EP3284875A1

EP3284875A1 - Arched roof device and method for placing thereof

Info

Publication number: EP3284875A1
Application number: EP17186670.0A
Authority: EP
Inventors: Jean Marc Gilles Glorieux
Original assignee: Glorieux Jean Marc Gilles
Current assignee: GLORIEUX, JEAN MARC GILLES
Priority date: 2016-08-19
Filing date: 2017-08-17
Publication date: 2018-02-21
Anticipated expiration: 2037-08-17
Also published as: BE1024498A9; EP3284875B1; BE1024498A1; BE1024498B9; PL3284875T3; BE1024498B1

Abstract

Arched roof device intended for placing between a first and a second upstand, comprising an elongate first receiving structure, oriented in a longitudinal direction, on the first upstand; an elongate second receiving structure, oriented in the longitudinal direction, on the second upstand; at least a first and second transverse arch, oriented in a transverse direction, between the first and the second receiving structure, wherein each transverse arch is provided with an arched wire receiving channel extending in the transverse direction; at least a first wire grid with a first transverse wire which is slid in the wire receiving channel of the first transverse arch and a second transverse wire which is slid in the wire receiving channel of the second transverse arch; a covering arranged above the first wire grid.

Description

The present invention relates to an arched roof device intended for placing between two upstands, and particularly to roof constructions for use in barrel vault skylights and the like.
FR 2 948 953 in the name of Domeca SA describes an arched roof construction with a grid which is intended to prevent the covering of the roof construction being able to fall down in the case of an impact or in the case of fire.
The Belgian patent with publication number BE 1017118 and the Belgian patents with application numbers BE 2012/0438 and BE 2013/0865 further describe roof devices of the type stated in the preamble.
The present invention has for its object to propose an improved arched roof device which can be placed in simple manner, and is particularly suitable for longer roof constructions and provides protection against persons falling through.
The present invention provides for this purpose an arched roof device intended for placing between a first and a second upstand, which comprises a first and a second receiving structure, a first and second transverse arch lying therebetween, a first wire grid and a covering. The first and second receiving structure extend in a longitudinal direction to respectively the first and second upstand. The first and second transverse arches, oriented in a transverse direction, are each provided with an arched wire receiving channel extending in the transverse direction. The first wire grid has a first transverse wire which is slid in the wire receiving channel of the first transverse arch and a second transverse wire which is slid in the wire receiving channel of the second transverse arch. The covering is arranged above the first wire grid.
By making use of a wire grid which is slidable with its transverse edges in a first and second wire receiving channel of first and second transverse arches the roof construction can be assembled in simple manner, also for long constructions in which two and more grids and three and more transverse arches can then be used.
In an advantageous embodiment at least two wire grids (comprising said first wire grid) are arranged adjacently of each other as seen in the longitudinal direction. In such an embodiment at least three transverse arches (comprising said first and second transverse arch) are provided. Each wire grid is then provided with a first transverse wire which is slid in the wire receiving channel of a first transverse arch and a second transverse wire which is slid in the wire receiving channel of a second transverse arch. In such an embodiment the transverse arches are preferably provided with two wire receiving channels for receiving a transverse wire of a first wire grid and a transverse wire of a second grid situated adjacently thereof.
Each wire grid preferably comprises a plurality of transverse wires and a plurality of longitudinal wires attached thereto. The first and second wire receiving channel are then preferably provided with an arched slot, oriented in the transverse direction, through which the plurality of longitudinal wires protrude outward, wherein the height of the slot is greater than the thickness of a longitudinal wire and smaller than the sum of the thickness of the longitudinal wire and the transverse wire. A transverse wire is in this way anchored in the wire receiving channel.
The first and second wire receiving channel are preferably each formed with a hook-like element which extends partially over the first and second transverse wire such that the first and second transverse wire remain anchored in the first and second wire receiving channel in the case of an impact on the covering. The hook-like element preferably adjoins the slot. The hook-like element is for instance formed by an upright wall which is directed inward on an upper end, over the first/second transverse wire present in the first/second wire receiving channel.
In an embodiment a transverse arch is provided with a separating part between mutually adjacent transverse edges of mutually adjacent plates forming the covering. A wire receiving channel can be provided on either side of the separating part for the purpose of receiving mutually adjacent transverse wires of mutually adjacent wire grids.
In an embodiment the covering has a first and a second longitudinal edge which are attached in or to respectively the first and second receiving structure. The first wire grid can further comprise a first and second longitudinal wire which are received in respectively the first and second receiving structure.
In an embodiment each receiving structure is formed as a longitudinal profile with a support flange which supports on the respective upstand, a longitudinal channel for receiving the respective longitudinal edge of the covering, and with a connecting flange between the support flange and the longitudinal channel for the purpose of forming an intermediate space in which the respective outer end of each transverse arch is received. Such a receiving structure has the advantage that a good anchoring of the different roof elements is possible on the upstand.
In an embodiment the covering comprises at least a first and a second plate, preferably a plastic plate, arranged mutually adjacently in the longitudinal direction, and an elongate sealing profile is provided for sealing a space between a transverse edge of the first plate and a transverse edge of the second plate. The sealing profile is formed with an elongate upper flange which extends over the space between said transverse edge of the first plate and said transverse edge of the second plate. A first outer end of the sealing profile is attached to the first receiving structure and a second outer end of the sealing profile is attached to the second receiving structure. In this way a good seal is obtained and the plates are further secured between the first and second receiving structure.
Further advantageous embodiments are described in the dependent claims.
According to a second aspect of the invention, a method is provided for placing an arched roof device between a first and a second upstand. The method comprises the following steps. An elongate first receiving structure is mounted on a first upstand and, parallel thereto, an elongate second receiving structure is mounted on a second upstand. At least a first and second transverse arch, oriented in a transverse direction, are provided between the first and the second receiving structure, wherein each transverse arch comprises a transversely extending arched wire receiving channel. A first transverse wire of a first wire grid is slid in the wire receiving channel of the first transverse arch and a second transverse wire of the first wire grid is slid in the wire receiving channel of the second transverse arch. A covering is arranged over the first wire grid.
In an embodiment at least two wire grids (comprising the first wire grid) are arranged mutually adjacently as seen in the longitudinal direction. At least three transverse arches (comprising the first and the second transverse arch) are provided between the first and the second receiving structure, and for each wire grid a first transverse wire thereof is slid in the wire receiving channel of a transverse arch of the at least three transverse arches, and a second transverse wire is slid in a wire receiving channel of another transverse arch of the at least three transverse arches.
A first longitudinal edge of the covering is preferably attached in or to the first receiving structure and a second longitudinal edge thereof in or to the second receiving structure. Arranging of the covering preferably comprises of: arranging a first plate in an arc between the first and the second upstand, wherein a first longitudinal edge of the first plate is arranged in the first receiving structure and a second longitudinal edge of the first plate is arranged in the second receiving structure; arranging a second plate in an arc between the first and the second upstand, wherein a first longitudinal edge of the second plate is arranged in the first receiving structure and a second longitudinal edge of the second plate is arranged in the second receiving structure; arranging an elongate sealing profile for the purpose of sealing a space between a transverse edge of the first plate and an adjacent transverse edge of the second plate, wherein the sealing profile is formed with an elongate upper flange which is arranged over the space between said transverse edges; and attaching a first outer end of the sealing profile to the first receiving structure and a second outer end of the sealing profile to the second receiving structure.
The present invention will be further elucidated on the basis of a number of non-limitative exemplary embodiments of an arched roof construction according to the invention with reference to the accompanying drawings, in which:

Figure 1 illustrates a cut-away perspective view of an embodiment of an arched roof device;
Figure 2 illustrates a cross-section of an embodiment of a transverse arch of an arched roof device;
Figure 2A shows a detail view of figure 2;
Figure 3 illustrates a cross-section of an embodiment of a receiving structure of an arched roof device;
Figure 3A shows a detail view of figure 3;
Figure 4 illustrates a cross-section of an embodiment of a transverse arch with covering; and
Figure 5 illustrates a cross-section of an embodiment of a transverse arch with bracket.

Figure 1 illustrates an embodiment of a part of an arched roof device between a first upstand O and a second upstand (not shown, but similar to the upstand O). The roof device comprises a first receiving structure, oriented in a longitudinal direction L, in the form of a first longitudinal profile 400 on the first upstand O, a second receiving structure, oriented in the longitudinal direction L, in the form of a second longitudinal profile on the second upstand (not shown), a plurality of transverse arches 200 (only one of which is shown in figure 1) oriented in a transverse direction D, a first and second grid 100 and a covering 300. Covering 300 extends in an arc between the first upstand O and the second upstand.
The transverse arch shown in figure 1 extends between the first and the second receiving structure. Transverse arch 200 is provided on either side with a transversely extending arched wire receiving channel 210, see also figure 2. Each wire grid 100 has on a first transverse edge a first transverse wire 110 which is slid in a corresponding wire receiving channel 210 of a first transverse arch 200 and on a second transverse edge a second transverse wire which is slid in a wire receiving channel of a second transverse arch (not shown).
Although figure 1 shows only one transverse arch 200, the skilled person will appreciate that three transverse arches 200 are preferably provided for two wire grids 100. The skilled person will further appreciate that transverse arches can be provided on either side with a transversely extending arched wire receiving channel 210, but that it is also possible to provide a wire receiving channel 210 on one side only. This latter is particularly the case for transverse arches situated at an end of the roof device, where only one transverse wire 110 need be received. Instead of one transverse arch 200 with two wire receiving channels 210, it is however also possible to provide two transverse arches 200, each with one receiving channel 210, between two adjacent wire grids 100 in figure 1.
Wire grid 100 comprises a plurality of transverse wires 110, 111 and a plurality of longitudinal wires 120, 121 attached thereto. In the shown example the plurality of longitudinal wires 120, 121 lie above the plurality of transverse wires 110, 111, and these wires 110, 111, 120, 121 are welded to each other at the intersections between the longitudinal and transverse wires. The wires of the wire grids are preferably manufactured from metal, such as steel, still more preferably from stainless steel.
Transverse arch 200 is shown in more detail in figure 2 and figure 2A. Transverse arch 200 comprises a middle part 220 which is provided on the underside with a left-hand and right-hand wire receiving channel 210 in which is received a transverse wire 110 of respectively a left-hand and right-hand wire grid 100, these arranged adjacently of each other. Wire receiving channel 210 is here a substantially U-shaped channel with a first side wall 211 which is attached to middle part 220, a lower wall 212 and a second side wall 213. Wire receiving channel 210 is delimited on the upper side by an upper wall 214 which forms part of middle part 220. Extending between upper wall 214 and second side wall 213 is an arched slot 216, oriented in the transverse direction, through which the plurality of longitudinal wires 120, 121 protrude outward. The height h of slot 216 is greater than the thickness d₁ of a longitudinal wire and is smaller than the sum of the thickness of the longitudinal wire d₁ and the thickness of the transverse wire d_d. Transverse wire 110 is in this way anchored in wire receiving channel 210. Wire receiving channel 210 is further formed with a hook- like element 213, 215 which extends partially over transverse wire 110 such that transverse wire 110 remains anchored in wire receiving channel 210 in the case of an impact on the covering. The hook-like element is formed by the side wall 213 which is directed inward at an upper end 215, over the transverse wire 110 present in wire receiving channel 210.
Transverse arch 200 is further provided with a separating part 230 which extends upward from middle part 220 and is intended to form a separation between adjacent transverse edges 310 of a first and second plate 300, wherein these plates 300 form the covering. Plates 300 are typically plastic plates, and for instance multi-walled plastic plates. Plates 300 are preferably manufactured from a material from the group of: polycarbonate, acrylate and other thermoplastics. The plates are preferably flexible such that they can be bent in the transverse direction into a radius of curvature of at least 10 metres.
An elongate sealing profile 500 is provided for sealing a space between a transverse edge 310 of first plate 300 and a transverse edge 310 of second plate 300. Sealing profile 500 is formed with an elongate upper flange 510 which extends over the space between the transverse edge 310 of first plate 300 and the transverse edge 310 of second plate 300. A first outer end of sealing profile 500 is attached to the first longitudinal profile 400 and a second outer end of sealing profile 500 is attached to the second longitudinal profile. Provided for this purpose on the underside of upper flange 510 is a screw channel 560 in which a bolt 610, which runs through an opening in longitudinal profile 400, is tightened on both outer ends, see figure 3. Sealing profile 500 can in this way be tensioned in an arc between the first upstand and the second upstand.
Separating part 230 of transverse arch 200 is here formed by two upright walls 231, 232 and screw channel 560 is dimensioned so as to be receivable between upright walls 231, 232. A good positioning of sealing profile 500 is ensured in this way.
Middle part 220 of transverse arch 200 is provided on its underside with a transversely running screw channel 260 in which a bolt 620, which runs through an opening in longitudinal profile 400, is tightened on both outer ends, see figure 3. Transverse arch 200 can in this way be further secured between the first upstand and the second upstand. These bolts 620 are optional.
Other possible embodiments of sealing profiles 500 are described in the Belgian patent application BE 2016/5060 , the text of which is included integrally herein by way of reference. The sealing profile can more particularly be an elongate profile manufactured from plastic. The sealing profile can for instance be formed with an elongate upper flange, an elongate lower flange, a connecting flange and an elongate screw receiving channel. The elongate upper flange extends over the space between the edges of the plates and co-acts in sealing manner with an upper side of the first plate and an upper side of the second plate. The upper flange can comprise close to a first edge and close to a second edge sealing strips configured to co-act in sealing manner with the upper side of the first and second plates. In an advantageous embodiment the sealing profile is manufactured from the same material as the plates such that the coefficients of expansion of the plates and of the sealing profile are the same. The plates and the sealing profile can thus for instance both be manufactured by extrusion from a polycarbonate material. The sealing strips can then be coextruded, wherein a well sealing material is chosen for the sealing strips, preferably a soft plastic such as a thermoplastic elastomer (TPE).
The first longitudinal profile 400 is intended for the purpose of receiving a first longitudinal edge 320 of a plate 300 and of receiving a longitudinal edge formed by the first longitudinal wire 120 of grid 100. The second receiving profile (not shown) is similarly intended for the purpose of receiving a second longitudinal edge of the plate and of receiving a second longitudinal wire of the grid. Longitudinal profile 400 is here an extrusion profile which is formed with a longitudinal channel 420 with an upper wall 421, a lower wall 422 and a side wall 423. These walls are dimensioned such that a longitudinal edge 320 of a plate 300 fits between upper wall 421 and lower wall 422, see also figure 3A. An outer end of screw channel 560 further also fits in this longitudinal channel 420, and bolt 610 protrudes through an opening in side wall 423. A longitudinal edge 320 of a plate 300 can thus be firmly secured in the longitudinal channel 420 of longitudinal profile 400. The longitudinal profile further comprises a longitudinally running support flange 430 which supports on the upstand O. The outer ends of transverse arches 200 are supported on this support flange 430. Provided between support flange 430 and longitudinal channel 420 is an intermediate space 450 for longitudinal wires 120 and the outer ends of transverse arches 200. Support flange 430 is connected to longitudinal channel 420 by means of a connecting flange 460. The outer end of screw channel 260 is situated in intermediate space 450 and the optional bolt 620 protrudes through an opening in connecting flange 460.
Figure 4 illustrates a further embodiment of a transverse arch 200. The transverse arch comprises a middle part 220 which is provided on the upper side with a left-hand and right-hand wire receiving channel 210 in which is received a transverse wire 110 of respectively a left-hand and right-hand wire grid 100. Wire receiving channel 210 is here a substantially U-shaped channel with a first side wall 211 which is attached to middle part 220, an upper wall 212 and a second side wall 213. Wire receiving channel 210 is delimited on the underside by a lower wall 214 which forms part of middle part 220. Extending between lower wall 214 and second side wall 213 is an arched slot 216, oriented in the transverse direction, through which the plurality of longitudinal wires 120, 121 protrude outward. Just as in the variant of figure 2A, the height of slot 216 is greater than the thickness of a longitudinal wire and smaller than the sum of the thickness of the longitudinal wire and the thickness of the transverse wire. Wire receiving channel 210 can optionally be formed with a hook-like element (not shown) which extends partially over the transverse wire such that the transverse wire remains anchored in the wire receiving channel in the case of an impact on the covering. Middle part 220 of transverse arch 200 is further provided on its upper side with a transversely running screw channel 260 in which a bolt, which runs through an opening in the longitudinal profile 400, can be tightened on both outer ends in a manner similar to the manner described above with reference to figure 3. Transverse arch 200 can in this way be further secured between the first upstand and the second upstand.
The variant of figure 4 further comprises an elongate sealing profile 500 for the purpose of sealing a space between a first transverse edge 310 of a first plate 300 and a transverse edge 310 of a second plate 300. Sealing profile 500 is formed with an elongate upper flange 510 which extends over the space between transverse edge 310 of the first plate 300 and transverse edge 310 of the second plate 300. A first outer end of sealing profile 500 is attached to first longitudinal profile 400 and a second outer end of sealing profile 500 is attached to the second longitudinal profile. Provided for this purpose on the upper side of upper flange 510 is a screw channel 560 in which a bolt, which runs through an opening in longitudinal profile 400, can be tightened on both outer ends in a manner similar to the manner illustrated with reference to figure 3. Sealing profile 500 can in this way be tensioned in an arc between the first upstand and the second upstand. The elongate upper flange 510 is further provided on the underside thereof, substantially in the centre, with a downward directed dividing wall 530, on the outer end of which a support flange 540 is provided. A transverse edge 310 can in this way be received between the elongate upper flange 510 and the elongate support flange 540. For a good sealing the upper flange 510 can be provided on the underside with elongate sealing strips 511, which can optionally be formed by co-extrusion. Support flange 540 can be provided in similar manner with sealing strips 541, which are configured to engage against the underside of the first and second plate 300.
Figure 5 illustrates a cross-section of a transverse arch 200 which is similar to the transverse arch 200 shown in figure 2A, with the difference that a bracket 700 is provided around wire receiving channel 210. Such brackets 700 can be provided at different positions as seen in the transverse direction D. These brackets 700 provide for an additional strengthening and can prevent wire receiving channels 210 from opening by bending in the case of an impact. Brackets 700 can for instance be secured with screws 710 for the purpose of attaching brackets 700 to the side wall 211 of wire receiving channel 210.
Embodiments of the invention are typically used in so-called barrel vault skylights, wherein a number of multi-walled plastic plates can be arranged mutually adjacently in transverse direction between a first and a second upstand. Several layers of plates are herein often arranged one above the other, and the covering can for instance also comprise an arched plate manufactured from a composite material. Further possible embodiments in which the present invention can be applied are described in the Belgian patent with publication number BE 1017118 , in the Belgian patents with application numbers BE 2012/0438 and BE 2013/0865 , and the contents of these patents (in the name of Applicant) is included here by way of reference.
The skilled person will appreciate that the invention is not limited to the above described exemplary embodiments and that many modifications and equivalent embodiments are possible within the scope of the invention, which is defined solely by the following claims.

Claims

Arched roof device intended for placing between a first and a second upstand, comprising:
- an elongate first receiving structure (400), oriented in a longitudinal direction, on the first upstand;

- an elongate second receiving structure, oriented in the longitudinal direction, on the second upstand;

- at least a first and second transverse arch (200), oriented in a transverse direction, between the first and the second receiving structure, wherein each transverse arch is provided with an arched wire receiving channel (210) extending in the transverse direction;

- at least a first wire grid (100) with a first transverse wire (110) which is slid in the wire receiving channel (210) of the first transverse arch (200) and a second transverse wire which is slid in the wire receiving channel of the second transverse arch;

- a covering (300) arranged above the first wire grid.
Arched roof device according to claim 1, wherein at least two wire grids, comprising the first wire grid, are arranged adjacently of each other as seen in the longitudinal direction; wherein at least three transverse arches, comprising the first and the second transverse arch, are provided; and wherein each wire grid of at least two wire grids is provided with a first transverse wire which is slid in the wire receiving channel of a transverse arch of the at least three transverse arches and a second transverse wire which is slid in the second wire receiving channel of a transverse arch of the at least three transverse arches.
Arched roof device according to the foregoing claim, wherein a transverse arch of the at least three transverse arches is provided with a separating part and wherein a wire receiving channel is provided on either side of the separating part for the purpose of receiving mutually adjacent transverse wires of mutually adjacent wire grids of the at least two wire grids.
Arched roof device according to the foregoing claim, wherein the covering comprises at least two plates lying mutually adjacently in a longitudinal direction, and wherein the separating part lies between mutually adjacent transverse edges of two mutually adjacent plates.
Arched roof device according to any of the foregoing claims, wherein each wire grid comprises a plurality of transverse wires and a plurality of longitudinal wires attached thereto; and wherein the first and second wire receiving channel are provided with an arched slot, oriented in the transverse direction, through which the plurality of longitudinal wires protrude outward, wherein the height of the slot is greater than the thickness of a longitudinal wire and is smaller than the sum of the thickness of the longitudinal wire and the transverse wire.
Arched roof device according to any of the foregoing claims, wherein the first and second wire receiving channel are each formed with a hook-like element which extends partially over the first and second transverse wire such that the first and second transverse wire remain anchored in the first and second wire receiving channel in the case of an impact on the covering.
Arched roof device according to claim 5 and 6, wherein the hook-like element is adjacent to the slot.
Arched roof device according to claim 6 or 7, wherein each hook-like element is formed by an upright wall which is directed inward on an upper end, over the first/second transverse wire present in the first/second wire receiving channel.
Arched roof device according to any of the foregoing claims, wherein the covering has a first and a second longitudinal edge which are attached in or to respectively the first and second receiving structure; and/or wherein the first wire grid comprises a first and second longitudinal wire which are received in the first and second receiving structure.
Arched roof device according to the foregoing claim, wherein the first and second receiving structure are formed as a first and second longitudinal profile, each with a support flange which supports on respectively the first and second upstand, a longitudinal channel for receiving respectively a first and second longitudinal edge of the covering, and with a connecting flange between the support flange and the longitudinal channel for the purpose of forming an intermediate space in which respectively a first and second outer end of each transverse arch is received.
Arched roof device according to any of the foregoing claims, wherein the covering comprises at least a first and a second plate, arranged mutually adjacently in the longitudinal direction, and an elongate sealing profile is provided for sealing a space between a transverse edge of the first plate and a transverse edge of the second plate; which sealing profile is formed with an elongate upper flange which extends over the space between said transverse edge of the first plate and said transverse edge of the second plate; and wherein a first outer end of the sealing profile is attached to the first receiving structure and a second outer end of the sealing profile is attached to the second receiving structure.
Arched roof device according to any of the foregoing claims, characterized in that the wire grid is manufactured from metal, preferably steel, still more preferably stainless steel; and/or that the covering comprises a multi-walled plastic plate; and/or that the covering is manufactured from a material from the group of: polycarbonate, acrylate and other thermoplastics; and/or that the covering is flexible such that it can be bent in the transverse direction into a radius of curvature of at least 10 metres.
Method for placing an arched roof device between a first and a second upstand, comprising of:
- arranging an elongate first receiving structure on the first upstand and, parallel thereto, an elongate second receiving structure on the second upstand;

- providing at least a first and second transverse arch, oriented in a transverse direction, between the first and the second receiving structure, wherein each transverse arch is provided with a transversely extending arched wire receiving channel;

- sliding a first transverse wire of a first wire grid in the wire receiving channel of the first transverse arch and a second transverse wire of the first wire grid in the wire receiving channel of the second transverse arch;

- arranging a covering over the first wire grid.
Method according to the foregoing claim, wherein at least two wire grids, comprising the first wire grid, are arranged mutually adjacently as seen in the longitudinal direction; wherein at least three transverse arches, comprising the first and the second transverse arch, are provided between the first and the second receiving structure; and wherein for each wire grid of the at least two wire grids a first transverse wire is slid in a wire receiving channel of a transverse arch of the at least three transverse arches, and a second transverse wire is slid in a wire receiving channel of another transverse arch of the at least three transverse arches; and/or wherein a first longitudinal edge of the covering is preferably attached in or to the first receiving structure and a second longitudinal edge thereof is attached in or to the second receiving structure.
Method according to the foregoing claim, wherein arranging of the covering comprises of:
- arranging a first plate in an arc between the first and the second upstand, wherein a first longitudinal edge of the first plate is arranged in the first receiving structure and a second longitudinal edge of the first plate is arranged in the second receiving structure;

- arranging a second plate in an arc between the first and the second upstand, wherein a first longitudinal edge of the second plate is arranged in the first receiving structure and a second longitudinal edge of the second plate is arranged in the second receiving structure;

- arranging an elongate sealing profile for the purpose of sealing a space between a transverse edge of the first plate and an adjacent transverse edge of the second plate, wherein the sealing profile is formed with an elongate upper flange which is arranged over the space between said transverse edges;

- attaching a first outer end of the sealing profile to the first receiving structure and a second outer end of the sealing profile to the second receiving structure.