Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A molding strip assembly is provided for use in covering a support surface with a flexible material and is particularly adapted for retaining facing interior marginal edges of a pair of material panels within the interior of a framework which surrounds the area to be covered on the support surface. The molding strip assembly has a base wall to be positioned adjacent the support surface and first and second raised support walls along opposite lateral sides of the base wall. The support walls are oriented and supported in spaced relation above the support surface. Preferably, first and second interior side walls extend between the base wall and the first and second raised support walls, respectively, to define a U-shaped channel region; first and second outer side walls extend downwardly from the first and second raised support walls, respectively, and terminate in outwardly turned attachment flanges for securing the strip to the support surface.

Abstract: A roofing membrane securement system having an upper member and a lower member each of which is formed of a relatively hard, unyielding material. The lower member includes a bottom surface from which extends a preferably cylindrical wall. In one embodiment a plurality of ledges extend downwardly and inwardly from the upper edge of the inner surface of the circumferential wall. The upper member is preferably of circular shape, having a diameter less than that of the interior cross-sectional dimension of the cylindrical wall but greater than the distance between the innermost edges of circumferentially opposed ledges. In a second embodiment, ledges extend downwardly from the upper edge of the outer surface of the lower member circumferential wall, and the upper member has a downwardly extending wall adjacent the circumferential wall outer surface with ledges extending radially inwardly therefrom to engage beneath the lower member ledges.

Abstract: The internal wall such as the rear wall in the passenger compartment of a commercial aircraft, and separating compartments which are under different pressure, is rendered safe by providing a wall capturing net on the low pressure side of the wall and fastening that net to the fuselage proper.

Abstract: A gazebo and a lean-to shelter have rigid panels with a soft material canopy spread over an arrangement of spokes or ribs. The gazebo has a compression spoke arrangement for holding the canopy in a dome configuration. The spokes of the gazebo include a flat hook underneath each spoke adapted to engage a draw cable at the top periphery of the rigid panels, and a sleeve fits over the end of the spoke and the end of the flat hook to lock the draw cable within the hook. A tip engages the end of the tube and the sleeve to lock it in position on the flat hook. The ribs of the lean-to have a toggle arrangement for extending the ribs when the lean-to shelter has been assembled and to apply tension on the canopy. The end of the toggle is adapted to fit in a rail which in turn also receives the edge of the canopy, and the rail is mounted in a track.

Abstract: A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material.

Abstract: A lightweight, portable shelter structure is provided having an aerodynamically stable configuration which is particularly resistant to wind loads. The stability of the shelter structure results from the construction of the canopy portion wall panels and their interaction with the rod members of the shelter. The canopy portion is formed of an elastic material so that the base of the canopy panel may be stretched to tension the rod members, which are formed of a resilient, flexible material. In a preferred embodiment, the canopy panel has a triangular configuration, and the rod member is secured at the base and at the apex of the triangle so that when the base is stretched, compressive forces are exerted on the rod member causing it to bow. The canopy of the present shelter structure includes at least two panels of this construction and the shelter further includes a loose, expandable floor portion attached to the canopy portion.

Abstract: A vehicle support structure for a detachable roof includes a roof panel extends along an exterior portion of the vehicle and includes a recessed frame having an upper support surface. A sealing member is positioned along the upper support surface for providing weather sealing along the roof panel and the detachable roof when the detachable roof is closed. A liner extends beneath the roof panel for lining at least a portion of the interior of the vehicle. The liner has a support base spaced from the roof panel, as well as at least one lining pad having an end section secured along the recessed frame. An inner panel member is aligned with at least a portion of the support base and extends between the support base and the recessed frame. A clamping member is secured to the inner panel member and contacts the end section for resiliently retaining the end section in engagement with the recessed frame.

Abstract: A false ceiling or false wall is constituted by a stretched sheet fastened, along its edges, to a support fixed to the wall or to the ceiling. The sheet bears, at the passage of an element projecting with respect to the wall, such as a pipe, a reinforcing plate glued on its face turned towards the celing or wall, this reinforcing plate presenting a cut-out allowing passage of the projecting element through it and through the sheet.

Abstract: A solar collector water heater is provided in kit form suitable for installation by a homeowner using a minimum of ordinary tools. The kit includes a rectangular insulation board serving as a baseboard, and a solar absorber plate mountable on the insulation board and including a heat exchanger with couplings for connection to a tank. A thermosiphon water tank is provided together with couplings for connecting to the heat exchanger. A main frame is assembled of a rear rail, a pair of side rails, and a front rail, all of extruded aluminum, using corner keys for adjoining adjacent ones of these rails at their ends. At least one side glazing panel having a top surface and a pair of legs inwardly disposed therefrom is cooperatively retained within the assembly by a first depression formed in one of the rail members insertably receiving and retaining one of the legs and a second depression formed in a glazing rim insertably receiving and retaining another of the legs.

Abstract: Pressure-sensitive adhesive composition, sheet material coated therewith, and a kit for installing insulation around windows comprising the coated sheet material. The adhesive composition consists essentially of a first component consisting essentially of a tackified, emulsifiable adhesive and a second component consisting essentially of at least one terminally unsaturated vinyl monomer, at least one vinyl-unsaturated, homopolymerizable, emulsifier monomer, and, optionally a small amount of an external emulsifier. The adhesive provides high tack and excellent adhesion at both low temperatures and high temperatures, thus rendering it suitable for outdoor use in areas that encounter extremes of weather.

Abstract: The simulated pipeline construction gives the outward appearance of an actual plumbing pipeline but without the weight or expense. The pipeline is constructed using a pair of parallel mounting rails which hold one or more outwardly bowed flexible plastic panels. One-piece plastic corner members are used to simulate a pipeline extending around a corner of a building, and one-piece plastic end caps are used to simulate an actual plumbing end cap. The corner members and end caps are also inserted into the channels of the mounting rails.

Abstract: A sheet gripping assembly for thin pliable sheet material, such as plastic film, having a channel shaped base member with a side opening through which may be inserted a fold of the sheet material to be secured, and innerlock and gripping bar members insertable into the base member through its side opening to assembled positions within the fold of sheet material within the base member wherein the sheet material is gripped between the base member and the innerlock and gripping bar members and the innerlock member recesses expulsion of the gripping bar member from the base member by tension in the sheet material being gripped. According to an important feature of the invention, the innerlock member has a lip which pojects externally of the base member through its side opening and the innerlock member is laterally flexible by finger pressure on the lip to facilitate insertion of the innerlock member into and removal of the innerlock member from the base member.

Abstract: An illuminated awning assembly has a frame with an upright rear frame portion having upper and lower frame members and a pair of upright side members extending between respective opposite ends of the upper and lower frame members. A horizontal frame portion has a pair of horizontal side members extending forwardly from the respective junctions of the rear lower frame member and the upright side members, and a lower front frame member extending between front ends of the horizontal side members. A pair of further side frame members are on opposite sides of the frame, each extending from the junction of the lower front frame member and respective horizontal side frame member to the junction of the upper frame member and the respective upright side member.

Abstract: A pair of snap fitted linear rigid strut members together defining a panel frame end is disclosed. A male member includes a matrix which defines at least one linear channel and a part of a linear shaft internal to the matrix. A female member also includes a matrix which defines part of a panel edge. A fabric panel cover surrounds at least a portion of the female member to conceal the joinder.

Abstract: A fastening device and method is disclosed for use in fixedly attaching a single-ply roof membrane to a roof structure of a building. The device comprises an elongated member formed with spaced-apart, upwardly extending arms forming an elongated channel therebetween. The elongated member is positioned on the roof surface and is fixedly attached to the roof prior to installation of the single-ply membrane. The elongated member may also be used to rigidly fix the roof insulation to the roof decking. A separate elongated plate is inserted into the elongated channel after the single-ply membrane is positioned over the roof surface. The single-ply membrane is positioned over the spaced-apart upwardly extending arms and lies within the elongated channel formed between the arms.

Abstract: This canopy system is supported by alternate poles and features edge cords to stress the center of the canopy fabric to reduce sag. The cords are attached adjacent each edge of each canopy segment and resembles a bell curve with respect to that edge. Longitudinal stresses placed on each cord urge the cord to straighten. As the cords straighten, they tension the center of the fabric without undue strain on the edge fabric. The result is a large area canopy with few interior poles and few peak elevations to the affected by wind forces.

Abstract: An improved two-piece lock for securing polymeric sheeting for use in covering greenhouses. The lock has an elongated lower member affixed to the frame of the greenhouse and one or more layers of polymeric sheeting are held in the lock between the lower member and an upper member. The upper member has two downwardly extending bars one of which fits into a channel of the lower member and the other of which abuts a concave contact bar of the lower member which faces the channel.

Abstract: Method for assembling an awning, including method for tensioning awning material about an awning frame. The awning material is secured to the top rear of the frame and stretched over the bottom front and each bottom side of the frame. Pieces of spline are thereafter placed atop the material and pressed into slots defined by frame members on the bottom front and bottom sides of the frame. Keeper members are thereafter inserted into the slots in abutting engagement with the spline and are secured to the inner frame members.

Abstract: A fastening assembly for mechanically attaching a waterproof flexible membrane to a roof construction at spaced apart intervals, comprising a post member that is mounted over an insulation member and that receives the flexible membrane in overlying relation thereon, a flexible circular member being forced into overlying relation on said flexible membrane as located over the post member to cause said flexible membrane to encircle said post member in tight fitting relation thereon, wherein the flexible membrane is sandwiched between the post member and the flexible circular member for mechanically fixing the flexible membrane on the roof construction.

Abstract: A roof membrane anchoring system is provided of the non-penetrating type, including a base member with an enlarged head carried by an upstanding stem, a disc, and a socket cap which includes a top, depending legs, and feet carried at the bottoms of the legs, the cap being of somewhat resilient material. A clamp is provided for constricting the legs after the socket cap is placed over the head. When uplift forces on the membrane act to deform the disc, it acts against surfaces of the feet of the socket cap, to urge the feet together, thereby providing greater security of the socket cap during periods of high wind velocity. The base member has a passage for insertion therethrough of a fastener, the passage including a quantity of self-curing adhesive material which is cured after insertion of the linear fastener, the adhesive material serving to adhere the linear fastener either to the base member or to a holding element for the linear fastener, or both.

Abstract: A molding strip assembly comprising linear edge pieces adapted to form a structure for holding the edge of a flexible material. The edge pieces may be configured in a framework so that the material covers a desired support surface. One edge piece is a molding strip that has a mounting base and upwardly extending connecting wall and a raised support wall in spaced parallel relation to the base. A lip extends upwardly from the base, spaced from the connecting wall, and a retaining wall extends upwardly from the base between the lip and the connecting wall, and, with the connecting wall, forms a narrow groove. A mating locking member defines a moveable profile that is received by the molding element and has a top wall, a first, downwardly depending side wall that is positioned in the groove to trap the material edge therein, and a second downwardly depending side wall that has a locking structure configured to engage the lip of the molding element.

Abstract: A panel frame created by attaching molding pieces or tracks to a wall or other substrate to support a fabric panel whose margin has an excess tail that is anchored in the tracks. Each track is constituted by a plastic extrusion having a flat base that lies against the substrate and an overlying profiled strip having an edge wall joined to the base at right angles thereto along a line intermediate the upper and lower edges of the base, the section of the base below this line functioning as a mounting flange for the track. The strip further includes a raised flat face which is parallel to the base to define a storage channel therebetween, the face extending from the edge wall to a rounded cove terminating in a bent-in nose that normally abuts the upper border of the base to define a dilatable inlet leading into the storage channel.

Abstract: A solar collector water heater is provided in kit form suitable for installation by homeowner using a minimum of ordinary tools. The kit includes a rectangular insulation board serving as a baseboard, and a solar absorber plate mountable on the insulation board and including a heat exchanger with couplings for connection to a tank. A thermosiphon water tank is provided together with couplings for connecting to the heat exchanger. A main frame is assembled of a rear rail, a pair of side rails, and a front rail, all of extruded aluminum, using corner keys for adjoining adjacent ones of these rails at their ends. The rails include a generally cylindrical bead along their lengths. A front glazing panel and a pair of side glazing panels are provided with frames designed so that the side glazing panels are snap-fit mounted onto the side rails of the frame, and the front glazing panel is snap fit onto the front rail of the frame and onto the top rails of the side glazing panels.

Abstract: An improved building assembly in which a flexible membrane is employed as a stabilization element for secondary structural members. The building assembly is also provided with a plurality of tertiary support assemblies and an improved bracing system for selected tertiary support assemblies to minimize or prevent failures of the tertiary structural assemblies due to the translational and rotational movement of the tertiary structural assemblies as a load is applied thereto, while at the same time other tertiary structural assemblies connected to other elements of the roof move in unison with the roof as the roof changes shape because if expansion and contraction or other forces. An improved roof structural bracing system for interconnecting the wall of the building via a wall connector to a primary support beam so as to minimize or prevent failures of the wall connector due to translational and rotational movement of the wall connector as a load is applied thereto.

Abstract: A reflective insulation blanket of folded flexible metal foil having dead air spaces between a principle member (20) and one or more outer members (22) and (24). The blanket being held apart in spaced relationship with one or more pairs of expanders (28) terminating with a mounting flange (26) at each end. A pair of retaining clips (36) cooperate with each other to hold the blanket in place against building structural members (30) and (32). Each clip having an elongated base (38) folded over upon itself (40) to provide a retaining section terminating with a pair of radial arcuate surfaces (42) and (48) with an angular abuttment point on the extreme end. The clips (36) embrace the structural members (30) and (32) at the leg and compressably engage and retain the mounting flange (26) of the blanket against the web of the building structural members.

Abstract: An apparatus and method for straightening warped doors of a residential type includes an elongate member anchored at opposite ends to the top and bottom section of the warped door. Means are provided for adjusting the length of the elongate member to create tension along the length of the door. Spaced pressure blocks slidably maintained along the elongate member rotate about the axis of the elongate member for selectively pressing against the warped surface of the door. Contact of the spaced pressure block means with the door increases tension on the elongate member which in turn exerts increased force against the spaced pressure block means and provides maximum efficiency for straightening the door.

Abstract: An acoustic fabric-mounting system includes a fabric stretched across a wooden frame of an acoustic panel. Some frame members are fixed to a wall, while other frame members are connected to one or more brackets which allow them to move relative to the fixed members along the wall. A tensioning bracket mounted beneath the panel exerts an expansion force against the movable frame member, tending to move it translationally apart from the fixed frame member, so that the fabric is stretched taut. The tensioning bracket is spring-loaded and adjustable.

Abstract: Apparatus for mounting continuous length sheets of thermo-expansive transparent plastic includes longitudinal rods for affixation along the longitudinal edges of each sheet to form a thickness enlargement thereat and mounting members having channels formed therein adapted to receive and retain the enlargement. The channel has an interior area larger than the rods and a restricted outward opening smaller than the rods but larger than the sheet thickness whereby in assembly space exists in the receiving area unoccupied by the rods and in the restricted opening unoccupied by the sheet permitting shifting movement of the enlargement and the sheet therewithin for relatively free thermo-expansion of the sheet. Each sheet is supported in flexed condition along its lengthwise edges by two such mounting members. Plural sheets may be mounted in side-by-side arrangement to form a roof or other structural or architectural surface. Sheets may be mounted by this system to form overhead skylights, canopies or the like.

Abstract: An earthquake resistant self-balancing dome structure is provided which employs a counter-balanced self-adjusting weight system to adjust tension in supporting cables to which the dome is attached. As ground movement, such as that caused by an earthquake, causes relative movement between the cable supports and the supported dome, the weight system operates to adjust the tensile force in the cables to bring the system into equilibrium.

Abstract: An inflatable structure for totally enclosing a predetermined area such as sports ground, swimming-pool and the like comprises a flexible envelope having a single or double wall which is placed during service over the area to be protected and a base which is anchored to the ground. The envelope is maintained in the distended condition during service by a pressure which exceeds atmospheric pressure. The wall or walls of the envelope are each joined to the base by means of a detachable assembly device such as a zipper-type slide fastener which permits assembly or disassembly of each wall independently of the other.

Abstract: A captive column structure comprising a plurality of spaced-apart elongated column portions having a plurality of spaced-apart compression core members interconnecting the same. The compression core members may take either the shape of flat sheets, hollow tubes, solid tubes or square tubes. The column portions and the compression core members may be constructed of a variety of different materials.

Abstract: A device for holding flexible sheet material to a structure including a fixed element that is attachable to the structure and has at one end an elongated cavity and at the other end an intrinsic lock mechanism and a locking device having at one end an arm for holding sheet material against the interior portion of the cavity and for bearing against the open edge of the cavity, the locking element also having the second half of an intrinsic lock device that is adapted to snap into the intrinsic lock device half on the fixed element.

Abstract: A captive nut plate for engagement by a screw useful when attaching corrugated composite or plastic sheets together includes a semi-cylindrical body shaped to match the curvature of a corrugated sheet. A pair of upstanding irregular pentagon-shaped piercing prongs are centrally positioned along curved edges of the body and are aligned with a central hole therethrough, for receiving the screw. The captive nut plate is installed by positioning it in a convex pocket on a semi-cylindrical tool in proper alignment with a concave edge corrugation of a first sheet. A soft mallet is then used to drive the corrugated material down onto the nut plate so that the upstanding prongs pierce through the sheet. The irregular pentagon-shape of the prongs assures that the prongs extend through the sheet beyond their widest portion. The prongs are then peened over to provide a permanent installation on the first sheet.

Abstract: A panel system for walls, ceilings, and the like is disclosed in which the panels are provided with a flexible surface material which extends into resilient means that operate to press the surface material of adjacent panels into face-to-face contact to provide a closed, neat joint between adjacent panels. Because of the resiliency along the joints, brackets, screws, and the like may be inserted through the joints and secured to the panel supporting frame structure without damage to the panel materials. Subsequently, if the brackets, screws, and the like are removed, the resilient means returns the flexible sheet material into the face-to-face abutting condition, re-establishing the closed joint and concealing the fact that anything had previously been inserted through the joint. In some embodiments, the surface sheet material is provided with a loose flap which is inserted into the resilient means after the panels are installed.

Abstract: A captive column structure comprising a plurality of spaced-apart elongated column portions having a compression core interconnecting the same. The compression core and column portions are comprised of bonded fibrous material. The fibers are pultruded through a pultrusion machine and bonded with a suitable epoxy material or the like.

Abstract: A reinforced construction panel which is bent around a longitudinal flexure axis. The panel has a plurality of parallel, dovetail-shaped grooves in its inner surface. Each of the dovetail-shaped grooves lies in a plane which is perpendicular to the longitudinal flexure axis. A number of tension elements, each one of which is disposed in a plane which is perpendicular to the longitudinal flexure axis, end in two male fittings, one at either end. Each of the male fittings is sized and shaped so as to be received and held in one of the parallel, dovetail-shaped grooves.

Abstract: An attachment device for securing a flexible sheet within a channel member via an insert member of generally inverted V-shape wherein the latter is made of a ductile but rigid material having a central longitudinal portion of reduced rigidity that serves to define two adjacent wing portions and permits the subsequent plastic deformation of the insert member into its installed shape after its insertion, together with the flexible sheet, into the channel member. A method for securing the flexible sheet within the channel member, via the ductile but rigid member, is also presented.

Abstract: In an attachment device, comprising a channel member and an insert member, for securing an elastic membrane within the channel member via the insert member, one of the insert and channel members being capable of deformation to permit the insertion of the insert member, together with adjacent portions of the elastic membrane, into the channel member, the improvement, taking the form of a locking device, insertable into the channel member to prohibit the subsequent removal of the elastic membrane by elastic deformation of one of the channel and insert members.

Abstract: The present invention provides the structure of a multilayered unit for windows, comprising a plurality of planar members, a flexible film disposed between, and spaced from, two of said planar members, and a stretching member capable of developing elasticity for stretching the flexible film taut by imparting thereto a force in a direction angularly displaced to the film surface of the said flexible film extending at least over that region of said planar members which forms a window, and the planar member present on at least one side of the flexible film being transparent or semi-transparent.The present invention also provides a multilayered unit for windows and a multilayered window having the same stretching member as in the above structure.

Abstract: The present invention relates to a stack or a vertical pipe for the flow of gas, said stack or pipe comprising a suspension mast defining a vertical axis; at least one supple surface, open downwardly and upwardly, and symmetrical with respect to this axis; substantially horizontal, rigid hoops, viz. an upper hoop and a lower hoop respectively fast with the upper and lower periphery of the surface, each hoop being symmetrical with respect to said axis; supple bearing ties suspending the upper hoop from the mast; and stays connecting the lower hoop to a fixed lower point of the mast or the ground to stretch the supple surface in a vertical direction. The invention finds application in the entire production or extension of stacks or pipes such as atmospheric cooling towers.

Abstract: This invention relates to an improved method and construction for straightening collector plates in an electrostatic precipitator by employing a torque bar. The torque bar includes an elongated bar which is positioned in an edge of a collector plate. A bracket is fixed to one end of the elongated bar. The bracket has an offset. A connector has one end fixed to a fixed portion of the electrostatic precipitator. A lock secures the bracket to the connector at a selected position to hold the elongated bar in a selected attitude. The method of straightening the plate includes a step of applying a torque moment to the elongated bar to apply a torque moment to the plate to straighten the plate.

Abstract: The present invention relates to a process for making false ceilings comprising a series of parallel strips of fabric of reduced width, reinforced transversely, tensioned longitudinally and oriented vertically in a mean horizontal plane located at an appropriate height below the ceiling of the construction, wherein each strip is tensioned individually and independently of those strips which surround it. The invention also relates to the false ceiling made by carrying out said process.

Abstract: Device for laying and stretching covering sheets over surfaces to be protected, the device comprising a first channel element, having a bottom and lateral walls, a second channel element having a bottom and lateral walls, smaller in depth than those of the former; first fastening means for securing one of said channel elements with its bottom facing towards the surface to be covered. Second fastening means being also provided in order to secure the other of said channel elements in position over the first one and with its lateral edges facing towards the bottom of the first channel element securing and tensioning the covering sheets interposed between the aforementioned channel elements.

Abstract: A frameless enclosure assembly, supported by the structural assembly of a pre-engineered building having first and second support members, comprising a flexible membrane; a membrane attaching assembly attaching a first end of the facing membrane to the first support member, and attaching a second end of the facing membrane to the second support member and extending the facing membrane substantially taut therebetween; an insulation layer of compressible insulation material supported by the facing membrane; a panel member positioned substantially parallel to the insulation layer to dispose same between the panel member and underlaying structural assembly; and a panel securing assembly for securing the panel to the structural assembly and transferring load from the panel member to the structural assembly while the insulation layer substantially uniformly retains its resistance to heat transfer.

Abstract: This invention relates to construction units and assemblies, and to structures fabricated from such units and assemblies, and is particularly concerned with stressed membrane structures, and specifically with modular, multiple membrane structures.

Abstract: Fire stops for structures formed of combustible materials such as frame dwellings and the like are formed of wire screen with support frames and positioned in spaced relation below wooden floor joists and wooden plates and other transverse wooden members positioned between wooden studding and the like in such structures. The wire screen introduces an element of high heat conductivity and effectively prevents the upward propagation of flame therethrough. Perforated metal sheets in contact with said wire screen support the same.

Abstract: Window thermal insulation device for thermal insulation of a window opening area, including a plurality of linear members arranged in successive end to end relation for forming a perimetric selectively sized and shaped enclosure frame defining a window space therewithin, a like plurality of interconnectors for interconnecting the adjacent ends of the linear members, linear locking grooves in the linear members and extending therealong peripherally outwardly of the window space, a pliable plastic thermal insulation sheet extending across the window space of the frame and having its peripheral margins disposed correspondingly in the locking grooves of the linear members, a like plurality of linear cover strips having linear locking tongues projecting therefrom and disposed correspondingly in gripping contact with the adjacent portions of the peripheral margins of the plastic sheet and in releasable locking engagement with the adjacent locking grooves and arranged for maintaining the plastic sheet in substantial

Abstract: A simple and inexpensive skeleton frame for a fabricated structure for housing electrical equipment comprises upstanding legs which are arranged at the corners of the frame and which are secured together at the top and bottom of the frame by endless flexible frame metal bands surrounding the legs and maintained in tension by bracing devices positioned between the legs. Each bracing device comprises a central hub, elongate braces extending outwardly from the hub and each engaging a leg, and screw threaded adjustable means for urging the braces outwardly to maintain the endless band under such a tension that the frame is held rigid. The bottom, sides and top of the frame are clad with sheet metal and a hinged door.

Abstract: A single foil is biaxially stretched on a frame for movement relative thereto by being secured intermittently to a single rubbing strip over a guide ledge. The rubbing strip is stretchable and movable lengthwise of the associated frame side. Torsional forces arising because of the one-sided loading of the frame by the stretched foil are taken up by the frame which is made with a torsionally rigid cross-section.The single foil can be clamped without creasing and in a manner which ensures freedom from creasing notwithstanding differences in the heat expansion of the foil and frame.