so that a distinction can be made between broad sides that extend along the width of the cross-section in the longitudinal direction of the steel strip and narrow sides that extend analogously along the height of the cross-section. The term "broad side" is also used below for other components or elements and thus analogously refers to their cross-section being wider than it is high. The steel component is preferably positioned so that the steel strip acts as a tension band when the moment is positive.However, it is also possible to position the steel band in such a way that it takes on the function of a compression belt, with a comparatively small negative moment at most.

[0008] Depending on the installation density, it may be advantageous to design the recess support of the steel fixture with more than one support opening instead of just one. Typically, all support openings will have the same height.

[0009] Due to the intended arrangement of the steel component in an area subject to relatively low transverse forces, a beam opening can advantageously be divided into separate sections by one or more stiffeners running between the top and bottom sides, whose extension in the longitudinal direction of the recess beam is less than the height of the respective beam opening. In practice, steel sheets with their broad sides arranged orthogonally to the longitudinal alignment of the recess beam will prove to be suitable as stiffeners.

[0010] For the majority of installation positions of the steel fixture, it is advantageous or even necessary for structural reasons that the steel fixture has a profile intended for encasing with concrete for the transfer of shear forces on the upper side of the recess beam. Such a profile is preferably beam-shaped, designed as a T-profile, or as a double-T profile and arranged parallel to the longitudinal alignment of the recess beam. Furthermore, it can be advantageous if the recess beam has a support plate to which the upper side of the recess beam belongs, which protrudes below the supporting profile and is intended for the structure (A), for example a floor slab, to rest on the areas not covered by the profile.

[0011] The shear force transfer profile preferably has holes designed to be penetrated by reinforcement bars perpendicular to the longitudinal alignment of the recess beam. When encasing such a profile with concrete, the concrete is applied up to the top of the recess beam or up to the support plate. For secure anchoring of the steel component, it is advantageous if bolts, preferably headed studs, protrude from the shear force transfer profile parallel to the shortest connecting section between the top and bottom of the recess beam, which are also designed to be encased in concrete.

[0012] A preferred embodiment of the steel component has an extension of the recess support on one or both sides on the underside in the longitudinal direction. Advantageously, such an extension is designed as a continuation of the steel strip beyond the plane of the respective connecting surface. Preferably, the concrete is applied both to the end face of the recess support and to the end face of the continuation of the steel strip. In this case, the end face of the recess support is considered the connecting surface, since it is larger than the end face of the continuation of the steel strip.

[0013] According to the invention, the steel component has a shear reinforcement intended for encasing with concrete for transmitting shear forces on at least one connecting surface, the broad sides of which are aligned parallel to the longitudinal direction of the recess support and to the shortest connecting section between its top and bottom sides. The anchoring of the shear reinforcement in concrete can be advantageously reinforced by designing it as a shear plate with transversely projecting bolts arranged on one or both sides, preferably with welded-on headed studs. Adequate and material-saving shear reinforcement is achieved by designing it as a shear cleat, which, in contrast to a shear plate typically guided from the level of the top side to the level of the bottom side of the recess support, only guides over a partial section between these two levels and is therefore more solid.

[0014] For the shear stiffness of the steel component, it is advantageous if the profile and the shear reinforcement are rigidly connected to each other, for example, by welding. Preferably, the thus connected parts enclose the recess support in a frame-like manner, with the exception of the underside.

[0015] Furthermore, the connection of reinforced concrete to the connecting surfaces can be advantageously achieved by arranging reinforcing bar sections on the connecting surfaces, parallel to the longitudinal alignment of the recess beam, for connecting the steel reinforcement of the reinforced concrete component, for example by means of screw joints or lap joints.

[0016] Bolts intended for encasing with concrete, preferably headed studs, can, if appropriately positioned, advantageously contribute to better embedding of the steel fixture in reinforced concrete, particularly if they protrude from a connecting surface parallel to the longitudinal alignment of the recess support or from the top side of the recess support.

[0017] Force-locked to a reinforced concrete component, particularly a reinforced concrete beam, the steel fixture forms a supporting structure by completely or partially replacing the reinforced concrete in an area where the effect of relatively low shear forces is preferably intended. The reinforced concrete extends up to the connecting surfaces in the longitudinal direction of the recess beam. If only the preferably section-like area is partially replaced, the reinforced concrete runs above and / or below the steel fixture in the longitudinal direction of the recess beam over the entire length to be underpinned.

[0018] The steel fixture can be arranged in various positions relative to the reinforced concrete component to form the supporting structure. For example, the top and / or bottom of the recess beam can be flush with the reinforced concrete component. If the profile has a support plate, this can be flush with the reinforced concrete component. If an area of ​​the reinforced concrete component is only partially replaced, the bottom of the recess beam can rest on a reduced cross-section of the reinforced concrete component, whereby it is advantageous if the reinforcement of the reinforced concrete is arranged continuously below the steel fixture. It can also be advantageous if, in addition to this or, in the case of a concrete-free underside, only the top of the recess beam or the support plate of the profile rests on a reduced cross-section of the reinforced concrete component, whereby here too the reinforcement of the reduced cross-section is preferably arranged continuously.

[0019] If the steel fixture has an extension of the recess support on the underside in its longitudinal direction, which is preferably designed as a continuation of the steel strip beyond the plane of a connecting surface, the extension can be encased in concrete if the underside rests on a reduced cross-section. However, it is also possible for the underside of the recess support, including the underside of the extension, to be kept free of concrete, and for the concrete to be applied up to the end faces of the extension and the connecting surfaces of the steel fixture.

[0020] The steel component and the supporting structure are explained in more detail below using some exemplary embodiments and illustrations, without the invention being limited to these. Legend:

[0021] 1Steel fixture 2Predetermined area 3Reinforced concrete component 4Connection surface 5Recess beam 6Top of the recess beam 7Bottom of the recess beam 8Front of the recess beam 9Rear of the recess beam 10Beam opening 11Edge of the beam opening 12Steel strip 13Broad sides of the steel strip 14Section of the beam opening 15Stiffener 16Profile for shear force transmission 17Bearing plate 18Holes for reinforcing bars 19Bolt 20Extension 21Shear stiffener 22Broad sides of the shear stiffener 23Reinforcing bar sections 24Supporting structure 25Reduced cross-section of the reinforced concrete component 26Reinforcing bars AStructure hHeight of the beam opening

[0022] Fig. 1 shows the steel component (1) in the front view. The recess support (5) shows here on its underside (7) a steel band (12) which acts as an extension (20) across the planes of the connection surfaces (4)At the top (6) of the recess support (5) is a beam-shaped profile (16) arranged for shear force transmission, the holes (18) which allows penetration with reinforcing bars ( Fig. 3 , Ziff. 26) are intended. The extensions (20) are reinforcing bar sections (23) welded on, which is connected to the reinforcement of the reinforced concrete component by means of a screw joint, represented as a thickening of the reinforcing bar sections (23) ( Fig. 3 , Ziff. 3) can be connected. At the connection surfaces (4) are shear stiffeners designed as shear plates (21) arranged, which with their broad sides (22) parallel to the longitudinal direction of the recess support (5) and to the shortest connecting section between the upper (6) and the underside (7) are aligned, here parallel to the front (8)or back (9) of the recess support (5), and with the profile (16) are welded so that the recess support (5) except for its underside (7) frame-like. From the shear stiffeners (21) protruding bolts (19), Here, they are designed as headed studs, projecting from the image plane towards the viewer. They are perpendicular to the shear stiffeners on both sides. (21) arranged and welded to them. The recess support (5) has a carrier opening (10) which are reinforced by stiffeners (15) into separate sections (14) and is divided between upper (6) and bottom (7) of the recess support (5) a height (h) which is greater than the distance of the carrier opening (10) to the connection surfaces (4). The carrier opening (10) is at its lower edge (11) through one of the broadsides(13) of the steel strip (12) limited.

[0023] Fig. 2 shows the supporting structure (24) from the steel component (1) and the beam-shaped reinforced concrete component (3) under the ceiling of a building (A) diagonally from below. In the middle area (2) of the reinforced concrete component (3) the reinforced concrete is completely covered by the steel component (1) which is flush with the reinforced concrete component at the top and bottom (3) The steel band (12) of the steel component (1) is in the process of (2) low shear forces, tensile forces resulting from the positive global moment and acts as a tension band. The beam opening (10) is here by two stiffeners (15) into three sections (14) The concrete of the reinforced concrete component (3) is up to the connecting surfaces (4) and the front sides of the processes(20) of the steel strip (12) whose lower broadside (13) can be seen from below. In relation to the total extent of the recess support (5) is the carrier opening (10) with its sections (14) Here it is so large that there is plenty of space available for the installation elements and at the same time comparatively little steel is used, since the distance of the support opening (10) to the connection surfaces (4) in relation to the height (h) the carrier opening (10) is low.

[0024] Fig. 3 shows the supporting structure (24) similar to Fig. 2 diagonally from below with the difference that the reinforced concrete component (3) and the ceiling of the building (A) are partially transparent so that the reinforcement bars (26) can be seen, which are parallel to the longitudinal alignment of the recess support (5) over the reinforcement bar sections(23) to the steel component (1) are connected and transverse to the longitudinal alignment of the recess support (5) through the holes (18) of the profile (16) which is beam-shaped here and absorbs the local moments alone or in conjunction with the ceiling and forms the compression belt for the global moment.

[0025] Fig. 4 shows an embodiment of the supporting structure (24) below the ceiling of the building (A) diagonally from below, where the reinforced concrete component (3) in the area (2) only partly by the steel component (1) is replaced and the reinforced concrete component (3) above the top (6) with reduced cross-section (25) is designed continuously.

[0026] Fig. 5 shows an embodiment of the supporting structure (24) below the ceiling of the building (A)diagonally from below, where the reinforced concrete component (3) in the area (2) only partly by the steel component (1) is replaced and the reinforced concrete component (3) below the bottom (7) with reduced cross-section (25) is designed continuously.

[0027] Fig. 6 shows part of the Fig. 5 shown embodiment without concrete, so that the continuous reinforcing bars (26) of the below the bottom (7) continuous reinforced concrete component ( Fig. 5 , Ziff. 3) are visible.

[0028] Fig. 7 shows part of the steel fixture (1), in which the shear stiffening (21) is designed as a shear lug. The beam-shaped profile (16) lies here on the support plate (17) Also shown here are the processes (20) welded reinforcement bar sections (23)on the connection surface (4).

Claims

1. A steel component (1) for structures (A) for the replacement of a predetermined area (2) of a reinforced concrete component (3) provided for load bearing, in particular, reinforced concrete beams, comprising a recess beam (5) comprising two connection surfaces (4) spaced away from each other in the longitudinal direction, each with an upper side (6), an underside (7), a front side (8) and rear side (9), each side being different from the connection surfaces (4), a steel band (12) comprising an upper and a lower broadside (13), wherein the lower broadside forms the underside (7) of the recess beam (5), one or a plurality of beam openings (10) provided for the passage of installation elements, leading from the front side (8) to the rear side (9), the distance of which to the respective adjacent connection surface (4) is less than its respective height (h), wherein at least one of the beam openings (10) is delimited by the upper broadside (13) of the steel band (12), and at, at least one of the connecting surfaces (4), a shear-reinforcement element (21) provided for enveloping in concrete for shear force transmission, the broadsides of which (22) are aligned parallel to the longitudinal direction of the recess beam (5) and the shortest connecting section between the upper side (6) and the underside (7).

2. The steel component (1) according to Claim 1, characterized in that the beam opening or at least one of the beam openings (10) is divided into separate sections (14) by one or a plurality of reinforcements (15) designed as steel sheets running between the upper side (6) and the underside (7), the extension of which steel sheets is less than the height (h) of the beam opening (10) between the upper side (6) and the underside (7) of the recess beam (5) in the longitudinal direction of the recess beam (5).

3. The steel component (1) according to any one of the preceding claims, characterized by a profile (16) provided for enveloping in concrete for the transmission of shear forces at the upper side (6) of the recess beam (5), wherein the profile (16) is designed in the form of a beam as a T-profile or as a double T-profile and is arranged parallel to the longitudinal direction of the recess beam (5).

4. The steel component (1) according to Claim 3, characterized in that the recess beam (5) comprises a support plate (17) to which the upper side (6) belongs, which projects from under the overlying profile (16) and is provided for the support of the structure (A).

5. The steel component (1) according to Claim 3 or 4, characterized in that bolts (19) provided for enveloping with concrete project from the profile (16), preferably shear studs parallel to the shortest connecting section between the upper side (6) and the underside (7).

6. The steel component (1) according to any one of the Claims 3 to 5, characterized in that the shear-reinforcement element (21) and the profile (16) are connected to each other in a rigid manner and enclose the recess beam (5), with the exception of the underside (7), in a frame-like manner.

7. The steel component (1) according to any one of the preceding claims, characterized by an extension (20) of the recess beam (5) in the longitudinal direction on the underside (7), which is designed as a continuation of the steel band (12) beyond the level of one of the connection surfaces (4).

8. The steel component (1) according to any one of the preceding claims, characterized in that the shear-reinforcement element (21) is designed as a shear plate with transversely projecting bolts (19) arranged on one or both sides, preferably with welded shear studs, or as a block shear connector.

9. The steel component (1) according to any one of the preceding claims, characterized by reinforcement bar sections (23) arranged parallel to the longitudinal alignment of the recess beam (5) at at least one of the connecting surfaces (4) for the connection of the steel reinforcements of the reinforced concrete component (3), for example, by means of screw joints or overlapping joints.

10. The steel component (1) according to any one of the preceding claims, characterized by bolts (19) provided for enveloping in concrete, projecting from at least one of the connecting surfaces (4) parallel to the longitudinal direction of the recess beam (5), which are preferably designed as head bolt end anchors.

11. The steel component (1) according to any one of the preceding claims, characterized by bolts intended for enveloping in concrete projecting from the upper side (6) of the recess beam (5), which are preferably designed as shear studs.

12. A load-bearing structure (24), characterized by a steel component (1) connected to a reinforced concrete component (3), in particular, a reinforced concrete beam, in accordance with one of the preceding claims, wherein the steel component (1) replaces the reinforced concrete component (3) in whole or partially in an area (2) in which the effect of relatively low shear forces is preferably provided, and the reinforced concrete component (3) is led in the longitudinal direction of the recess beam (5) to the connection surfaces (4).

13. The load-bearing structure (24) according to Claim 12, characterized in that the underside (7) of the recess beam (5) rests on a reduced cross-section (25) of the reinforced concrete component (3).

14. The load-bearing structure (24) according to any one of the Claims 12 or 13, characterized in that the upper side (6) of the recess beam (5) is adjacent to a reduced cross-section (25) of the reinforced concrete component (3).

15. The load-bearing structure (24) according to Claim 13 or 14, characterized in that the reduced cross-section (25) of the reinforced concrete component (3) comprises continuously arranged reinforcing bars (26) in the longitudinal direction of the recess beam (5).