Note: Descriptions are shown in the official language in which they were submitted.
CA 02541978 2007-02-28
21527-58(S)
1
Patent application
Inventor:
Prpf. Dr.=1ng. Gerd Giinther
Mittelweg 49
D-63619 Bad Orb (DE)
Asignee:
Fachhochschule Gief3en-Friedberg
Wiesenstraf3e 14
D-35390 Gief3en (DE)
REINFORCING ELEMENTS AND REINFORCED CONCRETE OR PRESTRESSED CONCRETE
PARTS PRODUCED BY MEANS OF THE SAME
The invention concerns a concrete reinforcement element as well as a
reinforced concrete or pre-
stressed concrete components made using this element.
Shear stressed reinforced concrete or pre-stressed concrete components, such
as a sup-
ported reinforced concrete ceiling, require shear reinforcement in the area of
columns of
the ceiling to ensure shear safety.
Known shear reinforcement includes the following: shear reinforcements made of
con-
crete reinforcing steel with shear reinforcement elements in the form of S-
hooks (although
this is no longer allowed according to DIN 1045) or stirrups , dowel bars,
double headed
dowels, open web girder, Tobler Walm, "Geilinger Kragen", retaining plate
mesh, "Riss
Stern", etc.
Shear reinforcement with reinforcement elements in the form of S-hooks or
stirrups has to
be encircled with a usually available flexural longitudinal reinforcement, due
to bad an-
chorage in order to prevent the shear reinforcement being ripped out. It must
be noted
that this only achieves a moderate increase in the shear force resistance. The
fitting of
CA 02541978 2006-04-07
WO 1148 CA 2 PCT/DE2004/000458
the concrete reinforcement elements is complicated and thus costly. In
addition, conven-
tional concrete reinforcement elements, such as stirrups are no longer
considered fittable
if exposed to high degrees of concrete reinforcement and a high proportion of
shear rein-
forcement.
The alternative option is to use dowel bars, which are usually put on the
lower formwork,
so that - if available - the lower layer of reinforcement is encircled by a
cross-section of
the bar. For the load bearing capacity, however, an exact positioning and
fixing of the bar
is crucial, which cannot always be ensured on a construction site. The dowel
bars are fur-
thermore individually made and welded, which in proportion to the very high
costs brings
hardly any demonstrable improvement of the shear force resistance.
Joining elements or spacers for the upper and lower layers of reinforcement
are known
from DE-U 1-71 18 881, DE-U 1-298 14 923, DE-OS-2 111 243 or DE-OS-1 913 104.
These elements, however, do not serve as concrete reinforcement elements;
instead they
fix only the reinforcement bars intended within the concrete component in a
desired loca-
tion or position before pouring in the concrete. This has no influence on the
punching
shear strength or even on the lateral load-bearing capability of the concrete
ceiling.
Other known concrete reinforcement elements such as double headed dowels,
Tobler
Walm and "Geilinger Kragen" can improve the load-bearing capability or the
punching
shear strength of reinforced concrete or pre-stressed concrete components, in
particular
in the area of ceiling support. However, the lateral load-bearing capability
of the concrete
component is also hardly influenced through their use. Furthermore, these
elements
which mostly have to be produced individually on site, are characterised by a
very expen-
sive production. They are also very time-consuming both in mounting and in
production,
and so much time is often not available on a construction site.
The task of the invention is to overcome these and further disadvantages of
the technical
state of the art, by providing concrete reinforcement elements to be mounted
in reinforced
concrete or pre-stressed concrete components, which have a simple structure
and are
cheap to produce. Furthermore the invention aims to achieve a good anchorage
of the
concrete reinforcement elements between the reinforcement bars, while keeping
the
mounting quick and uncomplicated to execute. The concrete reinforcement
elements
have to improve the stability of the finished reinforced concrete or pre-
stressed concrete
component, in particular increasing significantly the lateral load-bearing
capability of the
An 142/G ia 2
CA 02541978 2007-09-27
27527-58(S)
3
component. The reinforced concrete or pre-stressed concrete
component also has to be cheap to produce and easy to handle.
In accordance with the present invention, there is
provided a concrete reinforcement element (10) for a
reinforced concrete or pre-stressed concrete structural
component (1) wherein said concrete reinforcement
element (10) comprises a main component (12), an upper
surface and a lower surface and which further comprises at
least one reinforcement layer (Bo, Bu) on the upper surface
and one reinforcement layer on the lower surface wherein each
reinforcement layer comprises at least one outer layer
(Bo_x, Bu_x) which is adjacent to the upper surface or lower
surface and one inner layer (Bo_y, Bu_y) which is adjacent to
the outer layer (Bo_x, Bu_x) on a side opposite the upper
surface or lower surface and wherein the main component (12)
is a central element of the concrete reinforcement element
(10) and is adapted to extend substantially over the
thickness of the reinforced concrete or pre-stressed concrete
structural component (1) and up to at least an innermost
layer of the one inner layer (Bo_y, Bu_y) of the
reinforcement layer of the upper surface and the lower
surface and wherein the main component (12) is a bi-
dimensional structure which comprises an upper area (14) and
a lower area (15) and further comprises at least one
retaining element (20) in each of the upper and the lower
area wherein said retaining element (20) is adapted to at
least partially encircle the circumference of a concrete
reinforcement bar (S) of the reinforcement layer on the upper
surface and of the reinforcement layer on the lower surface
and wherein at least one retaining element (20) comprises a
single or double recess formed at an end of the main
component (12 ) .
In a further aspect of the invention, there is provided a
reinforced or pre-stressed concrete structural
CA 02541978 2007-02-28
21527-58(S)
3a
component comprising the concrete reinforcement element of the subject
invention.
A concrete reinforcement element in the form of a bi-dimensional component,
which joins
together, with a continuity of strength, the upper and lower layers of the
reinforcement,
located on the surface of the concrete component, with suitable upper and
lower retaining
elements, forms the core of the invention. This significantly'increases the
shear force re-
sistance of the reinforced concrete or pre-stressed concrete components.
The concrete reinforcement elements can be made as simple free-falling punched
parts,
to which further splays can be added if necessary. This enables a very cost-
effective pro-
duction, which has a positive effect on the production costs for the concrete
components.
The concrete reinforcement elements are easy to handle and quick to assemble.
They
simply have to be hooked in. No special knowledge or skifls are required, as
for example
in the case of welding work.
The retaining elements can be realised as drilled holes, side recesses out of
the bi-
dimensional component and/or as splays, which encircle at least the innermost
layers of
each upper and fower layer of reinforcement in the case of there being more
than one
upper and more than one lower layer of reinforcement.
Surprisingly it was found that concrete reinforcemeht elements of this kind
improve espe-
cially the shear force resistance, as well as the punching shear strength as
compared to
conventional structures, when they are mounted according to the invention
interacting
with the layers of reinforcement within a concrete component.
In addition to this surprising result, it was aiso found that a minimum
thickness of the bi-
dimensional components, of 1mm for example, was sufficient when using
conventional
structural steel, which has a very favourable effect on production costs.
CA 02541978 2006-04-07
WO 1148 CA 4 PCT/DE2004/000458
Further traits, details and advantages of the invention arise from the text of
the claims, as
well as in the following description of execution examples by means of the
illustrations.
They show:
Fig. 1 a schematic side view of a concrete reinforcement element,
Fig. 2 a schematic side view of another embodiment of a concrete reinforce-
ment element,
Fig. 3 to 6 a schematic side view each of further embodiments of a concrete
rein-
forcement element,
Fig. 7 a schematic side view of a concrete reinforcement element with a secur-
ing means,
Fig. 8 a schematic side view of a concrete reinforcement element with a differ-
ent embodiment for a securing means,
Fig. 9 a schematic side view of a concrete reinforcement element with yet an-
other embodiment for a securing means,
Fig. 10 to 15 a schematic side view each of further embodiments of a concrete
rein-
forcement element,
Fig. 16 a schematic representation of a further embodiment of a concrete rein-
forcement element,
Fig. 17 a schematic representation of a concrete reinforcement element with a
indented bi-dimensional structure,
Fig. 18 two joined concrete reinforcement elements,
Fig. 19 three joined concrete reinforcement elements,
Fig. 20 a different embodiment of two joined concrete reinforcement elements,
Fig. 21 another different embodiment of two joined concrete reinforcement ele-
ments,
Fig. 22 a schematic sectional view of a concrete reinforcement element divided
into two parts,
Fig. 23 a schematic sectional view of a different embodiment of a concrete
rein-
forcement element divided into two parts,
Fig. 24 yet another embodiment of a concrete reinforcement element divided
into
two parts,
Fig. 25 a further variation of a concrete reinforcement element,
An 142/G ia 2
CA 02541978 2006-04-07
WO 1148 CA 5 PCT/DE2004/000458
Fig. 26 a schematic representation of a reinforced concrete or pre-stressed
con-
crete component,
The concrete reinforcement element which is generally called 10 in Fig. 1 is
for use in the
reinforced concrete or pre-stressed concrete component 1 (which is not
represented here
in any further detail). It has as its main part 12 a simple flat structure
made of structural
steel, which has a recess 30 each in its upper area 14 and its lower area 15.
The recess
is formed by a slot, which is open to the longitudinal edge 16 on the side of
the bi-
dimensional structure 12, which extends vertically from its longitudinal
centre M.
Each recess 30 forms a retaining element 20 for the concrete reinforcement
element S
(which is also not shown here), in particular for a reinforcement bar of an
upper and lower
reinforcement layer Bo, Bu in the reinforced concrete or pre-stressed concrete
component
1 (see Fig. 26). These lie on each surface of the component (which is also not
shown in
any further detail here). They are formed by a least one inner layer Bo_y,
Bu_y and at
least one external layer Bo_x, Bu_x, which runs vertically to the inner layer.
During assembly, the bi-dimensional structure 12, with its side-opening
recesses 30, is
simply put on two reinforcement bars S of the inner layers Bo_y, Bu_y, lying
directly on
top of each other and running in the same direction. This means that each
reinforcement
bar is at least partially encircled. The clearance of the recesses 30 is
calculated in such a
manner that the bi-dimensional structure 12 with force transmission by
friction sits tightly
on the reinforcement bar S, so that it can not become loose while the concrete
is poured
in.
Hereby it is important that each concrete reinforcement element 10 always lies
laterally to
its bi-dimensional structure 12, and preferably vertically to the
reinforcement bars S, ex-
tending, on the whole, over the thickness of the reinforced concrete or pre-
stressed con-
crete component 1, namely to at least each upper and lower of the innermost of
at least
one inner layer Bo_y, Bu_y of the upper and lower reinforcement layers Bo, Bu.
The latter
are thereby bound together with a continuity of strength.
Comparative measurements have surprisingly shown that the concrete
reinforcement
element 10 according to the current invention significantly increases the
punching shear
strength as well as the shear force resistance of the reinforced concrete or
pre-stressed
concrete component 1 as compared to conventional constructions. It is
sufficient here to
An 142/G u 2
CA 02541978 2006-04-07
WO 1148 CA 6 PCT/DE2004/000458
produce the bi-dimensional structure 12, using conventional structural steel,
with a thick-
ness of 1 mm. This has a very favourable effect on material costs.
A further advantage of the concrete reinforcement element 10 is that due to
its simple
geometry it can be made, for example, as free failing punched parts, which
further lowers
production costs. They are quick and uncomplicated to mount and do not require
any
special knowledge or skills. This also leads to a considerable reduction in
production
costs for the reinforced concrete or pre-stressed concrete component 1.
In the embodiment of Fig. 2 the concrete reinforcement element 10 has as a
retaining
element 20 in the upper area 14 a slot 30, whereas a round or oval recess 30
is desig-
nated for the lower area 15.
The embodiment of Fig. 3 designates two slots 30 open on the side as retaining
elements
20, which run diagonally to the top at an angle a to the longitudinal centre M
of the bi-
dimensional structure 12. In contrast, the shape of Fig. 4 intends that the
slots 30 run di-
agonally down at an angel a. In both cases putting the concrete reinforcement
element 10
on the reinforcement bars S is made easier, in particular within tight spaces.
The concrete reinforcement elements 10 represented in Fig. 5 has proven to
have a par-
ticularly high increase in the lateral load-bearing capability of the
reinforced concrete or
pre-stressed concrete component 1. Here a total of four retaining elements 20
are desig-
nated for the upper and lower areas 14 and 15 of the bi-dimensional structure
12, namely
two recesses 30 each, which are open to the longitudinal edge 16 and lie
symmetrically to
the longitudinal centre M.
Therefore, each concrete reinforcement element 10 covers in total four
reinforcement
bars S of the upper and lower reinforcement layers Bo, Bu, binding them
together with
continuing strength, which has a particularly positive effect on the lateral
load-bearing ca-
pabilities of component 1. At the same time, each concrete reinforcement
element 10 is
firmly anchored between the reinforcement layers Bo, Bu. It can neither
mistakenly fall
out, nor can it slip when the concrete is poured in. The intervals and the
positions of the
reinforcement layers Bo, Bu are reliably secured at all times.
In order to further improve the fixing of the reinforcement bars S to the
retaining elements
20 or in the recesses 30, the latter can have an extension 32 each up and
down, so that
An 142/G ia 2
CA 02541978 2006-04-07
WO 1148 CA 7 PCT/DE2004/000458
in the area of the longitudinal edges 16 of the concrete reinforcement element
10 notched
edges 33 are formed for the reinforcement bars S.
The embodiment in Fig. 6 designates that the extensions 32 of the recess 30 in
the upper
area 14 of the bi-dimensional structure 12 lie across the longitudinal centre
M, whereas
the recess 30 in the lower area 15 is mainly L-shaped, namely with an upturned
extension
32. Here one can see that the sub-area 31 of the recess 30, which is open to
the longitu-
dinal edge 16, has a lower clearance than the part of the recess 30 which lies
in the longi-
tudinal centre.
In order to further secure the reinforcement bars S of the upper and lower
reinforcement
layers Bo, Bu of the concrete reinforcement elements 10, the recesses 30 can
be pro-
vided with a securing means 34. This can, for example, be a mainly U-shaped
clip made
of elastic material which can be reduced breadthwise by pressure on both of
its outer
legs, so that it can fit into the recess 30 (see Fig. 7). If the legs are
released, they then lie
within the walls of the slot 30 in the bi-dimensional structure 12, so that a
reinforcement
bar which lies in the recess 30 can not slip out sideways.
In the embodiment in Fig. 8 the securing means 34 consist of pins which are
brought into
the gable-end of the bi-dimensional structure 12 or onto the side mounted
receptions 35.
It is advantageous to use preferably brightly coloured indicatory agents, so
that the inser-
tion of a pin 34 can be easily marked and recognised on the construction site.
Alternatively a rotatable pin 34 or another rotatable bolting element, as well
as a position-
ing pin, can be arranged on the longitudinal edge 16 of the bi-dimensional
structure 12,
whereby the pin 34 is turned after the concrete reinforcement element S is
brought in be-
tween the concrete reinforcement element 10 and the positioning pin. The
indicatory
agents 36 on the pin 34 would then show all in the same direction, or indicate
the same
inclination or position relative to the concrete reinforcement element 10,
thus enabling a
fast check of the secured condition even for a large number of concrete
reinforcement
elements.
Fig. 9 shows further advantageous embodiments for securing means 34, for
example in
the form of a simple elastic element, such as a strip or a simple wedge.
An 142/G ii 2
CA 02541978 2006-04-07
WO 1148 CA 8 PCT/DE2004/000458
Another important embodiment of the concrete reinforcement element 10
according to
this invention is shown in Fig. 10. The retaining element 20 is formed by an
end-sided
formed simple splay 40 in the upper area 14 of the bi-dimensional structure.
Preferably
this will encircle a reinforcement bar S of the outer layer Bo_x of the upper
reinforcement
layer Bo (see Fig. 26, left element 10). The retaining element 20 in the lower
area 15 of
the bi-dimensional structure 12 is a L-shaped recess 30, which encircles a
reinforcement
bar S of the inner layer Bu_y of the lower reinforcement layer Bu.
As shown by Fig. 11 to 13, the retaining elements 20 can be combined in almost
any way
in the form of recesses 30 and splays 40, whereby reinforcement bars S of the
inner or
outer layers Bo_y, Bu_y, Bo_x, and Bu_x can be grasped at the same time.
In Fig. 11a the splay 40 which is formed onto the upper area 14 is bent
upwards, whereas
the splay 40 in the lower area 15 points forward. The concrete reinforcement
element 10
has thereby a mainly Z-shaped form in a cross-section- as can be seen in Fig.
11 b,
whereas the execution form of Fig. 12 and 12a has a U-profile in a cross-
section.
According to Fig. 13a and 13b the splays 40 can be doubled or multiplied,
whereby the
concrete reinforcement element 10 can have an S-shape in the cross-section -
as shown
by Fig. 15b.
The embodiment of Fig. 16 is based on the construction form of Fig. 6, that
means that in
the upper and lower areas 14 and 15 of the bi-dimensional structure 12 a total
of four re-
cesses 30 are intended symmetrical to its longitudinal centre as retaining
elements 20,
which encircle the reinforcement bars with a continuity of form. The recesses
30 are not
open to the longitudinal edges 16, that means that the reinforcement bars S
are mainly
introduced vertically into the bi-dimensional structure 12. Additional splays
40 encircle in
each case the outer layer Bo_x, Bu_x of the upper and lower reinforcement
layers Bo, Bu
as additional retaining elements, so that the concrete reinforcement elements
10 are inte-
grated in an optimal manner into the reinforced concrete or pre-stressed
concrete com-
ponent 1 for the purpose of increasing the lateral load-bearing capability.
Furthermore, its
ductility is also increased when there is strain on the shear force.
The same advantages are also found in yet another form of the concrete
reinforcement
element (Fig. 17). Here the bi-dimensional structure 12 is indented in the
cross-section,
An 142/G 02
CA 02541978 2006-04-07
WO 1148 CA 9 PCT/DE2004/000458
whereby the indentation 24, formed through simple and preferably right-angled
splays, is
realised between the upper and lower reinforcement layers (Bo, Bu).
If required, the concrete reinforcement elements 10 can encircle more than
four rein-
forcement bars S. The bi-dimensional structure 12 must correspondingly be
extended
horizontally to its longitudinal centre M and the required number of retaining
elements 20
must be added.
In the embodiment of Fig. 18 two concrete reinforcement elements 10 are
arranged in
longitudinal direction at least one reinforcement bar (S) next to each other
in a V-shape,
whereby the bi-dimensional structures in their upper areas 14 are joined to
one another or
are one piece.
The construction form of Fig. 19 provides for many concrete reinforcement
elements 10 to
be standing parallel one after the other. Each bi-dimensional structure 12 is
bound in a T-
shape with its upper area 14 to a flat bar 26, which protrudes over the
breadth of the con-
crete reinforcement element 10 in order to at least partially hold or encircle
an element S
of the upper reinforcement layer.
The embodiment in Fig. 20 is made up of concrete reinforcement elements 10 and
a flat
bar 26, which together form a U-profile, whereby the latter also serves as a
retaining ele-
ment 20, in that it encircles at least one reinforcement bar S of the upper
reinforcement
layer Bo.
The recesses 30 in the upper area 14 of the bi-dimensional structure 12 can
also be real-
ised in a rectangular form - as shown by Fig. 21- and join two parallel
concrete rein-
forcement elements 10, which are arranged next to each other, with a flexible
spring
clamp 28, whereby the clamp 28 with its legs (which are not described in any
further de-
tail) is set in the recesses 30, encircling also at least one reinforcement
bar S of the upper
reinforcement layer Bo.
Yet another important embodiment of the current invention can be seen in Fig.
22 to 24,
when namely the bi-dimensional structure 12 of the concrete reinforcement
element 10 is
divided, vertically to its longitudinal centre M, into a lower half 50 and an
upper half 60,
whereby both halves 50 and 60 are joined to each other in a separable manner.
An 142/G 02
CA 02541978 2006-04-07
WO 1148 CA 10 PCT/DE2004/000458
Thereby it is possible, for example, to prefabricate reinforced concrete or
pre-stressed
concrete components, for example ceiling elements in which the lower halves 50
of the
concrete reinforcement elements 10 are built or poured into the lower half of
the ceiling.
Therefore, on the construction site, only the missing upper reinforcement
layer Bo has to
be added, whereby the upper halves 60 of the concrete reinforcement elements
10 are
joined to the lower half 50 which is protruding from the prefabricated ceiling
component.
Afterwards, the ceiling can be completed by pouring in the concrete.
Ceiling elements which have been prefabricated in this way have the advantage
of being
much easier to handle and transport, as not only do they weigh less, but also
the dimen-
sions are smaller. Furthermore it also enables more flexible arrangement
possibilities on
the construction site. For example the thickness of the concrete ceiling can
be individually
designed, by using upper halves 60 with different lengths of the concrete
reinforcement
elements 10. Various retaining elements 20, in particular also splays 40, can
be added to
them in their final areas 14 and 15.
The halves 50 and 60 are preferably joined by means of the hook-shaped joining
ele-
ments 52 and 62, which encircle one another with a continuity of strength and
form. It is
important here that the joint is constantly subjected to tension.
In the embodiment of Fig. 24 the lower half 50 of the concrete reinforcement
element 10
is complemented by an upper half 60 made of coiled rods 66, whereby this is
tilted in a Z-
shape and can be put into an appropriate recess in the lower half 50.
Fig. 25 shows two views on the broad side of a further embodiment of the
concrete rein-
forcement element 10 according to the current invention. This embodiment is
character-
ised by the fact that the area between the broken lines compared to the areas
above or
below is shifted backwards or forwards from the image plane, going in or going
out
against the upper and lower area. This becomes visible when viewed on the
narrow edge
of both components. Alternatively, component 10 can also be realised in such a
way, that,
for example, only an upper part is shifted against a lower part of the
component, for ex-
ample, by tilting or stressing.
Herby, in both cases it is achieved that two such identical components 10, if
they are
pushed into each other with the edges 16, in which there are the openings of
the side re-
cesses 30, form a dovetail and a covered area comes into being, so that both
compo-
An142/Gii 2
CA 02541978 2006-04-07
WO 1148 CA 11 PCT/DE2004/000458
nents 10 together form a recess 30, which secures an element S, which is
threaded
through it, of a reinforcement layer Bo or Bu from slipping upwards or
downwards. The
concrete reinforcement element 10 in the middle of Fig. 26 encircles per
element S each
of the outermost layers Bo_x and Bu_x of the upper and lower reinforcement
layers Bo,
Bu, while the concrete reinforcement element 10 represented on the right of
Fig. 26 only
joins elements S of the inner layers Bo_y, Bu_y of the upper and lower
reinforcement lay-
ers Bo, Bu.
The number and embodiment of components 10 have to be calculated according to
the
type of concrete used and the desired load-bearing capability, in order to
achieve the
necessary punching shear strength, for exampie in the area of a column. In
each case
this results in a significant increase in the shear force resistance of the
component 1.
The current invention is not limited to one of the aforementioned embodiments,
but in-
stead can be varied and altered in many different ways. The concrete
reinforcement ele-
ments can, for example, be fabricated from other materials such as steel
sheeting, plastic
or composite material. One can also extend the concrete reinforcement elements
10 or
their bi-dimensional structure 12 horizontally to their longitudinal centre M,
in order to be
able to encircle several reinforcement bars S of the upper and lower
reinforcement layers
Bo, Bu simultaneously. It is important here as well that the concrete
reinforcement ele-
ments 10 are always simple, flat sheet metal components, if necessary tilted
at the ends
or in the middle, featuring retaining elements in the upper and lower areas
which receive
or encircle the reinforcement bars S of the upper and lower reinforcement
layers Bo, Bu.
Mounting is achieved without any complex welding or assembly work, whereby the
upper
and lower reinforcement layers Bo, Bu are pulled tight by the concrete
reinforcement ele-
ments 10, joining them with a continuity of strength.
All of the traits and advantages in the claims, description and the
illustrations, including
constructive details, spatial arrangements and procedural steps can be
essential to the
current invention on there own or various different combinations.
An142/Gu 2
CA 02541978 2006-04-07
WO 1148 CA 12 PCT/DE2004/000458
List of reference numerals
a Angle
Bo, Bu Reinforcement layer
Bo_y, Bu_y Inner layer
Bo_x, Bu_x Outer layer
M Longitudinal centre
S Concrete reinforcement element
1 Reinforced concrete or pre-stressed concrete component
10 Concrete reinforcement element
12 Main component
14 Upper area
15 Lower area
16 Longitudinal edge
Retaining elements
24 Indentation
26 Flat bar
20 28 Clamp
Recess
31 Sub-area
32 Extension
33 Notched edge
25 34 Securing means
Reception
36 Marking
Splay
5 0 Lower half
30 52 Joining element
60 Upper half
62 Joining element
66 Coiled rods
An142/Gu 2
