GB2161845A

GB2161845A - Ceiling panels in a visible framework with panel retaining members actuated at about 70 DEG C

Info

Publication number: GB2161845A
Application number: GB08518069A
Authority: GB
Inventors: Paul Loicq
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-07-18
Filing date: 1985-07-17
Publication date: 1986-01-22
Also published as: GB8518069D0; FR2567938B1; FR2567938A1; BE902909A; GB2161845B; DE3525693A1

Abstract

The invention relates to the use of metal members 3 made of a shape-memorizing alloy, e.g. nickel and titanium, to retain suspended ceiling panels in their visible framework when their temperature reaches the critical value, of e.g. 70 DEG C. The framework is made up of commercially available T-sections (1) to whose web (2) the metal members (3), e.g. of nickel and titanium alloy, are secured, and that the metal members, by their deformation, which is programmed at a critical temperature of about 70 DEG C, retain the suspended ceiling panels (4). The system according to the invention is intended more particularly for the fire protection of buildings having ceilings suspended on a visible framework. <IMAGE>

Description

SPECIFICATION A system for retaining suspended ceiling panels in their visible framework when the temperature thereon reaches the critical temperature, which may eg be 70'C.

This invention relates to fire protection in buildings for ceilings suspended on a visible framework.

According to French regulation art. C011 of the Fire Safety Rules No. 1477-1: "Suspended ceilings cannot be taken into consideration in calculating the fire resistance of the associated floors when: ... They can be removed by simple thrust or pressure;. . . ' .

Conventionally, ceiling panels are retained in their visible framework by spring clips which clamp the panels in the framework when the suspended ceiling is used as a fire protection element. When such a ceiling is not so used, the panels which form it rest purely by gravity in the visible framework, so that the panels can just be pushed to give access to the space which is present between the ceiling and the floor above and which is frequently used to conceal technical items connected with electricity supply or air-conditioning.

The device according to the invention fulfils the two requirements of being able to remove ceiling plates on a visible framework just by pushing them at a normal temperature, for example, below 70"C, and of being able to clamp the panels in their visible framework when the temperature thereof reaches and exceeds the critical temperature.

The device comprises shape-memorizing metal members which are made, for example, of nickel-titanium alloy and which are fitted to existing commercially available T-sections for suspended ceilings. The metal members are positioned at a between-axis distance of approximately 50 mm in the vertical part of the sections between the base thereof and the top surface of the vertical part.

The metal members, when at a temperature below the critical temperature of, for example, 70"C, adapt to the working clearance between the web of the section and the ceiling panels so that the same may be lifted readily.

When the temperature of the framwork reaches the critical level, the metal members according to the invention distort in a movement memorized during the preparation of the alloy, such movement being the result of a change in crystalline structure due to a reversible transformation in the solid state between an austenitic state and a martensitic state.

The metal members according to the invention therefore clamp the ceiling panels on the base of their framwork by confronting them with a projection which takes up the force perpendicularly to the direction of the programmed distortion.

The shape-memorizing alloy members according to the invention can have a variety of forms. For example, the system can be embodied by members made entirely of a shape memorizing alloy which are secured to the web of the sections, for example, by riveting and which distort by changing from a normal state-i.e., at a temperature below approximately 70'C-which is a flat angle (Fig. 1), to a distortion giving an angle of less than 180"C (Fig. 2).

The system can also be embodied by sheetmetal members 5 (Fig. 3) engaged in apertures 6 (Fig, 3) with which the web of the Tsection is formed to receive them, the sheetmetal members being connected to the section member, for example, by pivot pins or the like 7 (Fig. 3) made of a shape-memorizing alloy (Fig. 3) which, as a result of distortion in same temperature conditions, make a partial rotation transmitted to the members 5 (Fig. 4) which clamp the ceiling panels on either side of the T-section (Fig. 4).

1. A device for securing suspended ceiling panels in their visible framework, characterised in that it comprises a panel support section (1) to whose web (2) the metal members (3) made of a shape-memorizing alloy are secured.

2. A device according to claim 1, characterised in that the panel support section (1) has a T shape.

3. A device according to claims 1 and 2, characterised in that the metal members (3) made of a shape-memorizing alloy enable the suspended panels to be removed when the temperature of the framework is below the critical temperature.

4. A device according to any of claims 1 to 3, characterised in that the metal members (3) made of a shape-memorizing alloy distort when the temperature of the framwork is at least equal to the critical temperature and present to the panels projections which prevent the panels from rising, taking up their pressure forces perpendicularly to the direction of deformation of the metal members.

5. A device according to any of claims 1 to 4, characterised in that the metal members fitted to the panel support sections are made of a shape-memorizing alloy, the shape-memorizing feature being the result of a change in crystalline structure due to a reversible transformation in the solid state between an austenitic state and a martensitic state.

6. A device according to any of claims 1 to 5, characterised in that the members for clamping suspended ceilings to a visible framework are made entirely of shape-memorizing alloy.

7. A device according to any of claims 1 to 4, characterised in that the members for

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A system for retaining suspended ceiling panels in their visible framework when the temperature thereon reaches the critical temperature, which may eg be 70'C. This invention relates to fire protection in buildings for ceilings suspended on a visible framework. According to French regulation art. C011 of the Fire Safety Rules No. 1477-1: "Suspended ceilings cannot be taken into consideration in calculating the fire resistance of the associated floors when: ... They can be removed by simple thrust or pressure;. . . ' . Conventionally, ceiling panels are retained in their visible framework by spring clips which clamp the panels in the framework when the suspended ceiling is used as a fire protection element. When such a ceiling is not so used, the panels which form it rest purely by gravity in the visible framework, so that the panels can just be pushed to give access to the space which is present between the ceiling and the floor above and which is frequently used to conceal technical items connected with electricity supply or air-conditioning. The device according to the invention fulfils the two requirements of being able to remove ceiling plates on a visible framework just by pushing them at a normal temperature, for example, below 70"C, and of being able to clamp the panels in their visible framework when the temperature thereof reaches and exceeds the critical temperature. The device comprises shape-memorizing metal members which are made, for example, of nickel-titanium alloy and which are fitted to existing commercially available T-sections for suspended ceilings. The metal members are positioned at a between-axis distance of approximately 50 mm in the vertical part of the sections between the base thereof and the top surface of the vertical part. The metal members, when at a temperature below the critical temperature of, for example, 70"C, adapt to the working clearance between the web of the section and the ceiling panels so that the same may be lifted readily. When the temperature of the framwork reaches the critical level, the metal members according to the invention distort in a movement memorized during the preparation of the alloy, such movement being the result of a change in crystalline structure due to a reversible transformation in the solid state between an austenitic state and a martensitic state. The metal members according to the invention therefore clamp the ceiling panels on the base of their framwork by confronting them with a projection which takes up the force perpendicularly to the direction of the programmed distortion. The shape-memorizing alloy members according to the invention can have a variety of forms. For example, the system can be embodied by members made entirely of a shape memorizing alloy which are secured to the web of the sections, for example, by riveting and which distort by changing from a normal state-i.e., at a temperature below approximately 70'C-which is a flat angle (Fig. 1), to a distortion giving an angle of less than 180"C (Fig. 2). The system can also be embodied by sheetmetal members 5 (Fig. 3) engaged in apertures 6 (Fig, 3) with which the web of the Tsection is formed to receive them, the sheetmetal members being connected to the section member, for example, by pivot pins or the like 7 (Fig. 3) made of a shape-memorizing alloy (Fig. 3) which, as a result of distortion in same temperature conditions, make a partial rotation transmitted to the members 5 (Fig. 4) which clamp the ceiling panels on either side of the T-section (Fig. 4). CLAIMS

7. A device according to any of claims 1 to 4, characterised in that the members for clamping suspended ceilings to a visible framework are made of metal and are actuated by a pivot or pin or the like made of shape-memorizing metal.

8. A device substantially as herein described and shown in the accompanying drawings.