A cold-formed steel beam for forming a composite beam of a modular building frame, a cassette, and a modular unit

Abstract

A beam 1 is suitable for forming composite beams of a frame of a modular building. The beam has means for rigidifying a connection 11 of a flange 7 of the beam to a flange of a stacked-adjacent beam

Description

The invention relates to a cold-formed steel beam for forming a composite beam of a modular building frame, a cassette, and a modular unit. BACKGROUND Cold-formed steel beams feature widely in modern methods of construction including volumetric modular construction methods involving light steel framing. When individual modular units are connected to one another, conventionally at the corners thereof, the frames form an interconnected frame of a modular building. Common examples of such buildings are residential buildings and hospitals. For the modular building to be safe, its frame must not collapse under normal and maximum loading and also must not collapse in the case of a fire, at least for long enough to allow occupants to escape. Whether or not a modular building frame will collapse is in part determined by the design of the load bearing components of the individual modular units, and of the connections therebetween. Another consideration is that it is advantageous to reduce the section height of edge beams used for floor and ceiling beams of modular units. This reduces the unusable space between ceiling and floor joists of stacked modular units, reduces the void in the same area that can allow fire to spread, and reduces material usage, thereby improving efficiency and saving costs. However, it can be challenging to reduce the section height of beams which make up a frame of a modular unit while maintaining safety because the deflection of a structural component is primarily determined by the second moment of area, a geometrical property of a beam section which generally speaking leads to a greater deflection for a beam having a decreased height. By decreased height we mean a height dimension of the beam’s section, wherein the height dimension is aligned with the direction of gravitational force in use. It would be advantageous if there were a system for reducing the section height of cold-formed steel beams of modular units without compromising the safety of modular buildings. It is therefore an object of the present invention to obviate or mitigate the problems outlined above in relation to cold-formed steel beams used in the formation of modular building frames. SUMMARY OF THE INVENTION Accordingly, the present invention provides a cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, wherein the cold-formed steel beam comprises a means for rigidifying a connection of a flange of the cold-formed steel beam to a flange of a stacked-adjacent cold-formed steel beam for forming the composite beam of the modular building frame and / or for rigidifying a connection of a web of the cold-formed steel beam to a web of a side-adjacent cold-formed steel beam for forming the composite beam of the modular building frame, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flange and / or said web of the cold-formed steel beam. By longitudinally proximal portion we mean a longitudinally central portion of the flange and / or web. By this we mean longitudinally extending along the flange and / or web and proximal to the web. By ‘means for rigidifying’ we mean means for forming a rigid component by connecting the cold-formed steel beam and the stacked-adjacent and / or side-adjacent beam. Advantageously, the means for rigidifying the connection between the first cold-formed steel beam and the or each neighbouring cold-formed steel beam restricts the two beams sliding relative to one another. By the ‘first’ beam we mean the beam according to this first aspect of the invention and by ‘neighbouring’ we mean the stacked-adjacent and / or side-adjacent beam. This advantageously forms a composite beam by limiting the sliding action of the cold-formed steel beam and the adjacent cold-formed steel beam. The composite beam is more rigid and experiences less deflection under a given load, has increased strength, and has increased resistance to buckling. This is compared with beams which are identical to the beams described in the preceding statement of invention but having a lack of the connection rigidifying means, i.e., two beams which are in a sliding-abutting connection stacked-adjacent and / or side-adjacent to one another. Ideally, the connection rigidifying means is suitable for forming a plurality of mechanical connections generally spaced apart longitudinally over the proximal portion of the flange and / or the web. By ‘proximal portion’ we mean the longitudinally proximal portion previously described. Ideally, the connection rigidifying means is suitable for forming a plurality of mechanical connections generally spaced apart longitudinally over an entire length of the flange and / or the web. Ideally, the connection rigidifying means is suitable for forming a plurality of mechanical connections generally spaced apart longitudinally over the flange and / or the web having a substantially equal spacing between each of the mechanical connections. Ideally, the connection rigidifying means is suitable for forming a plurality of detachable mechanical connections. By ‘detachable mechanical connections’ we mean mechanical connections formed by nuts and bolts. Ideally, the cold-formed steel beam is a prismatic beam. The flange of the preceding statements of invention may be the only flange of the cold-formed steel beam. Alternatively, the flange of the preceding statements of invention may be one of two or more flanges of the cold-formed steel beam. Ideally, the cold-formed steel beam comprises two flanges, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of one of the two flanges. Ideally, the cold-formed steel beam is a C section. Ideally, the cold-formed steel beam is a lipped channel. Ideally, the lipped channel comprises two lips extending from longitudinal edge portions of two flanges towards a central axis of the cold-formed steel beam. Ideally, the cold-formed steel beam is formed as a single body comprising bends between the web and the one or more flanges and between the flanges and the lips. Ideally, the cold-formed steel beam is a non-prismatic beam. Ideally, the cold-formed steel beam is straight. Ideally, the cold-formed steel beam is curved. Ideally, the cold-formed steel beam is an edge beam for a modular unit. By edge beam we mean a structural member which defines the outermost structural member of a modular unit and in use connects to corner posts. Ideally, the cold-formed steel beam is a longitudinal edge beam. Ideally, the cold-formed steel beam is a transverse edge beam. A transverse edge beam may also be referred to as an edge joist or primary joist. Ideally, the cold-formed steel beam is an edge beam for a floor cassette of a modular unit. Ideally, the cold-formed steel beam is an edge beam for a ceiling cassette of a modular unit. Ideally, the cold-formed steel beam is a trimmer beam for a floor cassette of a modular unit. Ideally, the cold-formed steel beam is a trimmer beam for a ceiling cassette of a modular unit. Ideally, the connection rigidifying means comprises a plurality of through holes in the body of the one or more flange and / or in the body of the web for receiving mechanical fasteners for forming the mechanical connections. Ideally, the connection rigidifying means comprises a plurality of circular through holes in the body of the one or more flange and / or in the body of the web for receiving mechanical fasteners for forming the mechanical connections. Ideally, the through holes in the body of the one or more flange and / or in the body of the web for receiving mechanical fasteners for forming the mechanical connections are formed centrally in circular sunken portions of the one or more flange and / or the web. By sunken we mean that the sunken portions are sunken relative to a plane defined by an outer-facing surface of the one or more flange and / or web of the cold-formed steel beam. By this we mean that the cold-formed steel beam comprises countersinks around the through holes of the connection rigidifying means. By outer-facing surface we mean a surface facing away from a central axis or point of a cross section of the cold-formed steel beam which in use is placed adjacent a flange or web of an adjacent modular unit. Advantageously, the sunken portions allow the cold-formed steel beam to be in a planar abutting stacked and / or side-by-side relationship with one or more adjacent components, such as one or more adjacent cold-formed steel beams, to minimise unusable space and to provide mechanical support to the cold-formed steel beams arising out of the planar abutment. Ideally, the cold-formed steel beam is suitable for securing one or more fin plate and / or one or more end plate onto a longitudinal end portion of the one or more flange and / or the web of the cold-formed steel beam. Ideally, the cold-formed steel beam comprises a plurality of through holes in the body of the one or more flange and / or in the body of the web formed at opposing longitudinal end portions of the cold-formed steel beam for receiving mechanical fasteners for securing one or more fin plate and / or one or more end plate onto the one or more flange and / or web of the cold-formed steel beam at longitudinal end portions thereof. Ideally, the plurality of through holes for securing one or more fin plate and / or one or more end plate are formed centrally in circular sunken portions of the body of one or more flange and / or the web. By this we mean that the cold-formed steel beam comprises countersinks around the through holes for securing one or more fin plate and / or one or more end plate. Advantageously, fin plates and / or end plates provide a means of securing the cold-formed steel beam to square hollow sections forming corner posts of a building module. The fin and / or end plates may be utilised to secure the cold-formed steel beam to alternative components. Ideally, the cold-formed steel beam comprises one or more fin plates and / or end plates secured onto the one or more flange and / or web of the cold-formed steel beam at longitudinal end portions thereof by means of steel fastening means such as Hollobolts®. Ideally, the cold-formed steel beam comprises one or more fin plates and / or end plates secured onto the one or more flange and / or web of the cold-formed steel beam at longitudinal end portions thereof by means of welding. Ideally, the cold-formed steel beam is less than 600mm in height. Ideally, the cold-formed steel beam is between 200mm and 400mm in height. Ideally, the cold-formed steel beam is between 250mm and 350mm in height. Ideally, the cold-formed steel beam is 300mm in height. Ideally, the cold-formed steel beam is less than 300mm in height. Ideally, the cold-formed steel beam is less than 150mm in width. Ideally, the cold-formed steel beam is between 80mm and 100mm in width. Ideally, the cold-formed steel beam is 90mm in width. Ideally, the cold-formed steel beam is less than 90mm in width. Ideally, the cold-formed steel beam is between 2.5mm and 4mm in thickness. Ideally, the cold-formed steel beam is 3mm in thickness. Ideally, the cold-formed steel beam is 3m to 8m in length. Advantageously, a 3m cold-formed steel beam is suitable for forming a transverse edge beam of a floor and / or ceiling of a modular unit and an 8m beam is suitable for forming a longitudinal edge beam of a floor and / or ceiling of a modular unit. Ideally, the cold-formed steel beam comprises a stiffening means. Ideally, the or each flange of the cold-formed steel beam comprises a stiffening means. Ideally, a first flange of the cold-formed steel beam comprises the stiffening means and wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections over a proximal portion of a second flange of the cold-formed steel beam. Ideally, the stiffening means extends longitudinally along the or each flange comprising the stiffening means. Ideally, the or each flange comprising the stiffening means comprises a main planar surface, wherein the stiffening means extends away from the main planar surface towards a centre of the cold-formed steel beam. Ideally, the or each flange comprising the stiffening means comprises an in-flange formed stiffening means. Ideally, a flange of the cold-formed steel beam comprises an in-flange formed stiffening means extending longitudinally along said flange. Ideally, the or each flange comprising the stiffening means is formed from a single piece of material. This is what we mean by ‘in-flange’. Advantageously, this saves material compared with stiffeners which are applied to the flange in the form of welded or mechanically fastened stiffening components which are formed from a piece of material separate to that from which the flange is formed. Alternatively, the stiffening means is formed from a separate piece of material as the or each flange comprising the stiffening means. Ideally, the or each flange comprising the stiffening means is formed a single piece of material in a cold forming process. Ideally, the cold-formed steel beam comprises no welded joints connected to the stiffening means or any other part of the flange. Advantageously, the stiffening means can be used to increase the second moment of area about the height axis of the cold-formed steel beam relative to a comparable beam which is identical in outer dimensions including height and width, and which has the same thickness. A greater second moment of area, also sometimes called the quadratic moment of area or (area) moment of inertia, leads to a greater stiffness of the section and decreased deflection under a given load applied in the direction across the height of the beam. This permits a reduction in height of the cross section of the cold-formed steel beam. Further advantageously, the stiffening means increases the maximum bending resistance (strength) of the section about height and width axes of the cold-formed steel beam. Ideally, the stiffening means extends from a first longitudinal free end of the flange to a second longitudinal free end of the flange. Ideally, the stiffening means extends continuously from a first longitudinal free end of the flange to a second longitudinal free end of the flange. Ideally, the stiffening means is located between longitudinally extending lateral edge portions of the or each flange of the cold-formed steel beam. Ideally, the stiffening means is a rib. Ideally, the stiffening means of the or each flange is proximal to the web. Ideally, the rib extends inwards towards a centre of the cold-formed steel beam. Ideally, the flange comprising the stiffener comprises flange portions extending from opposing longitudinally extending portions of the stiffener. Ideally, the rib is flange-interposed. By this we mean that the rib is set between portions of the at least one flange of the cold-formed steel beam such that a portion of the flange extends from opposing longitudinal edges of the rib. Ideally, the at least one flange in which the rib is formed comprises three sections which each extend longitudinally from a first free end of the flange to a second and longitudinally opposing free end of the flange. The three sections are displaced from one another in the flange along a width direction of the flange. The three sections comprise a first planar section connected to the web by a 90-degree bend. The three sections comprise a second section displaced from the first planar section towards a central axis of the cold-formed steel beam. The three sections comprise a third planar section at the same plane as the first planar section, wherein the third planar section extends from the second section and is supported by the second section. Advantageously, the at least second section displaced from the first planar section towards the central axis of the cold-formed steel beam means that the second section does not protrude above an outer-facing planar surface of the first and third sections. This means that the flange is suitable for receiving planar components of the modular building for securing onto the first and third sections. The cold-formed steel beam is suitable for receiving planar components onto the outer-facing surface of another flange of the cold-formed steel beam and / or the web of the cold-formed steel beam. Advantageously, planar components, such as floor or roof sheeting or decking, and / or concrete slabs, and / or plasterboard can be configured to provide restraint to the cold-formed steel beam when in use in the modular building in order to increase the buckling capacity of the cold-formed steel beam. Ideally, the at least one flange in which the rib is formed comprises fourth and fifth sections connecting the first planar section to the second section and the second section to the third section. Ideally, the fourth section is connected to the first section at the same angle as the fourth section is connected to the second section. Ideally, the fifth section is connected to the third section at the same angle as the fifth section is connected to the second section. Ideally, the second section is connected to the first section via the fourth section at a 20-degree to 70-degree angle. Ideally, the second section is connected to the first section via the fourth section at a 40-degree to 50-degree angle. Ideally, the second section is connected to the first section via the fourth section at a 45-degree angle. Ideally, the second section is connected to the third section via the fifth section at a 20-degree to 70-degree angle. Ideally, the second section is connected to the third section via the fifth section at a 40-degree to 50-degree angle. Ideally, the second section is connected to the third section via the fifth section at a 45-degree angle. Ideally, the second section is formed centrally in the C section of the flange. By this we mean centrally in respect of the width of the flange. Ideally, the second section is planar. Ideally, the first second and third sections are parallel. Ideally, the fourth and fifth sections are planar. Ideally, the cold-formed steel beam comprises a fire protecting means attached thereto. The fire protecting means may be a profile fire protecting means being a sprayed product and / or a box fire protecting means being a planar, or board, fire protecting means. The fire protecting means is applied to the cold-formed steel beam except in outer-facing planar surfaces of the flange and / or web. According to a second aspect of the invention there is provided a composite beam for a frame of a modular building comprising at least two building units, wherein the composite beam comprises at least two cold-formed steel beams in a stacked-adjacent configuration and / or a side-adjacent configuration, wherein the at least two cold-formed steel beams comprise a means for rigidifying a connection between flanges of the cold-formed steel beams in the stacked-adjacent configuration and / or for rigidifying a connection between two webs of the cold-formed steel beams in the side-adjacent configuration, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flanges and / or said webs. Ideally, the at least two cold-formed steel beams are lipped channels comprising longitudinal openings between edge portions of lips, wherein in the stacked configuration the openings of the cold-formed steel beams are facing in the same direction. Ideally, in the side-adjacent configuration, the openings of the cold-formed steel beams are facing in opposite directions. Ideally, one or more of the cold-formed steel beams comprise a stiffening means according to the preceding statements of invention. Ideally, in the stacked configuration, the stiffening means is located in a distinct flange as the connection rigidifying means. Ideally, the mechanical connections of the adjacent cold-formed steel beams are formed by a plurality of steel fastening means such as Hollobolts®. According to a third aspect of the invention there is provided a modular unit comprising a cold-formed steel beam for connection to at least one adjacent cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, wherein the cold-formed steel beam comprises a means for rigidifying a connection of a flange of the cold-formed steel beam to a flange of a stacked-adjacent cold-formed steel beam for forming the composite beam of the modular building frame and / or for rigidifying a connection of a web of the cold-formed steel beam to a web of a side-adjacent cold-formed steel beam for forming the composite beam of the modular building frame, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flange and / or said web. Ideally, the modular unit is a floor cassette. Ideally, the modular unit is a ceiling cassette. Ideally, the modular unit is a building module comprising a floor cassette and a ceiling cassette and corner posts connecting said floor cassette and ceiling cassette. Ideally, the cold-formed steel beam is connected to a square hollow section at longitudinally opposing ends of the cold-formed steel beam by means of one or more end plates and / or one or more fin plates. Ideally, the end plates and / or fin plates are connected to the longitudinally opposing ends of the cold-formed steel beam by means of one or more steel fastening means such as Hollobolts® and / or one or more welds. Ideally, the end plates and / or fin plates are connected to the square hollow sections at longitudinally opposing ends of the cold-formed steel beam by means of one or more end plates and / or one or more fin plates. Ideally, the modular unit comprises a fire-protecting means. Ideally, the fire-protecting means comprises a fire-protecting means in a planar configuration of a section of one or more cold-formed steel beams and / or a box configuration surrounding the section of one or more cold-formed steel beams and / or a profile configuration surrounding a profile of the section of one or more cold-formed steel beams. All of the beams of the modular unit may be protected in a manner expressed by one or more of these options. Ideally, the fire-protecting means comprises a board product. The board product may be fire-resistant plasterboard. Ideally, the fire-protecting means comprises a sprayed product. Ideally, the connection rigidifying means forms a plurality of detachable mechanical connections. Ideally, the plurality of mechanical connections comprise nuts and bolts. Ideally, the modular unit comprises one or more planar components secured to a flange of the cold-formed steel beam. Ideally, the planar components comprise floor sheeting and / or floor decking and / or roof sheeting and / or one or more concrete slabs. Advantageously, these apply restraint to the cold-formed steel beam. Ideally, the planar components of the modular building comprise fire-resistant plasterboard. According to a fourth aspect of the invention there is provided a kit of parts for forming a composite beam. The kit of parts comprises first and second cold-formed steel beams each comprising a means for rigidifying a connection of a flange of the first cold-formed steel beam to a flange of the second cold-formed steel beam and / or for rigidifying a connection of a web of the first cold-formed steel beam to a web of the second cold-formed steel beam. The first and second cold-formed steel beam are usable to form a composite beam of a modular unit and / or a modular building comprising multiple modular units. According to a fifth aspect of the invention there is provided a method of forming a cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, wherein the cold-formed steel beam comprises a C section comprising a web and two flanges, wherein at least one flange of the C section comprises an in-flange formed stiffening means extending longitudinally along said at least one flange, wherein the cold-formed steel beam further comprises a plurality of through holes in a longitudinally proximal portion of a body of a flange not comprising the stiffening means and / or formed in the body of the web for receiving mechanical fasteners for forming mechanical connections between the cold-formed steel beam and a stacked-adjacent and / or side-adjacent cold formed steel beam. Ideally, the cold-formed steel beam is cold-formed from a single sheet of steel. Ideally, the in-flange formed stiffening means is integrated during a cold-forming process. Ideally, the cold-formed steel beam is formed in a rolling process. According to a sixth aspect of the invention there is provided a method of mechanically connecting first and second adjacent cold-formed steel beams for forming a composite beam of a modular building comprising a plurality of modular units. Ideally, the method comprises forming a rigidified stacked connection between a flange of a first cold-formed steel beam and a flange of a second, stacked-adjacent, cold-formed steel beam, comprising aligning longitudinally extending side edges of the two cold-formed steel beams, aligning openings of a plurality of through holes formed in a longitudinally proximal portion of the body of the flanges of the two cold-formed steel beams, and inserting and tightening a plurality of mechanical fasteners in the aligned through holes of the two cold-formed steel beams for rigidifying the planar-abutting connection formed therebetween. Ideally, the method comprises forming the rigidified stacked connection between a main edge ceiling beam of a lower-stacked modular unit and a main edge floor beam of an upper-stacked modular unit. Ideally, the method further comprises forming a rigidified back-to-back connection between a web of a first cold-formed steel beam and a web of a second, side-adjacent, cold-formed steel beam, comprising the step of aligning openings of a plurality of through holes formed in a longitudinally proximal portion of the body of the webs of the two cold-formed steel beams, and inserting and tightening a plurality of mechanical fasteners in the aligned through holes of the two cold-formed steel beams for rigidifying the planar-abutting connection formed therebetween. Ideally, the method comprises forming the rigidified back-to-back connection between a main edge ceiling beam of a modular unit and a main edge ceiling beam of a side-adjacent modular unit. Ideally, the method comprises forming the rigidified back-to-back connection between a main edge floor beam of a modular unit and a main edge floor beam of a side-adjacent modular unit. Ideally, the method comprises forming a rigidified planar-abutting stacked connection between a flange of a first cold-formed steel beam and a flange of a second, stacked-adjacent, cold-formed steel beam and / or a rigidified planar abutting back-to-back connection between a web of a first cold-formed steel beam and a web of a second, side-adjacent, cold-formed steel beam by bringing outer planar surfaces of the flanges and / or webs into a planar abutting connection and inserting and tightening a plurality of mechanical fasteners in the aligned through holes. Ideally, the method comprises aligning longitudinal opposing ends of the two cold-formed steel beams having identical lengths. According to a seventh aspect of the invention there is provided a method of forming a cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, the method comprising the step of forming a means for rigidifying a connection of a flange of the cold-formed steel beam to a flange of a stacked-adjacent cold-formed steel beam for forming the composite beam of the modular building frame and / or for rigidifying a connection of a web of the cold-formed steel beam to a web of a side-adjacent cold-formed steel beam for forming the composite beam of the modular building frame, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flange and / or said web of the cold-formed steel beam. Ideally, the method comprises a step of forming the means for rigidifying by performing a step of punching through holes along a piece of steel for forming the cold-formed steel beam. Ideally, the method comprises a step of forming a beam section comprising the flange and web comprising rolling a single piece of steel for forming the cold-formed steel beam through at least one cold rolling machines. Ideally, the method comprises a step of forming a flange of the beam comprising a stiffening means by rolling a single piece of steel for forming the cold-formed steel beam through at least one cold rolling machines. The skilled person will appreciate that all preferred or optional features of the invention described with reference to only some aspects or embodiments of the invention may be applied to all aspects of the invention. It will be appreciated that optional features applicable to one aspect of the invention can be used in any combination, and in any number. Moreover, they can also be used with any of the other aspects of the invention in any combination and in any number. This includes, but is not limited to, the dependent claims from any claim being used as dependent claims for any other claim in the claims of this application. The invention will now be described with reference to the accompanying drawings which show a single embodiment of a support arrangement according to the invention by way of example only. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example only, with reference to the accompanying drawings. Figure 1 is a section view of two stacked cold-formed steel beams according to the prior art. Figure 2 is an isometric view of a cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units according to the invention. Figure 3 is a side elevation view of the cold-formed steel beam of figure 2. Figure 4 is a sectional view of the cold-formed steel beam of figures 2 and 3 along line BB’ of figure 3. Figure 5 is an isometric view of a composite structural member according to the invention. Figure 6 is an isometric exploded view of a composite structural member according to the invention. Figure 7 is a section view of a composite structural member according to the invention. Figure 8 is an isometric view of a composite structural member according to the invention. DETAILED DESCRIPTION The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognise that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents. It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Figure 1 is a sectional view of two stacked-adjacent cold-formed steel beams B1 and B2 of stacked adjacent modular units. The beams B1 and B2 are in a sliding-abutting connection because there is no means of rigidifying the connection between the two beams B1 and B2. The connection of the two beams B1 and B2 therefore has decreased rigidity, strength, and resistance to buckling compared with the present invention and / or has greater section dimensions compared with the present invention. Referring to the drawings 2 to 8 there is shown a cold-formed steel beam 1 for connection to at least one adjacent cold-formed steel beam 3 for forming a composite beam 5 (see figures 5 and 6) of a frame of a modular building which comprises at least two modular units (not shown). The cold-formed steel beam 1 according to the invention comprises a means for rigidifying a connection of the cold-formed steel beam 1 to an adjacent cold-formed steel beam 3, in one example a stacked adjacent cold-formed steel beam 3 (figures 5 and 6), for forming the composite beam 5. The composite beam 5 is formed by connection of a flange 7 of the cold-formed steel beam 1 to a flange 9 of a stacked-adjacent cold-formed steel beam 3 (see figures 5 and 6) for forming the composite beam 5 of the modular building frame. The composite beam is formed by connection of a web 12 of the cold-formed steel beam 1 to a web 14 of a side-adjacent cold-formed steel beam 3 (see figure 8). The composite beam may be formed by connection of flanges of two pairs of stacked-adjacent beams which are each connected to webs of side-adjacent beams (not shown). Beam 3 may be formed identically in structure to the beam 1, and for the depicted embodiments this is the case. Therefore, where the structure of one of the beams 1, 3 is described, this should be taken to be a suitable description for the structure of the other beam 1, 3, unless context clearly dictates otherwise. The flange 7 of the cold-formed steel beam 1 is connectable to a flange 9 of the cold-formed steel beam 5 (see figure 6). The means for rigidifying the connection is suitable for forming a plurality of mechanical connections 11 (see figure 5) spaced apart over a longitudinally proximal portion of said flanges 7, 9, in the examples shown the mechanical connections 11 spaced apart over an entire length of the flanges 7, 9. By longitudinally proximal portion we mean a longitudinally central portion of the flanges 7, 9 and / or webs. By this we mean longitudinally extending and proximal to the webs 12, 14. The mechanical connections 11 are detachable. The cold-formed steel beam 1 is a prismatic beam. The cold-formed steel beam 1 is a C section beam. The cold-formed steel beam 1 is a lipped channel. The cold-formed steel beam 1 is formed as a single body comprising bends between the web 12 and the flanges 7, 22 and between the flanges 7, 22 and the lips 24. The cold-formed steel beam 1 is straight. The cold-formed steel beam 1 is an edge beam for a modular unit. By edge beam we mean a structural member which defines the outermost structural member of a modular unit and in use connects to corner posts. The cold-formed steel beam is a longitudinal edge beam. The cold-formed steel beam 1 is a transverse edge beam 1. A transverse edge beam 1 may also be referred to as an edge joist or primary joist. The cold-formed steel beam 1 is an edge beam for a floor cassette of a modular unit. The cold-formed steel beam 1 is an edge beam for a ceiling cassette of a modular unit. The cold-formed steel beam 1 is a trimmer beam for a floor cassette of a modular unit. The cold-formed steel beam 1 is a trimmer beam for a ceiling cassette of a modular unit. Connecting the cold-formed steel beams 1, 3 in this manner having mechanical connections 11 spaced apart over the length of the beams 1, 3 restricts the two beams 1, 3 from sliding relative to one another, i.e., this forms a composite beam 5 of a modular building frame. The composite beam 5 formed in this manner is more rigid and experiences less deflection under a given load, has increased strength, and increased resistance to buckling when compared with two beams which are identical but not having a plurality of mechanical connections 11 along the length of their flanges (see figure 1 for example) i.e., two beams which are in a sliding-abutting connection stacked adjacent and / or side-adjacent to one another. The same is true in the case of the cold-formed steel beams 1, 3 being connected in a back-to-back configuration (figure 8) of their webs 12, 14 when compared with cold-formed steel beams which do not have a plurality of mechanical connections along the length of their webs. The beam according to the invention having this back-to-back connection advantageously leads to an increased resistance of a building frame to lateral loads such as wind loads. The connection rigidifying means comprises a plurality of through holes 16 in the body of the flange 7 for receiving mechanical fasteners 20 (see figure 5) for forming the mechanical connections 11. The mechanical fasteners are Hollobolts® 20 in one example. The through holes 16 are circular and evenly spaced along the entire length of the flange 7 of the cold-formed steel beam 1. Through holes 16 in the body of the one or more flange 7 for receiving mechanical fasteners 20 for forming the mechanical connections 11 are formed centrally in circular sunken portions (not shown) of the flange 7. This may be extended to providing similar sunken portions around through holes formed in the body of the web 12 and / or the other flange 22. Advantageously, the sunken portions allow the cold-formed steel beam 1 to be in a planar abutting stacked and / or side-by-side relationship with one or more adjacent components to minimise unusable space and to provide mechanical support to the cold-formed steel beam 1 arising out of the planar abutment. The cold-formed steel beam 1 is a prismatic, straight, lipped channel having lips 24. The cold-formed steel beam 1 may also be a C section without lips. A lipped channel is a type of C channel comprising two lips 24 extending from longitudinal edge portions of the respective flanges 7, 22 towards the centre of the cold-formed steel beam 1. The lips 24 are integrally formed with the flanges 7, 22 and the web 12 as a single piece of material by means of a cold-forming process. The cold-formed steel beam 1 is between 200mm and 400mm in height. The cold-formed steel beam 1 is between 250mm and 350mm in height. The cold-formed steel beam 1 is 300mm in height. The cold-formed steel beam 1 is between 80mm and 100mm in width. The cold-formed steel beam 1 is 90mm in width. The cold-formed steel beam 1 is between 2.5mm and 4mm in thickness. The cold-formed steel beam 1 is 3mm in thickness. The cold-formed steel beam 1 is 3m to 8m in length. Advantageously, a cold-formed steel beam 1 being three meters in length is suitable for forming a transverse edge beam of a floor and / or ceiling of a modular unit and an 8m beam is suitable for forming a longitudinal edge beam of a floor and / or ceiling of a modular unit. The flange 22 of the cold-formed steel beam 1 comprises an in-flange formed stiffening means 28 extending longitudinally along said flange 22. Flange 30 of stacked-adjacent cold-formed steel beam 3 comprises an in-flange formed stiffening means 32 extending longitudinally along said flange 30. Stiffening means 28, 32 can be used to increase the second moment of area about the height axis of the cold-formed steel beams 1, 3 relative to a comparable beam which is identical in outer dimensions including height and width, and which has the same thickness (see figure 7 for the cold-formed steel beams 1, 3 without stiffening means). A greater second moment of area, also sometimes called the quadratic moment of area or (area) moment of inertia, leads to a greater stiffness of the section and decreased deflection under a given load applied in the direction across the height of the beam 1, 3. This permits a reduction in height of the cross section of the cold-formed steel beam 1, 3. Further advantageously, the stiffening means 28, 32 increases the maximum bending resistance (strength) of the section about height and width axes of the cold-formed steel beam 1, 3. Stiffening means 28, 32 extend continuously from first longitudinal free end of the flange 22, 30 to a second longitudinal free end of the flange 22, 30. Stiffening means 28, 32 are ribs 28, 32. The ribs 28, 32 extend inwards towards a centre of the cold-formed steel beams 1, 3. The ribs 28, 32 are flange-interposed, meaning set between portions of the flanges 22, 30 such that a portion of the flanges 22, 30 extend from opposing longitudinal edges of the rib 28, 32. Referring again to just cold-formed steel beam 1 but applying also to cold-formed steel beam 3, the flange 22 in which the rib 28 is formed comprises three sections 34, 36, 38 (see figure 4) which each extend longitudinally from a first free end of the flange 22 to a second and longitudinally opposing free end of the flange 22 (see figure 2). The three sections 34, 36, 38 (see figure 4) are displaced from one another in the flange 22 along a width direction of the flange 22. The three sections 34, 36, 38 comprise a first planar section 34 connected to the web 12 by a 90-degree bend. The three sections 34, 36, 38 comprise a second section 36 displaced from the first planar section 34 towards a central axis of the cold-formed steel beam 1. The three sections 34, 36, 38 comprise a third planar section 38 at the same plane as the first planar section 34, wherein the third planar section 38 extends from the second section 36 and is supported by the second section 36. The flange 22 in which the rib 28 is formed comprises fourth and fifth sections 40, 42 connecting the first planar section 34 to the second section 36 and the second section 36 to the third section 38, respectively. The fourth section 40 is connected to first section 34 at the same angle as the fourth section 40 is connected to the second section 36. This angle is approximately 45 degrees, however other angles between 20 degrees and 70 degrees are possible. The fifth section 42 is connected to third section 38 at the same angle as the fifth section 42 is connected to the second section 36. This angle is approximately 45 degrees, however other angles between 20 degrees and 70 degrees are possible. Second section 36 is planar, as are fourth and fifth sections 40, 42. First, second and third sections 34, 36, 38 are parallel. The rib 32 of flange 30 is identically formed in cold-formed steel beam 3 compared with rib 28 of flange 22. Composite beam 5 comprises at least two cold-formed steel beams 1, 3 in a stacked-adjacent configuration (figures 5 to 7), wherein the at least two cold-formed steel beams 1, 3 comprise a means for rigidifying a connection between flanges 7, 9 of the cold-formed steel beams 1, 3 in the stacked-adjacent configuration, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections 11 spaced apart over a longitudinally proximal portion of said flanges 7, 9. The at least two cold-formed steel beams 1, 3 are lipped channels comprising longitudinal openings between edge portions of lips 24, 26, wherein in the stacked configuration the openings of the cold-formed steel beams 1, 3 are facing in the same direction. The cold-formed steel beams 1, 3 are formed as mirror images of one another. By mirror images we mean that they are connected in the composite beam 5 symmetrically in the examples of the drawings. The cold-formed steel beams are identically formed and mirror images of one another, therefore in the following where a description is made of the structure of one of the cold-formed steel beams 1, 3, this should be taken, unless context dictates otherwise, to be a description applicable to the structure of the other cold-formed steel beam 1, 3. The lipped channel 1 is ideally formed from a metal and / or a metal alloy, for example steel. The lipped channel 1 is formed from cold-formed steel in a cold forming process involving a rolling process to form the flanges 7, 22, the lips 24, and the rib 28. The flanges 7, 22 and the lips 24 provide stiffening in addition to the stiffening provided by the stiffening means 28. The embodiment depicted has two flanges 7, 22 formed at opposing upper and lower longitudinal edge portions of the web 12. The two flanges 7, 22 are of uniform width along the respective upper or lower longitudinal edge portion of the web 11, and the width of the flange 7 is equal to the width of the flange 9. This may not be the case in that flange 7 may have a uniform width not equal to a uniform width of flange 9, and widths of flanges 7 and 9 may be non-uniform along their lengths. Likewise, modifications are envisaged for the lips 24 which are depicted in the drawings as having uniform width along the lengths of the lips 24. When two cold-formed steel beams are connected in a composite beam according to the invention, the height of the beams, that is the height of the webs may be equal as depicted or may be unequal especially where the cold-formed steel beams form floor and ceiling beams of stacked adjacent modular units in which case the cold-formed steel beam forming the floor beam may have a greater height than the cold-formed steel beam forming the ceiling beam. The web 12, flanges 7, 22 and lips 24 comprise externally facing planar surfaces. It is advantageous to provide a straight structural member component according to the invention with externally facing planar surfaces as this permits a large amount of reinforcement to be applied to the structural member component in the form of one or more planar reinforcing components sitting flat thereon. A planar reinforcing component may take the form of cold-formed steel beam 3 or other components such as concrete slabs, floor sheeting, ceiling sheeting, and plasterboard (not shown). Further advantageously, externally facing planar surfaces permit the cold-formed steel beam 1 to be an efficient use of space within a modular building in use as the cold-formed steel beam 1 can be more tightly packed against other components of the building that have similarly planar surfaces. Furthermore, externally facing surfaces of the lips 24 are located on a common plane and parallel to one another. Thus, the depicted lipped channel 1 can be effectively reinforced by further planar structural components (not shown). In the depicted embodiment, the stiffening means 28 is limited to the flange 7, although a cold-formed steel beam 1 according to the invention may comprise the stiffening means 28 in one of many alternative arrangements, for example a flange 22 and / or web 12 may comprise a portion of the stiffening means 28 in the form of one or more ribs. The stiffening means 28 shown in the drawings is a rib 28 extending continuously and longitudinally centrally along the entire length of flange 7. Alternative embodiments may have the stiffening means 28 comprising a single rib extending along part of the flange, multiple ribs arranged side-by-side and / or end-to-end along the flange 7, and these modifications may be employed for the stiffening means 28 when not restricted to the flange 7 as previously described. The rib 28 is entirely located inwards of externally facing planar surfaces of the first and third sections 34, 38 of the flange 7. This is advantageous as in this embodiment the rib 28 will not interfere with the application of planar reinforcing components. The section 36 of rib 28 is also surrounded at two longitudinal edges by the two sections 34, 38, via sections 40, 42 of the flange 7. The rib 28 uniformly extends towards the centre of the lipped channel along the length of the flange 7 and comprises a uniform cross section along the flange 7. The cross section of rib 28 resembles a regular trapezium. The composite beam 5 is a bolted composite beam 5, and nuts and bolts are provided as part of the securing assembly of a kit for forming the composite beam 5 (see figure 6). Composite bolting is located along the flanges 7, 9 of the cold-formed steel beams 1, 3 and may additionally or in preference be located on the webs 12, 14 thereof. WORKED EXAMPLE As disclosed herein, a composite beam comprising cold-formed steel beams of the present invention possesses improved stiffness and deflection performance under a given load, has increased strength and has increased resistance to buckling compared with a composite beam comprising cold-formed steel beams which are identical to the beams described in the preceding statements of invention but having a lack of the connection rigidifying means, i.e., two beams which are in sliding-abutting stacked-adjacent connection and / or side-adjacent connection. A corollary of this is that for a given maximum permissible deflection of a cold-formed steel beam, using the present invention allows for a reduction in the height of the section of the cold-formed steel beam which advantageously allows less unusable space between floor and ceiling joists and material savings. The mechanical fasteners used to provide the mechanical connections should be accounted for when calculating net material savings. To substantiate the claim of these improvements, we herein provide calculations to demonstrate the increased effectiveness provided by using a composite beam according to the present invention in a particular embodiment thereof. In modular construction this can be best illustrated by consideration of deflection. A typical scenario is considered. Two modular units 3 meters wide and 8 meters span are stacked vertically. We consider at the first-floor level the main side trimmer beams. The ground floor ceiling beam is used to assist in supporting the floor beam of the second storey. In the typical scenario considered, the beams are simply supported, and the loads considered to be uniformly distributed. Since deflection arises as a result of loading, we first quantify the loading in the scenario described above. Loads are divided into permanent and imposed loads. The permanent load of the floor gx comprises first permanent load gxl, totalling 0.4kN / m2 and comprising the finish of the modular unit amounting to O.lkN / m2, the deck amounting to O.lkN / m2, the insulation amounting to0.05kN / m2 and the joists amounting to0.15kN / m2. The permanent load gx comprises second permanent load gx2 comprising the partitions of the modular unit, which is assumed to amount to lkN / m2. The imposed load of the floor, qxl, comprises 3.0kN / m2, which is the assumed load of the people and their equipment / furniture in an office or classroom. The permanent load of the ceiling, gx2 , is assumed to be 0.4kN / m2. The imposed load of the ceiling, qx2 , comprises a load of 0.5kN / m2 being that of the services (plumbing, electrical, etc.). For the trimmer beam we get: Floor: 3 0 gx. (0.4 + 1) Xy = 2.1kN / m 3 0 qx. 3 x — = 4.5kN / m Ceiling: 3 0 gx. 0.4 x^ = 0.6kN / m 3 0 qx. 0.5 X y = 0.75kN / m Therefore, as a result of gx and qx for the floor and ceiling we get 2.7kN / m and 5.25kN / m, respectively for the permanent and imposed loads. As noted, one of the main considerations in these longer spans is the deflection of the beam. Design guidelines suggest limiting values for the deflection caused by the permanent load (self-weight, etc.) and by the imposed load (people, equipment, etc.). The deflection is primarily controlled by the moment of inertia. In order to model the typical scenario outlined above, we consider a composite beam 5 according to the invention shown in figure 7 and a beam arrangement BA according to the prior art shown in figure 1. Both beam 5 and beam arrangement BA are simply supported at both longitudinal ends, the flanges of the two beams B1, B2 are in a planar abutting relationship. The two beams B1, B2 are stacked-adjacent in the language of the present application and are permitted to slide relative to each other because they do not comprise the means for rigidifying the connection according to the invention. The composite beam 5 comprises two cold-formed C-Section beams 1, 3. The dimensions of sections of the beams 1, 3 are 300mm in height by 90mm total width measured from the lips 24, 26 to the back of the web 12, 14 (as illustrated), with a thickness of 3mm. The present worked example is aided by numerical methods provided by the SCIA Engineer software. Using the SCIA Engineer software, this provides the section of the composite beam 5 with an effective area of 3057mm2 and an effective inertia of 11125cm4 about the principal y axis indicated by line CC’ of figure 7. Each beam B1, B2 of the beam arrangement BA according to the prior art has a height of 400mm, a total width of 90mm and a thickness of 4mm. The resultant effective area of the section of the beam arrangement BA is 4848mm2 and the effective inertia of beam B1 is 5365.5cm4 about the principal y direction indicated by line AA’ of figure 1 which is multiplied by two, since the two beams B1, B2 are structurally identical and stacked one on the other, to give an effective inertia of 10731cm4. A finite element method analysis was performed on centreline data using the effective area and inertia for each of beam arrangement BA and composite beam 5, which were mapped to fibres of the respective cross sections. The resultant values of the effective inertias were then used to calculate deflection for a given load. We consider the maximum allowable deflection to be given by the following formula: _ L ^max = Ten Where L is the span of the beam and wherein the value of is a relatively strict deflection limit based on building codes and design standards. This gives: L 8000 5max = = . = 17.8mm max 450 450 We use the following formula to calculate deflection: 5wL4 6 =---- 384E7 Where w is the (uniformly) distributed load, L the length (span) of the cold-formed steel beams B1, B2, 1, 3, E the modulus for the material, I the moment of inertia or second moment of area. These values are w = 5.25 being the imposed load and L = 8000mm, E = 2.1E5), and I = 1.0731E8 for the beam arrangement BA according to the prior art (figure 1) and I = 1.1125E8 for the composite beam 5 according to the invention (figure 7). We get the deflection 5BA of the beam arrangement BA according to the prior art: _ 5 x 5.25 x 80004 _ 5ba “ 384 X 2.1E5 X 1.0731E8 “ 12'4mm Which is less than the value of 5max given above. According to the invention, the deflection <5comp °f composite beam 5: _ 5 x 5.25 x 80004 _ 5comp' “ 384 X 2.1E5 X 1.1125E8 “ 12'°mm Which is also less than the value of 5max given above. Therefore, the reduced height and thickness of the beams 1, 3 has acceptable deflection when formed as a composite beam according to the invention. The skilled person will appreciate that all preferred or optional features of the invention described with reference to only some aspects or embodiments of the invention may be applied to all aspects of the invention. It will be appreciated that optional features applicable to one aspect of the invention can be used in any combination, and in any number. Moreover, they can also be used with any of the other aspects of the invention in any combination and in any number. This includes, but is not limited to, the dependent claims from any claim being used as dependent claims for any other claim in the claims of this application. In relation to the detailed description of the different embodiments of the invention, it will be understood that one or more technical features of one embodiment can be used in combination with one or more technical features of any other embodiment where the transferred use of the one or more technical features would be immediately apparent to a person of ordinary skill in the art to carry out a similar function in a similar way on the other embodiment. The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof.

Claims

1. A cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, wherein the cold-formed steel beam comprises a means for rigidifying a connection of a flange of the cold-formed steel beam to a flange of a stacked-adjacent cold-formed steel beam for forming the composite beam of the modular building frame and / or for rigidifying a connection of a web of the cold-formed steel beam to a web of a side-adjacent cold-formed steel beam for forming the composite beam of the modular building frame, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flange and / or said web of the cold-formed steel beam.

2. A cold-formed steel beam according to claim 1, wherein the cold-formed steel beam comprises two flanges, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of one of the two flanges.

3. A cold-formed steel beam according to claim 1 or claim 2, wherein the connection rigidifying means is suitable for forming a plurality of mechanical connections generally spaced apart longitudinally over the longitudinally proximal portion of the flange and / or the web.

4. A cold-formed steel beam according to any preceding claim, wherein the connection rigidifying means is suitable for forming a plurality of mechanical connections generally spaced apart longitudinally over an entire length of the flange and / or the web.

5. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is a prismatic beam.

6. A cold-formed steel beam according to claim 5, wherein the cold-formed steel beam is a C section beam.

7. A cold-formed steel beam according to claim 5, wherein the cold-formed steel beam is a lipped channel.

8. A cold-formed steel beam according to any preceding claim, wherein the connection rigidifying means comprises a plurality of through holes in the body of the one or more flange and / or in the body of the web for receiving mechanical fasteners for forming the mechanical connections.

9. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is suitable for securing one or more fin plate and / or one or more end plate onto a longitudinal end portion of the one or more flange and / or the web of the cold-formed steel beam.

10. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is between 200mm and 400mm in height.

11. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is less than 300mm in height.

12. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is between 80mm and 100mm in width.

13. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is between 2.5mm and 4mm in thickness.

14. A cold-formed steel beam according to any preceding claim, wherein the cold-formed steel beam is 3m to 8m in length.

15. A cold-formed steel beam according to any preceding claim, wherein the or each flange of the cold-formed steel beam comprises a stiffening means.

16. A cold-formed steel beam according to claim 15, wherein a first flange of the cold-formed steel beam comprises the stiffening means and wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections over a proximal portion of a second flange of the cold-formed steel beam.

17. A cold-formed steel beam according to any one of claims 14 to 16, wherein the stiffening means extends longitudinally along the or each flange comprising the stiffening means.

18. A cold-formed steel beam according to any one of claims 14 to 17, wherein the or each flange comprising the stiffening means comprises a main planar surface, wherein the stiffening means extends away from the main planar surface towards a centre of the cold-formed steel beam.

19. A cold-formed steel beam according to any one of claims 15 to 18, wherein the or each flange comprising the stiffening means is formed from a single piece of material.

20. A cold-formed steel beam according to any one of claims 15 to 19, wherein the stiffening means of the or each flange is proximal to the web.

21. A cold-formed steel beam according to any one of claims 15 to 20, wherein the cold-formed steel beam comprises no welded joints connected to the stiffening means or any other part of the flange.

22. A cold-formed steel beam according to any one of claims 15 to 21, wherein the stiffening means extends from a first longitudinal free end of the or each flange to a second longitudinal free end of the or each flange.

23. A composite beam for a frame of a modular building comprising at least two building units, wherein the composite beam comprises at least two cold-formed steel beams in a stacked-adjacent configuration and / or a side-adjacent configuration, wherein the at least two cold-formed steel beams comprise a means for rigidifying a connection between flanges of the cold-formed steel beams in the stacked-adjacent configuration and / or for rigidifying a connection between two webs of the cold-formed steel beams in the side-adjacent configuration, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flanges and / or said webs.

24. A modular unit comprising a cold-formed steel beam for connection to at least one adjacent cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, wherein the cold-formed steel beam comprises a means for rigidifying a connection of a flange of the cold-formed steel beam to a flange of a stacked-adjacent cold-formed steel beam for forming the composite beam of the modular building frame and / or for rigidifying a connection of a web of the cold-formed steel beam to a web of a side-adjacent cold-formed steel beam for forming the composite beam of the modular building frame, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flange and / or said web.

25. A method of forming a cold-formed steel beam for forming a composite beam of a frame of a modular building comprising at least two modular units, the method comprising a step of forming a means for rigidifying a connection of a flange of the cold-formed steel beam to a flange of a stacked-adjacent cold-formed steel beam for forming the composite beam of the modular building frame and / or for rigidifying a connection of a web of the cold-formed steel beam to a web of a side-adjacent cold-formed steel beam for forming the composite beam of the modular building frame, wherein the means for rigidifying a connection is suitable for forming a plurality of mechanical connections spaced apart over a longitudinally proximal portion of said flange and / or said web of the cold-formed steel beam.

26. A method according to claim 25, wherein a step of forming the means for rigidifying comprises a step of punching through holes along a piece of steel for forming the cold-formed steel beam.

27. A method according to claim 25 or 26, further comprising a step of forming a beam section comprising the flange and web comprising rolling a single piece of steel for forming the cold-formed steel beam through at least one cold rolling machines.T +44(0)30 0300 2000A

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