HK1018295B - Grid framework for suspended ceiling, the ceiling and the system thereof - Google Patents

Description

Mesh frame for suspended ceiling, suspended ceiling and system thereof

Suspended ceilings, which include a metal mesh frame that supports panels formed of sound absorbing sheets in a rectangular space formed by the frame, are widely used in commercial and industrial buildings. The present invention relates to the problem of keeping the above-mentioned ceiling intact during a fire so that the ceiling can be used as a fire barrier for a supporting structure above the ceiling.

More particularly, the present invention relates to a net-like frame that allows a rectangular frame space to remain relatively intact during a fire, such that the frame continuously supports and surrounds the rectangular insulation panels during the fire.

The present invention relates to the known problem that the above-mentioned metal frame parts are deformed due to expansion, buckling and torsion during a fire, so that the panel supported is displaced and falls through the holes formed by the buckling rib parts; thus, as a fire barrier, it can destroy the effectiveness of the suspended ceiling and cause fire to encroach upon the building's support structure.

Attempts have been made to solve the problem of bulging of the net-like element by forming cuts, or "weakened points", along the element. Under compression, the component will buckle in the longitudinal direction to compensate for the expansion that occurs during the temperature increase due to a fire in an attempt to extend the component in the longitudinal direction in an effective rectangular network. The method is mainly used for the main beam. The main problems of the method are as follows: the above-mentioned incisions weaken the net frame, and a waste of strength and material of the net frame occurs in the portions of the net frame having no incisions. The strength of the main beam having a T-shaped section is the same as that at its cut, as in the case where the strength of the chain is only the same as that of the weakest link portion thereof. In fact, under normal operating conditions, the weakened portions of the mesh framework produce a strength limit for the mesh framework at which the non-weakened portions of the mesh framework are damaged.

According to another approach to the above problem, the cross-beam is not weakened by cuts, but attempts are made to bend the fasteners at the ends of the component to counter the expansion of the component by: the beams are moved diagonally in the grid line or laterally at the ends. The problem with the above method is that it creates gaps in the ceiling, which reduces the effectiveness of the ceiling as a fire barrier.

In yet another approach, the cross beam is likewise not weakened, but end fasteners on the component pass through the main beam at their slots, thereby providing the necessary expansion of the cross beam to avoid buckling. This method does not enable the known prior art concept in which the fastener makes an internal connection with the fastener in both directions, particularly not in the forward direction in which the fastener is forced toward the main beam. The above approach sacrifices all of the important features that are present when having a backset-like end abutment between opposing fasteners that is important to control the dimensions and tolerances of the standard components. This approach sacrifices an exact fit between the fasteners at the joint, resulting in a loose joint.

The invention does not produce controlled destruction of the component in the longitudinal direction by weakening the net-like component in order to compensate for longitudinal expansion during a fire, but rather in the exact opposite direction. Beams that do not fail when inflated are avoided, but are reinforced against failure by longitudinal compression, such as by web ridges. The above components do not break during a fire but expand in a controlled manner so that the ceiling retains its original rectangular shape.

End fasteners are used on the cross beams that mate with limited slots in the main beams to form multiple stops, or resists, that resist continued expansion of the cross beams at multiple stages during expansion of the cross beams. The resistance portion generates increasing and decreasing forces in successive stages so that the cross beam is continuously and securely connected to the tee of the main beam in all stages of the cross beam without forming a stiff barrier to the expansion which would cause the cross beam to buckle and form an opening in the ceiling.

The present invention continues to employ the concepts of the prior art for the back end. This is important because it forms a strong, inflexible barrier between the opposed interlocking fasteners under normal non-fired conditions. However, in the practice of the invention, during one of the release phases, the beam is used and the back-stop is disengaged by a cam action during the expansion caused by a fire, due to the action of the web reinforcement, in particular of the beam.

Thus, the present invention takes advantage of the maximum strength of the mesh framework in its normal, non-fired state. This allows the use of thinner gauge metal stock to form a part that is T-shaped in cross-section, when the gauge metal stock is reinforced at its web by transverse ridges, or welds. The reinforced mesh frame can exert the necessary force during expansion without having to buckle to overcome the series of resistance forces created by the interconnection of the fasteners on the cross beams and the main beam slots, particularly by the action described above, to disengage the rear rail, which requires 100 pounds of force, or more.

The present invention allows the above-mentioned resistance to be reduced or completely eliminated, and then to be gradually developed again, as the mesh framework expands, in a plurality of periodic intervals or phases.

Thus, during the various stages of the expansion process of the mesh frame, the resistance force begins to vary until it accumulates to a point where the fastener bends laterally if it does not decrease or disappear, thereby causing the mesh frame to become misaligned in the rectangular configuration in which it is placed. In addition, the resistance exerted by the fasteners is reduced or eliminated, so that the continuous expansion of the rigid mesh frame, oriented according to the rectangular configuration, continues.

During a fire, typically 1 foot produces an amount of expansion of 0.1 inches, so that in a beam having a length of substantially 4 feet, the total amount of expansion is around 0.4 inches. In the present invention, the restrained resistance and release is achieved until full expansion occurs in an extreme fire condition, at which point the fastener is in its final condition at the end of beam expansion.

In summary, the present invention utilizes a member that maintains its integrity in an expanded state, which expansion generates a longitudinally extending compressive force on the web member. This is due to the fact that during expansion, a greater force is required to overcome the tailgate barrier, in particular between the fasteners, which reinforces the beam and the fasteners, so that it is necessary to increase the strength of the beam, in particular when overcoming the tailgate barrier. These stresses are resisted and relieved in stages during expansion of the mesh framework by the fasteners and slots of the present invention. This allows the beams and girders to continue to form a support frame around each rectangular panel, thereby holding the panel in place.

FIGS. 1-6 illustrate components in a mesh framework, including main beams, cross beams, and fasteners;

FIG. 1 is a partially exploded perspective view of a portion of a main refractory component having a vertical web with a slot through which a buckled end of a refractory and divider beam passes;

FIG. 2 is an enlarged side view of the fastener of the present invention;

FIG. 3 is a plan view of the fastener of FIG. 2;

FIG. 4 is a left side view of the fastener shown in FIG. 2, taken along line 4-4 of FIG. 2;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 2;

FIG. 6 is a side view of the fastener showing the back side of the fastener of FIG. 2;

FIGS. 7-9 show the beam as a zero expansion joint prior to a fire;

FIG. 7 is an enlarged, partially cross-sectional, elevational view of the components illustrated in FIG. 1 assembled in a first and normal use interlocked manner;

FIG. 8 is an enlarged, fragmentary sectional plan view taken along line 8-8 of FIG. 7 showing the interlocking configuration of the refractory main beams, cross beams and end fasteners;

FIG. 9 is an enlarged, fragmentary, sectional, elevational view taken along line 9-9 of FIG. 7, showing the two fasteners shown in FIGS. 7 and 8 interlocked with one another in a normally interlocked manner, in a side-by-side condition;

FIG. 10 is an enlarged, fragmentary, sectional, elevational view similar to FIG. 7, but showing the ends of two opposed cross-beams and corresponding fasteners which expand toward each other under the heat of fire, the ends of each cross-beam and corresponding fasteners expanding toward each other by a distance S-2, or 0.01 inches relative to zero expansion, such that the bottom stops of the two fasteners are in pressure contact with the vertical webs in the main beam on either side of the slot in the main beam;

FIG. 11 is a cross-sectional plan view taken along line 11-11 of FIG. 10, showing the two opposed fasteners in an unlocked engagement relative to the slot in the main beam;

FIG. 12 is an enlarged fragmentary sectional elevational view similar to FIG. 9 taken along line 12-12 of FIG. 10 but showing the fastener being directionally adjusted within the slot in the main beam as the ends of the cross beams are expanded an unlocked distance S-2 relative to the zero interlock rest position;

FIG. 13 is an enlarged fragmentary sectional elevational view similar to FIGS. 7 and 10 but showing one of the beam ends and its associated fastener shearing the bottom stop of the fastener against zero expansion distance S-3 with the opposite fastener and beam end at rest at expansion distance S-2 under continued action of the heat source;

FIG. 14 is a sectional plan view taken along line 14-14 of FIG. 13 showing the interlocked portions of the opposed fasteners as one beam and the corresponding fastener are held at an expansion distance S-2 with a relatively zero expansion of the opposed beam and fastener by an expansion distance S-3;

FIG. 15 is an enlarged fragmentary sectional elevational view similar to FIGS. 7, 10 and 13 but showing the first free and expanding cross member and corresponding fastener being expanded by a distance S-4 by the heat generated by a fire whereby the end of the opposite member and corresponding fastener are expanded relative to their fixed positions to shear the bottom stop tabs thereof and cause the end of the cross member and fastener to expand relative to each other;

FIG. 16 is an enlarged, fragmentary sectional elevational view similar to FIGS. 7, 10, 13 and 15, but showing the ends of the cross beam and the corresponding fastener which expand under the heat of a fire to reach their total expansion limit where the ends of the cross beam, as well as the top and bottom, projecting limit stops in the fastener, forcefully contact either side of the slot in the main beam;

FIG. 17 is a sectional plan view similar to FIGS. 8, 11 and 14 taken along line 17-17 of FIG. 16 but showing the relative limits of the expansion positions of the ends of the cross beam and their respective fasteners relative to the main beam and the slots therein;

FIG. 18 is an elevational view, in partial section, taken along line 18-18 in FIG. 16, similar to FIGS. 9 and 12, but showing the relative positions of the opposed fasteners within the confines of the slots in the main beam when the ends of the opposed cross beams and the respective fasteners reach a threshold amount of expansion;

FIG. 19 is a graph showing the total amount of expansion in inches continuously produced by a fastener controlling the expansion of a beam and the expected resistance force applied in pounds;

FIGS. 20A and B are partial schematic plan views showing how the cross beams extend in an axial direction perpendicular to the plane of the axis of the main beam;

fig. 21A and B are partial schematic plan views of a typical prior art beam assembly with typical interconnecting fasteners that do not pass through slots in the main beams during elongation but do flex due to the large arcuate displacement of the beams relative to the center line of the slots in the main beams as a result of the design of the fasteners for the beams.

Structure of the product

Fig. 1-6 show a main beam 20 with slots 30, a cross beam 22, and fasteners 40 at the ends of the cross beam 22. The fixed dimension of the vertically extending rectangular slot 30 serves to control the relative movement between the fasteners 40 and, in the case of fasteners moving longitudinally into the slot, the relative movement between the fasteners. The movement of the fasteners 40 into the slots produces a controlled expansion of the beam 22 so that the mesh frame maintains a rectangular shape during a fire. As for the fixed shape of the slot 30, the following definitions are included:

vertical: as shown in fig. 1, the direction between the top 31 of the slot 30 and the bottom 32 of the slot;

outward: from the inside of the slot 30 towards the side 33, or from the inside of the slot 30 towards the side 34;

inward: from side 33 towards the inside of the slot 30 or from side 34 towards the inside of the slot 30. Just as one's hands hold, the inner sides of the interlocking fasteners 40 abut each other;

upwards: a direction from the inside of the slot 30 toward the top 31;

downwards: a direction from the inside of the slot 30 toward the bottom 32;

before: a direction from the outer side of the slot 30 toward, or through, the slot 30;

and (3) after: a front rear side;

the clip 40 includes a web 41, and two rivet holes 42 are formed in the web 41. The fastener 40 includes a top 43, a bottom 44, a front edge 45 and a back edge 46.

As shown in fig. 4 and 5, the web 41 in the clip 40 includes an inner side 47 and an outer side 48. The resilient fixing lugs 50 extend at an angle to the web 41 on the outside of the fastener. The bottom of the lug 50 is provided with a notch 51. The cut-out 51 allows the lug 50 to be bent at a suitable angle, such as a compound angle of 45 ° relative to the web. As shown in fig. 3-6, the lugs 50 extend in a slightly inclined manner, with the edge dimensions of the top 52 of the lug being greater than the edge dimensions of the bottom 53 of the lug.

The function of the lugs 50 is to initially lock the fastener 40 in the slot 30. The tab 50 is immediately bent by pushing the fastener 40 through the slot 30, thereby passing through the slot 30, after which the tab 50 returns to its original position and prevents withdrawal. The above-described initial fixing has a temporary property that it does not reach any degree of firmness of a locking structure to be described later, which is formed later. The design and function of the lug 50 is well known in the art.

In the web 41, the front edge 45 and the rear side of the lug 50 are indentations, or cutouts 54. The front edge of the cutout 54 has an arcuate edge 55 and the rear portion of the cutout 54 extends with a straight edge 56.

In front of the front edge 55 and the rear edge 56 of the cutout 54, projections are formed on the inner side 47 of the web 41. For example, as shown in fig. 3 to 5, the first convex portion constituting the cam 57, which is somewhat parabolic, is pressed inward or punched inward.

The cam 57 has an edge 55 which is not only arcuate in shape, as shown in figure 2, but also has an angled edge which is hooked 58, as shown in figure 3.

The surface of cam 57 forms an inclined surface 59 with respect to web 41.

As set forth in the previous definition, terms such as "inwardly" and "outwardly" refer to the location of the clip 40 when disposed within the slot 30.

The rear side of the inwardly projecting cam 57 is a lobe, or backset 60, which also projects inwardly. As shown particularly in fig. 3, the backstop 60 projects inwardly relative to the web 41 by a distance less than that of the cam 57. The back stop 60 is stamped and formed relative to the web 41. The backstop 60 includes a straight edge 56 in the shape previously described that acts as a stop.

As shown particularly in fig. 2 and 6, a vertical strip 63 is formed at the front end of the fastener 40, the vertical strip 63 being formed by the edge 45, the arcuate edge 62, and the top and bottom of the web 41 at the location of the cut-out 49. This constitutes a front vertical locking portion, or tab 63.

An outwardly disposed flange 65 extends from the top 63 of the clip 40, the flange 65 being inclined at about 30 to the plane of the web 41 of the clip 40. The inclined flange 65 comprises an outer edge 66, which outer edge 66 comprises an inclined portion 67, a rectilinear portion 68, a triangular portion 69, a concave portion 70 and a raised portion 71 constituting a limiting edge.

Extending at the bottom of the clip 40 is an inclined bottom flange 72, the flange 72 including an outer edge portion 73, the portion 72 including a ramp 74, a flat 75, a stop 76, a bottom inclined portion 77 and a raised portion 78 which also constitutes the stop. At the rear edge of the fastening members 40, the outer edge portions enable the fastening members to be formed in pairs only by the rear edge common to each pair of fastening members, which are then cut apart from each other at the portions 79.

The cross beam 22 is reinforced at its web 84 by transverse ridges 90. When the beam is formed from a flat strip, the ridges are machined in the web, such as by rollers that collectively form the ridges. The formation of beams having a T-shaped cross-section is a well-known technique in which the strip is gradually bent, seen in cross-section, by means of rolls into cavities, double webs, and outwardly projecting flanges. The transverse ridges are actually formed by punching and bending portions of the metal, which prevent the layers in the web from moving relative to each other under pressure and thus avoid buckling. The flanges are suitably covered with separate strips. The above-mentioned transverse ridge machining and the machining of a cross beam into a T-section using a flat strip are described in the U.S. patent application specification having the name "roll-formed component and method of producing the same" filed on US08/375261, filed on 1/19/1995, and in the british patent specification having the name "ceiling beam and method of producing the same" filed on 6/9/1995, and having the name "ceiling beam and method of producing the same" filed on GB2274080B, both of which are incorporated herein by reference. The flanges are covered in a suitable manner by separate strips.

As shown in fig. 1, beam 22 includes a cavity 85, a laminate web 84, a flange 81 and a cover 87. The main beams 20 have the same T-shaped cross-sectional shape. When the cross-sections of the cross beams 22 and main beams 20 are the same, corresponding parts thereof are given the same reference numerals.

It will be appreciated that the fasteners 40 are all identical and when they are engaged in the manner described above, they constitute a complementary relationship in much the same way as a handshake is made between two persons.

Working process

In operation, when the temperature of the mesh framework rises due to a fire, the cross-beam 22 expands from a cooled state to a fully expanded state. The horizontal axis of the graph in fig. 19 represents the amount of expansion of a standard, 4 foot length beam. Since both ends of the cross beam 22 accommodate this expansion, it will be appreciated that the fastener 40 will move through the slot 30 in the main beam 20 at each end of the cross beam 22 by half the distance shown in fig. 19.

Fig. 8 shows in particular the connection which remains stationary when there is no fire and no expansion occurs. Which corresponds to a 0 shift in the graph of fig. 19.

To form such a connection, the net framework is assembled by first suspending the main beam 20 from the support structure, such as by wire, in a manner known in the art. The main beams 20 are spaced apart 4 feet transversely across the ceiling in parallel relationship with each other, and the main beams 20 are provided with slots 30 which are punched out at spaced intervals, such as 2 or 4 feet, along the main beams 30. The cross beams 22, each end of which has a rivet fastener 40, are connected to the main beams 20, respectively, by: fasteners 40 at the ends of the cross beams 20 are inserted into the slots 30 in the main beams 20 from opposite sides of the slots in a well known, prior art manner.

In the position shown in fig. 7-9, the slot 30 presses the inner sides of the opposed clips 40 against each other because the outwardly extending flanges 65 in the clips 40 abut the sides of the slot 30. The raised front edges 80 of the cross members 22 are offset from each other and contact the skin 83 of the main member 20. The vertical strips 63 are located inside the cut-outs 54 and the front edge 45 is pressed against the straight edge 56 in the rear rail 60. The abutment forms a stop preventing the clip from moving further into the slot 30. The removal of the strip 63 from the slot 30 is also prevented by the action of the hook 58 and of the curved edge 62 in the portion 63. In the area defined by the slot 30, the strip 63 is held in the position shown in the figures in the cut-out 54 by means of a flange 65. This position corresponds to a position on the horizontal axis in the graph shown in fig. 19 where the fastener front shift is set to 0. The hook 58 serves to prevent the fastener from being withdrawn when the beam is pulled and resists pulling forces of 350 pounds or more.

The distance S shown in fig. 8 represents the initial distance separating the ends of two opposing cross beams 22 where their respective fasteners 40 lock within the area defined by the slots 30 in the vertical web 86 in the main beam 20 and no fire occurs.

Controlled expansion due to a fire, as a result of expansion of two opposing cross beams and corresponding locking fasteners confined within slots in the main beams, is described with reference to the graphs shown in fig. 7-18 and in particular fig. 19.

a) The expansion of the opposing cross beam 22 generates a force of 100 pounds or more against its locking fastener 40 due to the heat generated by the fire.

b) Each opposing locking fastener 40 is moved toward each other a distance S-1 of about 0.0095 inches.

c) The interengagement of the cam surfaces 59 in each fastener forces the fastener 40 to disengage the unlocked vertical strip 63 from the cutout 54, thereby allowing each opposing fastener 40 to continue to expand a distance S-2 of about 0.01 inches until the bottom stop 76 in each fastener 40 presses against the vertical walls 86 on either side of the slot 30 in the main beam 20, see fig. 10, 11 and 12.

d) At this distance S-2, the expansion force is reduced to about 15 pounds.

e) If the heat from a fire is removed at this location, the beam 22 and its corresponding fastener 40 may be locked again due to beam shrinkage.

f) As the fire progresses, the heat generated by the fire increasingly applies force to the opposing cross member 22 and its corresponding fastener 40, thus preventing further expansion of the fastener at distance S-2 by the bottom stop 76 on the fastener 40.

g) The force increases from about 15 pounds at distance S-2 to about 84 pounds at distance S-3, shearing the stop 76 in one of the fasteners, see fig. 13. Here, the free cross beam and its corresponding fastener 40 are expanded 0.066 inches from their normal 0 position and are free to expand to their limits of expansion that are unimpeded except by the small forces that result from frictional contact of the top and bottom flanges 65, 75 of the fastener 40 acting in an adjustable manner through the area defined by the slot 30 in the main beam 20, and the contact surface 59 of the opposing cam 57 in the opposing fastener 40, see fig. 14. The opposing cross member 22 and fastener 40 are prevented from expanding by the bottom stop tab 76 as shown in fig. 13 and 14.

h) As the heat generated by the fire increases, the free cross beam 22 continues to expand from the zero position shown in fig. 15 by an expansion distance S-4 of about 0.22 inches, and the expansion force increases from 0 to about 78 pounds in the opposing cross beam and fastener, shearing the opposing bottom fastener 76, which causes the opposing cross beam 22 and fastener 40 to frictionally expand within the slot 30 of the main beam 20.

i) As the heat generated by the fire increases, the cross beam 22 and its corresponding fastener 40 continue to expand toward each other until the ends of the cross beam 22 and the stop lifts 71 and 78 in the fastener 40 are forcibly pressed against either side of the vertical wall 86 of the main beam 20, as shown in fig. 16, 17 and 18. As best seen in fig. 18, the top and bottom outer edges of the flanges 66 and 73 in the clip 40 penetrate diagonally into the top and bottom corners of the slot 30 due to the inward engagement of the opposed cam surfaces 59, as the two opposed clips 40 move to their extreme positions under the expansion of the cross member 22, due to the outwardly directed forces that separate the clips from each other. In addition to these frictional forces which resist full free expansion, other frictional forces are generated, which are clearly described with reference to fig. 13. As the cross beam 22 expands, the raised front edge 80 at the end of the cross beam 22 acts on the bottom flange 83 of the main beam 20, which in addition to the frictional engagement described above, causes the flange 83 to flex locally, and the triangular portion 69 in the top outer flange 65 of the clip 40 deflects the clip 40 downwardly in the slot 30 in the main beam 20, thereby causing the flanges 81 and 83 to form a greater frictional snap fit. As the opposing fasteners 40 move toward each other within the slots 30 of the main beams 20, they are subjected to a series of intermittent, greater and lesser design resistances, thereby preventing uncontrolled expansion of the cross beams. As shown in fig. 17, the expanded cross beam 22 and the fastener 40 are aligned axially in line with the centerline of the slot 30 in the main beam and remain perpendicular to the vertical and horizontal planes of the web 86 of the main beam at all times.

The above description, by way of example, relates to a single connection in respect of the working aspects of the invention. Obviously, there are many such connections in a mesh ceiling. The various stages of the invention that occur in a single connection need not occur simultaneously in each connection, as the total amount of expansion may occur in one connection, while at the other connection, the amount of expansion S-3 will occur.

It can thus be seen that the net frame of the present invention in the resting state shown in fig. 20A maintains its rectangular frame orientation and position without any minimal movement during a fire due to the controlled expansion of the cross-beam described above, as shown in fig. 20B.

In contrast, the conventional mesh structure moves and bends before the fire as shown in fig. 21A, and deforms during the fire as shown in fig. 21B. In this prior art frame, the panels would fall off the ceiling creating gaps that would compromise the effectiveness of the ceiling as a fire resistant partition. The prior art clip 90 is only bent at the weakest point shown in the drawings, which causes the beam to move out of its panel support position.

Although the invention is described above with separate fasteners, it is possible, if best, to allow the fasteners to be formed integrally with the beam web itself.

The fasteners 40, which serve and contribute to increase the strength against buckling exerted by the reinforcement on the cross beam, may also be reinforced, particularly against bending, by their angled flanges 65 and 72. In particular, as shown in fig. 20B, the fastener 40 is not bent, whereas the prior art fastener is fully bent, as shown in fig. 21B, which moves the beam to a position where it no longer provides significant support for the panel in the original, pre-fired rectangular shape of the grid structure.

Claims (9)

1. A system in a suspended ceiling for maintaining a metal frame providing support for panels in a substantially intact condition during a fire, comprising:

1) the main beam is provided with a vertical slotted hole;

2) a pair of cross members, each cross member having end fasteners oppositely insertable into said slots in opposite directions, wherein:

a) each fastener is in resilient contact with the main beam, the contact preventing the fastener from passing through the slot

Withdrawing;

b) a pair of fasteners forming a locking member with each other, the locking member avoiding each fastener

Further movement toward or away from another fastener;

c) the bottom of each fastener has a bottom stop portion that presses against the main beam

To prevent the fastener from further entering the slot;

d) the top of each fastener has a top stop portion that presses against the main portion

A beam which prevents said fastener from further entering the slot;

3) the above-mentioned locking elements, and the top and bottom stops pressed against the main girders, form a part on the end fasteners which allows the generation of a controlled longitudinal expansion which relieves the longitudinal pressure generated in the cross girders in case of fire, which expansion occurs in a plurality of stages;

whereby during the expansion of the beam caused by the fire the beam remains substantially straight and aligned with the rectangular net structure.

2. The system of claim 1, wherein: the bottom stop is adapted to shear the fastener under the influence of an expansive force, the top stop is adapted to be forced through the slot under the influence of an expansive force, and the locking element is adapted to disengage under the influence of an expansive force.

3. The system of claim 2, wherein: in its final stage, the controlled longitudinal expansion allows the beam to expand to its maximum length, due to the effect of the heat generated by the fire.

4. The system of claim 1, wherein: the expansion takes place over a certain distance and in a plurality of stages under the action of force.

5. The system of claim 1, wherein: the locking member formed by the fasteners includes a back stop on each fastener which can be engaged and disengaged.

6. The system of claim 4, wherein: the locking element comprises a cam on which an increased longitudinal pressure acts in order to disengage the rear gear.

7. The system of claim 1, wherein: the maximum resistance to expansion of the beam applied by the fastener is about 45.4 kg.

8. A suspended ceiling useful as a thermal insulation component when exposed to a fire environment, the ceiling comprising a rectangular metal frame made up of interconnected main beams and cross beams, and panels supported on the frame, the frame comprising:

1) a main beam with a vertical cross hole therein;

2) a pair of cross members each having end fasteners oppositely inserted in opposite directions into said slots;

a) each fastener and the main beam are elastically connected to prevent the fastener from withdrawing from the slot

Contacting;

b) the pairs of fasteners forming locking elements with each other, the locking elements being avoided each time

Further movement of one fastener toward or away from the other fastener;

c) the bottom of each fastener includes a bottom stop that presses against the main beam

To prevent the fastener from further entering the slot;

d) the top of each fastener has a top stop portion that presses against the main portion

A beam which prevents said fastener from further entering the slot;

3) the above-mentioned locking elements, and the top and bottom stops against which the main girders are pressed, form a part on the end fasteners which allows a controlled longitudinal expansion to be generated which relieves the longitudinal pressure generated in the cross girders in case of fire, which expansion occurs in several stages; the method is characterized in that:

1) the longitudinal pressure acting on the cross beam is reduced to a value less than the longitudinal pressure which can cause the cross beam to buckle during a fire;

2) during a fire, the cross-members are positioned in substantially the same direction continuously in the net frame;

3) the frame continuously supports the panels so that the ceiling acts as a fire barrier.

9. A mesh framework for a suspended ceiling comprising:

1) a main beam provided with a slot;

2) cross beams connected to each other by fastener connections at the ends of the cross beams, which pass through the above mentioned slotted holes and extend in the longitudinal direction of the net frame, wherein:

a) the cross beam is a component which is processed into an inverted T shape by adopting a flat metal strip,

the component comprises a web, a cavity and a flange, wherein the web comprises multiple layers;

b) the cross-beam has a reinforcement that helps to resist during a fire

Resisting longitudinal pressure generated by the beam, thereby enabling the beam to accumulate the beam before buckling

A longitudinal pressure increase;

c) the reinforcement comprises a part in the web of the T-shape which avoids the upper part

The layers are moved relative to each other so as to avoid buckling when pressed in the longitudinal direction;

3) a member in the fastener connection for releasing longitudinal compressive forces, including the above-mentioned additional compressive forces, which are generated in the cross-beam during a fire and build up through the reinforcement, wherein:

a) the fasteners are overlapped and slide oppositely;

b) the reinforcing pieces in the cross beams are matched with the connecting parts of the fasteners, so that a plurality of continuous and linear cross beams are formed in the net-shaped framework;

the above-mentioned frame includes:

1) a main beam with transverse slots

2) A pair of cross members, each cross member having end fasteners oppositely inserted into the slots in opposite directions;

wherein:

a) each fastener and the main beam form elastic contact which can prevent the fastener from withdrawing from the slotted hole;

b) the pair of fasteners forming a locking member with each other, the locking member preventing further movement of one fastener toward or away from the other fastener;

c) the bottom of each fastener is provided with a bottom stop part which is pressed against the main beam and prevents the fastener from further entering the slotted hole;

the reinforcement improves the resistance of the individual beam to buckling due to longitudinal stresses caused by expansion during a fire, while the fastener connection relieves the increase in longitudinal stresses in multiple stages to avoid buckling.