EP0675990B1

EP0675990B1 - Building unit, preferably for roofing structures, and a method of manufacturing it

Info

Publication number: EP0675990B1
Application number: EP92909651A
Authority: EP
Inventors: Peehr Mathias Oernfeldt Svensson
Original assignee: SVENSSON Peehr Mathias Oernfeldt
Current assignee: SVENSSON Peehr Mathias Oernfeldt
Priority date: 1991-04-29
Filing date: 1992-04-29
Publication date: 1997-07-09
Anticipated expiration: 2012-04-29
Also published as: EP0675990A1; DK77991D0; DK0675990T3; DE69220817T2; AU1688192A; WO1992019826A1; DE69220817D1

Abstract

A beam or girder (1) for building construction comprises a base profile (3-5), mainly for tensile loads and an upper covering plate (2) of a mainly for compressive loads suitable material, which is considerably stiffer in all directions than the plate of the base profile (3-5), said covering plate (2) being rigidly and moment transmittingly (resistant to bending moments) connected directly to the base profile via a glue layer, so that the covering plate (2) and the base profile (3-5) form a static cooperating supporting unit. Since the covering plate (2) has the same width as the base profile (3-5) and along both its longitudinal sides flush with the sides of the base profile, and that the rigid connection between the covering plate and the base profile also comprises securing elements extending fully or partly through the covering plate (2), there is hereby achieved a form stable, comprehensively applicable beam or girder of low weight and a high strength, and a predetermined curvature in the longitudinal direction of the beam is easy to adapt to the application conditions during its manufacture.

Description

The present invention relates to a building unit of the kind mentioned in the introductory part of claim 1.
From DE published patent application No. 2,520,255 and US patent No. 4,346,544 is known a light building element constructed by several carrier elements or structural members in which roofing plates and channel configurated base members form integrated building units, such as for roofing elements each consisting of at least one open base profile glued directly onto an upper construction plate forming the covering as well as part of the load carrier, and whereby the construction plate is wider than the base profile, and along both the longitudinal sides thereof extends outside the base profile. This implies that each construction plate has a freely protruding, unsupported side part getting a certain deflection by loading of the construction plate. Said deflection exposes the joint between neighbouring construction plates to high material stressing and renders it practically impossible in and below the joint to obtain reasonable vapour diffusion tightness or resistance by known means.
This is a drawback being very serious in roofing structures.
It is the purpose of the present invention to provide a building unit which, if used for roofing, ceiling, wall or floor structures, may eliminate said drawbacks.
This is achieved by a building unit according to the invention, said building unit being characteristic by the items set forth in the characterizing clause of claim 1. Thereby is achieved a light building unit construction with a high supporting ability. And since the beams of a building unit of this invention have no protruding side edges, the beam may be arranged outermost at the longitudinal side edges of the building unit, whereby the deflection of said longituinal side edges become as small as possible during weight load, and consequently a lasting vapour diffusion tightness in the joints between two neighbouring building units is achieved and may be made by common vapour sealing means. The rigid edge joints thereby achieved between neighbouring building units enable them to transfer high bending moments, and the supporting ability of the building units locally in the joints or at the longitudinal edges becomes very high. When the building unit is used in heat and sound isolating floor, ceiling and roofing elements where isolating material, such as mineral wool, is arranged inside the beams and between the beams, a high heat isolating ability and a good sound isolation too is achieved at the joints of the building units, partly because the beams in the joints can be arranged directly abutting the beams of neighbouring elements.
By a material which is mainly suitable for compressive loads is to be understood a compression resistant material being better suited for compressive loads than for tensile loads. As examples thereof may be mentioned massive veneered or laminated wood, cement bound or adhesive bound chip board, cell plast or wood core plywood. By a material mainly suitable for tensile loads is to be understood a tension resistant material being better suited for absorbing tensile loads than compressive loads. As examples may be mentioned relatively thin sheet or plate material of metal, such as iron, steel, brass and aluminium, and steel and/or fiber reinforced concrete, plastic or wood.
None of said materials has, however, a Young's modulus below 5800 MPa, a bending strength below 49 MPa, a tensile strength below 49 MPa and a compressive strength below 19.6 MPa in the temperature range -40 to +50 degrees C.
An embodiment of a building unit according to claim 2 may preferably have a further, mainly for compression loads resistant plate being firmly secured over the total length of the beam to that part of its base profile located most distant from its covering plate. Thereby is provided a more universally applicable building unit, seeing that it is suitable for applications as a heavy loaded building unit, e.g. as cantilever building unit, and as a vertical load bearing wall unit.
By the building unit according to the invention is achieved that it may absorb forces or loads in the plane of the building unit and loads from the facades, more secure or safe building unit joints, seeing that the beams of the elements at the side edges of the building unit may be secured directly to each other. Furthermore may the building units at the joints easily by known means be made vapour diffusion resistant and/or may absorb extra loads from e.g. tubing, lighting equipment etc. below the element joinings and possible extra loads from roofing units or installations arranged on a roof above the building unit joints or from heavy objects, such as shelves arranged on a floor above the building unit joints. Said arrangement of the beams in the building units furthermore implies that arbitrary distances or openings for staircases, lifts, skylights etc. are possible between the building units where the supporting beams form the strong supporting side edges of neighbouring building units. Furthermore, relatively larger throughgoing openings in the building units between its beams can be performed at given building unit dimensions 1) for skylights, chimneys, roof caps etc. in roof units, 2) for chimneys, staircases, lifts and dropping pits in ceiling or floor units, and 3) for doors, hatches and windows in wall units, where such relatively high loads for the building units may be taken up directly by the beams. This would not have been possible if the covering plates of the beams were wider than the base profile of the beam, or if the building units did not have a beam far out at their longitudinal edge. Furthermore is achieved 1) that the building units with their beams arranged at their side edges can be assembled resistant to bending moments directly at their side edges, 2) that the building units can be constructed completely alike at both side edges, so that they can be rotated 180 degrees about an axis perpendicular to the unit during the mounting, which again means 3) that different fewer building unit types may be necessary for a given building, particularly if the building units of the invention have box shaped beams at their longitudinal sides, and 4) that a greater constructional freedom of choice is obtained. Furthermore is achieved 5) that the vapour seal of the building unit can be hidden in and along its longitudinal sides, so that said vapour seal cannot be damaged during transportation and mounting of the building unit.
Furthermore, the invention relates to a method according to the introductory clause of claim 4 for manufacturing a building unit according to the invention for building purposes, e.g. roofing, ceiling, wall or floor purposes, and the method is characterized by the items set forth in the characterizing clause of said claim. Thereby it becomes possible not only to manufacture rectilinear building units, but also upwardly and downwardly curved building units, seeing that the curvature of the units is decided by the longitudinal curvature of the base profile of the beams before the covering plates are secured to the base profiles. Since each beam per se is a finished unit, they might by simple means and before their mounting on a roofing or floor construction plate for forming a building element be provided with a predetermined curvature in their longitudinal directon, so that the roof or the floor in mounted and loaded condition e.g. becomes totally planar.
The invention will now be described in more detail in connection with some embodiments and with reference to the drawing in which

fig. 1 shows two known beams having uniform wall thickness,
fig. 2 a beam for the building unit according to the invention,
fig. 3 in perspective and partly in section an end embodiment of a building unit according to the invention,
fig. 4 a cross section through an embodiment of a building unit according to the invention, corresponding to the one shown in fig. 3,
fig. 5 another embodiment of a building unit according to the invention and intended for a vapour barrierless roof,
fig. 6 a cross section through a longitudinal joint between two building units according to the invention,
fig. 7 a section through an end joint between two building building units according to the invention above a supporting girder,
figs. 8-9 cross sections through beam embodiments for building units according to the invention,
figs. 10-12 cross sections through beams for building units according to the invention with an extra compressive load resistant plate at the inside bottom of the beams,
figs. 13-15 beam embodiments for building units according to the invention with an extra compressive load resistant plate at the outside bottom of the beams,
fig. 16 a cross section through a further embodiment of a beam for building units according to the invention, and
fig. 17 a cross section through a side edge of a building unit having a beam with two mutually secured base profiles for fire protectional purposes.

Fig. 1 shows two for building units known beams, socalled box girders, with square cross section and rectangular cross section, respectively, and of a uniform wall thickness.
Fig. 2 shows a beam 1 for a building unit according to the invention, where one of the plane sides 2, 3, 4, 5 of the beam consists of a covering plate 2 of a mainly for compressive load suitable and resistant material of a thickness of 1,5-115, preferably 32 times greater than the thickness of the abutting sides 3-5 of the beam 1. The covering plate 2 e.g. may be made of 22 mm thick waterproof plywood, and the base profile plate 3-5 may be a 0.7 mm thick galvanized steel profile, the height of which varies according to its span or other conditions, under which the beam is to be used. The sides 3-5 of the beam 1 being performed in one unit as a base profile consist of a mainly for tensile load suitable and resistant material as further defined in the introductory clause of the specification, and the mainly for compressive load suitable covering plate 2 is secured directly edge flushing and resistant to bending moments to the two longitudinal adhesive surfaces of flanges 6, 7 of the base profile 3-5. The securing means are chosen in dependence on which materials are to be assembled, and said securing means include an adhesive assembly and, for further reinforcement thereof, a screw assembly, bolt assembly, nail assembly or the like.
Thereby is provided a beam for the building unit having a low weight and a large supporting ability and without having any protruding side edges, and which beam can be manufactured at low costs. The supporting ability may be further increased by arranging bulkheads 10 inside the beam 1 with predetermined spaces as indicated in fig. 3. Each bulkhead 10 is e.g. secured perpendicularly to at least three of the inner walls of the beam, e.g. on the inner sides of the sides 3, 4 and 5.
Fig. 3 shows a building unit 12 according to the invention in which the beam 1 is used, and beams 1 are arranged as longitudinal girders in the building unit 12, which may be a roof element as shown, a ceiling element, a wall element or a floor element. Fig. 3 shows furthermore that one of the beams 1 is arranged at each of the longitudinal side edges of the building unit 12. The roof building unit shown in fig. 3 may e.g. at its upper side have a 16 mm thick waterproof plywood board 14 which is or will be covered by roofing foil or roofing felt. Said plywood plate 14 is directly secured to the three shown longitudinal closed beams 1 by glueing and nails or screws, and directly below the beams 1 may be arranged a vapour tightening seal 15, e.g. of PVC foil or of the material being known as hygrodiode foil, dampcourse or vapour sealing materials. Below the vapour seal may be arranged a heat isolating ceiling covering 16 of e.g. mineral wool or wood-wool building slabs, and said ceiling covering 16 is secured and protected at the longitudinal side edges of the building unit 12 by angle steel 17 secured to the beams 1. Between the beams 1 may be arranged a mineral wool isolation 18, and a mineral wool isolation not shown may be arranged inside the beams themselves.
Fig. 4 shows a section perpendicularly to the longitudinal direction of the building unit in fig. 3. As will be seen, there is enough room between the beams 1 for large throughgoing openings in the building unit without resulting in any mentionable reduction of the supporting ability of the building unit.
Fig. 5 shows a building unit in the form of a roofing unit with the beams 1 in a different arrangement. Here an isolating ceiling covering 16 is placed between the beams 1, and the vapour seal 15 is arranged above the beams 1 and the ceiling covering 16, but below the plywood board 14. The ceiling covering 16 which along with the vapour seal 15 is secured e.g. by glueing to the plate 14, is made e.g. of isolating plates with a high cohesive force and being known as isolation plates from Dow Danmark A/S in the STYROFOAM®-programme of said company. Upon the plywood board 14 is arranged a socalled outer isolation 20 which is vapour proof, heat proof and weather proof.
Fig. 6 shows a longitudinal joint between the longitudinal sides of two building units 12. Here is used a locking slab 22 above the joint between the units and a diffusion resistant and heat isolating sealing band 23 between the two abutting beams 1 of the two neighbouring units. Since the width of the construction plate 14 is less than the width of the building unit 12 with a value corresponding to the width of the locking slab 22 for the mutual locking of the neighbouring building units, a further advantage of the building unit according to the invention is achieved, due to the location of said two beams 1 along the longitudinal sides of the building unit, seeing that the building unit width e.g. can be made 2,5% wider than the present plate standard width of 244 cm by the same material consumption and fewer working operations. This is due to the fact that construction plates of standard width may be used, which width e.g. in Denmark are 244 cm as delivery measure, whereby the building units can obtain the convenient module width of 250 cm and the locking slabs get a width of 6 cm.
Fig. 7 shows an end joint between the ends of two building units 12 above a supporting girder 25, which supports the units 12 via their beams 1 and at their ends immediately below reinforcing end bulkheads 10 of the beams. Also by this assembly is used a locking slab 27.
Figs. 8-16 show some beam embodiments of the building unit according to the invention all being provided with a covering plate 2 and with abutting base profile sides 3 and 5 of less thickness. Some of the beams, viz. the ones shown on Figs. 10-15, have a further, mainly for compressive load suitable and resistant reinforcing plate 8 firmly secured over the full length of the beam to that part of the beam being most distant from the covering plate 2. Said extra reinforcing plate 8 may as shown in figs. 10-12 be arranged inside upon the bottom of the beam 1 or as shown in Fig. 13-15 be arranged outside upon the bottom of the beam 1. Such beams as shown in Figs. 10-15 are also suitable for use as girders in form of cantilevers or as wall supporting beams and columns.
In an embodiment of the invention not shown, the base profile side 4 may be a planar steel plate, which plate resistant to bending moments is secured to the sides 3 and 5 which may be U-formed so that short U-profile sides form the edge flanges 6, 7 of the base profile and the edge flanges for securing to the sides 3 and 5 of the steel plate 4 by riveting, welding or the like.
As examples of the relation between the wall thicknesses in the plate 2 and the plate of the base profile 3-5 can be mentioned following values in millimeters: 45:30, 40:21, 15:5, 20:5, 25:5, 35:5, 22:2, 24:2, 15:1, 20:1, 25:1, 20:0,7, 22:0,7, 32:1, 40:1, 100:2, 35:0,7, 60:1, 42:0,7, 50:0,7, 80:1, 90:1, 100:1, 70:0,7, 105:1, 80:0,7, 115:1.
The proportionals selected depend on the expected loadings for the building units and the number of beams, on the materials used and securing methods used and on the available standardized material thicknesses.
Fig. 16 shows an embodiment of a beam 1, when it, mounted in a building unit, is expected to be exposed to particularly high tensile loadings in the base profile sides 3 and 5, or where the sides 3 and 5 are manufactured in thicker material, such as fiber reinforced plastic.
Fig. 17 shows an embodiment of a beam on a building unit according to the invention, whereby a better fire resistance as well as a greater strength is achieved, so that the duration of the higher fire resistance is increased. In the outermost base profile 3-5 and at a distance therefrom there is inserted an inner base profile 30. In the space 31 between the two base profiles is arranged a heat isolating material 32, 33, of which at least the upper material 33 is nail proof and glued to the upper end parts of both profiles 3-5, 30. The upper surface 34 of the upper material 33 is flush with the upper end edges of the two profiles 3-5, 30 and forms a securing, abutting and glueing surface for the covering plate 2. A construction plate 14 is secured to the middle of the covering plate 2, said construction plate 14 here is made of a steel plate with intermediate reinforcing ribs.

Claims

Building unit, preferably for roofing structures, wherein two or more beams are arranged as longitudinal girders in the building unit (12), such as a roofing member, a ceiling member, a wall member or a floor member, and wherein the beam (1) is of a polygonal, geometric shape, such as box shape or trapezoidal shape, and comprises a base profile (3-5) of a mainly for tensile loads suitable material consisting of an upwardly open U shaped metal profile (3-5) of a sheet or thin plate material with adhesive surfaces on flanges (6, 7) being inwardly directed on the upper side of the profile, and an upper covering plate (2) of a mainly for compression loads suitable material e.g. consisting of plywood which is considerably stiffer in all directions than the plate of the base profile (3-5), said covering plate (2) being firmly connected directly and resistant to bending moments onto the base profile via a glue layer on the total surface of the adhesive surfaces on the flanges (6, 7) of the base profile, so that the covering plate (2) and the base profile (3-5) together form a static cooperating supporting unit, characterized in that two of the beams (1) are arranged each along and at each of the longitudinal side edges of the building unit (12), where they form the longitudinal sides of the building unit, that the covering plate (2) of the beam has the same width as the base profile (3-5) and along both longitudinal sides flushes with the sides of the base profile, and that the rigid connection between the covering plate (2) and the base profile (3-5) also comprises securing elements, such as screws, nails, rivets or the like elements extending fully or partly through the covering plate (2).
Building unit according to claim 1, characterized in that a further, mainly for compression loads resistant plate (8) is firmly secured over the total length of the beam (1) to that part of its base profile located most distant from its covering plate (2).
Building unit according to claim 1 or 2, where two or more beams are secured to- a building board (14) or construction plate (14) for the stiffening and reinforcing thereof, characterized in that the width of the construction plate (14) is less than the width of the building unit (12) by a value corresponding to the width of a locking slab (22) for mutual interlocking of neighbouring building units.
Method for the manufacture of a building unit (12) according to claim 1, preferably for roofing purposes, wherein each supporting beam (1) is formed of a three sided base profile (3-5, 30) being open to one side and made by a thin, mainly for tensile loads resistant plate, characterized in that said open longitudinal side of the base profile (3-5, 30) is then closed by securing a covering plate (2) directly to its two adhesive flange surfaces (6, 7, 30) forming the beam (1) in a way resistant to bending moments, said covering plate (2) being of a mainly for compression loads resistant material and having the same width as the width of the open base profile of the beam (1) and then at least two of such beams (1) are secured to a construction plate (14) for forming the building unit (12) in which one of the sides (3 or 5) in each of two beams (1) form the respective two longitudinal sides of the building unit.
Method according to claim 4, wherein the base profile is trilateral, characterized in that a longitudinal V-profile (35) is arranged in the inner of the base profile (3-5, 30), the flap edges of the V-profile (35) being supported in the lower two corners of the U-profile, and the bottom of the V-profile meets the middle of the covering plate (2) when it is secured to the base profile (3-5, 30).
Method according to claim 4 or 5, characterized in that all the base profiles (3-5) of the beams (1) for a building unit (12) are given an upward or downward curvature before the covering plates (2) are secured to their respective profiles (3-5) in order to prestress the building unit (12) into a direction opposite to the tensile and compressive stress acting upon the unit during future use.