WO1983003275A1

WO1983003275A1 - Method of bearing a metal sheet roof and roof structure for carrying out the method

Info

Publication number: WO1983003275A1
Application number: PCT/SE1983/000090
Authority: WO
Inventors: Edvin Lindell
Original assignee: Edvin Lindell
Priority date: 1982-03-16
Filing date: 1983-03-15
Publication date: 1983-09-29
Also published as: EP0103614A1; SE442129B; SE8306285D0; FI70620C; DE3337006T; SE8201660L; GB2127064A; GB8330117D0; JPS59500477A; NO834206L; FI834193A0; GB2127064B; SE8306285L; FI70620B; FI834193A

Abstract

A method of bearing a metal sheet roof where the sheet (1) constitutes a water-repelling surface layer and preferably is trapezoidally corrugated in known manner with ridges of trapezoid cross-section extending in the longitudinal direction of the sheet and with trapezoid valleys located between the ridges, said longitudinal direction extending substantially in parallel with the bearing distance direction, width direction, of the roof, and the sheet at least in connection to the longitudinal edges (23) of the roof laid on bearing beams (4) or corresponding members arranged perpendicularly to said width direction. The method is characterized especially in that load from the roof or a roof section is taken up as tensile forces in rods (27, 29) extending between the longitudinal edges (23) of the roof or a roof section, that reaction forces substantially corresponding to said tensile forces are introduced into the sheet (1) as compressive forces acting in the longitudinal direction of the sheet by means of anchoring said rods in the sheet at least at said edges, whereby the capacity of said corrugated sheet of taking up compressive forces acting in its longitudinal direction is utilized for bearing the roof. The invention also relates to a roof structure for carrying out the method.

Description

Method of bearing a metal sheet roof and roof structure for carrying out the method

This invention relates to a method of bearing a roof of metal sheet, at which the sheet constitutes a water-rep- elling surface layer, which preferably is corrugated trapezoidally in known manner, comprising ridges of trapezoid cross-section extending in the longitudinal direction of the sheet and trapezoid valleys between the ridges,said longitudinal direction extending substanti- ally in parallel with the bearing distance, width dir¬ ection, of the roof, arid the sheet at least in connect¬ ion to the longitudinal edges of the roof positioned on bearing beams or corresponding members arranged perpend¬ icularly to said width direction. The invention also relates to a roof structure for carr¬ ying out the method.

Roof structures are well-known, at which a water-repell¬ ing surface layer of metal sheet is carried on rafters of, for example, framework type laid on supports and arranged in a definite spaced relationship in the long¬ itudinal direction of the roof, and on a layer of roof panels or the like arranged between the rafters and the sheet. Structures of this kind, thus, comprise primary bearing members and secondary bearing members and a water-repelling surface layer. These structures, there¬ fore, are expensive.

At other known roof structures a framew-osz of corrugated sheet portions is applied to carry a water-repelling sheet layer. Structures of this kind are expensive and involve considerable jointing and load-carrying problems.

At other known structures a sheet vault is produced which is supported at the edges. These structures give rise to problems in respect of taking up horizontal forces, and only relatively limited bearing distances can be obtained. The present invention has the object to bring about a roof structure, at which the water-repelling layer, the sheet, also participates as primary and secondary bear¬ ing structure and thereby renders possible a roof struct- ure, which is simple, inexpensive and easy to mount.

The invention-^ thus, relates to a method of bearing a sheet roof, at which the sheet constitutes a water-rep¬ elling surface layer and preferably is corrugated trapez¬ oidally in known manner, comprising ridges of trapezoid cross-section extending in the longitudinal direction of the sheet and trapezoid valleys located between the ridges, said longitudinal direction extending substant¬ ially in parallel with the bearing distance, width dir¬ ection, of the roof, and the sheet at least in connection to the longitudinal edges of the roof positioned on bear¬ ing beams or corresponding members arranged perpendicul¬ arly to said width direction.

The method according to the invention is characterized especially in that the load from the roof or a section thereof is taken up as tensile forces in rods extending between the longitudinal edges of the roof or roof sect¬ ion, and that reaction forces corresponding substantially to said tensile forces are introduced into the sheet as compressive forces acting in the longitudinal direction of the sheet by anchoring said rods in the sheet at least at said edges, whereby the capacity of the trapez¬ oidally corrugated sheet of taking up compressive forces acting in the longitudinal direction of the sheet is utilized for bearing the roof.

The invention also relates to a roof structure, at which a water-repelling surface layer in the form of prefer¬ ably trapezoidally corrugated sheet of known type com¬ prises ridges of trapezoidal cross-section extending in the longitudinal direction of the sheet and trapezoid valleys located be¬ tween the ridges, which longitudinal direction extends substantially in parallel with the bearing distance, width direction, of the roof, and bearing beams or corresponding members are arranged substantially perpen- dicularly to said width direction at least in connection to the longitudi nal edges of the roof.

The roof structure is especially characterized in that rods of steel or corresponding material are provided for taking up tensile forces, which rods extend between the longitudinal edges of the roof or a roof section and are anchored in the sheet at least at said edges, whereby reaction^' forces corresponding substantially to said tensile forces are taken up as compressive forces acting in the longitudinal direction of the sheet, and whereby the capacity of the trapezoidally corrugated sheet of taking up compressive forces acting in its longitudinal direction is utilized for bearing the roof structure.

The invention is described in greater detail in the following by way of some embodiments and with reference to the accompanying drawings, in which

- Fig. 1 schematically shows a first embodiment of a roof structure accord ing to the invention seen in the longitudinal direction of the roof, - Fig. 2 is a section A-A according to Fig. 1,

- Fig. 3 is a section B-B according to Fig. 1,

- Fig. k schematically shows a second embodiment of a roof structure accor ing to the invention seen in the longitudinal direction of the roof,

- Fig. 5 is a section C-C according to Fig. k , - Fig. 6 schematically shows a portion of a third embodiment of a roof structure according to the invention where a vault has been formed by pre- stressing the rod,

- Fig. 7 is a section D-D according to Fig. 6,

- Fig. 8 schematically shows a portion of a fourth embodiment of a roof structure according to the invention where a vault has been formed, and

- Fig. 9 schematically- shows a portion.of a fifth embodiment of a roof structure according to the invention where a vault has been formed.

In Fig. 1 the numeral 1 designates the sheet, which constitutes a.o. the water-repelling layer of the roof structure and which preferably is corru- gated trapezoidally in known manner, Fig. 2, comprising ridges 2 of trape¬ zoid cross-section extending in its longitudinal direction and trapezoid valleys 3 located between the ridges, which longitudinal direction extends s bsten-t al 1 l ection, of the roof. -i designates bearing beams or simil¬ ar members arranged substantially perpendicularly to said width direction at least in connection to the longitud¬ inal edges 5_a6 of the roof. According to the invention ₃rods 7 of steel or correspond¬ ing material are provided for taking up tensile forces. Said rods 7 extend between the longitudinal edges 5,6 of the roof and are anchored in the sheet 1 at least at said edges 5,6, so that reaction forces corresponding substantially to said tensile forces are taken up as compressive forces acting in the longitudinal direction of the sheet 1, whereby the capacity of the trapezoidally corrugated sheet of taking up compressive forces acting in its longitudinal direction are utilized for bearing the roof structure. According to the embodiment shown in Pigs. 1-3 said compressive forces are introduced into the sheet 1 by end supports 9₃ which act substant¬ ially perpendicularly to the end surface 8 of the sheet and co-operate with the rods 7_} and which consist, for example, of flat steel-ha-rs 9 with holes for the rods, which are secured by nuts 10 or the like.

According to the invention, intermediate supports 11 are provided substantially vertically between the rods 7 and sheet 1 and are carried by the rods. The intermediate supports 11, of course, can be designed in several diff¬ erent ways. According to the embodiment shown in Fig. 1, every intermediate support comprises a section 12 ex¬ tending horizontally and perpendicularly to said width direction and abutting the rods 7, and, at least at each of the ends 13-,14 of the section 12 avertical sect¬ ion 15,16 abutting the sheet 1. -At the intermediate supp¬ orts 11 the rods 7 change their direction in a substant¬ ially vertical plane, whereby the vertical load can be carried. At the embodiment shown in Pigs. 1-3, rods 7 extend from one edge 5 to the other edge 6 via the lower end 17 of each of two intermediate supports 11, between which intermediate supports the rods extend substantially horizontally.

For water runoff in connection to the edges 5,6, the end supports are designed in an expedient way-, . for example with recesses 18 at portions located between the ridges 2, as shown in Pig. 3. In Fig. 4 a second embodiment is shown, which is intended for a greater bearing distance and an improved water runoff. It comprises two sections 19,20 of sheet which extend in parallel in the longitudinal direction of the roof and which meet at a roof ridge 21 or corresponding member and are inclined in the width direction therefrom. Each roof section 19,20 comprises end supports 22. at the edge 23 of the roof and end supports 24 at the roof ridge 21, and at each roof section 19,20 two intermed¬ iate supports 25,26, an outer one 25 and an inner one 26, are provided. Rods 27 extend between the end supp¬ orts 22 at the edges 23 of the roof via the lower end 28 of each of said intermediate supports 25,26. At each roof section 19,20 rods 29 extend from the end support 22 to the end support 24 at the upper end 30 of the outer in- ter ediate support 25 and the lower end 28 of the inner end support 26. The end supports 24 are jointed in a suitable way at the roof ridge and covered with a ridge sheet 31 or the like.

In Fig. 6 a third embodiment of a roof structure according to the invention is shown where the rods or taking up tensile forces are prestressed. 32 designates the sheet of a roof section, of which one half, the right-hand one, is shown. The sheet is intended in the width direction of the section to consist of an entire unbroken sheet 32. At the embodiment shown in Fig. 6, a wide roof is intend- ed to be assembled of several roof sections arranged to the side of each other in the width direction of the roof. Between two adjacent sections the roof is intended to be supported by supports 33 of a suitable kind, and a gutter 3-i for water run off from the roof sections is located between the sections, as appears from Fig. 6.

The numeral 35 in Fig. 6 designates a first, outer inter¬ mediate support, and 36 designates an in-between intermed¬ iate support. 37 designates rods, which extend from one end support 38 or corresponding member at a first edge 39 of the roof section to a corresponding end support 8 at a second edge (not shown) via the upper end 40 od said first, outer intermediate support 35, the lower end 4l of the in-between intermediate support 36 and the upper end of a second, outer intermediate support (not shown). Rods 42 extend between the end supports 38 at the edges 39 via the lower end 43 of the first, outer intermediate support, the lower end 41 of the in-beteen intermediate support and the lower end of .the second, outer inter- mediate•-.--support.

The rods 37, ^2, as mentioned, are prestressed, for ex¬ ample in connection to the end supports 38 or in another suitable known way. By means of the rods 37,^2, the sheet is intended by compressive forces to be imparted vault DΓ arc shape extending in the longitudinal direction of the sheet 32, i.e. in the width direction of the roof, as shown in Fig. 6. In Fig. 7a suitable rod arrangement is shown by way of a section D-D according to Fig. 6. 44 in Fig. 7 designates angular ,irons or corresponding memb- ers, which constitute a.o. supports for the intermediate supports and extend in the width direction of the roof below the rods.

In Fig. 8 a fourth embodiment is shown where the sheet is intended to be prestressed to vault shape and where the sheet is intended to be entire, unbroken in each roof half and where a central joint 45 is located with end support 46 at the sheet and a central joint 7 is located also in connection to the angular irons 48.

Rods 49,50 and intermediate supports 51,52 are arranged in the manner as should be apparent from the Figure.

In Fig. 9 a fifth embodiment is shown where a roof is in¬ tended to be assembled of several, in the present case two, roof sections with an entire unbroken sheet, and where each roof section by rods is prestressed to vault or arc shape, and where the vault-shaped sections so join each other, that a substantially continuous vault is formed. At this embodiment, at the edges 53,5.4 of each section are located an upper rod holder 59,60, end supports 55,56 at the end surface 57,58 of the sheet and a lower rod holder 59,60, where the upper and the lower holder are connected by stay members 6l or corresponding members. At each section rods 62 prefer¬ ably extend from an upper rod holder 55 at one edge 53 to an upper rod holder 56 at the other edge 54 via the lower end 63 of a first outer intermediate support 64 and a .second outer intermediate support 65. At each section-also rods 66 are located which preferably extend from a lower rod holder 59 at one edge 53 to a lower rod holder 60 at the other edge via the upper end 67 of said first and second outer intermediate supports 64 and 65. Preferably also rods 68 extend substantially horizontally between the outer free edge 53 of the two outer sections. 69 designates angular irons or corres¬ ponding members extending from one lower rod holder 59 to the other lower rod holder 60.

The embodiment according to Fig. ^~ can be changed to a greater bearing distance by arranging more, for example three, sections in width direction. By maintaining the condition that the vaults of the sections shall join substantially continuously one to the other, the rise of the vault thus assembled is increased. At t_he em_bodiment, for example, according to Fig. 9 the rods are intended so to be prestressed that a vault or arc shaoe is obtained which substantially agrees with the pressing for an arc loaded with a uniformly distrib- uted load.

Embodiments are also imaginable where an additional struttening is obtained.To the^' sheet is imparted, in add¬ ition to the trapezoid corrugation, a wave shape, which can be said to be superimposed the corrugation and is in a plane^*substantially. perpendicuLarto the longitudinal dir¬ ection of the ridges 2 and valleys 3 of the corrugation. Said wave shape is indicated and exemplified in Fig. 2 by the wavy line 1' which includes a wave top. The amplit- • ude and wave length of the wave shape, of course, can be varied within wide limits within the scope of the invent¬ ion. The wave shape V is imparted to the sheet 1 prefer¬ ably in connection to the intermediate supports 11, which thus include portions 15,16, 15',16' with different height in vertical direction. The sheet is here attached to the intermediate supports. The wave shape V successively can disappear outward to the ends of the sheet, such as 5,6, at which load is applied to the sheet. The wave shape 1', preferably to a lesser extent, can also be provided at said ends, such as at the roof ridge 21 and the edges 23 in Fig. 4.

Applications of said wave shape 1' can be imagined, for example, at roofs which are not subjected to snow loads and the rods for taking up tensile forces can be omitted. The roof can be laid by means of a conventional rafter- bearing arrangement or be supported only at longitudinal edge portions of the roof or roof sections. The rigidity of the corrugated and wavy sheet is here not utiliized, or to a very small degree, by the introduction of com¬ pressive forces in its longitudinal direction, but the

OMPI rigi_dity o_f the co-rugated and wavy sheet is utilized directly for increasing the cantilever length.

_The strutting by τ~eans of said wave shape 1' is of course applicable at any

of a roof according to the invention.

The method and the function of the structure according to the invention should substantially have become apparent from the aforesaid. The load from the roof or a roof sect¬ ion is taken up as tensile forces in rods extending betw¬ een the longitudinal adges of the roof or roof section. The reaction forces, substantially corresponding to said tensile forces, are introduced into the sheet, i.e. the water-repelling layer, as compressive forces acting in the longitudinal direction of the sheet, the ridges 2 and valleys 3, by anchoring said rods in the sheet at least at said edges. Hereby the capacity of the trapezoid¬ ally corrugated sheet of taking up compressive forces ^■ acting in its longitudinal direction is utilized for carr¬ ying the roof. Load is transferred from the roof, the

_** sheet, to said rods by intermediate supports. The change in direction of certain rods at the intermediate supports contributes to the capacity of carrying vertical loads.

Through the end supports abutting the end surfaces of the sheet,the said compressive forces are introduced subst¬ antially centrally. The end supports preferably are designed, for example as flat steel bars, so that the load from the rods is distributed uniformly in the long¬ itudinal direction of the edges.

At prestressing in such a manner, that the vault shape substantially agrees with the shape of a pressed arc load- ed with a uniformly distributed load, substantially norm¬ al forces are obtained in the sheet. Snow loads, for^"ex¬ ample, are of this uniformly distributed kind.

A roof structure according to the invention preferably is mounted substantially entirely before the roof is lifted in position. The roof thereafter is anchored to withstand wind loads. As should have become clear from the aforesaid, the.in¬ vention renders it possible, that roofs with water-rep¬ elling layer of corrugated metal sheet can be constructed in a very simple and cheap way by utilizing the capacity of the sheet to take up compressive forces acting in its longitudinal direction. The sheet participates here both as water-repelling layer and as primary and secondary bearing structure. By the invention large bearing dist¬ ances can be established at low cost. The vault shape achieved by prestressing increases the buckling resist¬ ance of the sheet and at the same time facilitates the water runoff.

The invention has been set forth above with reference to some variants and embodiments. It should be obvious, that further variants and minor changes and complements can be imagined without deviating from the invention idea. The number of intermediate supports, for example, and their positioning can be varied depending on the bearing distance of the roof or section, etc. The arrange- ent of rods described here must be regarded as embodim¬ ents by way of example. The rod arrangement, prestress¬ ing etc. is to be adapted to the bearing distance etc. according to known theoretical strength principles.

The invention, of course, can be applied to corrugation other than trapezoid one.

As should have been understood, the sheet is intended not to be jointed in lengths one after the other between end supports or corresponding members, i.e. with joints extending perpendicularly to the longitudinal direction of the ridges and valleys. In width direction, however, the jointing can be carried out in known manner, as marked in Fig. 7-

The additional wave shape 1" , of course, can be effected in several ways. Lightweight cross-beams or corresponding members can be arranged at the lower surface of the sheet, where at each lightweight beam a flat iron or corr¬ esponding memeber is located formed to said wave shape, to which flat iron the sheet is intended to be attached in order thereby to assume wave shape.

The invention, thus, is not to be regarded restricted to the variants and embodiments set forth above, but can be varied within the scope of the attached claims.

Claims

1. A method of bearing a sheet roof where the sheet con¬ stitutes a water-repelling surface layer and preferably is trapezoidally corrugated in known manner with ridges 5 of trapezoid cross-section extending in the longitudinal direction of the sheet and trapezoid valleys located betw¬ een the ridges, which longitudinal ^'direction extends n substantially in parallel with the bearing distance dir¬ ection, width direction, of the roof and the sheet at

10 least in connection to the longitudinal edges of the roofis.laid on bearing beams or corresponding members arranged perpendicularly to said width direction, c h a r a c t e r i z e d i n that the load from the . roof or a roof section is taken up as tensile -forces in

15 rods (7,27,29,37,42,49,50,62,66,68) extending between the longitudinal edges (5, ,23,53,5 ) of the roof or roof section, and that'reaction forces substantially corresponding to said tensile forces are introduced into the sheet (1,32) as compressive forces acting in

20 the longitudinal direction of the sheet by anchoring said rods in the sheet at least at said edges, whereby . the capacity of the trapezoidally corrugated sheet of taking up compressive forces acting in its longitudin¬ al direction is utilized for bearing the roof.

252. A method as defined in claim 1, c h a r a c t e r ¬ i z e d i n that load is transferred from the sheet (1,32) to said rods by intermediate supports (11,25, 26,35,36,51,52,64,65) arranged substantially vertic¬ ally between at least certain of said rods and the sheet,

30 and that the rods change their direction in a subst- • antially vertical plane at at least certain intermedi¬ ate supports, whereby vertical load can be carried.

3. A method as defined in claim 1 or 2, c h a r a c t ¬ e r i z e d i n that said compressive forces are introduced into the sheet (1,32) by means of end supp¬ orts (9,22,38,46,55,56) or corresponding members acting substantially perpendicularly to the end surface (8,51, 58) of the sheet and co-operating with said rods.

4. A method as defined in claim 1, 2 or 3, c h a r ¬ a c t e r i z e d i n that at least certain of said rods are prestressed so that a vault or arc shape extend- ing in the longitudinal direction of the sheet is impart¬ ed to the sheet by said compressive forces.

5. A method as defined in claim 1,2,3 or 4, c h a r- a c t e r i z e d i n that a roof is assembled of two

• or more roof sections located to the side of each other in said width direction.

6. A method as defined in claim 5, c h a r a c t e r ¬ i z e d i n that to each roof section is imparted a vault or arc shape by prestressing the rods, and that adjacent sections are jointed to each other so that their vaults join each other so that a substantially continuous vault shape is formed.

7. A method as defined in claim 4,5 or 6, c h a r a ct- e r i z e d i n that by prestressing said rods a vault or arc shape is brought about, which substanti- ally agrees with the form of a pressed arc loaded with a uniformly distributed load.

8. A method as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that water runoff at the adges of the roof or a roof section is effected by an expedient design of the anchoring of the rods at the edges.

9.. A method as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that to the sheet (1,32) is imparted, in. addition to the corrug-

OMPI ation, a wave shape (1') in its width direction at least at the sheet portions located between said longitudin¬ al edges (5, ,21,23,53,5^) with a substantially greater wave length than of the corrugation, whereby an addit- 5 ional strutting is obtained.

10. A method as defined in claim 9, c h a r a c t e r ¬ i z e d i n that said wave shape (1') is imparted to the sheet (1,32) by means of intermediate supports (11,25,26,35,36,51,52,64,65).

1011. A method as defined in claim 9 or 10, c h a r a c t¬ e r i z e d i n that the wave shape (1' ), at least to some extent, is imparted also at said longitudinal edges (5,6,21,23,53,54).

• 12. A method as defined in claim 9,10 or 11, c h a r - 15 a c t e r i z e d i n that the sheet (1,32) is laid only on conventional rafters or corresponding supports or is laid only on supports at said longitudinal edges (5,6,21,23,53,50, whereby compressive forces originat¬ ing from the bearing of the roof structure are not, or 0 to a small degree, introduced in the longitudinal dir¬ ection of the sheet, and whereby the rigidity of the corrugated and wavy sheet is utilized directly for in¬ creasing the cantilever length.

13. A roof structure where a water-repelling surface 5 layer in the form of preferably trapezoidally corrug¬ ated metal sheet of known kind is comprised with ridges of trapezoid cross-section extending in the longitud¬ inal direction of the sheet and with trapezoid valleys located between the ridges, said longitudinal direction 30 extending substantially in parallel with the bearing distance direction, width direction, of the roof and with bearing beams or corresponding members arranged . substantially perpendicularly to said width direction at least in connection to the longitudinal edges of

•—^■'A?^' the roof, c h a r a c t e r i z e d i n that rods (7,27,29,37,42,49,50,62,66,68) of steel or corresponding material are provided for taking up tensile forces, which rods extend between the longitudinal edges (5,6,23,53, 5^) of the roof or a roof section and are anchored in the sheet (1,32) at least at said edges, whereby react¬ ion forces corresponding substantially to said tensile forces are taken up as compressive forces acting in the longitudinal direction of the sheet, and whereby the capacity of the trapezoidally corrugated sheet of taking up compressive forces acting in its longitudinal dir¬ ection is utilized for bearing the roof structure.

14. A roof structure as defined in claim 13, c h a r ¬ a c t e r i z e d i n that substantially vertically arranged intermediate supports (11,25,26,35,36,51,52,64, 65) are located between at least certain of said rods and the sheet, which intermediate supports are carried by said rods, and at which intermediate supports at least certain of said rods change their direction in a substantially vertical plane, whereby vertical load can be carried.

15- A roof structure as defined in claim 13 or 14, c h a r a c t e r i z e d i n that said compressive forces are introduced into the sheet by means of end supports (9,22,38,46,55,56) or corresponding members acting substantially perpendicularly to the end surface (8,57,58) of the sheet (1,32) and co-operating with said rods.

16. A roof structure as ^"defined in claim 13,1 or 15, c h a r a c t e r i z e d i n that at least some of said rods are prestressed. so that a vault or arc shape extending in the longitudinal direction of the sheet can be imparted to the sheet by said compressive forces.

OMPI

17. A roof structure as defined in claim 13,14,15 or •16, c h a r a c t e r i z e d i n that said sheet consists of sheets entire and unbroken in said width direction and extending from one edge to the other of 5 the roof or a roof section.

18. A roof structure as defined in claim 17, c h a r ¬ a c t e r i z e d i n that rods (42) extend from one of the edges (39) to the other via the lower end (43) of a first outer intermediate support (35) and

10 the lower end (43) of a second outer intermediate supp¬ ort (35), which intermediate supports (35) are located substantially symmetrically in said width direction, and between which intermediate supports the rods (42) extend substantially horizontally, and that rods (31)

15 extend from one edge (39) to the other (39) via the upper end (40) of said first outer intermediate supp¬ ort (35), the lower end (41) of at least one intermed¬ iate support (36) located between said outer intermed¬ iate supports (35) and the upper end (40) of said second

20 outer intermediate support (35).

19- A roof structure as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that two or more roof sections are located to the side of each other in said width direction.

2520. A roof structure as defined in claim 19, c h a r¬ a c t e r i z e d i n that each roof section is pre¬ stressed by the rods to vault or arc shape, that the vaults of the sections join each other so that a subst¬ antially continuous vault is formed, and that each sect-

30 ion at its edges comprises an upper rod holder (55,56) at the end surface (57,58) of the sheet and a lower rod holder (59,60) in connection to the end surface (57,58) of the sheet, and that at each section rods (62) pref¬ ably extend from an upper rod holder (55) at one edge

35 (53) to an upper rod holder (56) at the other edge (54)

OMP via the lower end (63) of a first (64) and a second (65) outer intermediate support, and that at each section rods (66) preferably extend from a lower rod holder (59) at one edge (53) to a lower rod holder (60) at the 5 other edge (54) via the upper end (67) of said first (64) and said second (65) outer intermediate support, and that rods (68) preferably extend substantially hor¬ izontally between the outer free edge (53) of the two outer sections.

1021. A roof structure as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that members such as int.eimediate supports (11,25,26,35,36, 51,52,64,65) are provided, by means of which the sheet (1,32) is intended to be imparted with an additional

15 wave shape (1') in its width direction at least at the portions of the sheet (1,32) located between said long¬ itudinal edges (5,6,21,23, 3,5 , which wave shape (l has_.a substantially greater wave length than the corr¬ ugation, whereby additional strutting is obtained.

20 22. A roof structure as defined in claim 21, c h a r¬ a c t e r i z e d i n that said wave shape (1") at ieast so some extent is imparted also at said- longit¬ udinal edges (5,6,21,23,53,54).

23. A roof structure as defined in claim 21 or 22, 5 c h a r a c t e r i z e d i n that supports are provided only for supporting the sheet, and thereby the rigidity of the corrugated and wavy sheet is utilized directly for increasing the cantilever length.