FIELD OF THE INVENTION
-
The present invention concerns a substantially plane
metal trestle for building constructions and a construction
system using a plurality of said metal trestles. The latter
consist of metal profiles, such as L bars or plates, easily
found on the market and can be arranged and connected one
to the other so as to form beams and/or pillars, by means
of conventional clamping elements, such as for example
bolts, nails or other. The size of the trestles according
to the present invention can be standardized, making them
more economical.
BACKGROUND OF THE INVENTION
-
In the field of building constructions different types of
metal elements are known by means of which the main bearing
structures of buildings are achieved. Such structures,
mainly consisting of beams and pillars, can be achieved
with profiles of different cross sections: HE, IPE, UPN, L-shaped,
T-shaped; they can be used individually, or joined
together by means of bolting, or welding, according to
their size and the loads they have to support.
-
The metal elements have the disadvantage, however, that
they cannot easily be integrated with the concrete
structures cast on site, generally used to achieve the
secondary structures of the buildings (floors), since the
solid cores of the profiles prevent the passage both of the
concrete and also of the relative reinforcements.
-
It is also known to achieve beams using metal elements
arranged in parallel stringers, connected by one or more
elements configured in a lattice and positioned between a
lower stringer and an upper stringer. The lower stringer is
formed by a base sheet, perpendicular to the lattice,
and/or by at least two metal round pieces, while the upper
stringer is formed by at least two metal round pieces. The
upper and lower stringers are welded at opposite ends to
the metal connection elements.
-
These conventional metal beams, which are only suitable
for mixed structures of steel and concrete, also have the
following disadvantages and the following limitations:
- they are not suitable for achieving both the elements of
the structural frames (pillars and beams) since their use
is limited only to the beams;
- they pose serious executive problems in achieving the
nodes between pillars with a traditional reinforcement and
beams with prefabricated reinforcement; these problems are
connected with the restoration of the continuity of the
upper stringers which, necessarily performed through
superimposition, causes excessive bulk and, in the outer
nodes, problems with anchorage;
- their self bearing capacity is limited by the fact that
the upper stringers, subject to instability due to the
combined bending and compressive load, are not mutually
connected by elements able to contrast their listing on the
horizontal plane.
-
A purpose of the present invention is to achieve a metal
trestle which consists of simple elements, easily found on
the market, and can constitute a modular element able to be
coupled with at least another modular element of the same
or similar type, in order to achieve structures both
completely metal and also of the mixed steel-concrete type.
-
The present Applicant has devised and embodied the metal
trestle according to the present invention in order to
overcome the shortcomings of the state of the art and to
obtain these and other purposes.
SUMMARY OF THE INVENTION
-
The present invention is set forth and characterized in
the main claims, while the dependent claims describe other
innovative characteristics of the invention.
-
In accordance with the above purpose, the metal trestle
for building constructions according to the present
invention comprises a first stringer, a second stringer and
a central connection element between the two stringers.
Each of the two stringers consists of a metal profile
having at least a plane surface on which the above central
connection element is attached. Moreover, the plane
surfaces of the two stringers are co-planar. In this way,
each metal trestle is substantially plane, or lying on a
plane.
-
Advantageously the metal profiled elements that make up
the stringers are plates or L bars, while the central
connection element is a metal round piece or other profile
of a different section other than circular, having a
substantially zigzag development and welded to the plane
surfaces of the metal profiled elements in correspondence
with its variations in direction.
-
If the metal profiled elements consist of L bars, the
metal round piece can be welded inside the angle formed by
the two wings of the angular element, or outside it.
-
The trestles according to the present invention can be
applied both to make reinforced concrete structures and
also to make metal trestled structures. To be more exact,
in the construction of reinforced concrete structures the
traditional metal reinforcement of the beams, and possibly
that of the pillars, is totally or partly replaced with one
or more trestles according to the present invention, which
are combined or arranged so as to form a box-like element.
Each trestle can advantageously be made in a workshop or
production plant, preferably by means of automated
machines. The connection of the central element to the
upper and lower bar is performed by welding, for example
electro-welding. The metal profiles, angular or flat, are
provided with through holes by means of which, with bolts,
threaded bars or nails, they can be joined to other similar
metal profiles.
-
For beams in reinforced concrete, using the trestles
according to the present invention, partial pre-fabrication
is also provided with a cast of concrete into the lower
part of the section.
-
The trestles according to the present invention allow to
implement a new construction system to make frames or
structures both totally metal and also in reinforced
concrete. The new construction system advantageously
differs from conventional systems:
- in the original way in which the beams are made, by
assembling the plane metal trestles;
- in the way in which the beams thus achieved are
constrained to the vertical supports during the
construction step;
- because the partly pre-fabricated beams, suitable for the
direct support of the floors, can be self-bearing for loads
during the construction step;
- in the simplicity of construction;
- in its executive precision;
- in its technological reliability.
-
When the trestles according to the present invention are
used to make reinforced concrete structures, the connection
bolts, or alternatively the threaded bars with double nut,
not only make the trestles solid with each other but also
perform, if properly proportioned, the function of
connectors between the metal elements and the concrete, in
order to improve adherence.
BRIEF DESCRIPTION OF THE DRAWINGS
-
These and other characteristics of the present invention
will become apparent from the following description of some
preferential forms of embodiment, given as a non-restrictive
example with reference to the attached drawings
wherein:
- fig. 1 is a front view of a metal trestle for building
constructions according to the present invention;
- fig. 2 is a section from II to II of fig. 1;
- fig. 3 is a front view of a first variant of the trestle
in fig. 1;
- fig. 4 is a section from IV to IV of fig. 3;
- fig. 5 is a front view of a second variant of the
trestle in fig. 1;
- fig. 6 is a section from VI to VI of fig. 5;
- fig. 7 is a cross section of a first coupled structure,
made using two trestles as in fig. 1;
- fig. 8 is a cross section of a second coupled structure,
made using two trestles as in fig. 1;
- fig. 9 is a cross section of a third structure, made
using two trestles as in fig. 1 and one trestle as in
fig. 5;
- fig. 10 is a cross section of a fourth structure, of the
box-like type, made using four trestles as in fig. 1;
- fig. 11 is a cross section of a fifth structure, of the
box-like type, made using four trestles as in fig. 1;
- fig. 12 is a cross section of a sixth structure, of the
box-like type, made using four trestles as in fig. 1;
- fig. 13 is a cross section of a seventh structure, of the
box-like type, made using three trestles as in fig. 1 and
one trestle as in fig. 5;
- fig. 14 is a cross section of an eighth structure, of the
multi-cell type, made using six trestles as in fig.1 and
one trestle as in fig. 5;
- fig. 15 is a cross section of a box beam made partially
inside the floor using four trestles according to the
present invention;
- fig. 16 is a plane view of the beam in fig. 15, mounted
on two vertical supporting elements; to be more exact,
for better understanding, in the left part of the drawing
only the basic reinforcement is shown, while on the right
part of the drawing only the additional reinforcement is
shown;
- fig. 17 is a longitudinal section from XVII to XVII of
fig. 16;
- fig. 18 is a cross section of a perimeter box beam made
partially inside the floor using a structure in fig. 13;
- fig. 19 is a cross section of a box beam made totally
inside the floor using a structure similar to that in
fig. 11;
- fig. 20 is a cross section of a variant of the box beam
made totally inside the floor in fig. 19;
- fig. 21 is a front view of two consecutive pillars,
during the assembly step, made using trestles according
to the present invention;
- fig. 22 is a front view of the two consecutive pillars in
fig. 21 after assembly;
- fig. 23 is a cross section from XXIII to XXIII of fig.
21;
- fig. 24 is a plane view of a structure comprising: a
pillar in fig. 21 and a beam in fig. 16; to be more
exact, for a better understanding, in the left part of
the drawing only the basic reinforcement is shown, while
in the right part of the drawing only the additional
reinforcement is shown;
- fig. 25 is a section from XXV to XXV of fig. 24;
- fig. 26 is a front view of a coupled beam, during
attachment to external constraints, made using two
trestles according to the present invention and having
the wall rods phased;
- fig. 27 is a front view of the coupled beam in fig. 26,
attached to the external constraints;
- fig. 28 is a cross section from XXVIII to XXVIII of fig.
27;
- fig. 29 is a view from above of the coupled beam in fig.
27;
- fig. 30 is a front view of a coupled beam, made using the
trestles according to the present invention, and having
the wall rods counterphased;
- fig. 31 is a cross view of the coupled beam in fig. 30;
- fig. 32 is a front view of a beam with cross stiffening
brackets, made using two trestles according to the
present invention;
- fig. 33 is a transverse view of the beam with cross
stiffening brackets in fig. 32;
- fig. 34 is a view from above of the beam with cross
stiffening brackets in fig. 32.
DETAILED DESCRIPTION OF SOME PREFERENTIAL
FORMS OF EMBODIMENT
-
With reference to figs. 1 and 2, a trestle 10,
substantially plane, according to the present invention
comprises an upper stringer 11 and a lower stringer 12,
parallel to each other and made with two angular metal
profiles provided with through holes 13 and 15. The two
stringers 11 and 12, which have plane and co-planar
surfaces, are mutually connected by means of wall rods 16,
consisting of a zigzag shaped metal round piece. The
latter, in correspondence with its variations in direction,
is welded to the plane and co-planar surfaces of the
stringers 11 and 12, so as to be arranged inside the right
angle formed by the wings of the angular elements.
-
According to a first variant, shown in figs. 3 and 4, in
a trestle 110 according to the present invention the wall
rods 16 are welded outside the right angle formed by the
angular stringers 11 and 12, instead of inside the wings of
said angle.
-
According to a second variant, shown in figs. 5 and 6, in
a trestle 210 according to the present invention the
parallel stringers 211 and 212 are made with flat metal
profiles and the wall rods 16 are welded onto one of their
plane surfaces.
-
Both the angular profiles and the flat profiles are of
the type easily found on the market.
-
Each metal trestle 10, 110, 210 can advantageously be
made at a specialized work shop.
-
According to a characteristic of the present invention,
by joining together two or more metal trestles 10, 110, 210
it is possible to achieve an extremely various plurality of
structures, some examples of which are shown in figs. 7 to
17.
-
As can be seen, the metal trestles 10, 110, 210 are
easily joined together using connection bolts 20 and
threaded bars 21, or nails (not shown in the drawings),
possibly with the aid of conventional elements that are
easily found on the market, such as intermediate plates or
spacers 22, flat wall rods 23, bayonet joints 25,
supporting cross-pieces 26, diagonal flat bracing rods 27
and cross stiffening brackets 29.
-
To be more exact, fig. 7 shows a first structure 30
consisting of two coupled trestles 10, coupled together and
with intermediate plates 22 interposed.
-
Fig. 8 shows a second structure 31 consisting of two
bracketed coupled trestles 10, that is, coupled with cross
stiffening brackets 29 interposed.
-
Fig. 9 shows a third structure 32 consisting of two
trestles 10, arranged laterally, and a trestle 210 arranged
centrally and parallel to the lateral trestles 10. The
trestles 10 and 210 are coupled together by means of bolts
20 and threaded bars 21, with cross stiffening brackets 29
and intermediate plates 22 interposed.
-
Fig. 10 shows a fourth structure 33, of the box-like type
and with a substantially square cross section, which
consists of four trestles 10 arranged in a quadrilateral,
with the angular elements 11 and 12 directly coupled by
means of bolts 20, without any cross stiffening brackets 29
and/or intermediate plates 22 interposed.
-
Fig. 11 shows a fifth structure 34, of the box-like type
and with a substantially square cross section, which
consists of four trestles 10 arranged in a quadrilateral,
but with the different angular elements 11 and 12 coupled
by means of bolts 20, with intermediate plates 22
interposed.
-
Fig. 12 shows a sixth structure 35, similar to the fifth
structure 34, but where the lower trestle 10 is arranged in
a turned over position compared with structure 34.
-
Fig. 13 shows a seventh structure 36, similar to the
fifth structure 34, but where a trestle 210 with flat metal
profiles 211 and 212 is used instead of a trestle 10 with
angular elements.
-
Fig. 14 shows an eighth structure 37 similar to the third
structure 32, but where two pairs of horizontal trestles 10
are used instead of the cross stiffening brackets 29 and
where the intermediate plates 22 are arranged between the
vertical and horizontal trestles.
-
If we examine the structures from 30 to 37 as shown
above, it can easily be seen that the design engineers of
building constructions can use the trestles 10, 110, 210 to
make structural sections of different shapes and sizes,
obtaining a numerous series of solutions suitable for the
various requirements which occur in structural design.
-
Moreover, with the trestles 10, 110, 210, that is, by
means of the structures 30 to 37 described above, it is
possible to achieve different types of beams, some of
which, to give an example, are shown in figs. 15 to 20. We
shall now give some examples of said beams.
Example No. 1 - Box beam made partially inside the floor
-
With reference to fig. 15, we shall describe a box beam
40, made partially inside the floor using three trestles 10
and a trestle 110, joined together so as to form a
structure similar, but not equal to the fifth structure 35
as described above.
-
The partial prefabrication of the beam 40 can
advantageously occur in the prefabrication workshop by
performing the following operations:
- two trestles 10, indicated by 10a and 10b, and a trestle
110, are assembled to form the two flanks and the lower
side of the beam;
- a possible additional metal reinforcement is introduced,
consisting of brackets 41, longitudinal bars 42, possibly
shaped bars 43 and possibly diagonal flat bracing rods 27;
- the fourth trestle 10d is assembled, which constitutes
the upper side, attaching it to the upper stringers 11 by
means of bolts 20;
- the flat wall rods 23 (fig. 16) and the bayonet joints 25
are assembled at the ends of the beam 40;
- the lower joints are mutually connected by means of the
supporting cross-piece 26;
- the concrete cast 45 is made, to achieve the lower part
of the beam 40, taking care that in the end segments
hollows 46 must be left in the thickness of the cast 45 in
order to allow the installation of the lower connection
reinforcements 47, provided to make the structural nodes.
-
Once pre-fabricated, the beam 40 is installed on site, by
means of the following steps, described with reference to
figs. 16 and 17, in which two vertical supporting elements
50 and 51 are shown, made for example with any traditional
system:
- the partly pre-fabricated beam 40 is positioned on the
vertical supports 50 and 51, after levelling the supporting
zones;
- the ends of the beam 40 are attached to the vertical
supports by means of vertical blocks 52 passing through the
holes made in the supporting cross-pieces 26;
- the segments of reinforcement 47 are inserted in
correspondence with the nodes;
- the floors 55 (fig. 15) and the relative reinforcements
are positioned;
- the concrete is cast to complete the whole.
Example No. 2 - Perimeter box beam made partially inside
the floor
-
With reference to fig. 18, we shall describe a perimeter
box beam 62, made partially inside the floor, which
consists of three trestles 10, respectively 10b, 10c, 10d,
and a trestle 210 which makes possible to not go beyond the
outer edges 63 of the vertical supports 50 and 51. The four
trestles 10b, 10c, 10d and 210, joined together, form a
structure equal to the seventh structure 36 described
above.
Example No. 3 - Box beam made totally inside the floor
-
With reference to fig. 19, we shall describe a box beam
made totally inside the floor 65, which consists of four
trestles, respectively 10a, 10b, 10c, 10d. The assembly of
the four metal trestles is performed in the same way as
indicated in example 1. The thickness of the concrete 66,
cast in the pre-fabrication site, in this case is limited
to the height of the lower stringers 12 of the trestles 10a
and 10b. The assembly on site and the completion on site
differ from what was indicated in example n° 1 in that for
the provisional support of the floors 55 the wings 12a of
the external angular elements of the lower stringers 12 are
used, which for this purpose can be chosen on uneven wings,
with the wings 12a wider than the others.
-
According to a variant, shown in fig. 20, a box beam made
totally inside the floor 68, similar to the beam 65,
differs from the latter in the arrangement of the lower
trestle 10c, which is turned over by 180° with respect to
that of the beam 65 in order to allow to achieve a greater
thickness of the ironcover of the lower metal
reinforcements and hence a greater protection of the
reinforcements themselves. This variant, obviously, can be
adopted in all applications.
-
We shall now illustrate another application of the
trestles according to the present invention, which can also
be used to make the base reinforcement of supporting
pillars.
Example No. 4 - Frame where the pillar reinforcement
consists of box trestles
-
With reference to figs. 21 to 25, a base reinforcement of
a pillar 70 consists for example of a box-like structure
similar to the fifth structure 34 (fig. 11), which can
possibly be integrated with longitudinal bars and brackets,
not shown in the drawings.
-
The construction of the pillars 70 of a general plane or
floor occurs by means of the following steps:
- the trestles 10 of the box-like structures that make up
the base reinforcement of the pillars 70 of the general
plane are connected with the similar reinforcement of the
pillars 70 below, by using flat rods 23, bayonet joints 25
and bolts 20. Figs. 21 and 22 show the connection of the
box trestles of the pillars 70 of the general plane. The
joint must be made in a zone outside the nodes. For pillars
which protrude from the foundations it is necessary to
prepare in the foundations the connecting elements for the
trestles of the pillars 70 above;
- the formworks of the pillars are made;
- the concrete is cast to make the pillars as far as
elevation 90 (fig. 22) where the beams above are disposed.
-
The construction of the horizontal beams above the
pillars 70 of the general plane occurs by means of the
following steps:
- the partly prefabricated beams 40 that make up the truss
are installed, after supporting elements 91 (semi-joints)
have been inserted into the lower stringers 12 of each beam
of the truss (figs. 24 and 25);
- the additional reinforcements 47 of the beams 40 are
installed in correspondence with the nodes of the frame;
- the upper stringers 11 of the consecutive beams located
on the same truss are connected by means of the bayonet
joints 25;
- the floor elements are installed;
- the concrete is cast to complete the whole.
Another use of the trestles 10, 110, 210 according to the
present invention is to make metal structures. This allows
to obtain a very versatile new construction system, which
allows the construction of trestled structures of various
shapes and sizes, by assembling two or more trestles 10,
110 and/or 210 by means of the connection elements
described above.In the following examples some possible applications are
indicated, given as an indication only: from them it is
clear that the design engineers and constructors who use
the present invention can achieve a numerous series of
structural solutions suitable for various requirements that
arise in the construction industry.
Example No. 5 - Coupled beam
-
With reference to figs. 26 to 31, as in the first
structure 30 (fig. 7), by using two trestles 10 only we
obtain a coupled beam 80. To be more exact, figs. 26, 27,
28 and 29 show a coupled beam 80, with the wall rods 16
phased, in the front view (fig. 27), transverse (fig. 28)
and from above (fig. 29). Fig. 26 shows the same beam 80
during its attachment to external constraints 81.
-
Figs. 30 and 31 show a coupled beam 82 with the wall rods
16 counterphased. This solution offers the advantage that,
for the frequent case of normal loads to the axis of the
beam 82, any cross section of the beam intersects a wall
rod 16; this circumstance contributes to improve the local
stability of equilibrium. For this case the holes, needed
to couple the trestles 10, must be staggered by about 90°
with respect to the position shown for cases previously
seen.
Example No. 6 - Coupled beam with cross stiffenincr bracket
-
With reference to figs. 32, 33 and 34, by using two
trestles 10 and cross stiffening brackets 29 we obtain the
coupled beam 85.
-
In addition to the uses set forth above, with the
trestles 10, 110, 210 according to the present invention
and using for example box trestle elements like those
described above, it is possible to construct frames with
many bays and floors, operating in a similar way to that
indicated in example 4 concerning reinforced concrete
frames. For this type of use (steel trestled frames)
substantially the same methods of execution are used as
indicated in example 4, with the variant that the lower
stringers 12 too of consecutive beams can be connected with
bayonet joints since the connection zones are free because,
obviously, no concrete casts are provided.
-
We shall now give, purely as an example, some performance
characteristics of some structural sections obtained using
the trestles 10, 110, 210 according to the present
invention.
Reinforced concrete beam, partly pre-fabricated
-
With reference to fig. 15, the static behavior is
analyzed of a horizontal beam deriving from a beam 40
defined by the following data;
Geometric parameters
-
- B = 70 cm;
- b = 60 cm;
- H = 30 cm;
- h = 25 cm;
- a = 10 cm;
- i = 48 cm;
- stringers 11 and 12: 50 mm x 50 mm x 5 mm;
- wall rods 16: d = 12 mm - pitch 20 cm;
- additional longitudinal reinforcement 47: d = 24 mm;
- additional brackets 41: d = 8 mm - pitch 20 cm;
- shaped transverse reinforcement: d = 8 mm - pitch 20 cm;
- bolts 20: M10.
-
Materials
-
- Hot rolled steel, for base reinforcement, type Fe 510;
- Steel for additional reinforcement type FeB 44K
Welding with corner beads - II class;
- Bolts class 8.8.
-
Concrete class Rck 35
Performance characteristics of the partly pre-fabricated
section
-
- Bending moment resistant to last limit state: M = 135.5
KNm;
- Shearing stress resistant to the last limit state: T =
50.3 KN
Performance characteristics of the complete installed
section
-
- Bending moment resistant to last limit state: M = 211.8
KNm;
- Shearing stress resistant to the last limit state: T =
253.7 KN;
Coupled beam
-
With reference to figs. 27, 28 and 29, the static
behavior is analyzed of a horizontal beam deriving from a
coupled beam 80 defined by the following data:
Geometric parameters
-
- B = 17 cm;
- H = 25 cm;
- stringers 11 and 12: 50 mm x 75 mm x 6 mm;
- wall rods 16: d = 12 mm - pitch 20 cm.
-
Materials
-
- Hot rolled steel for base reinforcement, type Fe 510;
- Welding with corner beads - II class;
- Bolts class 8.8.
-
Performance characteristics of the section
-
- Bending moment resistant to last limit state: M = 105.5
KNm;
- Shearing stress resistant to the last limit state: T =
50.3 KN.
-
It is clear that modifications and/or additions of parts
may be made to the metal trestles 10, 110, 210 as described
heretofore, without departing from the field and scope of
the present invention.
-
It is also clear that, although the present invention has
been described with reference to some specific examples, a
person of skill in the art shall certainly be able to
achieve many other equivalent forms of metal trestles for
building constructions, having the characteristics as set
forth in the claims and hence all coming within the field
of protection defined thereby.
