NO177724B - Connection between wall element and joist plate as well as connecting means for such connection - Google Patents

Description

The present invention relates to a well-known type of prefabricated multi-storey construction, the outer walls of which are composed of storey-high prefabricated concrete wall panels and the floor of which is composed of prefabricated, often pre-stressed, single-stressed joist plates (hollow deck element), which in the finished building form horizontal stiffening joist panels. At the outer perimeter of the building, the joists join the walls at the height of the horizontal connections between wall units placed on top of each other, or with regard to the final roof level, on top of the uppermost wall elements. Wall units that are substantially transverse to the longitudinal direction of the joist plates serve as storage for normal vertical forces when the plate ends are supported on the upper side of or on a ledge near the top of the wall units at each joist level, while wall units that are parallel to the span direction of the joist plates also serve as shear-absorbing wall discs and thus must be properly connected to the joists. There are thus two types of connections between the outer walls and joist panels in this building construction, namely a support connection and a shear connection for walls, each of which has a variant for the middle joist layer and the top joist layer (ceiling joist layer).

In addition to load-absorbing support for joist plates (self-weight and load in the failure limit state), the support connection must also have: - the ability to place, accommodate and cast in the joist's disk reinforcement (ring reinforcement),

*- possibility to place, accommodate and cast in steel tension connections to ensure the effect of the ring reinforcement, to ensure the correct composite effect between the wall and floor-beam layer in use condition and, by having pronounced tensile properties, provide the possibility of an alternative in in the event that there is a limit state with regard to accident load,

- sufficient joint space, which means space between connected connecting plates of the existing wall and joist units to allow adequate filling of the joint

with masonry or concrete in order to thereby achieve the intended composite cooperation between the joined prefabricated units, as well as the ring reinforcement and the tension connections.

In addition to preventing any vertical displacement between a shear-absorbing wall and joist units up to and along the shear-absorbing wall, the shear-absorbing connections must also ensure a horizontal braced shear connection with the wall and must thus have: - means to place, accommodate and cast in steel shear connections between the wall and joist boards, - sufficient space in the joint to allow for in-situ embedment of masonry or concrete in the joint area, thereby achieving the intended attachment by means of composite action.

According to the state of the art, tension connections and shear connections used for the construction method described above normally consist of reinforcing bars or tension rods, which are anchored in the joist slab in concrete cast on site in various outlets (hollow channels) in the joist elements, or in masonry in the joint between mutually adjacent joist plates . The anchoring of the connecting element to the wall can be carried out in different ways: - the tie rod, which is often curved into a hairpin shape, is partially cast into the wall units and protrudes from their surface, - the tie rod is welded to a steel plate on the surface of the wall, and which is anchored in the wall concrete, - the tie rod is fixed or hooked onto cast-in nuts or other steel pieces in the wall concrete, - tension rods in the form of hairpin-shaped hoops are anchored by hooking the closed end onto studs that protrude from the upper end surfaces of the walls, whereby the connections are made effectively by pouring concrete in the joint.

All the mentioned means for anchoring the tie rod to the outer walls have a common characteristic, namely the fact that it is necessary to provide the wall units with cast-in steel devices of one kind or another, and which project from or are located level with the surface and are anchored in the wall unit's concrete.

Furthermore, the cast-in devices must be extremely precisely positioned to match corresponding outlets or joints in the composite floorboard.

As a result of this, the known methods and devices are easily susceptible to construction errors due to errors in construction drawings and/or errors made by the manufacturing factory.

The purpose of the present invention is then to avoid such errors and to reduce to a minimum or make the aforementioned embedded devices in the wall units completely redundant, and at the same time to make the previously necessary exact placement of these unnecessary, and a consequence of this is that the number and location of the tie rods can only be finally determined during the construction's later assembly process.

The method and means for carrying out the invention are characterized by the use of tension connection and shear connection means consisting of at least one elongated tensile force transmitting member, such as a reinforcing bar of suitable length, and which is bent to fit a connection for embedment in concrete in the joist plate on site, and which at its wall end is provided with a first anchoring means consisting of at least one transverse steel plate, the face of which facing the bar is placed in direct contact with the outer wall surface near either the upper edge of the load-bearing wall element or the lower edge of the adjacent upper wall element, while the connecting element rests on the lower wall element's horizontal upper end surface and the rod extends mainly across the plane of the walls into outlets or joints in the floor assembly, whereby the tensile connections are made effective and cooperation between joist boards and wall boards is established after the pouring of the masonry or concrete in all fu ger and outlet are hardened.

With due regard for different requirements with respect to the tensile connections of the above-mentioned load-bearing support connections and the shear connections, the corresponding tensile connections can be given a different design.

For support connections (that is, connections between wall elements and short ends of joist plates), it will be sufficient to use tension rods with an attached steel end plate (usually by means of welding), which is then only placed on the upper end surface of the wall element after the joist plates have been placed on a projecting shelf that lies somewhat below the aforementioned upper end surface, whereby the contact between the steel plate and the outer wall element surfaces is secured by wedging the steel plate between the wall surface and the outer insulation or possibly a non-bearing cladding panel if the outer wall has several layers.

The upper wall plate can now be mounted, as the support connection is made effective by pouring in masonry or concrete in the joint spaces and/or outlets, possibly parts of hollow channels in the joist boards. According to this process, the tie rods will be sufficiently anchored behind the upper edge of the lower wall element for the required tensile capacity within the serviceability limit state, while any direct contact between the surface of the steel end plate and the lower outer surface of the upper wall element cannot be guaranteed. A small space between the two surfaces can, however, be an advantage in the event of a condition bordering on accidental loading, in that movement of the steel plate within contact is also established against the surface of the upper wall element to a significant extent and increases the toughness of the tie rod anchorage.

At the roof level, where there is no wall element, only a variation of the anchoring end plate of a single inverted U-shaped steel profile is hooked over the upper edge of the supporting wall on the upper side of the projecting support shelf.

When it comes to shear connections (that is, for connections between wall elements and the long sides of joist elements) at intermediate joist levels, a different design of the tie rod anchoring is required due to different geometrical conditions and an absolute requirement for full contact between the steel anchor plate and the outer surface of the wall. In order to achieve such a contact and at the same time facilitate the wall assembly, the tie rod anchorage is given the shape of a steel U-profile so that the inner width between the profile's flanges is somewhat greater than the width of the outer wall element, and so that the U-section at the bottom of the web section is provided with a downwardly directed pin or other member for shear cooperation between the upper edge of the lower wall element. When the lower wall elements and joist boards have been installed, holes are drilled from the upper end surface of the wall elements (if these are not designed during manufacture as standard), the length of the holes being made corresponding to the length of the stud. The tension rods can now be placed on top of the wall's end plate, so that the U-shaped anchoring irons form a seat for the upper wall elements, the pins extend down the drilled holes which are filled with mortar, and the rod preferably extends across the wall at the top of the beam layer level so that it can be anchored in an outlet or a joint between two adjacent joist boards. The upper wall element can now be mounted on the aforementioned seats, and the close contact between the steel end plate, which is now the facing flange of the U-bar against the outer wall, and the wall element is secured by placing a wedge between the inward-facing surface of the wall element and the inner flange of the U-bar. The transfer of support and shear forces by sliding friction can now be produced by pouring in masonry or concrete in the joint openings between the wall and joist units, as well as in the joints between adjacent joist elements or in outlets in them. In the described case, a mortar leveling will also be necessary to protect the tie rods.

At the uppermost joist level or roof level, it is appropriate to have a design variant of the tie rod anchorage that lacks one of the distinctive features of the design used for support connections. In this case, the drawbar anchoring means has an L-shaped cross-section, the lower flange of which is provided with a hole and whose web portion serves as a fastening means for the drawbar, thereby allowing free choice of drawbar level. The anchor is attached to the upper end surface of the uppermost wall element by means of a screw/nut connection. The other distinctive features of the invention, which means the freedom to place the tie rod connection anywhere can, however, be maintained if the screw in question is anchored in holes that are drilled out in place on the upper side of the wall elements, using embedding or expansion devices. A high degree of freedom can be achieved by using wall elements that have holes produced during manufacture as standard, provided that there is an abundance of such holes.

The invention will now be explained in more detail, under which reference is made to the attached drawings, on which: fig. 1 shows in perspective a building with several floors and which is suitable for the use of the method and means according to the present invention,

fig. 2 shows a plan sketch of an intermediate beam level in the building shown in fig. 1,

fig. 3 shows a plan view of the upper level or roof beam level of the building shown in fig. 1,

fig. 4 shows a partially sectioned perspective sketch of connections between wall elements and supported ends of several joist slabs in an intermediate joist layer level, with tension rods arranged between adjacent joist slabs,

fig. 5 shows a section through a connection according to fig. 4,

fig. 6 shows a section through a connection of a similar nature as in fig. 4 and 5, where, however, the tie rod is placed in a channel in a hollow joist plate,

fig. 7 shows a section through a connection between an upper wall element and a short end of a joist plate in an upper joist level, the tie rod being placed and anchored between adjacent joist plates,

fig. 8 shows a section through a connection of a similar nature as in fig. 7, where, however, the tie rod is placed in a channel in a hollow joist plate and anchored in this,

fig. 9 shows a section through a shear connection between a wall element and a long side of a joist plate in an intermediate joist layer level,

fig. 10 shows a section through a shear connection between an upper wall element and a long side of a joist plate in an upper joist level, and

fig. 11 shows a section through a shear connection between an internal load-bearing wall element and beam layer plates in an intermediate beam layer level.

Fig. 1 shows a roofless building 1 made up of prefabricated storey-high wall elements 2, 3, 4, 5 and joist slabs 6. Locations of connections between wall elements and joist slabs, and which are the subject of the present invention, are indicated as examples at the reference locations I, II, III and IV. Fig. 2 shows an intermediate beam layer in building 1 at the locations indicated by references I and III. Fig. 3 shows the upper beam layer of building 1 in the places indicated by the references II and IV. Fig. 4 shows a connection between upper wall units and joist boards at reference location I. An upper wall unit 2 and a lower wall unit 3 are indicated to be of the multi-layer type and each one to comprise an inner load-bearing wall element 7, an outer wall disc 8 and an intermediate insulation layer 9. At least the inner wall element 7 of the lower wall unit 2 is designed with a ledge shelf 10, which serves to support short ends 11 of joist boards 6, of which 3 such boards 6a, 6b, 6c are shown in fig. 4. The beam layer plates 6 are suitably of the hollow type. According to the present invention, the joist plates are connected to the wall units by means of tension rods 12, which extend in

the longitudinal direction of the joist plates. The tie rods consist of steel rods, preferably reinforcing rods which are available in the trade and have an elongated part 13 which at one end is provided with a construction device, such as a steel plate 14, which is welded at right angles to the tie rod, and at the other end with a suitable anchoring means, such as a bent end 15 designed to produce anchoring in a hardened mass, such as concrete. In its active state, each tie rod is positioned so that its main part extends between two mutually adjacent joist plates 6 and its attachment member rests at least against the outer surface 16 of the inner wall element 7 of the lower wall unit 2. If necessary, there can be between the insulation layer 9 and the attachment member inserted a wedge (not shown) which is used to force the latter member into contact with said surface. In this position, the end of the tie rod which is connected to the attachment member 14 rests on the upper horizontal end surface 17 of the lower wall unit's innermost wall element 17. When a tie rod is mounted, the end which carries the attachment member is accordingly displaced along the edge 17 to a position where the elongated part of the rod 13 and anchoring means 15 can be inserted into a space between two adjacent joist plates 6. If necessary, such a space can be enlarged to provide space for the tie rod shaft in a manner that will be well known to those skilled in the art. After the tie rods have been placed as described, the spaces between adjacent joist plates are filled with mortar or concrete (at 18) to anchor the tie rods stably to the joist plates. At the same time, the outlet 19 with an extension in the transverse direction at the ends of the joist plates is filled with mortar or concrete (at 20), as is well known within this technique. In that case, the joist plates are of the hollow channel type, as indicated in the cross-section shown in fig. 5, the filling with masonry or concrete (at 21) can also be carried out in parts of the slabs' channels 22 which are separated from the rest of the channels by means of suitable plugs 23. A ring reinforcement 24, which suitably extends in the transverse direction of the joist slabs and is placed in

their outlets are fixed at the same time during the construction of the structure.

The cross section in fig. 6 shows an embodiment of a connection at reference location I, where a tie rod 12 is placed in a channel 22 in a joist plate 16 which is provided with hollow channels and slotted at 25 to allow placement of the tie rod in the channel, and which is fixed in this by of masonry or concrete 26. In this embodiment, the tie rod 12 is terminated at its inner end with an anchoring device in the form of a bent hook 27. Fig. 7 shows a connection at reference point II between a wall unit 3 on an upper level and a joist plate 6. As stated above, a drawbar 13 is used as a connecting element, and which has an elongated part 13 and a bent inner end 15. At its outer end, however, the drawbar is provided with a mounting element in the form of an inverted U-iron 28, which has a web part 29 as well as outer and inner flange parts 30, respectively 31. The web part 29 rests on the upper end surface 17 of the wall element 7, while the outer flange part 30 rests against the outward facing side surface 16 of the wall element 7 Ring reinforcing bars 24 extend in the transverse direction of several joist plates 6 through closed reinforcing bars 32, which are mainly placed in places where there are tension bars. The braces 32 are inserted into the channels 22 through an outlet 3 3 in the joist plate 6 and are attached to the structure together with the rods 24 by means of masonry or concrete 34. In this embodiment, the elongated part 13 of the tie rod 12 is placed in spaces between mutually adjacent joist boards 6, as well as anchored by casting with masonry or concrete (not shown). Fig. 8 shows an embodiment of a connection at reference point II, and which utilizes a tie rod 12 of a similar nature as indicated in fig. 6, but with a construction device 28 of a similar nature as indicated in fig. 7. The tie rod's elongated part 13 and its bent inner end 27 are placed in a channel 22 in a joist plate 6 with hollow channels and are fixed as described above. Reinforcing bars 24 and hoops 32 are also of a similar nature as indicated in fig. 7. Fig. 9 shows a shear connection at reference location III according to figures 1 and 2 between wall units 4 and 5 as well as a long side of a joist plate 6 in an intermediate joist layer. As before, the wall units 4 and 5 comprise an inner load-bearing wall element 7, an outer element 8 and between these an insulating layer 9. The wall units 4 and 5 are terminated at the top by a horizontal end surface or edge 35. The short ends of the beam layer plate 6 are supported by wall elements 7 which belong to wall units 2 at mutually opposite positions I on building 1. In this case, the connecting member has the form of a tie rod 36 with an elongated part 37, which is terminated at its inner end with a downwardly directed anchoring member 38. At its outer end, the tie rod 36 is provided with a U-iron 39 with a web part 40 as well as outer and inner flange parts 41, respectively 42, so that the distance between the flange parts is somewhat greater than the width of the wall element 7. The web part of the U-iron 39 is provided with a downwardly directed pin 43, which fits into in a hole 44 in the upper end face 35 of the lower wall element 7. The U-iron 39 is placed on the upper end face 35 with the drawbar's elongated part 37 aligned in the beam gsplatene's transverse direction and with the pin 43 pushed down into the hole 44, where it is anchored with masonry. If necessary, a spacer 46 is suitably placed between the U-bar's web part 40 and the upper end 3 5 of the wall element 7. In this position, the anchoring member 3 8 extends downwards in the area between two nearby joist plates 6, where it is anchored with the help of mortar 46. Then placed an upper wall unit 5 with its inner wall element 7 supported between the U-iron's flange parts 39 on its web part 40. In order to achieve the correct height level for the upper wall element, spacers 47 are appropriately placed between this and the web part 44. A wedge 48 is inserted between the U-iron's inner flange part and the wall element 7 to force the latter into contact with the outer flange part 41 of the U-bar. Fig. 10 shows a section at the reference point IV according to Figures 1 and 3 through an upper wall unit 5 and joist plates 6. In order to transfer shear force in this position, where no further wall units are placed on the wall unit 5, it is necessary to provide for forced anchoring of connecting elements t. In this embodiment, the connecting member comprises a tie rod 49, which at its inner end has an anchoring member 50, corresponding to that indicated in fig. 9, as well as at its outer end an L-shaped profile 51 with a base or body part 52 and an upright flange part 53 which faces the joist plate and is connected to the tie rod 49. The body part 52 has a hole 54 to receive the threaded upper part of a bolt 55, the lower end of which is fixed in a hole 56 at an appropriate location on the upper end surface 35 of the wall element 7. In order to produce a more binding attachment of the bolt 55 than that achieved by embedding with mortar, the bolt 55 is preferably executed as an expansion bolt. After placement of the L-profile 51 with the threaded part of the bolt 55 passed through the hole 54, as well as, if necessary, appropriate spacers not shown arranged between the upper end surface 35 of the wall element 7 and the web part 52, a nut 55' is screwed onto the threaded part and tightened. Next, the space between the wall unit's 5 insulation layer and the joist plate 6 on the upper side of the wall element 7 is filled with masonry at 57, as is also the space between the joist plates 6. Fig. 11 shows a section through a shear connection between an inner load-bearing wall and two joist plates at an intermediate joist level. The wall shown then comprises a lower wall element 58 and an upper wall element 59. On the upper end surface or end edge 60 of the lower wall element, a hole 61 is arranged, in which an internally threaded insert 62 is fixed. A U-shaped profile 63 with a web portion 64 and flange portions 65, 66 are provided with a threaded stud 67, which is connected to the web portion 64 to be screwed into the insert 62. The flange portions 65, 66 are each provided with a tie rod 68, 69, which extends in a substantially straight angle out from the flange parts and ends with downward anchoring

bodies 70, respectively 71. With the threaded pin 67 screwed into the insert 62 to set the height of the waist part 64 at the appropriate level, the upper wall element 59 is placed on this and fixed laterally by inserting a wedge 72, 7 3 between each of the flange parts 65, 66 and the corresponding side of the wall element. In this position, the anchoring members 70, 71 extend down into each space between adjacent joist plates 6, where they are anchored by injection with mortar or concrete at 74, 75 respectively. To complete this connection, the space between the lower and upper wall elements as well as connected end- edges of the joist boards with masonry or concrete at 76.

Claims (14)

1. Connection between at least one wall element and at least one joist plate, and which comprises at least one tie rod with a first and a second end respectively provided with a first and a second anchoring means, characterized by the drawbar (13; 36; 49; 68; 69) is arranged to be able to be moved along an upper end edge (17; 35) of the wall element (7) and a joist plate (6) to a suitable position for anchoring the tie rod's other end (15; 27; 38; 50, 70, 71) ) to at least one joist plate (6), while an engaging member (14; 30; 43; 55; 67) on the first anchoring member is arranged for engagement with the upper end edge (17; 35) of the wall element (7) in this position. 2. Connection as stated in claim 1, characterized in that the first anchoring means (14) is arranged for engagement with a side surface (16) of the wall element, and which faces away from the tie rod (13), the tie rod resting on the upper end edge (17) of the wall element (7). 3. Connection as stated in claim 1, characterized in that the first anchoring means is in engagement with a side surface of the wall element facing away from the tie rod (13), while the first anchoring means (28) rests on the upper end edge (17). 4. Connection as stated in claim 1, characterized in that the first anchoring member (43; 55) is designed to engage in a hole (44; 61) which is drilled into the upper end edge of the wall element on the spot. 5. Connecting device which is designed to form a connection between at least one wall element and a joist plate, characterized by the wooden tie rod (12; 37; 49) which is provided at one end with a first anchoring device (14; 28; 39; 51) and in another end with another anchoring means (15; 27; 38; 50), where the first anchoring means is arranged for engagement with at least an upper part (16; 35) of a first wall element (7) and the second anchoring means is arranged for anchoring to at least one joist plate (6), the first anchoring member being arranged to be able to be displaced along said upper part to a selected engagement position. 6. Connecting device as specified in claim 5 and designed to be used for connection between a load-bearing wall element and a joist plate which is supported by the wall element, characterized in that the first anchoring device comprises at least one installation device (14; 30) which is designed for engagement with an outer surface ( 16) of the first wall element. 7. Connecting element as stated in claim 6, and designed to be used in a connection at the level of the intermediate beam layer in a building, characterized in that the construction element consists of a plate (14) which is fixed at an essentially right angle to the tie rod and has a downwardly directed part designed for engagement with the outer surface (16) of the first wall element, as well as an upwardly directed part arranged for engagement with an outer surface of another wall element which is placed on top of the first wall element, the pull rod being arranged to rest against an upper end edge (17) of the first wall element. 8. Connection body as specified in claim 6 and designed to be used in a connection at an uppermost joist level in a building, characterized in that the construction element consists of an inverted U-profile with a web part (29) and two flange parts (30, 31), a first part (30) of the flange parts being arranged to rest against the outer surface (16) of the first wall element ( 7), the body part (29) is designed to rest on an upper end edge (17) of the first wall element (7), and the second flange part is attached to the tie rod (13). 9. Connecting device as stated in claim 6, 7 or 8, characterized in that the second anchoring device is made up of a bent outer end (15; 27) of the tie rod. 10. Connecting device as stated in claim 5 and designed to be used in a shear connection between a wall element and a beam layer plate, characterized in that the first anchoring means comprises an engagement means (43; 53) arranged for engagement with the upper end edge of the first wall element (7). 11. Connecting device as specified in claim 10, characterized in that the second anchoring device (38; 50) is designed to engage in a space between the joist plate and an adjacent joist plate. 12. Connecting device as stated in claim 10 or 11 and designed to be used in a connection between a wall element and a joist plate at an intermediate joist level in a building, characterized in that the first anchoring member consists of a U-profile with a web part (40) as well as a first and a second flange part (41, 42), the first flange part being arranged to rest against an outer surface of another wall element placed on top of it first wall element, and as the second flange part is connected to the tie rod (37) and the web part carries the engagement members (43). 13. Connecting device as specified in claim 10 or 11 and designed to be used in a connection between a wall element and a joist plate on an upper floor level in a building, characterized in that the first front circuit member consists of an L-section (51) with a web part (52) and a flange part (53), the flange part being attached to the tie rod (49) and the web part carrying the engagement member (55). • 14. Connecting device as stated in claim 12 or 13, characterized in that the engaging device consists of a pin (43; 55) designed to engage in a hole in the upper end edge (35) of the first wall element (7).