Reinforcing element for built-ins in concrete constructions
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.
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
The SB force model 41 is illustrated in
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 (
In the drawing:
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
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.
Other embodiments are illustrated in
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 (
As described above, the anchor 3 does not have to be an upset portion or a welded-on part. As illustrated in
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
In certain cases, it may be worthwhile or it is required to use specially shaped SB structural elements 22.
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
The TC structural elements 21′-21′″ illustrated in
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
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
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).
Type: Application
Filed: Sep 3, 2010
Publication Date: Sep 27, 2012
Applicant: GUTZWILLER HOLDING AG (Kirchberg)
Inventors: Clément Gutzwiller (Kirchberg), André Robert (Rebstein)
Application Number: 13/394,556
International Classification: E04C 5/06 (20060101);