WO2013093533A2

WO2013093533A2 - Truss, heat expansion unit, light construction building and method for improving stability thereof

Info

Publication number: WO2013093533A2
Application number: PCT/HU2012/000142
Authority: WO
Inventors: Lajos HÉDER
Original assignee: Heder Lajos
Priority date: 2011-12-22
Filing date: 2012-12-21
Publication date: 2013-06-27
Also published as: HUP1100715A2; HU230313B1; WO2013093533A3

Abstract

The invention relates to a truss (1) for forming a light construction building, said truss (1) comprising vertical posts (2,3,4) arranged in at least two base rows (L1,L2), and a couple roof (8) formed by rafters (6), binding beams (6a), purlins (7a) and a purlin ridge (7) is fixed to the vertical posts (2,3,4); and a bracing member arranged between at least two, first and second adjacent vertical posts (3,4) is connected said posts (3,4) in each row (L1.L2), and the bracing member is connected to the upper section of the first post (3) at its first end, and the bracing member is connected to the lower section of the second post (4) at its second end, the bracing member is a bracket bar (10) to be loaded equally by compression and tensile forces, wherein a further bracket bar (11) to be loaded equally by compression and tensile forces is arranged between the first vertical post (3) and the adjacent third vertical post (5) in each row (L1.L2), the bracing member (11) is connected to the upper section of the first post (3) at its first end, and the bracing member (11) is connected to the lower section of the third post (5) at its second end; the bracing members (10,11) is connected to the same fixing point (12) in the upper section of the first vertical post (3); and push bars (13) arranged in planes parallel to the plane (S1,S2) of the couple roof (8) and connected to at least the rafters (6) are attached to the fixing point (12) at their first end, and each push bar (13) is attached to the purlin ridge (7) at their second end; and further push bars (13) are connected to vertical posts (2a, 2b) in the base rows (L1,L2) at their first ends and fixed to the purlin ridge (7) at their second ends; the invention also relates to a heat expansion unit formed by trusses (1 ), and to a light construction building formed by heat expansion units, and a method for improving stability of a light construction building.

Description

TRUSS, HEAT EXPANSION UNIT, LIGHT CONSTRUCTION BUILDING AND METHOD FOR IMPROVING STABILITY THEREOF

The invention relates to a truss for forming a light construction building, said truss comprising vertical posts arranged in at least two base rows, and a couple roof formed by rafters, binding beams, purlins and a purlin ridge is fixed to the vertical posts, and a bracing member arranged between at least two, first and second adjacent vertical posts is connected said posts in each row, and the bracing member is connected to the upper section of the first post at its first end, and the bracing member is connected to the lower sec- tion of the second post at its second end. The invention further relates to a heat expansion unit formed by trusses and to a light construction building formed by heat expansion units, and a method for improving stability of a light construction building is also disclosed.

For light construction buildings, especially greenhouses, vertical supporting posts of the building are arranged along the walls or in the plane thereof, spaced by a distance, which is generally equal and statically well determined. Each vertical post is attached to a horizontal member: the arris fixed to upper ends of the posts. According to the widespread and dominant building solution a rectangular frame arrangement of two vertical posts and the arris are fixed by means of an assembly of two bracing members diagonally crossing each other in the common plane of the arris and the posts and generally made of round bars to be tensioned by tensile forces and each bracing member is prestressed by means of a strain spindle. Since this kind of bracing arrangement has low bearing capacity, it must be repeated by every 20-30 m along a base row of a long building.

Because above solution causes many problems, it is not suitable for achieving stability of light construction buildings, e.g. greenhouses, when getting a huge snow load along with a serious wind load. Changes in temperature are resulted in very huge internal tensions created between bracing assemblies spaced apart in the same plane along the base row. Bracing assemblies spaced apart by 20-30 m tend to maintain their positions, while forces coming into play by a dimensional change of the metal structure therebetween due to a heat effect are beyond the load bearing capacity both of the bars of brac- ing assemblies and the basement of the vertical posts. Forces thus created are greater than the tensile strength of the bars resulted in a permanent deformation that is elongation. With a rising environmental temperature one of the bars and the spindle of the clamping assembly as well as the pier foundation of the post fixed thereto get an overload, and the most weaker point will be loosen, elongated or released. Reducing the temperature the same process as above takes place in connection with the other bar of the assembly.

To solve this problem published patent document CA 1108371 teaches a solution, namely a static support structure for a roof, in particular a green house, comprising posts lined up in rows for supporting a roof structure, and said posts is provided with cross beams, which are rigidly connected with said posts and which run toward a direction, deviating from the direction, in which the posts are located, and which also deviate from a di- rection perpendicular to said row, said cross beams being connected with cross beams of a neighbouring post. Patent document CH 644247 proposes a greenhouse structure comprising bearing beams which extend longitudinally with respect to the greenhouse element, that is parallel to the gutters and to the roofing section, and each beam has several segments connected to the gutters and to the uprights of the greenhouse by means of gussets.

However, these solutions do not result in proper strength for a huge light construction building having great footing area, in particular a greenhouse, since the heat extension of the extremely long structural elements damage the building structure at different locations even if the tensioning bars of the clamping assemblies were replaced by bars having any great strength, that is these stabilizing structures do not handle properly the problem of heat extension but being damaged continuously and become more and more insecure, because released and elongated fixing elements, that should hold the roof structure stable in relation to the ground, allow the roof to be displaced longitudinally in an uncontrolled manner. The mass of the roof is very huge, particularly with an amount of snow in it. The roof displacing by the effect of the wind due to the loose fixing structure has a considerable kinetic energy, thus the building can get into critical state by the impulsive loading forces acting upon the loosen fixing elements. A further risk for the building and for a staff working in it is that the displacement of the roof surfaces having a lost fixed position distorts the right angles of holding the system for roofing elements, e.g. glass panes, resulting in breaking of the roofing elements. Further drawback of the solution taught by CA 1108371 is the application of a huge structure having great mass and casting considerable shadow also increasing the costs of the building project, in the one hand, and, iii the case of a greenhouse, decreases the quantity of solar radiation reaching the soil unfavourably, in the other hand.

Therefore, an object of the present invention is to eliminate the drawbacks of above mentioned solutions and to provide a light construction building, particularly a greenhouse, having an area of even several tens of hectares, withstanding extreme weather conditions and maintaining its own stability in despite of stormy winds while loaded by a thick snow layer on the roof and it does not become deformed in such a way that a danger of life or a damage of the building could be ahead.

The above object is achieved by a truss structure according to the invention for forming a light construction building, said truss comprising vertical posts arranged in at least two base rows, and a couple roof formed by rafters, binding beams, purlins and a purlin ridge is fixed to the vertical posts; and a bracing member arranged between at least two, first and second adjacent vertical posts is connected said posts in each row, and the bracing member is connected to the upper section of the first post at its first end, and the bracing member is connected to the lower section of the second post at its second end, wherein the bracing member is a bracket bar to be loaded equally by compression and tensile forces, wherein a further bracket bar to be loaded equally by compression and tensile forces is arranged between the first vertical post and a directly adjacent third vertical post in each row, the bracket bar is connected to the upper section of the first post at its first end, and the bracket bar is connected to the lower section of the third post at its second end; the bracket bars are connected to the same fixing point in the upper section of the first vertical post; and push bars arranged in planes parallel to the plane of the couple roof and connected to at least the rafters are attached to the fixing point at their first end, and each push bar is attached to the purlin ridge at their second end; and further push bars are connected to vertical posts in the base rows at their first ends and fixed to the purlin ridge at their second ends; and the ends of said push bars fixed to the purlin ridge are attached to the end of at least another push bar fixed to the purlin ridge.

The ends of said push bars fixed to the purlin ridge are attached to the ends of at least three other push bars by means of connection plates.

Push bar is formed by bar sections extending between said rafters and bar sections are adjoined to each other by means interconnecting pieces fixed to the rafters.

Said first vertical post, the second vertical post, the third vertical post and vertical posts directly adjacent the second vertical post and the third vertical post are fixed in a concrete block sunk in the soil or in an element having equivalent strength.

Above object is also achieved by providing a heat expansion unit formed by truss structures according to the invention, by arranging a plurality of adjacent truss structures in the heat expansion unit along their base rows, and the adjacent base rows of two adjacent truss structures are formed by the same vertical posts.

Above object is further achieved by providing a light construction building formed by heat expansion units according to the invention, arranging a plurality of adjacent heat expansion units in the light construction building along both length and cross directions thereof, and vertical posts of two adjacent heat expansion units are connected by means of first hydraulic fastening units attached to hinges mounted on said vertical posts, and two heat expansion units adjacent to each other in length direction are connected by means at least one second hydraulic fastening unit and further hinges.

Said first hydraulic fastening unit consists of a work cylinder formed with first and second work chambers; a piston arranged in the work cylinder and separating the work chambers; a piston rod connected to the piston and a hinge as well; and a connecting bar connected to the work cylinder and a as well; wherein each work chambers is provided by hydraulic fluid inlet ports fluidly connected to a hydraulic fluid tank by means of respective hoses at least one of the latter is provided by a hydraulic valve operated by a control unit connected to a wind speed sensor.

Said second hydraulic fastening unit consists of two first hydraulic fastening units arranged in cross directions, and said hinges are fastened to adjacent rafters of two longi- tudinally adjacent heat expansion units.

Above object is also achieved by providing a method for improving stability of a light construction building, forming a light construction building by using heat expansion units, the method comprising the steps of: arranging several heat expansion units side by side in length and cross directions; connecting adjacent vertical posts of two adjacent heat expansion units by means of a first hydraulic fastening unit attached to hinges fixed on the vertical posts; connecting two heat expansion units being adjacent in length direction by means of a second hydraulic fastening unit and respective hinges; presetting and storing a wind speed value in a control unit; measuring a wind speed value by means of a wind speed sensor connected to the control unit; comparing said measured value to the preset value; and fixing the hydraulic fastening unit by closing hydraulic valves when measured value is greater than/equal to the preset value.

Opening hydraulic valves when measured value is less than the preset value.

The present invention will be disclosed in details with preferred embodiments by reference of attached drawings. In the drawings

Fig.1a is a side elevational view of a preferred embodiment of a truss for a light construction building according to the invention,

Fig.lb is a top side view of a preferred embodiment of a truss for a light construction building according to the invention,

Fig.1c is a front side elevational view of a preferred embodiment of a truss for a light construction building according to the invention, Fig.ld is a perspective view of a preferred embodiment of a truss for a light construction building according to the invention,

Fig.2 shows the connection of the push bars and the rafters as well as the purlin ridge at an intersection node placed on the top of a rafter, in bottom view,

Fig.3 depicts a push bar formed by bar sections,

Fig.4 is a perspective view of a heat expansion unit consisting of trusses according to the present invention,

Fig.5 depicts a preferred embodiment of a light construction building according to the present invention, in which three and four heat expansion units are arranged side by side in length and cross directions, respectively, in

Fig.6 a first hydraulic unit is shown, which is connected to adjacent vertical posts of two adjacent heat expansion units fixing thermal dilatation distance in one direction, in

Fig.7 a preferred embodiment of as second hydraulic unit according to the invention is shown, which is fixing thermal dilatation distances in two directions and prevents longitudinal displacement, and

Fig.8 shows a further advantageous embodiment of the second hydraulic unit depicted in Fig. 7.

Fig. 1a is a side elevational view of a preferred embodiment of a truss 1 for a light construction building according to the invention, while truss 1 is shown in top side view in Fig. 1b and in front side elevational view in Fig. 1c. In this embodiment truss 1 has vertical posts 2, 3, 4, 5, 2a, 2b arranged in two parallel base rows L1 ,L2. Vertical posts 2, 3, 4,5, 2a, 2b are fixed by discrete groundings made in the soil and spaced apart at predetermined, preferably equal distances, having e.g. rectangular shape, and, in addition, a continuous footing A made of concrete is built around the periphery of the building. In this view, base row L2 and vertical posts 2a, 2b are behind the base row L1 hidden from view. A couple roof 8 formed by units consisting of rafters 6, binding beams 6a, purlins 7a, troughs 9, and a purlin ridge 7 is arranged on and supported by the vertical posts 2,3,4,5,2a,2b. In each base row L1.L2 a bracket bar 10 arranged between at least two adjacent vertical posts 3,4 is connected to the first vertical post 3 and the second vertical post 4. A first end of the bracket bar 10 is connected to the upper end of the first vertical post 3, and a second end of the bracket bar 10 is connected to the lower end of the sec- ond vertical post 4. In each base row L1.L2 a further bracket bar 1 is arranged between the first vertical post 3 and a directly adjacent third vertical post 5 is arranged, in such a way that the first end of the bracket bar 11 is connected to the upper end of the first vertical post 3, and a second end of the bracket bar 11 is connected to the lower end of the third vertical post 5. The number of vertical posts 2,3,4,5,2a,2b preferably is equal in base rows L1 ,L2, and vertical posts 3 are placed in the middle of the rows L1.L2, consequently the number of vertical posts 2,3,4_I5,2a,2b in a row L1.L2 is odd. Bracket bars 10,11 are designed to bear both tension and compression loads occurring at given climatic conditions equally. Lower sections of both vertical posts 3,4,5 and vertical posts 2 directly adjacent to vertical posts 4,5 from left and right, respectively, are fixed in each row L1.L2 in a concrete block B having great mass sunk in the soil and preferably being continuous be- neath the soil or in an element having equivalent strength. The two opposed bracket bars 10,11 are connected to the first vertical post 3 in a joint 12. Push bars 13 extend diagonally from joint 12 in the directions of both ends of the truss 1 and in the direction of the other base row L1.L2 in a plane parallel to the plane S1.S2 of the double roof 8, traversing the intersections of transversally arranged rafters 6 and longitudinal purlins 7a, e.g always traversing the subsequent intersections. The ends of the push bars 13 are fixed to the top of the rafters 6, e.g by means of a connection plate Z attached to the purlin ridge 7 from beneath (Fig.2), and further push bars 13 extend diagonally down from there to be connected finally to vertical posts 2a, 2b. It is possible to create an embodiment (not shown), in which upper ends of only two push bars 13 starting at the joint 12 are connected to the connection plate Z. In this case the upper ends of push bars 13 connected to the vertical posts 2a, 2b are fixed to another connection plate Z attached to the purlin ridge 7 next to the first connection plate Z. Bracket bars 10,11 are connected to the same joint 12 of the upper section of first vertical post 3. Designs of bracket bars 10,11 , push bars 13 and the concrete block B depend on the measure of required stability and form part of the knowl- edge of a skilled person.

Fig. 1d depicts a perspective view of a preferred embodiment of a truss 1 according to the invention, in which rafters 6 are not shown in order to make the drawing clear- cut, but their positions is unambiguous according to Fig. 1a, 1 b and 1c. In this embodiment further vertical posts 2, 2a, 2b are arranged in the base rows L1.L2, in such a way that ver- tical posts 3 are placed again in the middle of the base rows L1.L2, thus the total number of the vertical posts 2,3,4,5,2a, 2b remains preferably odd in each base row L1 ,L2, and further push bars 13 arranged in a plane parallel to the plane S1 ,S2 of the double roof 8 and connected to rafters 6, longitudinal purlins 7a and the purlin ridge 7 and also connected to vertical posts 2a,2b by their first ends are attached to vertical posts 2a, 2b of the other base row L1 ,L2 by their other ends. Push bars 13 extend up to the purlin ridge 7 by crossing the rafters 6 preferably but not necessarily at the longitudinal purlins 7a, then, by crossing each other and bending according to the layout of the double roof 8, extend up to the vertical posts 2a, 2b of the other base row L1 ,L2. Truss 1 can be lengthened by placing further vertical posts in direction H on each side. Diamond shapes thus formed in top view can be repeated till outermost vertical posts 2aa,2bb in the base rows L1.L2 of the truss 1 are reached finally.

Push bars 13 are attached to rafters 6 and a node point situated on the top of the rafter 6 beneath the purlin ridge 7 preferably to a connection plate Z by means of bolt connections Cs, as it can be seen in Fig. 2. Truss 1 can dilate and contract in both directions freely from the joint 12. The truss 1 is not restricted to move in above way, and the length of different elements changes according to the thermal expansion. In view of thermal expansion joints 12 are in a neutral position in the middle of the base rows L1 ,L2, thus any forces occurred will quench each other.

Forces acting upon the truss 1 due to the wind pressure and wind suction as well as forces acting on the surface of the double roof 8 due to the frictional drag of the wind are transmitted to the joint 12 through longitudinal troughs 9, purlins 7a and push bars 13. Due to the symmetry of the truss 1 forces acting in longitudinal direction H are equal resulting in a zero resultant force at joint 12. Arrangement of the push bars 13 (Fig. 1 b and 1d) resulted in a shape consisting of subsequent diamond forms. This shape interconnect all rafters determining the surface of the double roof 8, thus a force acting on the double roof 8 from any direction is always exerted on two opposite sides of the diamond shape, which transforms the laterally acting force into longitudinal tension or compression forces, respectively. For greenhouses having a large truss 1 structure, the dynamic force of a wind blast reaches the upwind side of the greenhouse few seconds earlier than its farther side, resulting in a deformation of a building technically not preconditioned to similar events. Diamond shapes extending along longitudinal direction ensure orthogonal features of the building (that is vertical posts 2, 3,4,5,2a, 2b are substantially perpendicular to both troughs 9 and to binding beams 6a as well) for forces acting from all directions, thus preventing glass breakings. Stability of the greenhouse against wind storms can be determined at choice by proper design of bracket bars 10,11 , push bars 13, joints 12, purlin ridge 7 and purlins 7a parallelly arranged to the latter. Consequently, the wind resistance of such a building may be in a wondrous range. Nevertheless, to achieve this aim, a proper and accurate calculation of safe dimensions of the joints 12 of bracket bars 10,11 and push bars 13, as well as of node points of push bars 13 and rafters 6 is essential to be between 0,3 mm, which ensures a play free double roof 8. The planes of the double roof 8 can be displaced longitudinally H, in proportion to the length of the bracket bars 10,11 , up to the elastic limit of the material, e.g. steel, of the elements constituting the truss 1, and this value may be a few mm only at joints 12. These conditions contribute considerably to increase the snow bearing ability of the building, since this way the double roof 8 with very high mass has no play even when huge snow load and wind load as greatest static loads act simultaneously.

In a preferred embodiment of the invention any push bar 13 consists of rod sections 14 extending between rafters 6 as it can be seen in Fig. 3, and rod sections 14 are joined to each other by means of a clamping element K fixed to the rafter 6 e.g. by bolt connections Cs. This solution enables easy assembling of a truss 1.

Buildings constructed using trusses 1 according to the invention, especially green- houses, tolerate a wind load of at least 200 km/h and a snow load of at least 200 kg/m². For maintaining the orthogonal features and for the protection against a longitudinal H wind load acting parallelly to the base rows L1.L2 of a truss 1 suitable for constructing a light construction building, the bracket bars 10,11 and push bars 13 are responsible, as mentioned above. However, the forces resulting from a cross directional K wind load be- ing perpendicular to the plane of the vertical posts 2,3,4,5,2a,2b bears the same vertical posts 2,3,4,5,2a,2b arranged in the base rows L1 ,L2.

By the use of trusses 1 for creating light construction buildings according to the invention buildings, e.g. greenhouses, forming a single heat expansion unit E can be built, which consists of several trusses 1 according to the invention placed side by side. Such a light construction heat expansion unit E can be seen in Fig. 4. This heat expansion unit E is made of trusses 1 according to the invention in such a way, that a plurality of trusses 1 are arranged side by side along their base rows L1 ,L2, that is along the longitudinal direction H, and adjacent base rows L1.L2 of two adjacent trusses 1 consist common vertical posts 2,3,4,5,2a, so the two base rows L1 ,L2 are unified. The heat expansion unit E pref- erably consists of four trusses 1 , but it can contain more or less trusses 1 depending on material quality of the same.

Due to a huge snow load occurring in the temperate zone a large span must be designed between the base rows L1.L2 in order to form a snow trap HZ of adequate size to receive a huge quantity of snow between the double roofs 8 of an expansion unit E, fail- ing which nightly darkness overtakes the greenhouse after a heavy snowfall. In the case of very low outer temperature the snowbreak needs much time or huge amount of heating energy either. Conversely, a large span between the base rows L1 ,L2 is disadvantageous as regards the strength of the heat expansion unit E, since forces resulting from a cross directional K wind load being perpendicular to the plane of the vertical posts 2,3,4,5,2a,2b bears the same vertical posts 2,3,4,5,2a,2b arranged in the base rows L1.L2, as mentioned above. For this, the strength of the vertical posts 2,3,4,5,2a,2b should be increased along with an increase of the span, e.g. by means of applying reinforced vertical posts 2,3,4,5. But, in a heat expansion unit E consisting of several trusses 1 each vertical post 2, 3, 4,5,2a, 2b has an optimal size. Conducting a computer simulation it has been revealed by the applicant, that applying vertical posts 2,3,4,5,2a,2b greater than that optimal size resulted in a controversial effect. The cross directional K width of a truss 1 containing vertical posts 2, 3,4,5,2a, 2b greater than the optimal size can be at most 1 10 m, because above this value the base rows L1 ,L2 may came to critical conditions due a snow load of 200 kg/m². A distance between the vertical posts 2a and 2b in front and rear positions in the base row L1 ,L2 of a truss 1 , respectively, can be 200 m at most. This way, a heat ex- pansion unit E of optimal size consisting of trusses 1 of optimal number formed by vertical posts 2,3,4,5 of optimal number can be created, the dimension of which cannot be increased reasonably, since along with such an increase the snow load bearing ability will be lost, because the double roof 8 sprawls an becomes wider due to the load and widths accumulate from the longitudinal H centreline and the vertical axes of the vertical posts 2,3,4,5 of lateral base rows L1 ,L2 are going to be tilted outwardly and the load becomes eccentric.

In despite of above, dimensions of a light construction building, e.g. a greenhouse, can be increased according to the invention in such a way, that several heat expansion units E are placed side by side, but these units E cannot be joined to each other in a sta- tionary way due to the problems mentioned above, since fixed structural elements could not tolerate any heat expansion occurring in each units E without a damage, because only one heat expansion unit E having optimal size has its own optimal heat motion, as aforesaid.

In case of considerable wind load, heat expansion units E fixed together could tol- erate stronger wind loads, than heat expansion units E standing independently, since in the case of heat expansion units E standing independently side by side the strongest load occurs on a unit E standing lateral position upstream of the wind pressure, and among the units E standing behind it the farthest one is the most loaded due to the force of the wind suction, which is, however, smaller than the force of the wind pressure.

Consequently, a light construction building must be created by applying heat expansion units E arranged side by side in both longitudinal H and cross directions K, in which the heat expansion in each units E is unconfined at no-wind conditions, but the units E can be fixed together rigidly in case of considerable wind loads, thus the wind load is not born by the lateral heat expansion units E only, considerably enhancing the strength of the whole light construction building. In an exemplary light construction building seen in Fig. 5 in top view three heat expansion units E are placed side by side in longitudinal direction H and four units E in cross direction. In order to join the heat expansion units a hydraulic fastening unit T1 is provided allowing unconfined individual movements of the heat expansion units E due to the changes of temperature, but it provides a temporary rigid fixing between the units E when the wind speed measured by a wind speed sensor is beyond a preset value. Since several heat expansion units E are positioned side by side and attached by hydraulic fastening unit(s) T1 fixing a dilatation gap, in the case of closing the hydraulic fastening unit T1 the light construction building can be considered as a single unit as a whole. Hydraulic fastening units T1 adjoin the adjacent vertical posts 2,3,4,5,2a,2b of two outermost adjacent trusses 1 of two adjacent heat expansion units E.

A hydraulic fastening unit T1 attached to adjacent vertical posts 2, 3,4,5,2a, 2b, 2aa,2bb of two adjacent heat expansion units E can be seen in Fig. 6. A hydraulic fastening unit T1 contains a work cylinder 17 formed with first and second work chambers 15,16, and a piston 18 arranged in the work cylinder 17 and separating the work chambers 15,16. Each work chamber 15,16 is provided by hydraulic fluid inlet ports 19,20. Hydraulic liquid is stored in a hydraulic fluid tank 21. Hydraulic fluid inlet ports 19,20 fluidly connected to the hydraulic fluid tank 21 by means of respective hoses 23,24. At least one of the hoses 23,24 can be closed by a hydraulic valve 22. Valve 22 consists of e.g. a simple ball valve, however, of a spring biased single-way magnetic valve 22 in this embodiment. Valve 22 can be controlled - opened, closed - by a simple control unit V connected to a wind speed sensor S and formed by parts well known to a skilled person.

Both work chambers 15,16 of the work cylinder 17 and the hydraulic fluid tank 21 of a hydraulic fastening unit T1 are filled preferably with e.g. brake dressing being ready for operation in a large range of temperatures, and hydraulic valve 22 is maintained in a normal open position by means of a spring. In this open position heat expansion units E can be swung in respect of each other due to the heat expansion, while, according to this movement, hydraulic fluid freely flows from a work chamber 15 of the work cylinder 17 into the other work chamber 16 and back through the open hydraulic valve 22 and the fluid tank 21. When a wind speed value S1 detected by the wind speed sensor S is greater than a value S2 preset in the control unit V the latter closes the magnetic valve 22, flow of fluid ceased, piston 18 keeps a fixed position anchoring the heat expansion units E to each other. Further, when a wind speed value S1 decreased below the preset value S2 the control unit V opens the magnetic valve 22, blocking the swing of heat expansion units E no longer. Hydraulic fastening units T1 according to Fig. 6 are fixing only the distance between two adjacent heat expansion units E, while the inner reinforcement of the unit E is achieved by bracket bars 10,11 and push bars 13 arranged in trusses 1 forming the unit E. In a preferred embodiment of the invention not depicted in Figures both hoses 23,24 can be provided by respective valves 22.

However, adjacent base rows L1.L2 of two heat expansion units arranged side by side both in longitudinal H or cross K directions can swing relative to each other by rows together even if hydraulic fastening units T1 are in closed position. In order to block this movement a hydraulic fastening unit T2 seen in Fig. 7 may be applied, by means of which ail movements occurring in its plane can be handled, providing blocking effect both in longitudinal H and cross K directions, when it is in fixed position. Hydraulic fastening unit T2 of Fig. 7 consists substantially of two hydraulic fastening units T1 having lines of action separated by an angle, preferably a right angle therebetween, and contains two work cylinders 17,17a each formed with first and second work chambers 15,16, and pistons 18,18a arranged in the work cylinders 17,17a, respectively, and separating the work chambers 15,16, and each work chambers 15,16 is provided by hydraulic fluid inlet ports 19,20,19a,20a, and hydraulic liquid is stored in a hydraulic fluid tank 21 , and respective hoses 23, 23a, 24,24a arranged between the hydraulic fluid tank 21 and hydraulic fluid inlet ports 19,20, 19a, 20a can be opened simultaneously and independently by means of a two way hydraulic valve 22 and e.g. moving an electromagnet, and controlled - opened, closed - by a control unit V connected to a wind speed sensor S. A hydraulic fastening unit T2 is connected to adjacent rafters 6 of adjacent heat expansion units E by means of hinges C3, C4, C5, C6 so as it is shown in Fig 7. Operational features of hydraulic fastening unit T2 are the same as those of a hydraulic fastening unit T1. In a preferred embodiment the two way hydraulic valve 22 shown in Fig.7 is maintained in open position by a spring. In this open position heat expansion units E can move, i.e. swing in relation to each other due to thermal motion of the structure, while, according to this movement, hydraulic fluid freely flows from a work chamber 15 of the work cylinder 17,17a into the other work chamber 16 and back through the open hydraulic two way valve 22 and the fluid tank 21. When a wind speed value S1 detected by the wind speed sensor S is greater than a value S2 preset in the control unit V the latter closes the hydraulic valve 22, flow of fluid ceased, both pistons 18 keep a fixed position anchoring the heat expansion units E to each other in both longitudinal H and cross K directions. When a wind speed value S1 decreased below the preset value S2 the control unit V opens the magnetic valve 22, blocking the swing of heat expansion units E no longer. In a preferred embodiment only one assembly consisting of a control unit V and a wind speed sensor S is provided for a single light construction building containing several heat expansion units E. In this case the control unit V controls operation of all hydraulic fastening units T1 ,T2 arranged in a light con- struction building. It is, however, possible to implement a specific embodiment, in which the hydraulic fastening units T1 ,T2 are grouped and each group is provided by its own control unit V and wind speed sensor S.

In a preferred embodiment shown in Fig. 8 each hoses 23, 23a, 24,24a can be closed/opened by a respective valve 22, e.g. by a four way, spring biased magnetic valve 22.

Thus, a method according to the invention can be provided for improving stability of a light construction building, so that a light construction building is formed by using heat expansion units E according to the invention in such a way that arranging several heat expansion units E side by side in longitudinal H and cross K directions. Then, connecting adjacent vertical posts 2,3,4,5,2a, 2b,2aa,2bb of every two adjacent heat expansion units E by means of at least one, preferably by several first hydraulic fastening unit T1 attached to hinges C1 ,C2 fixed on the vertical posts 2,3,4,5,2a,2b,2aa,2bb, and connecting two heat expansion units E being adjacent in longitudinal H direction by means of a second hydraulic fastening unit T2 and respective hinges C3, C4, C5, C6. Presetting and storing a wind speed value S1 in a control unit V and measuring a wind speed value S2 by means of a wind speed sensor S connected to the control unit V, and comparing said measured value S2 to the preset value S1. When measured value S2 is greater than/equal to the preset value S1 the hydraulic fastening units T1 ,T2 will be fixed by closing hydraulic valves 22 arranged in the light construction building, and opening the hydraulic valves 22 when measured value S2 is less than the preset value S1.

Therefore, applying a light construction building and a method for improving stability thereof according to the present invention the drawbacks of above mentioned prior art solutions can be eliminated and light construction buildings having footing area of even several tens of hectares, particularly greenhouses, can be provided that withstand extreme weather conditions and maintaining its own stability in despite of stormy winds while loaded by a thick snow layer on the roof and it does not become deformed in such a way that a danger of life or a damage of the building could be ahead. A light construction building according to the present invention is also able to bear a maximum snow load in- creased by a coefficient of safety prescribed by the Hungarian Standard relating to fixed building constructions (112 kg/m²) even in case of a wind speed of 200 km/h.

Claims

Claims 5

1. A truss (1 ) structure for forming a light construction building, said truss (1 ) comprising vertical posts (2,3,4) arranged in at least two base rows (L1.L2), and a couple roof (8)

10 formed by rafters (6), binding beams (6a), purlins (7a) and a purlin ridge (7) is fixed to the vertical posts (2,3,4); and a bracing member arranged between at least two, first and second adjacent vertical posts (3,4) is connected said posts (3,4) in each row (L1.L2), and the bracing member is connected to the upper section of the first post (3) at its first end, and the bracing member is connected to the lower section of the second post (4) at its

15 second end, characterized in that the bracing member is a bracket bar (10) to be loaded equally by compression and tensile forces, wherein a further bracket bar (1 1 ) to be loaded equally by compression and tensile forces is arranged between the first vertical post (3) and a directly adjacent third vertical post (5) in each row (L1.L2), the bracket bar (1 1 ) is connected to the upper section of the first post (3) at its first end, and the bracket bar (1 1 )

20 is connected to the lower section of the third post (5) at its second end; the bracket bars (10,11 ) are connected to the same fixing point (12) in the upper section of the first vertical post (3); and push bars (13) arranged in planes parallel to the plane (S1.S2) of the couple roof (8) and connected to at least the rafters (6) are attached to the fixing point (12) at their first end, and each push bar (13) is attached to the purlin ridge (7) at their second

25- end; and further push bars (13) are connected to vertical posts (2a, 2b) in the base rows (L1.L2) at their first ends and fixed to the purlin ridge (7) at their second ends; and the ends of said push bars (13) fixed to the purlin ridge (7) are attached to the end of at least an other push bar (13) fixed to the purlin ridge (7).

2. Truss (1 ) structure according to claim 1 , characterized in that the ends of said 30 push bars (13) fixed to the purlin ridge (7) are attached to the ends of at least three other push bars (13) by means of connection plates (2).

3. Truss (1 ) structure according to claim 1 , characterized in that said push bar (13) is formed by bar sections (14) extending between said rafters (6) and bar sections (14) are adjoined to each other by means interconnecting pieces (k) fixed to the rafters (6).

35 4. Truss (1 ) structure according to claim 1 , characterized in that said first vertical post (3), the second vertical post (4), the third vertical post (5) and vertical posts (2) di- rectly adjacent the second vertical post (4) and the third vertical post (5) are fixed in a concrete block (B) sunk in the soil or in an element having equivalent strength.

5. A heat expansion unit formed by truss (1 ) structures according to any of claims 1-

4, characterized in that a plurality of adjacent truss structures (1 ) is arranged in the heat expansion unit (E) along their base rows (L1 ,L2), and the adjacent base rows (L1.L2) of two adjacent truss structures (1 ) are formed by the same vertical posts (2,3,4_J5,2a,2b,2aa,2bb).

6. Light construction building formed by heat expansion units (E) according to claim

5, characterized in that a plurality of adjacent heat expansion units (E) is arranged in the light construction building along both length (H) and cross (K) directions thereof, and vertical posts (2,3,4,5,2a,2b) of two adjacent heat expansion units (E) are connected by means of first hydraulic fastening units (T1 ) attached to hinges (C1.C2) mounted on said vertical posts (2, 3, 4,5,2a, 2b), and two heat expansion units (E) adjacent to each other in length direction (H) are connected by means at least one second hydraulic fastening unit (T2) and further hinges (C3, C4, C5, C6).

7. Light construction building according to claim 6, characterized in that said first hydraulic fastening unit (T1 ) consists of a work cylinder (17) formed with first and second work chambers (15,16); a piston (18) arranged in the work cylinder (17) and separating the work chambers (15,16); a piston rod (18a) connected to the piston (18) and a hinge (C1 ) as well; and a connecting bar (17a) connected to the work cylinder (17) and a (C2) as well; wherein each work chambers (15,16) is provided by hydraulic fluid inlet ports (19,20) fluidly connected to a hydraulic fluid tank (21 ) by means of respective hoses (23,24) at least one of the latter is provided by a hydraulic valve (22) operated by a control unit (V) connected to a wind speed sensor (S).

8. Light construction building according to claim 7, characterized in that said second hydraulic fastening unit (T2) consists of two first hydraulic fastening units (T1 ) arranged in cross directions, and said hinges (C3, C4, C5, C6) are fastened to adjacent rafters (6) of two longitudinally (H) adjacent heat expansion units (E).

9. Method for improving stability of a light construction building, characterized by forming a light construction building by using heat expansion units (E), the method comprising the steps of: arranging several heat expansion units (E) side by side in length (H) and cross (K) directions; connecting adjacent vertical posts (2,3,4,5,2a,2b,2aa,2bb) of two adjacent heat expansion units (E) by means of a first hydraulic fastening unit (T1 ) attached to hinges (C1 ,C2) fixed on the vertical posts (2,3,4,5,2a,2b,2aa,2bb); connecting two heat expansion units (E) being adjacent in length (H) direction by means of a second hydraulic fastening unit (T2) and respective hinges (C3, C4, C5, C6); presetting and stor- ing a wind speed value (S1 ) in a control unit (V); measuring a wind speed value (S2) by means of a wind speed sensor (S) connected to the control unit (V); comparing said measured value (S2) to the preset value (S1 ); and fixing the hydraulic fastening unit (T1.T2) by closing hydraulic valves (22) when measured value (S2) is greater than/equal to the preset value (S1 ).

10. Method according to claim 9, characterized by opening hydraulic valves (22) when measured value (S2) is less than the preset value (S1 ).