US20120240496A1

US20120240496A1 - Reinforcing element for built-ins in concrete constructions

Info

Publication number: US20120240496A1
Application number: US13/394,556
Authority: US
Inventors: Clément Gutzwiller; André Robert
Original assignee: GUTZWILLER HOLDING AG
Current assignee: GUTZWILLER HOLDING AG
Priority date: 2009-09-08
Filing date: 2010-09-03
Publication date: 2012-09-27
Also published as: WO2011030270A1; EP3181772B1; EP3181772A1; CA2773779A1; EP2475827B1; WO2011030178A1; EP2475827A1

Abstract

Construction elements (21) are disclosed which allows potential weaknesses of a concrete structure (10) caused by recessed parts (20), e.g. media lines, to be nearly or fully eliminated. Said construction elements (21) consist of two anchoring devices (2) and an intermediate draw bar (2). A mounting device (4) is fixedly or removably provided in the area of the draw bar such that the hollow space for running the media lines, for example, is defined. The disclosed construction elements (21) can be integrated in the planning phase and/or shortly before casting the concrete.

Description

The present invention relates to a device for strengthening concrete structures as per the preamble of patent claim 1.
Concrete constructions which are used as floors, walls and load-bearing members serve, inter alia, in all modern structures to accommodate service lines for water, wastewater, ventilation, electricity and communications. Because ventilation pipes normally have large diameters, they have in the past been built on separately for buildings having air-conditioning units, and the ventilation ducts have often been designed to be rectangular so that they could be concealed within the infrastructure, for example within suspended ceilings. In connection with energy conservation, which applies ever increasingly, pipes and ducts for forced ventilation systems have been built into constructions means in ever increasing numbers. This houses that ventilation lines of large cross section have to be laid in. Since nobody in private and commercial buildings is keen on lines which are laid on open view and which, apart from their aesthetic shortcomings, are also dust traps and dirt zones and restrict the overall room height, lines are increasingly being built into the concrete construction.
In general, on account of progressively changing comfort needs, more empty pipes for service lines, such as electricity lines, audio lines, heating lines and water lines, are being laid in, with the result that an acute weakening of the concrete constructions exists in many cases.
In the environment surrounding such media lines, there are formed in the concrete construction multiple hollow spaces which have a longitudinal extent and which often pass through large areas of the concrete construction. As a result, the shear-carrying capability in particular of the concrete constructions is massively compromised. However, particularly as concerns the static functioning, for example, of a reinforced steel concrete floor, the shear-carrying capacity is of crucial importance.
Anti-punching shear systems known to date only allow the concrete construction to be strengthened in the region of force application regions of pillars and the like. They are not suited to solving the problems which weakenings caused by service lines produce within concrete constructions. This is owing particularly to the fact that, to obtain the load-bearing capacity determined for these anti-punching shear systems, a full concrete cross section without inlays (for example service lines) must be present. However, such inlays create large zones without load-bearing capacity. This factor would have to be taken into consideration by locally installing special devices at the site of the weakening. Such devices have not been known up to now.
Document DE 19937414A1 describes a structural element which can be used to strengthen cutouts in the region of the pillars supporting flat floors made of reinforced concrete or prestressed concrete. The problem is recognized in that publication that the arrangement of cutouts has a fundamental influence on the load-bearing capacity of the construction. It is likewise recognized that the possibility must exist whereby such devices can also be installed while the building work is still taking place, shortly before the concrete is poured in.
This disclosure relates only to lines which are routed perpendicular to the floor and through the floor in the direct vicinity of the pillars, and solves the problems relating to punching resistance. However, the problem is more wide-ranging and often presents static design engineers with problems because, on site and at the time of acceptance inspection and/or monitoring of the reinforcement, it is difficult to estimate to what extent the strength is weakened by accumulations of service lines and large-diameter service lines and what procedure should be followed if it is suspected that the load-bearing capacity of a concrete construction is inadequate. Today, the more accomplished an installation is conducted by the plumbing engineer, the electrical engineer and the ventilation engineer, the more and, in particular, the larger are the number and the diameters of the pipes which are built into a concrete construction for subsequently accommodating the service lines. The static design engineer is not normally given any notification and he or she is confronted by the facts on site and must generally perform an acceptance inspection of the reinforcement under time pressure.
At the static planning stage, that is to say when designing the reinforcement of a concrete construction, this fact has to date at best been taken into consideration in relation to the dimensioning of load-bearing members. For floors and walls, the reinforcement, normally designed with safeguards, is relied on. The lines are laid in on site by the workers before the concrete has been poured in, but frequently after the statically necessary reinforcement has been fixed in place. The structural engineer, who must carry out an acceptance inspection of the static design before the concrete is poured in and who is liable for the quality of said static design, has to date had no means at his or her disposal whereby it could be possible at short notice for him or her to employ simple means on site to build in a static strengthening facility within the construction.
The present invention is thus directed at the object of using a structural element to improve the concrete constructions of the initially mentioned type in such a way that means are made available in the planning phase that, when inserted locally, reduce or even eliminate the weakenings caused by service lines. However, means are also made available which can still be installed locally at the time of the acceptance inspection of the reinforcement, these means ensuring that the concrete construction is strengthened after pouring in the concrete in that, by means of a clear force model which is easily discernible to the structural engineer, said means increase the shear-carrying capability in the region of the service lines in such a way that the statics of the concrete construction either completely or at least approximately correspond to the design originally implemented by the static design engineer including the calculation of the reinforcement.
This object is achieved by a structural element for concrete constructions having the features of patent claim 1. Further features according to the invention can be taken from the dependent claims, and the advantages thereof are explained in the description hereinbelow.
The basis of the invention is a process which allows the building engineer, both in the planning phase and on site, to take effective measures by means of structural elements incorporating force models in order to locally strengthen the conventionally reinforced concrete construction by using suitable means in such a way that the building construction is not excessively weakened by service lines and that unnecessary overdimensioning thereof does not have to lead to uneconomic building constructions. For this purpose, the inlays and service lines, which are designated in the following as built-ins 20, are enclosed by means of structural elements 1, 21, 22, 23 which transmit forces and form clearly discernible force-neutral zones 31. The shear forces 16, 16′ act on every concrete construction. The figures show such building constructions each in the horizontal arrangement, but apply to every desired position.
Various force models will be described in the following text. The TC force model 40 is realized by means of a TC structural element 21, the SB force model 41 is realized by an SB structural element 22, and the demands of an HS force model 42 are enabled by an HS structural element 23.
The TC force model 40 is illustrated in FIG. 1. The force-neutral zone 31 is formed by a tension zone 33 and a compression zone 32. The compression forces are absorbed by the concrete 12 and by further parts of the structural element 1, such as, for example, the extensions 8 illustrated in FIGS. 21 and 22, whereas a TC structural element 21 having at least one tension element 2 serves to take up the shear forces 16, 16′.
The SB force model 41 is illustrated in FIG. 2. The force-neutral zone 31 is made possible by an M-Q zone 37 which can transmit the bending moments 34 and the shear forces 36. The bending moments 34 and the shear forces 36 are absorbed by an SB structural element 22 having at least one bending-resistant element 6.
Two arbitrary force models and force-neutral zones can be combined key being connected via an HS force model in such a way that a horizontal shear zone 35, which takes up the horizontal shear forces 18, results (FIG. 3). The same combination can be made by an SB force model 41 and the HS force model 41, although this combination is not graphically illustrated here.

In the drawing:

FIG. 1 shows a TC force model;

FIG. 2 shows an SB force model;

FIG. 3 shows a combination of a TC force model with an HS force model;

FIG. 4 shows a TC structural element with round end pieces;

FIG. 5 shows a TC structural element with quadrilateral end pieces;

FIG. 6 shows a TC structural element installed in the concrete construction;

FIG. 7 shows various forms of the holders on the structural element;

FIG. 8 shows a TC structural element having a tie rod forming a hollow space;

FIG. 9 shows a TC structural element having a tie rod, reinforced, forming a hollow space:

FIG. 10 shows a TC structural element installed in the concrete construction and having a tie rod, reinforced, forming a hollow space;

FIG. 11 shows hollow space-forming tie rods of various designs of TC structural elements;

FIG. 12 shows a connection of a plurality of TC structural elements;

FIG. 13 shows a TC structural element having an angularly arranged tie rod and anchor;

FIG. 14 shows a crosswise and angularly arranged tie rod and anchor of TC structural elements;

FIG. 15 shows a plurality of crosswise and angularly arranged tie rods and anchors of TC structural elements;

FIG. 16 shows a U-shaped SB structural element with anchors;

FIG. 17 shows various forms of SB structural elements;

FIG. 18 shows an arrangement of an HS structural element in the floor;

FIG. 19 shows various embodiments of various HS structural elements;

FIG. 20 shows a tried and tested simple embodiment having a defined force-neutral zone;

FIG. 21 shows a tried and tested closed embodiment having a defined force-neutral zone; and

FIG. 22 shows a tried and tested open embodiment having a defined force-neutral zone.

The figures illustrate possible exemplary embodiments which are explained in the description hereinbelow.
The invention ensures the necessary shear-carrying capability is provided in the transverse direction in the region of the aforementioned hollow spaces by creating a clear flow of forces. Thus, the resulting tension component emanating from the shear forces (for example strut-and-tie model) is accommodated by the systems and devices described hereinbelow. A reinforced region for the transmission of force is created locally by the systems. Depending on the particular force model, this occurs using means, such as, for example, reinforcing stirrups, frame systems, rings, dowels and the like, which are described hereinbelow. This results in the concrete construction having an increased shear resistance. It allows the necessary arrangement and routing of the service lines and the suspension of the resulting tensile forces in such a way that the necessary force flows and concrete compression diagonals can form. This occurs by means of loops, straps, irons, etc. arranged on the aforementioned systems and devices. It is equally possible to leave the service lines in situ and arrange the new structural elements 1 such that the necessary compression diagonals can form freely in spite of the service lines.
One configuration of the structural element 1 on which the invention is based, namely the TC structural element 21, is depicted in FIGS. 4 and 5. The most essential part of the TC structural element 21 is the tie rod 2. This acts as a tension rod element in both directions. The tie rod 2 can be designed to be rectilinear or to have any conceivable configuration, for example to be in the form of a bent bar or a frame. In order to securely anchor the TC structural element 21 in the concrete 12, said element can be equipped with an anchor 3 at least at one end. This anchor 3 can consist of round or polygonal upset portions, of conventional end anchors, such as welded-on cross-irons, or bent-off portions. They always serve to anchor the tie rod 2 in the concrete 12 after the latter has been poured in.
FIG. 6 shows an installed TC structural element 21. The compression diagonals 30 act on the tie rod 2 connected to the anchors 3, 3′, which means that the built-ins 20 can be accommodated in a force-neutral zone 31. The TC structural element 21 takes over the task of transmitting the forces, with the result that the concrete construction 10, which incorporates an already laid-out and existing conventional reinforcement 11, suffers only minor static weakening, if any, even when built-ins 20, such as, for example, service lines, are installed in large number and/or size.
In order to hold the built-ins 20 in the force-neutral zone 31, that is to say in the hollow space provided therefor for the routing of the built-ins 20, even while the concrete 12 is being poured in, a holder 4 is fixedly or detachably connected to the tie rod 2 or to the anchors 3, 3′. Said holder consists, for example, of bars, straps or loops which are used to govern and define the possible hollow space for routing the service lines. FIG. 7 shows which embodiments are possible. Furthermore, it is also conceivable for these holders 4 to take the form of wires or straps which are detachably secured at least by one end to the tie rod 2 or to the anchors 3, 3′. In this way, a TC structural element 21, or an SB structural element 22 and also an HS structural element 23 can still be inserted even at the last moment before the concrete 12 is poured in, and the built-ins 20 can be enclosed by the holder 4, which is loose at one end, and thus connected to the corresponding structural element 21, 22 or 23. Indeed, this course of action is relevant for holding the built-ins 20 in the hollow space provided therefor, i.e. the force-neutral zone 30, even during the pour-in operation.
Other embodiments are illustrated in FIG. 8 to FIG. 11. In the case of such embodiments, the tension element 2 simultaneously also forms the holder 4 for the built-ins 20. Elements illustrated in these figures are suitable for planned installation, which means that the workers are given predetermined locations where they may and should lay their service lines. If a structural element 21, 22, or 23 is provided at an early point in time, that is to say, for example, if it has already been planned in by the plumbing engineer, the ventilation engineer or the electrical engineer, said engineer can route in his or her lines into the holders 4 of the structural elements 21, 22, or 23 which are already present in situ. The invention thus presents the various construction people with a possibility of providing a static safeguard for the laying of built-ins 20 at an early point in time.
In order to fix the position of a plurality of structural elements 21, 22 and/or 23 in the longitudinal direction of the force-neutral zone 31, it is possible for a plurality of structural elements 21, 22 and/or 23 to be connected to one another by means of connectors 5 (FIG. 12). This is necessary when there is a risk that the structural elements 21, 22 and/or 23 could be displaced by the operation of pouring in the concrete 12, and would consequently not act exactly at the location at which the structural engineer wishes the strengthening to take effect.
As described above, the anchor 3 does not have to be an upset portion or a welded-on part. As illustrated in FIG. 13, the tie rod 2 and the anchor 3 can also consist of a bent-off angle piece. The tie rod 2 and anchor 3 then mutually absorb the shear forces 16 in the compression diagonals 30. The tie rod 2 and anchor 3 can both absorb the tensile forces resulting from the shear forces 16. They are in general arranged at an angle of 90°. As illustrated in FIGS. 13-15, this arrangement for the built-ins 20, and especially for service lines having a large diameter, can also be used to create a force-neutral zone 31.
It is precisely in the modern building construction which must meet the requirements of the Building Organization (Facility Management) that it often occurs that very many built-ins 20, above all including service lines having large diameters, are installed. Should this situation not already have been known at the static design stage of the concrete construction, major problems can result. It is therefore conceivable for use to be made of a plurality of crosswise-arranged combinations of angularly bent-off elements consisting of tie rods 2 and anchors 3. In this way, as shown in FIG. 15, a plurality of force-neutral zones 31 for accommodating built-ins 20 are created, with which arrangement the concrete construction 10 is as far as possible not weakened.
In certain cases, it may be worthwhile or it is required to use specially shaped SB structural elements 22. FIG. 16 shows such bending-resistant elements 6, these having the advantage that they create an even larger precisely predetermined force-neutral zone 31 for built-ins 20. The built-ins 20 can be bundled in a targeted manner using such bending-resistant elements 6. A bending-resistant element 6 consists, for example, of a frame 7 which absorbs the shear forces 16 in the form of bending moments and transverse forces, and thereby constitutes an SB structural element 22 as per FIG. 2. FIG. 17 illustrates a few variations of such SB structural elements 22 in the form of frames 7. It is also possible for such frames 7 to be connected to one another by means of connectors 5.
It is intended in principle for variants to be presented which make it possible, even at the last moment prior to pouring in the concrete 12, for the static design engineer still to take precautions to ensure that the concrete construction 10 does not have any weak points and meets the requirements. It should not be the aim to design the conventional reinforcement to be less stable. Rather, the aim is to be able to reduce or even eliminate any weakenings caused by unplanned built-ins.
In order to observe the facts explained in principle above and in FIGS. 1 to 19 in practical use, structural elements 1 in the form as shown in FIG. 20 to FIG. 22 were subjected to practical tests. It is found that the TC force model taking the forms shown in FIGS. 20-22 achieves the best results. In a technical sense, these forms are merely developments of the TC structural elements 21 illustrated in FIGS. 4, 5, 8 and 9. The force model 40 is illustrated in FIG. 1. The force-neutral zone 31 is formed by a tension zone 33 and a compression zone 32 (FIG. 1). The compression forces are absorbed by the concrete 12 and the anchors, whereas a TC structural element 21′-21′″ (FIGS. 20-22) having at least one tension element 2, 2′ serves to take up the tensile forces of the tension zone 33, 33′.
The TC structural elements 21′-21′″ illustrated in FIGS. 20-22 ensure that the necessary shear-carrying capability is provided in the region of the built-ins 20 by creating a clear flow of forces incorporating the force-neutral zone 31. Thus, the resulting tension component emanating from the shear forces (for example strut-and-tie model) is accommodated by the TC structural elements 21′-21′″, and a locally strengthened region for the transmission of forces is created. This takes place using means such as reinforcing stirrups and the like. The result is that the concrete construction has a clearly quantifiable, increased shear resistance. This construction allows the necessary arrangement and routing of the built-ins 20 (service lines) and the incorporation of the resulting tensile forces in such a way that the necessary force flows and concrete compression diagonals can form. It is possible to leave the service lines in situ and to arrange the TC structural elements 21 as illustrated in FIGS. 20-22 such that the necessary force flows can form freely in spite of the built-ins 20 (service lines). Therefore, local weakenings caused in the concrete construction 11 by built-ins 20 are compensated for locally and integrated within the entire concrete construction 11.
The most essential part of TC structural elements 21′-21′″ is the tie rod 2,2′. This acts as a tension rod element in both directions. In order to securely anchor the TC structural elements 21′-21′″ in the concrete, said tension rod element is equipped at the ends with anchors 3. The anchors 3 consist, for example, of welded-on cross-irons, screwed attachments, upset portions or bent-off portions. They serve to anchor the tie rod 2, 2′ in the concrete after the latter has been poured in. In this regard, the extensions 8 illustrated in FIG. 21 and figure can take on additional functions, such as, for example, the prevention of cracks and the avoidance of relatively large deformations, etc. in the immediate vicinity of the structural elements 21′-21′″. They also serve to provide a “gentle” transfer of the forces from the TC structural elements 21′-21′″ to the concrete.
The TC structural elements 21′-21′″ take over the task of transmitting the forces locally and can be used, even multiply, at any desired points. When installing built-ins 20 which are large in number and size, the concrete construction 10, which incorporates an already laid-out and existing conventional reinforcement 11, suffers little static weakening, if any. The local weakenings caused by built-ins 20 are compensated for by the use of TC structural elements 21′-21′″ according to the invention.
In principle, the variants of the TC structural elements 21′-21′″ presented in FIGS. 20-22 are also intended to make it possible, even at the last moment, for example while the static design engineer is performing a final monitoring inspection prior to the concrete being poured in, for said engineer to take precautions to ensure that the entire concrete construction 10 does not have any weak points and meets the requirements. It is neither the aim nor the object of the invention to have to design the conventional reinforcement to be less stable! Rather, the aim is to correct weakenings which emanate from built-ins 1 by taking appropriate measures. Intensive tests have confirmed that this is achieved by the TC structural elements 21′-21′″ illustrated in FIGS. 20-22.

Claims

1. A device for strengthening concrete structures, which bridges weakened zones using structural elements which can be inserted locally, wherein, in addition to the conventional reinforcement, and before pouring in the concrete, built-ins (20) are enclosed by at least one structural element (1) which transmits the forces, and hence improves the concrete construction weakened by said built-ins (20), in that said structural element (1) increases the local static shear-carrying capability in the region of said built-ins (20), wherein said structural element (1) generates at least one force model which forms force-neutral zones (31) for said built-ins (20), said zones defining the position of said built-ins (20), as a result of which the weakenings caused to the concrete construction by said built-ins (20) are at least minimized.

2. The device according to claim 1, wherein said structural element (1) consists of a TC structural element (21) which forms at least one TC force model (40) which consists of at least one compression zone (32) and at least one tension zone (33).

3. The device according to claim 1, wherein said structural element (1) consists of an SB structural element (22) which forms at least one SB force model (41) which consists of at least one M-Q zone (37), and absorbs bending moments (34) and shear forces (36).

4. The device according to claim 1, wherein said structural element (1) consists of an HS structural element (23) which forms at least one HS force model (42) which consists of at least one horizontal shear zone (35).

5. The device according to claims 2 and 4, wherein said structural element (1) forms a force model which consists of at least one TC force model (40) and at least one HS force model (42).

6. The device according to claims 3 and 4, wherein said structural element (1) forms a force model which consists of at least one SB force model (41) and at least one HS force model (42).

7. The device according to claim 1, wherein said structural element (1) comprises at least one tension element (2).

8. The device according to claim 7, wherein said structural element (1) has at least one tension element (2) and at least one holder (4).

9. The device according to claim 8, wherein said structural element (1) has at least one tension element (2), at least one holder (4) and at least one anchor (3).

10. The device according to claims 1 and 3, wherein said structural element (1) consists of at least one anchored and bending-resistant element (6).

11. The device according to claim 10, wherein said bending-resistant element (6) forms a frame (7).

12. The device according to claim 1, wherein at least two structural elements (1) are connected to one another by at least one connector (5, 5′).

13. The device according to claim 12, wherein said connector or connectors is or are arranged between at least two structural elements (1) along the force-neutral zone (31).

14. The device according to claim 12, wherein said connectors (5, 5′) are arranged between at least two structural elements (1) transversely with respect to the force-neutral zone (31).

15. The device according to claim 12, wherein said connectors (5, 5′) are arranged between at least two structural elements (1) along the force-neutral zone (31) and transversely with respect to the force-neutral zone (31).