FR2540162A1 - Rigid metal connection between raised slab floors and precast reinforced concrete columns for self-stable structures - Google Patents

Abstract

The connection forming the subject of the patent consists of a collar built into the floor : 1 vertical web, 2 lower horizontal flange, 3 stiffener of the upper edge of the web, 4 inclined local stiffeners of the flange, 5 passing hole for the raising. A gridlike cage is built into the column : 8 peripheral bars, 9 transverse bars in the column, 10 longitudinal bars in the column, 11 vertical bars in the column. They are connected by welds via local metal wedges 7 located near the upper and lower facing elements of the floor, at the places of the bars of the latter. A temporary fixing is carried out through reinforcing plates 15 provided with holes 16, which plates are built into the columns, by means of pins.

Description

RIGID MEsDXLLIOUE LINK BETWEEN PUkNCMERS - SLABS LIFT
AND PREFABRICATED POSTS IN REINFORCED 3PETON,
FOR SELF-STA3LE STRUCTURES
In buildings with raised slabs, a static and dynamic balance could be ensured - either by metal collars, in the form of an angle, incorporated into the
floors and supported on pins crossing the posts for balance
vertical, associated with concrete walls or interior buildings for
bracing, - either by complex links of the U-shaped metal collar type
coated, connected by continuous welding, with an incorporated metal jacket
to the concrete post.

 This patent also relates to a complex link, simultaneously ensuring vertical and horizontal balance, but calling on other technical methods which will be explained in the following pages.

This link is made up
10 - a collar incorporated into the floor slab (1 to 5)
20 - a reticulated "cage" incorporated in the prefabricated post (8 d 11)
3 - connecting parts between the two previous sets (7)
4 "- of temporary fixing parts, incorporated in the post (15 and 16)
5 - attachments to the floor lifting rods or to
temporary fixing parts (19 to 21).

Collar incorporated into the floor slab
The slab floors are prefabricated at ground level and stored by
stacking, they must be equipped for lifting, beforehand, with
necklaces intended to be part of the connection. These will therefore be found at
turn of each post.

The collar is formed by a metal profile whose shape is defined by
the functions it must fulfill.

These functions are as follows
- wear the floor when it is permanently fixed to the posts,
- carry the floor when it is lifted along the posts by tie rods
powered by motors located on the tops of the said posts, - carry the floor when it is temporarily fixed to the posts, at its
destination level, without fasteners encroaching on the area
lifting rods and holes in their passages, - -allow the transmission of torques, due to horizontal stresses
on the building, between the posts and the slab floors.

To satisfy these functions, the collar is made up of - a vertical core (1) located very close to the facing of the post, - a wing, at the lower edge of the core, horizontal (2), - a stiffener lateral of the friend's upper edge (3), - stiffeners - inclined bars - connecting the upper edge from place to place
laughing at the edge of the wing in order to stiffen it (4), - through and fixing holes, made in the wing, for tie rods
and their bolts (18), as well as for the bolts (18) intended for
the provisional fixing (15).

 This collar, when it is hooked by the lifting rods of the floor, must have a rigidity such that it can guarantee the good behavior of the surrounding concrete, in combination with the concrete bars located in the floor.

 The core (1) has the roll to support the shearing forces which occur between the different fixing points of the lifting and / or temporary fixing ties, or between the different points of the edge of the floor which surround the post.

The lateral stiffener of the upper edge of the unleavened (3) is intended - to resist "spillage" - lateral bending - during the lifting of the
floor and temporary fixing. The thickness of this stiffener is
limited by the presence of the lifting or provisional fixing bolts (18), - to carry the bars or cables of the upper reinforcement of the floor which
are fixed by welding.

The wing of the collar (2) is used for: - carrying the concrete with admissible local compression ratios, and occa
sion the formation of compression rods in the floor, - carry and fix by welding the bars or cables of the lower frame
from the floor (6), - contain the holes (5) for the location of the lifting bolts (18)
provisional fixing, as well as for the subsequent passage of the tie rods for the
for lifting the lower floors.

 The stiffeners (4) of the wing (2) are simple bars of a section and spacing determined by calculation, in order to guarantee the wing sufficient flatness.

Reticulated cage incorporated in the prefabricated post
This cage is made in the workshop. It has the following functions - to introduce into the post the vertical stress, symmetrical or not,
due to the floor loads, - to transmit to the floor the couple of horizontal forces, due to the inclination
local height of the post, under the horizontal stresses on
such as wind or earthquake, - to restore continuity between the two opposite edges of the floor, at
contact with the post, especially the continuity between the bars
both in bending the floor.

For this purpose, the cage is made up of - two bars grids (9 and 10), one upper and one lower,
connected on their peripheries tangent to the conto.ur of the post, by
vertical bars (11) located at the ends of the bars of the grids and
between the peripheral bars (8).

 A grid of the cage consists of two series of continuous bars (9 and 10) perpendicular to one another. These bars are welded together at the crossings and they are also welded to the peripheral bars (8). The latter have a rectangular section of dimensions such that the bars of the grids and the outer shims (7) can be welded thereto.

 On the other hand, these peripheral bars have the role of introducing into the post the vertical forces coming from the floor, by generation of inclined compression connecting rods in the concrete.

 The bars of the grids are located at the same level as the bars or cables of the floor that they must connect.

 In this way, we concretize the new principle of this connection which is for a given direction, we transmit directly, via the faces of the perpenticular collar to this direction, most of the horizontal forces of the bending torque coming from floor bars and going to the bars of the post cage grid and vice versa.

 A reduced part of this torque will be taken up by the lateral faces of the link thanks to the "torsion-resistant moment" of their set of bars.

 It is understood that the transmission of the horizontal forces between the bars of the cage and the concrete of the post is effected by the phenomenon of adhesion.

Connection pieces between floor collar and post "cage":
These parts are local wedges (7) of trapezoidal section and very reduced horizontal length forcefully introduced into the space between the edges of the upper peripheral bars (8) of the cage and the ends of the floor bars (6) fixed by weld on the upper edge of the collar or between the lower peripheral bars and the lower edge of the collar.

 All the edges of the contact surfaces of these shims are welded to the aforementioned parts of the post or of the floor.

 It is understood that the length of the weld bead is determined by calculation, taking into account the vertical, horizontal shear and the traction.

The horizontal length of the shims takes these factors into account.

Parts, of temporary fixing, incorporated in the post:
When the floor is raised to the final level, in order to release the lifting motors, it must be temporarily fixed on the post while waiting for the welds to be made.

 To this end, metal reinforcements are provided in the posts in the form of thick plates (15) connected to the frames of the post and / or those of the cage, depending on the situation.

 There are two or more plates per post, in principle located on two opposite faces, except for corner posts.

 Each of these plates is provided with a hole (16), and these holes are on the same horizontal.

 A pin (17), of adequate section, will pass through these holes, thus ensuring provisional fixing. This pin also passes through hooking pieces (21) of the floor which will be discussed below.

Floor hanging parts:
In order to hang the floor to the lifting rods to the temporary fixing pieces in the post, there are four large diameter bolts (18) related to the loads. needed, we can provide several.

 Each of these bolts is inserted into the hole reserved for this purpose (5) in the wing (2) of the floor collar.

The bevelled edge of this hole and the difference in level between the underside of the collar and the underside of the floor gives a thickness,
bolt head, sufficient to withstand the lifting load.

This bolt is protected against fresh concrete, when concreting the plan
dear, by a cardboard or plastic cylinder (19) which gives it a space where a metallic "turnbuckle" (20) will be screwed.

 This turnbuckle is provided, at its upper part, with a height-adjustable ring (21) for temporary fixing or for attachment to the lifting rod.

 Operation: these bolts are in their reserved spaces before concreting the floor. Before lifting, the turnbuckles (20) with their rings (21) are screwed onto the bolts (18) which, in this way, cannot fall. The lifting rings are hooked to the tie rods and the floor is raised. When you reach the destination of the floor, you set the turnbuckles for the temporary fixings and pass the spindle (17) through the turnbuckle rings (21) in the posts.

 This temporary fixing provides work safety for the space below the raised floor.

 At this time, the lifting rods can be released and lowered to the ground through their holes (5) in the floors from which the bolts have been removed.

 This is followed by the insertion phase of the wedges (7), of trapezoidal section, on the upper face of the floor and their welding. The shims on the underside will be put in place and welded when the bottom floor is lifted.

 Then the spindle and the temporary fixing bolts will be removed the space between floor and post will be stuffed with mortar. Finally, the exposed parts of the necklace will be covered with mortar or plaster.

 Advantages: the collar of the floor is equivalent to a metal capital, incorporated in its thickness, which distances the critical line of shearing, compared to the facing of the post, thanks to the formation of "compression rods" of concrete supported on its horizontal wing.

 The collar transforms the "fragile" rupture of the slab floors - rupture which does not prevent - slow rupture by generalized plasticization. The security of these floors is thus improved.

 The section of the collar is reduced to the minimum necessary, while keeping the rigidity of the wing, thanks to the local inclined stiffeners.

 The "cage", in the post, receives directly, in its horizontal bars, the forces coming from the horizontal reinforcements of the floor, and transmits them on the other side of the plate without parasitic efforts.

 The vertical forces are transmitted to the concrete of the post by the adhesion of the bars of the cage, more especially by the peripheral bars which generate compression rods. The welds are calculable and provide the desired security.

 The whole of this connection is of a relatively reduced weight and simple to manufacture.

 In the case of duct posts or walls of elevator shafts or stairwells, the same principle of connection is applicable by using a metal plate on the side of the hollow of the element considered, which will carry the nuts of the bars. , or hanger which will be welded the bars of the cage grid.

Non-limiting example
For a six-storey building with cross-section poles of the order of 0.6 x 0.60 m, spaced 10.80 m in the direction of the facade and 8.80 m in the direction perpendicular to the previous one , with prestressed slab floors in both directions, with a thickness of 0.25 m and with false supports of 1.40 m, the following dimensions are found
under the usual vertical stresses and for horizontal stresses due to the wind of a type I region, exposed site, the bars of the cage indicated on the drawings are of a diameter of about 14 mm, while the peripheral bars have a rectangular section of 20 x 30mm.

The collar is made of sheet metal of the order of 10 to 15 mm. The lengths of the weld beads are achievable to meet the safety required by regulations.

 Finally, in the post, the bars of the cage grids leave enough space for the post bars.

Claims (9)

 1 - Rigid metal connection, between raised slab floors and prefabricated reinforced concrete posts, offering stepped structures the character of self-stability thanks to its built-in value characterized in that it consists of a collar incorporated into the floor ( 1 to 5) and a cross-linked cage incorporated into the post (8 to 11).  2 - Connection, according to claim 1, characterized by the collar having a vertical core (1) close to the post, a horizontal wing (2) at its lower part, a stiffener (3) along the upper edge of the friend and inclined stiffeners (4) connecting the edge of the wing to the upper edge of the core.  3 - Connection, according to claims 1 and 2, characterized by the horizontal wing of the collar having holes (5) for accommodating vertical bolts (18) used for lifting and temporary fixing of the floor, as well as for the descent the lifting rods through the floor.  4 - Connection, according to claims 1 and 2, characterized in that the horizontal reinforcements (6) of the floor are fixed by welding on its horizontal wing and on its upper edge, thus arriving very close to the facings of the post.  5 - Connection, according to claim 1, characterized by the crosslinked cage incorporated in the post and consisting of two metal grids (9 and 10), one upper and one lower, located at the respective reinforcements of the floor. The bars of these grids must be able to transmit the forces coming or going to the floor through the post. The peripheral bars (8), of rectangular section, more specifically transmit the vertical forces to the posts by creating compression rods in the concrete. The two grids are connected by vertical bars (11) which stiffen the cage against the torsional effects of the assembly.  6 - Connection, according to all of claims 1 to 5, characterized in that the collar and the cage are connected by the welds made on local wedges (7), of trapezoidal section, introduced into the space between edges of the collar and peripheral bars of the cage.  7 - Connection, according to all of claims 1 to 6, characterized in that it also has reinforcing metal plates (16), fixed on the facings of the post, drilled (15) to receive a pin (17) for temporary fixing of the floor.  8 - Connection, according to all of claims 1 to 7, characterized in that it is provided with vertical bolts (18) located in the holes of the horizontal wing of the collar and which will be connected via the turnbuckles cylindrical (20) and rings (21), to the hooks of the lifting rods or to the temporary fixing pins.  9 - Connection, according to all of claims 1 to 6, characterized in that it has a vertical thickness less than that of the floor, which allows to cover it with mortar or plaster in order to hide and protect it against fire.