JPS5830977B2 - tension upholstered structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a curved rigid frame structure having a taut upholstered sheathing, and more particularly, to a curved rigid frame structure having a taut fabric covering that most effectively receives and distributes positive and negative loads on a plurality of truss members; It relates to rigid frame structures designed to most effectively reinforce, stabilize, and strengthen the framework.

Up until now, various types of buildings have typically been constructed of solid material structures such as wood, metal, stone, brick or concrete, and have generally served their respective purposes satisfactorily.

However, with the passage of time, the demands of the times have also changed, and now the demand for portable structures to meet the demands for temporary structures is increasing day by day.

Furthermore, since the cost currently required to construct buildings is extremely high, the development of buildings based on new ideas is being rapidly promoted in order to reduce the financial burden.

Air support fabric structures are portable and relatively inexpensive to construct.

This structure typically uses extremely strong synthetic fabric, which is inflated by air pressure to withstand wind and snow.

The air pressure inside the structure is maintained by a blower system that usually consists of one or more continuously operating fans and automatic controls.

In addition, these structures are often designed to have a large span and a low vertical cross-section height in order to minimize the influence of wind power.

Although this air support structure has several advantages over conventional rigid frame structures, it also has disadvantages.

For example, blowers and other power equipment for maintaining constant air pressure are prone to failure and stop operating in the event of a power outage.

Furthermore, if the cloth covering is not sufficiently expanded or is exposed to strong winds, it may easily vibrate and tear.

Furthermore, a disadvantage of this air support structure is that the anchorage must be designed to be sufficient to withstand the uplift forces created by the expanding air pressure and the uplift forces due to the wind forces experienced by the structure.

Additionally, air support structures are typically constructed of strong and durable fabrics, but when they break and tear,
Repairs may be difficult and the structure itself may become useless.

Yet another drawback is that it is difficult to prevent localized snow or ice build-up, which often results in destruction of the structure.

It is also very difficult, if not impossible, to insulate these types of structures, making it difficult to meet the air conditioning and heating requirements, and therefore making it difficult to meet the air conditioning and/or heating requirements of such structures. Moreover, it is impossible or at least not possible to suspend light fixtures, electrical wiring, sprinkler systems, water pipes, etc. from the fabric parts that make up the structure. Not done.

A primary object of the present invention is to provide a stable rigid frame tensioned structure that is relatively portable, inexpensive, and safe even in harsh natural conditions.

Another object of the invention is to provide a rigid frame upholstered structure that is self-supporting and capable of thermal insulation.

Yet another object of the present invention is to provide a rigid frame upholstered structure that is not subject to excessive tension or stress, yet does not flap in wind forces.

Still another object of the present invention is to provide a rigid frame clad structure in which light, heat, water, gas, etc. conduits can be suspended from the frame.

Yet another object of the present invention is to provide a rigid frame upholstered structure whose length can be added in stages by using modular pays between the ends.

Still another object of the present invention is to construct a framework using truss members having a polygonal cross section and a curved shape in the longitudinal direction, and to use the curved truss members and side truss together to achieve joint pay. It is an object of the present invention to provide a rigid frame upholstered structure characterized by comprising:

Yet another object of the present invention is to provide a rigid frame upholstered structure characterized in that an arcuate fixed cable is extended between the lower ends of a plurality of curved truss members to tension the fabric sheathing. be.

Still another object of the present invention is to improve the shape of the truss members, the shape of the cables, and between the truss members so that the static tension at all points in the fabric sheathing is substantially the same for the warp and weft threads of the fabric sheathing. An object of the present invention is to provide a rigid frame upholstered structure characterized in that the outline of the fabric portion is defined.

Still another object of the invention is that the rigid frame is constructed to be completely self-supporting under all design loads and that the fabric covering, in addition to providing shelter, provides greater strength to the structure. An object of the present invention is to provide a rigid frame fabric structure characterized by adding high safety.

Yet another object of the present invention is to provide a rigid frame upholstered structure comprised of components of such size, shape and weight that the structure is relatively easy to unload, transport and install.

The above objects and other objects as well as the advantages of the structure of the invention over prior similar structures are realized by the means set out in the following description and in the appended claims.

A preferred embodiment of a structure applying the principles of the present invention will be described in detail with reference to the accompanying drawings, but this is not intended to encompass all embodiments of the present invention, and various types of modifications may be made. It is intended that the invention be limited not by this detailed description, but rather by the claims appended hereto.

In FIG. 1, a rigid rigid upholstered structure 10 applying the principles of the invention consists of a framework 11 by which a fabric covering or membrane 12 is supported.

A static tensile stress is applied to the fabric of the covering membrane by means of a cable 13.

The framework 11 is formed from a plurality of truss members 20 that support the cladding 12 and have curved outer or upper chords that engage the cladding 12.

Each truss member 20 has its lower end connected to the base 19 as usual.
and its upper end is connected to a plurality of other similar or identical truss members to form a polygonal body.

If a long structure is desired, one or more intermediate truss members may be installed between the ends of the structure forming each half of a polygon with the same number of sides, as shown in Figure 1. You can also add additional pay by using this.

Curved truss members 20 are typically designed to maximize space utilization.

2A and 2B, the rectangular or cylindrical tube 3 forming the outer chord of the truss member 20.
1 is provided with an upright wall portion 21 of a predetermined length, and the structure 1 is
It is desirable to obtain a predetermined wall height along the zero turn.

Following this wall, a curved section extends toward the center of the structure.

In order to provide walls of the required height and a flat roof within the required height range, and to utilize the advantages of a curved structure, the truss member is constructed of haunch portion 22 and roof portion 23.
It is preferable to consist of two curved sections.

The radius of curvature of the haunch portion 22 is typically smaller than the radius of curvature of the roof portion 23 in order to obtain the required interior height and span and to minimize wasted space.

The upright wall portions 21 and the curved portions 22,23 can be combined in various ways, thereby forming structures of various shapes.

For example, if you want to use the structure 10 as a church,
The upright wall portion 21 can be made very high, and the haunch portion can also be curved with a relatively large radius of curvature.

If you want a Gothic design, please use the roof section 2.
If a Roman-style dome is desired, the radius of curvature of the roof portion 23 may be made relatively small.

In addition, if you want to use it as an exhibition structure at a trade show, etc., the upright wall part 21 is set to the normal height, and the roof part 23
It is better to make the span longer.

Depending on the type of exhibit being displayed, the radius of curvature of the corbel 22 may be relatively small to provide a relatively low roof height, or the radius of curvature of the corbel may be large to reduce the height of the structure 10. It is also possible to install relatively tall exhibits inside.

In order to realize the desired internal shape of the structure 10, the upright wall portion 2 is
It will be understood that 1 may also have a curvature.

Although the truss member 20 is not limited to the above-mentioned three parts, in order to accommodate the required span and roof height, the truss member 20 is usually composed of these three parts, at least the haunch part and the roof part. A curvature is given to the second part.

In the case of the above configuration, the radius of curvature of the haunch portion 22 is usually smaller than the radius of curvature of the roof portion 23.

The truss member 20 is curved, and can be parabolic, sinusoidal, arcuate, or any other compound curve.

In the specific embodiment shown, the two sections are curved, both arcuate.

That is, the haunch portion 22 has a length of approximately 3.66 m (12 feet) and extends along the chord from point B to point C (FIGS. 2A and 9), and has the same radius of curvature. 3.
66 feet (12 feet), facing a horizontal span of just over 1.2 meters (4 feet).

Further, the roof section 23 extends along the chord from point C to point D, has a length of approximately 9.7 m (32 feet), and a radius of curvature of 14.9 m (49 feet).
It faces a horizontal span of just over 9.7 meters (approximately 30 feet).

The upright wall portion 21 extends from point A to point B, and its height is approximately 1
．． It is 8 meters (6 feet).

Next, considering the configuration of the truss member 20, as described above, the truss member 20 is made of a curved rectangular tube part 31 that constitutes the outer or upper chord member and an angle member,
Lower or inner chord member 33a.

33b, 33c and 33d.

As is clear from FIGS. 2A and 2B, the lower chord members 33a, 33b, 33c and 33d roughly follow the outline of the curved rectangular tube portion 31 constituting the outer chord member.

A transverse spacer angle plate 32 extends between the inner chord members 33 at a predetermined distance.

In accordance with conventional truss design, the truss member 20 includes sloping reinforcing struts 34, also fabricated from angle members, connecting the square tube section 31 with the chord members 33 in the longitudinal direction of the truss member. .

The truss members 20 are interconnected to form the framework 11.

One or more types of face plates 35 are used to make this connection.
will be used, which will be discussed in more detail later.

The cross-section of the truss member 20 may generally be any conventional polygonal shape, or it may simply be a beam.

As shown in FIG. 3, the cross section of the truss member 20 is preferably triangular, as this shape saves on the amount of steel required and has a greater lateral This is because it provides strength and is therefore not only economical, but also provides sufficient lateral stability to ensure that the truss members do not bend or twist laterally during installation. This is because we will make sure that there is no such thing.

Furthermore, the triangular cross-section provides a sufficiently high resistance to torsional loads applied to the assembled truss by the truss members 20, and therefore the lightweight transverse stay bars 18 (the first (see Figure 29), it is possible to sufficiently balance the shear stress between adjacent trusses.

This position of the stay rods 18 leaves sufficient room for the fabric sheathing to assume its hoop shape as described below, without interfering with the ceiling inside the structure, and in a normal manner. Eliminates the need for drilling holes in the fabric covering, which would be required with tie rods.

Furthermore, the transverse tie rods may be designed in such a way that they are sufficient to support the fabric surface even if the fabric surface is completely torn.

At the end of the building, measures against torsional stress on the transformer include
It is sufficient to extend one horizontal bar between the intersections of 3b and 33c.

In particular weather conditions or in certain embodiments, it may be necessary to install additional stay bars between adjacent truss members at one or more locations within the structure.

The width of the bottom of truss member 20, like most polygonal cross-section truss members, is calculated in a conventional manner to withstand normal lateral loading forces.

Excessive base widths are not commonly used because they unnecessarily increase the weight and cost of the truss.

The dimensions of the truss member components can be calculated by conventional design methods well known to those skilled in the art.

Briefly, after determining the height of the upright wall portion 21 and the radius of curvature and length of the haunch portion 22 and roof portion 23 by the method described below, various loads including wind load are determined.

Based on these assumed loading conditions, a stress analysis of the structure is performed to determine minimum allowable dimensional conditions, including appropriate safety factors, for each truss component.

The basic horizontal shape of the framework 11 is a polygon,
If additional space is otherwise required, the pay 15 may be attached to the structure 10 by providing a pair or more truss members 20 spaced apart laterally between the ends.
can be added between the ends.

A combination of these pay truss members is connected to each other,
and/or a side truss 40 is provided for connection to the ends of the structure.

For the majority of structural assemblies, one side truss per pay section is sufficient, and this typically allows for the midpoints of a pair of opposed truss members to be laterally spaced apart. Connect to the intersection of the truss members at the midpoint or end of another pair of truss members.

The shape of the cross section of the side truss 40 is similar to that of the curved truss member 2.
0, generally polygonal, triangular as long as it has good lateral stability and is quite satisfactory in terms of weight, size, price and strength as seen in Figure 7. is desirable.

The side truss 40 usually has parallel members 43a and 43b.
It is similar to the curved truss 20 in that it has box-shaped or rectangular tubes 41 vertically spaced apart from the truss.

The parallel members 43a and 43b are themselves provided at regular intervals in the lateral direction by the bar 42.

The square pipe 41 is connected to the side truss 4 by the reinforcing struts 44.
0 is coupled to two string members 43a and 43b over the entire longitudinal direction.

Although any type of structural component may be used, angle iron is often preferred due to its relatively low cost, strength and bending properties.

As can be seen from FIG. 5, the side truss 40 has a straight shape, unlike the curved truss 20, and the square pipe 41
is inverted so that it becomes the lower chord member.

However, because the ends of the side truss 40 are horizontally sloped, their intermediate portions are lower than the ends, so that the taut fabric sheathing 12 is exposed to the adjacent ends of the pay truss members and the ends of the framework. To form a saddle between the pay truss members in the section.

Preferably, the amount of depression of the intermediate section is not much greater than the maximum depth required for the saddle formed by the membrane of the fabric covering extending between adjacent truss members.

This is because too large a drop would complicate the structure required to maintain the necessary lateral stability on the sides of the structure.

The dimensions of the various side truss components are generally determined solely by the horizontal forces applied to the structure 10.

According to conventional methods well known to those skilled in the art, various loads, including wind forces, are first determined, the required safety factors are added, and the tensile or compressive stresses in each structural component are calculated.

Next, the type and dimensions of each component are selected.

In the assembled framework 11, it is preferable that the truss members 20 are connected to each other at their upper ends as shown in FIGS. 1, 5, 6, and 8. In this case, each truss The member is bolted to the polygonal ceiling member 50 through the face plate 35.

The ceiling member 50 is designed to transfer loads between the truss members, provide sufficient opening for gravity or forced ventilation, and provide a watertight seal.

Generally, the ceiling member 50 has six sides or faces 51, which makes the structure extremely stable due to the regular hexagonal structure requiring six truss members, and the fabric sheathing 12. is subjected to substantially equal tension along both the warp and weft directions.

If it is desired to use more truss members, the ceiling member can have 8 to 10 or more sides, but in that case the number of sides should be as even as possible to facilitate the installation of pay sections. It is desirable to do so.

The ceiling section 50 can also be used to connect opposing pay truss members to each other and to join truss members to side trusses.

In most structures, if a plurality of side trusses are arranged in a line across the ceiling member 50 and the pay truss members are joined to opposing planar portions of the hexagonal ceiling member 50, the side trusses are The sloped end of the plate receives the apex 52 of the ceiling member and forms a stable joint therewith.
A face plate 45 having a letter shape is provided.

To assemble framework 11, curved truss member 20 is coupled to ceiling member 50 and lifted into position.

The bottom of the truss member is then secured to the base using conventional methods.

Thereafter, three more truss members are positioned and bonded to the same ceiling member 50, and these three truss members are also secured to pilings in the appropriate foundation.

Even if only one end structure is thus formed, it is self-supporting and thus greatly facilitates completion of the framework of the structure.

If intermediate pays are not used in the structure, the remaining trusses can be placed in place as well and joined together to form a polygonal framework.

If intermediate pay is used in the structure, a predetermined number of pairs of truss members are placed in predetermined positions and connected to each other by successive side trusses from the first ceiling member 50, and then the remaining half By fixing in place the truss members forming the polygonal ends, a rigid frame structure such as that shown in FIG. 1 can be constructed.

As with other rigid frame structures, various types of light, heat, and water pipes, such as sprinkler pipes, can be supported from the framework.

Additionally, the truss support chords 33 provide an ideal structural member for providing insulation and/or decorative interior wall surfaces.

A fabric membrane or fabric covering 12 is supported on the framework 11, thereby completing the encapsulated basic structure.

After the framework is completely assembled, the cover 12 may be applied.

To facilitate positioning of the sheathing 12 in position, it may first be conveniently folded and rolled into a small bundle, placed on the central top of the framework, and then unraveled in sequence until it is installed in position. .

One convenient method of bundling the sheathing is to first fold the side edges to the longitudinal centerline, as shown in Figures 10 and 11 (Figure 10 shows one side edge folded). ), then both longitudinal ends of the folded covering are rolled up to the center, and the mandrel 52 is inserted into each rolled up part.

As a result, the resulting bundle 53 is tied with a string 54 to maintain its shape.

Both ends of the mandrel 52 project laterally from the bundle and constitute means for lifting the bundle and moving it to a suitable location, as well as lifting it up to the central upper end of the framework 11, at which point the string 54 is untied and the mandrel is utilized. While unrolling this bundle of sheathing along the center line of the framework.

Once unrolled, the edges are spread outwardly and downwardly along the framework, thus placing the covering in its general position above the framework.

As will be discussed below, the covering 12 is pre-designed to have substantially equal tension at any point along both the warp and weft directions, and is made of a fabric that maintains dimensional stability over a wide range of temperatures and humidity. It is desirable to consist of

Although a variety of fabrics may be used for this purpose, polyester fabrics such as DuPont's Dacron have been found to have desirable properties for this purpose.

Further advantages of polyester over other fabrics such as nylon are that it has greater resistance to ultraviolet light, can withstand harsh natural conditions for longer periods of time, and has higher tear resistance.

In order to make the initial elongation of the warp and weft threads as identical as possible, stockinette can advantageously be used.

In that case, basically, a straight warp thread and a weft thread arranged almost at right angles to the straight warp thread are knitted together with a third thread, so that the warp thread and the weft thread are each kept relatively straight, and the weft thread is Make sure it doesn't shrink.

In a fabric with such a structure, even if the weft yarns shrink during the manufacturing process, the elongation rates of the warp yarns and weft yarns are almost the same.

As mentioned above, the difference in elongation between the warp and weft yarns caused by the shrinkage imparted to the weft yarns during the normal weaving process can be minimized by knitting the basic fabric; The linear elongation properties are not eliminated as well, since even the handling of the warp yarns puts some tension on the warp yarns, thereby slightly increasing the elongation of the weft yarns compared to the warp yarns.

It is desirable to coat the fabric membrane with a high quality vinyl compound by methods well known to those skilled in the art to prevent water from penetrating the fabric membrane and to provide resistance to rain, UV light and abrasion.

5. If we consider a special method of attaching a fabric membrane to a structure in such a way that almost uniform tension is obtained throughout the entire fabric membrane, the effect of wind uplift, that is, the effect of subatmospheric pressure on the outer surface of the fabric membrane, is It is extremely important to minimize "flutter".

In order to avoid this "flapping", the outer shape of the fabric membrane should basically not be a flat surface or a single curved surface.

Previous research has shown that the shape that can most effectively withstand positive and negative loads (wind lift or negative pressure) is a ring.

In order to obtain this external shape, it is necessary to apply various forces to the cloth membrane in advance.

In other words, it is necessary to apply a tensile load to the fabric membrane beforehand on the framework.

When orienting a fabric membrane, the warp and weft threads are placed along the longitudinal and vertical axes of the structure, respectively, so that the warp threads (with the least elongation) are exposed to long-term loads such as snow and ice. It is desirable to have a structure that supports a positive load and allows the weft to withstand loads such as flapping due to wind.

This orientation transfers positive loads to the truss with little deformation of the outer fabric membrane.

As previously mentioned, the height and width of the structural framework 11 are selected to obtain the required interior space.

However, these variables are well known to those skilled in the art, and practical considerations for the truss structure avoid making the required depth of the truss members, particularly the depth of the haunches 22, excessive or costly. Selected based on perspective.

Additionally, the radius of curvature of the corbels should be kept within practical limits to avoid excessive tension in the fabric membrane between adjacent corbels, creating undue stress on the fabric.

For example, in the embodiment shown in FIG. 2, the length of the upright wall 21 of the square tube 31 is approximately 1.8 m (6 feet), which constitutes the height of the wall, and which includes the haunches. However, the radius of the outer curved portion of the haunch portion is 3.6 m (12 ft), and its length is approximately 3 m (10 ft) when measured along the arched chord.

From a practical standpoint, this curvature is not so acute as to require excessive weight or expense in the truss component supporting the roof.

Furthermore, since the curvature of the haunch portion is not very large, excessive stress on the cloth of the covering can be prevented.

The radius of curvature of the roof section 23 is set to 14.9 m (49 feet) to match the structure of the haunch section described above, and its extended length is approximately 9.1 m (3 m) when measured along the arched chord.
0 feet).

If the above two truss members are connected to the ceiling member 50 in opposition, the resulting free span of the upper structure is 2.
0.7 m (68 ft) and requires no internal supports.

By arranging a pair of opposing truss members in the middle, separated by a distance of 6.1 m (20 ft) from both ends, as shown in Figure 1, 585 m2 (63 ft)
Two pay structures can be obtained with an unobstructed floor area of over 1,000 square feet).

By adding a pair of opposing truss members approximately 20 feet on center from adjacent truss members, approximately 716 m (7700 m) without intermediate struts
You can roam three pay structures with a floor area of

After selecting a fabric suitable for the covering, determining the proper orientation of the weft and warp threads, and determining the approximate height and width of the structure, the fabric covering will be The design is such that the warp and weft threads of the body are prestressed to approximately the same tensile stress at all points of the curved surface of the covering.

However, since the curvature of the covering 12 differs at each point, it is difficult to perfectly match the tensile stress of the warp and the weft throughout the covering.

The bowing stress of a warp or weft thread at any point on the covering is equal to the product of the load at that point and the radius of curvature of the curve followed by a particular thread at that point. The covering 12 has a double curved surface between two adjacent truss members.

This double curved or convoluted configuration of the fabric covering is termed a sheath shape, and the seat (center) "S" of this saddle is located in a plane centered between two adjacent truss members. It refers to the reference line of the cloth covering 12.

Each warp thread W draws a warp curve, and this warp curve is arranged in a direction so as to straddle two adjacent truss members in the fabric covering, and at the intersection point of each warp curve and the seat S of the saddle, Located in a plane perpendicular to the tangent to the seat of the saddle.

The radius % of the warp curve lies within this plane.

On the other hand, the weft thread F draws a weft thread curve, and this weft thread curve is arranged in the direction sandwiched between two adjacent truss members in the fabric covering 12, and is in a plane parallel to the plane containing the seat S of the saddle. To position.

The radius Rf of the weft thread curve lies within the plane of this weft thread curve.

When viewed from the structure 10, the warp radius ~ is on the outside,
Moreover, the radius Rf of the weft thread is located on the inside thereof.

A brief explanation of the method for designing the cloth covering that straddles the pay portion is as follows.

Starting from the top of the structure, a temporary weft radius Rf is selected, which necessarily ensures that the saddle seat S is not located radially outside the outer curved chord defined by the square tube 31. shorter than the maximum radius of the truss member.

In order to design the warp and weft stresses to maintain the required equilibrium state, the dimension of the temporary weft radius Rf selected as described above is then regarded as the dimension of the temporary warp radius ~, and in this relationship, this dimension is the saddle. The seat S is sufficiently far above the side truss 40,
The cover 12 is designed to allow expansion due to loads due to snow accumulation or freezing.

The next step in the fabric sheathing design is to select a second preliminary radius for the portion of the sheathing that lies between the centers of each haunch of adjacent trusses.

The dimension of this second provisional radius must be such that, when used as the warp radius, the seat S of the saddle is located outside the plane of the lower truss chord member 33.

This second temporary radius, when used as the weft radius, also allows one end of the saddle seat formed between the haunches of adjacent truss members to be in common contact with the saddle seat defined by the first temporary radius. They must be short enough so that they intersect on the line and the other end of the saddle seat formed between the corbels intersects the fixed point along the tangent to the saddle seat.

The overall saddle seat obtained by these two hypothetical radii is somewhat analogous to the outer member of a truss, with a short straight section extending upwardly from its fixed point, and above which a separate radius , intersect and extend to the apex of the structure 10 .

However, the weft radii of the sheathing are closer together than the radii of the truss member 20.

In the illustrated embodiment, the weft radius of the sheathing is approximately 13.7
m (45 ft) and 6.8 m (22,5 ft), and by interpolation we can modify this hypothetical saddle seat to a slightly parabolic curve, so that at any point along the saddle seat we can Make sure the radii of the weft threads are approximately equal.

The polygonal end sheathing is also designed with a radius similar to that used in the pay section design to maintain equal tension on both sides of the truss member at any point along the truss member.

At the ends, however, the seat of the saddle actually reaches the apex, rather than being less than the height of the apex, as in the case of Pei.

The strength and elongation of the fabric under design loads, including wind pressure (positive load) and wind uplift (negative load) and snow load, are calculated by methods well known to those skilled in the art according to actual site conditions. Ru.

Of course, these design loads and safety factors are also taken into account to calculate the tension applied to the sheathing in the portions adjacent to the ceiling member 50 and the haunches, and to calculate the stress on the sheathing due to the expected maximum load. determine whether the intensity is sufficiently below that of

If not, the radius of curvature can be reduced to reduce the tension as long as the product of the load multiplied by the radius of curvature of either the warp or weft is equal to the tensile load of the respective warp or weft.

Based on test data regarding the elongation of the fabric under various loads along the warp and weft, the air gap between the fabric and the side truss for the expected loading conditions can be calculated.

As a result of the above, if the two come into contact, it can be avoided in various ways.

For example, the truss members defining the pays could be placed somewhat closer together, thereby reducing the radius of curvature of the fabric or increasing the diagonal drop of the side beams.

In the case of the illustrated example, the tension of the fabric at the maximum load condition is 52.2 k per 2.54 α in the ceiling member area.
g (115 lb), and 2.54 at the haunch.
It is calculated to be approximately 20.4 in 9 (45 lbs) per C/IL.

This number is well within the strength of commercially available cloth.

After determining the appropriate radius and curvature to incorporate into the sheathing design as described above, and calculating that the fabric sheathing will be able to withstand the maximum loads expected, the next step is to Defining the shape is a matter of geometry and trigonometry, which can be sewn or welded together to complete the complete covering.

However, since cloth is not completely dimensionally stable,
It is necessary to predetermine the amount of preload so that the dimensions of the interspar feature are reduced by the amount of elongation that occurs in the warp and weft threads.

In the illustrated embodiment, the maximum tension due to the preload is approximately 4.9 ky per 2.54 CrrL (1 inch).
(10,8 pounds).

This maximum tension occurs in the sheathing located midway between the corbels of adjacent truss members, and the sheathing between the apexes of adjacent truss members, i.e. near the ceiling member 50, has a maximum tension of 2.
．． Approximately 2.45 kg (5 kg) per 54 crfL (1 inch)
, 4 lbs.) to approximately 2.86 kg (6.3 lbs.).

Since the tear strength of the fabric is at least 10 times the maximum value of the tension due to the preceding load, these tensions can be considered to have substantially equal values.

Since adding a positive load will reduce the negative leading load, and adding a negative load will reduce the positive leading load, a building applying the principles of the present invention will be able to reduce the cumulative amount of positive and negative loads. There is no need to consider it as a target.

In practice, the maximum value of the preload is limited by the elongation properties of the fabric.

For example, in the case of a fabric covering with low elongation, it may be extremely difficult to stretch it over a rigid structure after the elongation has been reduced by a very light preload.

Next, a method for determining the specific shape between the cloth girders will be briefly described.

As can be said of any cloth covering, its length is determined by the length of the covering when placed on the framework 11 in its longitudinal direction;
When stretched to provide the required preload tension, the negative radius of curvature, i.e., the radius of the warp yarns, becomes approximately equal to the positive radius of curvature, i.e., the radius of the weft yarns, Rf, resulting in a theoretically desirable shape, i.e., a saddle shape. I will make it happen.

Since the radius of curvature of the weft threads changes from the height of the corbel to the height of the ceiling, the radius of curvature of the negative warp threads must also change accordingly.

To determine the overall proper contour of the fabric covering, calculate the tension on the weft yarns at their midpoints, bottom and top.

Based on this, the radius of the warp is calculated and the fabric section is cut, but in this case, taking into account the elongation due to tension, the length at the midpoint changes approximately proportionally between the bottom and top. It should be of intermediate length.

The dimensions of the ends between the spars which are generally parallel to the weft curve and in contact with the upper chord square tube 31 of the truss member can be determined from the fixed arrangement of the truss member.

Based on this known dimension, an approximation of the dimensions of the weft thread curve of the saddle seat is calculated with a predetermined preload on the fabric and the weft thread elongation normally associated with this load.

Between these two dimensions, the dimensions vary proportionally, but since there is no fixed formula that precisely determines the spacing between girders along the weft curve, the design of individual structures is often done by trial and error. It is often necessary to incorporate

The fabric sheathing is designed in such a way that the warp and weft warp and weft warp and weft warp and weft warp tensioning loads are approximately the same, so that the fixing cable 13 is connected to the intersection of the convoluted saddle of the sheathing and a vertical protruding circle placed parallel to the cable fixing point. Set along the points.

The radius of the protruding circle must be at least half the distance between the fixed points.

In the illustrated embodiment, the maximum area of a possible rectangular opening for entry and exit under the fixed cable in the pay section is 2.4 m (8 ft) wide and 2.4 m (8 ft) high. The opening at the hexagonal end is 3.66 m wide (1
2 feet) and 4.27 meters (14 feet) high.

From a practical point of view, the highest point of the fixed cable arc in the pay section is never less than 1.2 m (4 ft), and in the case of the ends, it is no more than 2.4 m (8 ft). This is due to the cable dimensions that would be required to carry the load when the chord at the ground of the protruding arc traced by the entire fixed cable is offset from the diameter of that arc. .

Also, as shown in the illustrated embodiment, the relatively high arc of the preloaded cable 13 not only allows access between the two trusses, but also allows the closure curtain to be moved in various ways, as will be explained below. can be used.

When designing a sheathing in which the loads applied to the warp and weft threads are unequal, the position of the fixed cable should be an elliptical profile with a convoluted saddle and its principal axis in the vertical plane parallel to the point of fixation of the cable. Determined by the point of intersection with the line.

The main shaft itself is arranged parallel to the direction of the warp or weft threads that bear the greatest load.

After the sheathing has been fabricated and placed over the framework 11, a preload tension is applied to the sheathing by cables 13 contained within the edges of the sheathing 12.

As is clear from FIGS. 13 and 14, the fixed cables 13 on either side of the truss member 20 are adjustably fixed to the truss member by tension members 55.

Tension member 55 may be constructed from a continuous bar having ear loops 56A and 56B;
Cables 13A and 13B can be fixed to the cables 13A and 56B by means of a simple 57 and a crossbeam clip 58, respectively.

Stabilizer 59 is inserted into ear loop 56A across the outer surface of square tube 31 so as to extend between ear loops 56A and 56B.
and 56B.

From this stabilizing plate 59 a continuous bar extends inwardly hugging the side wall of the square tube 31 to form a lateral fixing bar 60 which extends rearwardly of the square tube 31. death,
It engages with a selective notch 61 provided in the toothed plate 62.

This toothed plate 62 is fixed to the rear wall portion 63 of the square tube portion 31.

On the outside of the square tube section 31, the continuous bar has a loop 64 which is spaced above the parallel projections 65 and 66, and on the other hand above the said projections 6.
5 and 66 project outward from the truss member 20.

The protrusions 65 and 66 are provided with holes 68 and 69, respectively, through which a pin 67 is provided which temporarily fixes one end of the means (not shown), and which fastens the other end of the means. can be temporarily secured to the loop 64.

Tightening means applying the required force to cables 13A and 13B.
is then used to pull loop 64 downwardly towards protrusions 65 and 66.

When a predetermined load is applied, the fixed bar 60 moves to the toothed plate 62.
By engaging a predetermined notch 61 of the cable and then removing the tightening means, tension can be applied to each cable converging on the truss member 20 in succession around the base of the structure 10.

The cloth sheathing tends to stretch under tension, and since there is a slight frictional resistance between the cloth and the rectangular tube section 31 forming the upper chord of the truss member 20, the britension of the cloth sheathing 12 is controlled at a predetermined level. It is impossible to achieve it at once on the street.

Therefore, the sheath 12 must be periodically tensioned many times to maintain the required static britension state.

Fixing cable 13 to apply tension repeatedly
In addition, the horizontal and vertical shapes of the three-dimensional curve drawn by the fixed cable 13 change, and therefore, if there is a part of the cloth membrane attached to the cable located between the cable and the ground, that part Unless tensioned separately from the rest of the covering 12, it will tend to wrinkle.

An embodiment of an independent lower curtain γ5 used to close off the section between the fixed cable 13 and the ground is shown in FIGS. 15-19.

As is apparent from FIG. 15, curtain 75 is comprised of a continuous sheet of fabric disposed across a predetermined number of adjacent truss members 20. As best seen in FIG.

The lower edge 76 of this fabric sheet is located close to the ground, and the upper edge 78 is located at a height slightly above the curved upper end of the fixed cable 13.

The fabric curtain 75 is secured by a series of positioning brackets 79 to prevent lateral movement relative to the truss member.
These brackets γ9 are connected to each truss member 2.
It is provided so as to embrace the rectangular tube section 31 that constitutes the upper chord member of 0.

As shown in FIG. 16, the bracket 79 is attached to the curtain 75
1 forming a web portion 81 fixed to the fabric constituting the
It may also include pieces of cloth.

Side flanges 82 and 83 of bracket 79 include lateral edges of the aforementioned fabric, each of which is secured around a forming member 84.

In the illustrated preferred embodiment, each forming member 8
4 may consist of a length of cable or rope.

The positioning bracket 79 extends upward to a height equal to or higher than the upper end of the curve drawn by the fixed cable 13, and at the above height, the positioning bracket 79
9 is preferably attached to a fixed yoke 85.

A fixed yoke 85 (FIG. 17) prevents vertical movement of the curtain.

A leaning portion 86 of the fixed yoke 85 is fixed to a web portion 81 of the bracket 79.

Forked arm portions 88 and 89 of fixed yoke 85 Flange portion 86
It extends outward in the longitudinal direction from the center and extends laterally on both sides of the outer chord rectangular tube 31 (see FIG. 18).

The end of each arm 88 and 89 forms a loop 90 that engages a fixing pin 91.

Fixation pins 91 extend through truss member 20 and are positioned above appropriate posts 34 to secure curtain 75 in the vertical direction.

In this way, before installing the outer covering 12, the curtain 7
5, the tightening of the fixed cables 13 can be performed by adjusting the convoluted shape of the sheath to the position of each fixed cable 1.
Curtain 75 forcing the covering over the entire length of 3
, thereby giving the curtain 75 the same convoluted shape as the covering that contacts the curtain 75 .

The lower edge 76 (FIG. 15) of the curtain 75 is fixed to the ground by a cable, which allows the curtain 75 to be tensioned independently of the covering 12.

In the configuration according to the preferred embodiment shown, the cable 9
1 extends continuously through a plurality of curves forming the lower edge 76 of the curtain 75 and attaches a chain 93 to each end of the cable 91 and each loop 94 forming a connection between successive curves. .

Adjustment clamps 95 (FIGS. 19-21) secure each chain 93 to a plate member 96 fixed to the ground.

The clamp 95 is provided with a hook portion 98 at one end thereof, and the hook portion 98 can be engaged with a predetermined link of the chain 93.

Further, a head 100 is provided at the other end of the clamp 95, and this head is configured to be able to interlock with the plate member 96.

As is clear from FIGS. 20 and 21, the plate member 9
6 has one or more T-slots 101, the head 100 has a stud 102 extending laterally outward, and the T-slot 1
It can be freely engaged through the lateral portion 103 of the T-slot 101 and can be positioned behind the stem portion 104 of the T-slot 101 as well.

The head 100 is provided with flat portions 105 and 106 facing in opposite directions to engage opposite side walls 108 and 109 of the stem portion 104, respectively, thereby causing the head 100 to engage the plate member 96. It is desirable to have a structure that prevents rotation when the

It is preferable that the hook part 98 is provided with a handle part 110, and the handle part 110 is provided with a thread 111 on the outside so that it can be freely engaged with a threaded groove provided in a hole 112 in the head part 100. .

Because of this threaded engagement, the handle 110 can be adjusted in the axial direction of the head 100 over a distance at least equal to the length of the link 99, so that the hook 98 can be adjusted in the axial direction of the head 100. 93, and the tension of the curtain 75 can be precisely determined independently of the covering 12.

The hanging portion 113 may be fixed to a portion of the curtain 75 above the curve drawn by the curtain cable 91 and may be extended to the ground.

Since it is undesirable for the sagging portion 113 to vibrate, the first
As shown in FIG. 9, it may be fixed to a support rod 114 fixed on the ground using nails or other means.

In the preferred embodiment shown in the figure, the tension member 55 has a tension member 55 intersecting with the curtain 75 in the truss member 20 when a curtain 75 is used. It is desirable to change the position of the curtains 75 to the outside of the curtain 75 and arrange them outside the truss member 20 at regular intervals.

- By way of example, an adjustable clamp 95A similar to clamp 95 is used with a second plate member 96A having at least one T-slot 101A.

As shown in FIG. 19, this clamp 95A is fixed between a chain 93A fixed to the cable 13 and a plate member 96A.

As the plate member 96A, one similar to the plate member 96 is used, and a second drawing board member as shown in FIGS. 20 and 21 is used.
A T-slot 115 is provided in which the bottom of a means (not shown) is temporarily and removably secured, and tension is applied to the cable fixed to the plate member, and the clamp 95 or 95A is adjusted appropriately. to maintain the britension load.

The curtain 75 may be provided with a vertically separating seam to facilitate access to the interior of the building using the curtain.

The edges of the seam may be suitably provided with ramps or other tensioning means to enable the curtain to be pulled laterally when closing at the seam.

As another example, the lower curved opening of the fabric covering in each pey formed between adjacent trusses comprises a seam strip extending laterally between the inner or lower chords of the trusses. Rectangular cloth curtain 125 (
(Fig. 22).

The fabric curtain 125 extends from the base angle to the top of the bottom angle of the compression member, which extends horizontally between adjacent trusses.

Curtain 125 is preferably made of cloth, but may also be constructed of a rigid material.

As shown in FIG. 26, the side edge of the fabric curtain 125 extends inwardly or along the lower chord member 33 of the truss member 20,
It covers the inner legs 126 of the adjacent angle members 128 forming the inner or lower chord member 33, and is formed in a loop shape above and below a series of curtain angle members 129.

The curtain angle member 129 extends inside the truss angle member 128 and along the same angle member 128, and the edges of the fabric curtain are joined at their own portions 130.

The curtain angle members 129 are arranged along the truss angle members 128 at a constant interval, and the truss supports 34 and the angle members 12 are arranged at a constant angle.
It accepts the joint between 8 and 8.

The curtain angle members 129 are adjustable and fixed to the outer leg portions 131 of the truss angle members 128 by adjusting bolts 132 arranged at regular intervals, thereby applying tension to the cloth.

As can also be seen in FIG. 23, parallel slits 134 are provided between the ends of adjacent curtain angles and extend over the joint between the truss angles 128 and the posts 34.

The lower edge of the fabric curtain 125 is attached to a base angle member 135, which is fixed to the foundation 19 or floor of the building and the adjacent truss member 20 (
27) and extend laterally between the inner surfaces of FIG. 27).

The curtain is constructed in a loop around the base angle 135 and its edges are joined to its own section 136.

A protective ground ledge 138 extends outwardly from the joint on the base angle and the curtain loop to the ground.

As shown in FIG. 24, a circular hole 139 and a semicircular hole 140 are provided at the locations of the fixing bolts 141 fixing the base angle member 135, thereby allowing the bolts 141 to extend through the fabric portion. , the nut 142 can be tightened onto the bolt 141.

As shown in Figure 25, there are slits 1 on the side edges of the curtain.
43 is provided, and the end of the ground hanging portion 138 is cut or provided with a notch to allow a fabric curtain to be attached around the base of the truss member 20.

As is clear from FIGS. 28 and 31, the upper edge of each curtain 125 is attached to compression members 145, which compression members are vertically spaced apart,
Angle members 14 extending horizontally between adjacent truss members
6 and 148.

The angle members 146 and 148 are mitered at their ends against the upwardly extending angle member 128 of the adjacent truss member, and are mitered by angle members 149 and end bars 150 spaced laterally at a predetermined distance. They are connected at regular intervals in the vertical direction.

As is apparent from FIG. 31, the inner legs 151 and 152 of each of the horizontal angle members 146 and 148 are inclined at a slight angle to each other and the adjacent inner chord members 33A and 33B of the truss member in which the compression member is located. They are arranged at an angle that corresponds to the direction of the angle between them.

As can be seen in FIG. 31, the upper edge of the curtain 125 extends over the inner legs 151 of the lower angles 146 inside the compression member 145 and then the lower angles 14.
It is wound in a loop shape from the lower side to the circumference of a curtain fixing horizontal bar 155 that extends over the entire length inside the curtain.

The bar 155 is adjustably connected to the bottom leg 156 of the angle member 146 by adjustment stops 158 at predetermined intervals, and the adjustment stops 158 extend through openings 159 in the legs. As it extends, its upper end is connected to a bar 155, and its lower end has an adjustment nut 160, by which the tension of the fabric can be adjusted.

This loop-shaped cloth is provided with a suitable hole 161 to expose the joint between the stopper 158 and the support bar 155.

A bias-cut filler panel is used to seal the gap between the compression member 145 to which the upper edge of the curtain panel 125 is secured and the outer sheathing 12 of the structure 10.

The shape of this filling panel 165 is as shown in FIG. 34, and its linearly beaded inner edge 166 is connected to the compression member 145, and a bent portion 168 is formed along the opposite edge. The inner surface of the cloth covering 12 is sealed.

As is clear from FIG. 37, a plurality of pockets 169 are provided at regular intervals along the filling panel 165 from the linear inner edge 166, and these pockets 169 are connected to the reinforcing bar 17.
0, and as shown in FIG.
By adding a predetermined curve to 68, the fabric covering 12
and are sealed together.

In FIG. 31, the outer portion of the compression member 145 is closed off by a metal plate 173, which is provided with a forwardly angled upper end 174;
A support bar 175 is fixed to 74, and this support bar 17
5 is fixed to the straight inner edge 166 of the filling panel 165 in the pretensioned state.

A sag 168 at the outer edge of the filler panel 165 seals the outer fabric sheath 12 from the underside.

Both ends of the filling panel 165 contact the legs of the angle support columns 34 of each adjacent truss member, and the angle members 172 are secured to the angle support columns 34 by bolts 176.

As shown in FIGS. 29 and 33, bracing angles 177 extend from the intermediate portions of each of the compression members 145 at an angle toward the reinforcing columns 34 of the truss 20. As shown in FIGS.

A reinforcing angle member 178 extends along the upper surface of the filling panel in the longitudinal direction thereof and is joined to a reinforcing angle member 177 at both ends thereof.

An angle member 178 is attached to the reinforcing rod 170 of the filling panel at the midpoint between its ends.

In this manner, the angle members 178 are able to withstand large wind loads applied upwardly to the fill panel.

After the filling panel 165 is pretensioned to the support bar 175, the outer ends of the two tension angle members 172 at the side ends of the filling panel 165 are rotated using their inner ends as fulcrums, and the tension members 172 are trussed. Pivoting the member 20 laterally away from each other toward the reinforcing struts 34 applies tension to the curved outer ends of the filler panels.

Next, the tension member 172 is attached to the support column 34 by means of bolts 176.
to maintain the filling panel 165 in a sufficiently taut condition.

Since the filler panel 165 is biased, when its free edge is tensioned in this manner, the sag 168 mates with the inner surface of the fabric sheathing 12 that is taut on the truss member 20 to form a seal. do.

If it is desired to provide a heat insulating space under the outer covering 12, the inner curtain 125 may extend upwardly at a constant distance from the outer covering 12.

In that case, another curtain panel is additionally provided in a manner similar to that of the curtain panel 125, exactly aligned with the lower chord 33 of the truss member.

Needless to say, the curtain panels at the ends of the building are tapered so as to match the intersection points of the end truss members from the base toward the ceiling member 50.

The ring-shaped fabric cladding 12 designed as described above has at least three structural advantages over conventional buildings.

First, since the roof and walls are structurally integrated, there is no need to create a cross-bracing structure for the truss members in 2,000 planes, as is the case with conventional methods.

Second, the negative load (wind lift) is resisted by the fabric sheathing's weft threads, which have a greater elongation when tension is applied, so the fabric sheath absorbs and releases more energy. It is possible to soften the impact load on the rigid frame structure.

Third, the negative loads due to wind lift are transferred to the truss members in a manner and direction that reverses the tension and compression forces within the truss due to dead and service loads.

Therefore, the share of the wind lift load transferred to the truss must exceed the total dead load of the truss before the truss is loaded.

In addition to providing a large floor area free of side obstructions, structures incorporating the principles of the present invention have at least three additional advantages over conventional buildings.

First, structures according to the invention generally have lower manufacturing and construction costs than conventional buildings of comparable dimensions.

Second, traditional buildings cannot be easily moved, and even if they can be moved, the cost is high.

Also, relocating a structure according to the invention requires only one set of scaffolding and some labor and equipment.

Third, if desired, one or more polygon ends can be separated from each other to add pay by assembling field seams to the fabric covering.

As is clear from the foregoing description, each of the above objects can be achieved by the taut upholstered rigid frame structure according to the present invention.

[Brief explanation of the drawing]

FIG. 1 shows a fabric cladding of a relatively portable modular complete building having two ends and two intermediate pays for a stable tensioned fabric rigid frame structure applying the principles of the present invention. FIG. 2A is a side view showing a generally curved lower portion of a truss member for supporting a fabric covering of a structure to which the principles of the present invention are applied; FIG. 2B is a perspective view with a portion of the body cut away; The figure is a side view of the upper part of the truss member shown in FIG. 2A, FIG. 3 is an enlarged cross-sectional view taken along line 3-3 in FIG. 2A, and FIG. 4 is a side view of the upper part of the truss member shown in FIG.
Figure 5 is an enlarged side view of the side truss and ceiling member taken along line 5-5 in Figure 1, and Figure 6 is a plan view of the side truss and ceiling member shown in Figure 5. , 7th
The figure is an enlarged cross-sectional view taken along line 77 in Figure 5, and Figure 8 is an enlarged cross-sectional view of Figure 5
9 is an enlarged cross-sectional view taken along line 9-9 in FIG. 1, and FIG. 10 is an enlarged plan view taken along line 88, and FIG. 11 is a plan view schematically showing a method of folding the fabric covering in the transverse direction before rolling it in the longitudinal direction; FIG. 11 is a plan view showing a bundle of fabric coverings folded and rolled up as described above; FIG.
The figure is a partial perspective view showing a cross section of the fabric sheath removed from between adjacent truss members formed into a double curved convoluted saddle shape by britension. Figure 14 is an enlarged partial elevation view showing the tensioning means; Figure 14 is a reduced side view taken along line 14-14 in Figure 13 (fixed cable removed); Figure 15 shows the tension in the space between the fixed cable and the ground. FIG. 3 is an enlarged elevational view showing a portion of the fabric-covered rigid frame structure, and is a view showing an example of a curtain used to close off the space;
16 is an enlarged cross-sectional view taken along the line 16-16 in FIG. 15, FIG. 17 is a plan view showing a fixing yoke for vertically fixing the curtain in FIG. Figure 18 - Enlarged cross-sectional view taken along line 18, No. 19
15 is another enlarged cross-sectional view taken along line 19-19 of FIG. 15, showing a side view of the means for fixing the curtain of FIG. 15 to the ground, and FIG. An enlarged view showing the plane of the plate, Fig. 21 is Fig. 20 212
22 is an enlarged elevation view showing another example of a barrier curtain located inside the curved lower end opening of the sheathing between the pays, and FIG. 23 is the curtain of FIG. 22. FIG. 24 is an enlarged elevational view showing the lower edge of the curtain in FIG. 22, FIG. 25 is an enlarged elevational view showing the lower corner of the curtain, FIG. The figure is an enlarged sectional view showing how to attach the side end of the curtain to the adjacent inner chord member, Figure 27 is an enlarged sectional view showing how to attach the lower end of the curtain to the base angle member of the base, and Figure 28 is an enlarged sectional view showing how to attach the lower end of the curtain to the base angle member of the base. An elevational view showing one of the compression members extending between the trusses to which the upper edge of the rectangular curtain is attached; FIG. 29 is a partial elevational view of the truss framework showing the location of the compression member and an outline of the structure of the truss;
Figure 30 is a partial side view showing a compression member attached to one of the trusses and a waterproof fill panel extending between the sheathing;
1 is an enlarged partial cross-sectional view showing how the upper edge of the curtain is attached to the compression member and filling panel; FIG. 32 is a cross-sectional view taken along line 32-32 in FIG. 30; and FIG. 33 is a cross-sectional view of FIG.
34 is a plan view showing only the filling panel, FIG. 35 is a partially enlarged sectional view taken along line 35-35 in FIG. 34, and FIG. 36 is a cross-sectional view taken along line 36-36 in FIG. The enlarged cross-sectional view and Fig. 37 are Fig. 34-37-
37 is a partially enlarged sectional view taken along line 37. FIG. 10...Tension hypertonic rigid-frame structure, 12...
...Fabric covering, 13...Cable, 11.
...Framework, 20...Truss member, 19.
...Base, 22...Haunch part, 23...
...Roof part, 31... Square pipe part, 33...
...Inner chord material, 35... Face plate, 40...
... Side truss, 50 ... Polygonal ceiling member, 53 ... Bunch of fabric coverings, 55 ...
Tension member, 60... Fixed bar, 65.66.
...Top part, 75...Lower curtain, 7
9...Positioning bracket, 85...
Fixed yoke, 93... Chain, 95... Adjustable clamp, 113... Lean portion, 114.
...Support rod, 125...Fabric curtain, 128...Angle material, 129...
Curtain angle material, 135...Base angle material, 145...Compression member, 125...
・Curtain panel, 170... Reinforced bar material, 16
5...Filled panel, 177...Reinforcement angle material, 178...Reinforcement angle material.

Claims (1)

[Scope of Claims] 1. A taut upholstered structure comprising: (a) a plurality of truss members each having a polygonal cross section and forming a circular framework; (b) the entire framework; (C) a cloth membrane extending between the bottoms of the truss members and extending between the bottoms of the truss members, and covering and supported on the framework and formed in a substantially saddle shape between the truss members; cable means for applying tension to the truss member, the truss member having a lower upright haunch portion joining a relatively flat upper portion, the lower end of the truss member being supported on a base and the upper end thereof is coupled to at least one other of the truss members, the saddle of the fabric membrane has a curved surface formed in the longitudinal direction and the lateral direction of the truss member, and the radius of curvature of the curved surface is: tensioning upholstery relative to the radius of curvature of the truss member to provide approximately equal tension in the longitudinal and lateral directions of the truss member at any point of the fabric membrane to form a stable structure; Structure.