IE86614B1 - A structural module for construction of buildings - Google Patents

Abstract

A structural module (1) comprising a structural floor (2), load bearing walls (3, 16), and a structural ceiling (5), arranged to support other structural modules (1) in a multi-storey building. The load-bearing walls comprise a structural frame (4) and lightweight concrete (20) between the frame members. The concrete has a density in the range of 400kg/m3 and 600kg/m3, and is cellular, including air entrainment. The concrete is moulded between the frame members, completely filling voids between the frame members along the plane of the wall, and the structural walls are configured so that when two modules are juxtaposed there is a combined wall comprising cavity between the structural modules. The structural walls (3) may lined on at least one side by MgO boards (21), the lightweight concrete and the boards providing at least two hours fire resistance. There may be a vertical socket (32) at a corner for engagement with a dowel pin (33) of an upper or lower adjoining module. The module may comprise a tie plate (30) configured to be secured to a plurality of other modules at a corner, the plate (30) comprising a through hole for receiving a dowel pin (33) of an adjoining module. <Figure 1>

Description

‘A. Structural Module for Construction of Buildings” INTRODUCTION Field of the Invention The invention relates to structural modules for construction of buildings.

Prior Art Discussion Our published specification no. WO2007080561 describes a structural module, its manufacture, and construction of a multi-storey building by placing one module atop the other.

This invention is directed towards achieving improved technical features to such modules such as superior robustness, greater fire resistance, improved acoustical performance, and improved sustainability, particularly in terms of materials used. Another objective is to achieve a more efficient manufacturing process. A further objective is to achieve improved resistance to hurricane forces and seismic activity.

SUMMARY OF THE INVENTION According to the invention, there is provided a structural module as set out in claim 1.

In one embodiment, the concrete is cellular, including air entrainment.

In one embodiment, the concrete is moulded between the frame members, completely filling voids between the frame members along the plane of the wall.

In one embodiment, the wall boards include MgO.

In one embodiment, at least part of the ceiling includes lightweight cellular concrete between structural members in trusses.

In one embodiment, the floor includes a perimeter structural steel frame and includes lightweight concrete with reinforcing steel. -2- * - 8 661 4 In one embodiment, the module includes at a corner a vertical dowel pin for engagement in a vertical socket in a comer of another module.

In one embodiment, the module comprises a vertical socket at a comer for engagement with a vertical dowel pin of an upper or lower adjoining module.

In one embodiment, the module comprises a tie plate for securing to a plurality of other modules at a corner.

In one embodiment, the plate comprises a through hole for receiving a dowel pin of an adjoining module.

In one embodiment, the module comprises an internal wall connected to a structural wall by a releasable joint.

In one embodiment, the releasable joint comprises a joint of a flexible filler extending in a vertical direction.

In another aspect, the invention provides an assembly of a plurality of modules as defined above in any embodiment mounted one atop another, wherein at least some of the modules adjoin a reinforced concrete core and abut it in a vertical plane, wherein at least one module has a tie with a head engaging behind a vertical slot in the core, and wherein the vertical slot is in an embedded insert within the core.

In one embodiment, the insert comprises flanges parallel to the plane of an outer surface of the core facing the module, and side walls connecting the flanges to a front wall and said front wall incorporates the slot.

In one embodiment, a plurality of the modules are tied together at adjoining comers by the or a tie plate and the vertical dowel pin extending through the tie plate and into a vertical socket of an upper or lower module.

In one embodiment, there is a cavity formed between two juxtaposed modules. -3 In another aspect, the invention provides a method of manufacturing a structural module as defined above in any embodiment, the method comprising manufacturing the structural floor, the load bearing walls, and the structural ceiling and interconnecting them together, the method including the steps of choosing a concrete composition and/or density for at least one load bearing wall according to intended location and function of said wall in a building to be constructed using the module, and casting in the chosen lightweight concrete into said wall.

In another aspect, the invention provides a method of constructing a building comprising the steps of manufacturing a structural module in a method as defined above in any embodiment, transporting the modules to a site with an erected core, placing at least some of the modules in position butting the core, and tying at least some of said modules to the core.

In one embodiment, said modules are tied by engagement of a tie within a vertical slot in the core and securing the tie to the module by welding or fasteners.

In one embodiment, a plurality of said modules are tied at adjoining comers by engagement of a vertical dowel pin on a module with a vertical socket in an upper or lower module.

DETAILED DESCRIPTION OF THE INVENTION Brief Description of the Drawings The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which :Fig. 1 is a perspective view of structural members of a structural module of the invention, and Fig. 2 is a perspective view showing a number of such modules arranged to form a building, again only showing the structural frameworks of the modules; Fig. 3 is a cross-sectional plan view through adjoining structural walls when two modules are placed side by side; -4 Figs. 4 and 5 are perspective views at corners of modules, showing how they are tied together for enhanced seismic resistance; Fig. 6 is a plan view showing connection of a non-load bearing internal wall to a loadbearing external wall of a module; and Figs. 7 and 8 are perspective views of tie parts for tying a module to a building core, Figs. 9(a) to (c) are side views showing use of the tie parts for tying a module at the floor level, and Figs. 10(a) to 10(c) are side views showing their use for tying at ceiling level.

Description of the Embodiments Referring to Fig. 1 a structural module 1 comprises a floor 2 having a perimeter structural steel frame and reinforced concrete. Structural walls 3 are supported on the floor 2 and they comprise box-section structural steel studs 4. A ceiling 5 comprises structural steel trusses 6 spanning the walls 3. The walls 3 have sufficient structural strength to support many modules in a multi-storey building such as a hotel or apartment block, as shown in Fig. 2. The wall studs 4 are 60mm x 60mm x 3mm SHS steel at 600mm centres, supported on a flanged edge frame member 7 of the structural floor 2. The trusses 6 have bearing plates 8 on the walls 3, directly overlying the studs 4. The arrangements of the structural walls, floor, and ceiling are as described in WO2007080561 in terms of their str uctural frameworks.

There are braces 9 extending from a central location of an end wall 10 and longitudinal walls 3.

Fig. 2 shows how there may be a break in a module 1, in this example 2.25 times the height of the module 1. Such a break in a structural wall 3 may occur due to any of a range of accidental events such as a vehicle crash or a gas explosion. The floor 2, the structural walls 3 and 10, and the structural ceiling 5 provide sufficient strength to prevent collapse in the event of an accidental event effectively removing a section of a structural wall up to 2.25 times the module height.

Referring to Fig. 3 the structural walls 3 comprise the steel studs 4 which are square hollow sections or rectangular sections typically 60mm x 60mm x 3mm SHS at varying design centres. Where two modules are installed adjacent to each other there are two module walls 3 and 16, -5with two aligned studs 4 separated by a cavity 15. Each of the walls 3 and 16 has moulded-in lightweight cellular concrete 20, produced using foam to provide air entrainment, resulting in a very low density. An example is that marketed by Neopor™ and referred to as cellular lightweight concrete. The density in this embodiment is about 500 kg/m , however it can range from 300kg/m3 to 1200kg/m3.

The structural strength of the module walls 3 and 16 is provided by the steel studs 4 assisted by the cast-in concrete 20. The cellular concrete 20 fills up the voids between the studs 4 and MgO facing board 21 on the internal surfaces. There are strips 23 of MgO board between the studs 4 and the MgO panels 21.

This combination of materials and their physical arrangement provides the following properties: - Fire resistance. The MgO board 21 has excellent fire resistance properties. The cellular concrete 20 reduces transfer of heat to the steel, and it has a thermal conductivity significantly lower than conventional concrete, which is a contributing factor to its improved fire performance. The delay in temperature rise of the steel to the critical level of about 500°C is very advantageous for fire safety of a multi-storey building. With ENI365-1 loaded fire testing, over 120 mins Fire Resistance has been achieved, despite the fact that the wall is relatively thin, in this example 82mm.

- High strength to weight ratio. With the low density cellular concrete a similar dead weight of structure can be achieved compared to the module of WO2007080561, which can be about 15% lighter than traditional build.

- Excellent acoustic performance. The acoustic performance of the module is significantly improved due to the wall composition as the wall is designed to deal with a wider range of sound frequencies. A compartment wall formed by two module walls has been tested in a laboratory and has achieved 62dB Rw and Rw + Ctr of 57dB. This is approximately 9dB better than the current Building Regulations in Ireland and 12 dB better than the current UK Building Regulations.

- Robustness.

- Improved thermal insulation in comparison to conventional concrete. The cellular lightweight concrete (CLC) at about 500 kg/m3 has on average 14 times better thermal insulation than that of conventional concrete. This reduces the requirement for insulation for external walls. -6- Sustainability. There are no man-made or manufactured aggregates needed. The foaming agent used in the mix is made from natural ingredients and is biodegradable and nonpolluting to water courses. Eco-cement can also be used with the product. It reduces the need for additional manufactured insulation.

It will be appreciated that the wall construction contributes very significantly to the required properties of a structural module both in terms of its manufacture, its use in constructing a building, and its ongoing use for residential or business purposes.

The wall properties can be varied in the factory according to the intended nature of use of the module 1. This is achieved by adjustment of the cellular concrete density 20 during off-site (factory) manufacture of the module 1. The cellular concrete preparation is as follows in one embodiment: - In a mechanical rotating drum mixer river run sand of the correct grading is firstly mixed with cement in the required proportions. Optionally, polypropylene fibres can be mixed in to reduce shrinkage. Then water is added to the required volume and mix consistency. Once this is reached the required volume of foam is added to produce the desired wet density of the mix.

- The foam is produced in a machine that takes water, compressed air, and a biological foaming agent that produces lightweight foam which encapsulates small air bubbles. This enables the foam to be mixed into a sand-cement-water mortar without the bubbles collapsing, thus keeping the mix at a stable density. Once the foam is fully integrated in the mixture, it is transferred into a hopper before being cast into the wall panels on a horizontal bed and screeded off level.

There are many advantages to the wall construction both in terms of the building constructed from the module and the method of manufacturing the module. One of the most important advantages is that the module solves a particular acoustic problem which is generally associated with modular construction.

It will also be appreciated that the process of manufacture is more efficient because of avoidance of manual infill of insulation, the lightweight concrete being cast by machine. In the factory the casting machine pours, levels, and screeds the infill concrete automatically. -7Referring to Figs. 4 and 5 a joint at corners if formed by a tie plate 30 with four corner holes 31, a socket 32, and a dowel pin 33. These interconnect eight modules 1 at a corner, four below and four above. The tie plate 30 is welded at a joint 37 to a corner member 32 of the module 1 below. Chamfered top edges 34 of the tie plate 30 facilitate the required amount of weld for securing the plate 30 directly to the bearing plates 8 of ceiling trusses 6 of the adjoining modules 1. This secures the plate to the four underneath modules 1, and these edges are accessible from above. These welds are indicated as numeral 36 in the drawings.

The next module 1 above is welded to the tie plate 30 at a weld 37 around the corner angle of the upper module floor 2. The tie plate 30 has four holes 31, one at each corner. The next two upper modules 1 are then placed and secured in a similar manner. The final upper module is secured in place by insertion of the dowel pin 33 through a hole 31 in the plate 30. It extends into the socket 32 which is directly below and has been filled with non-shrink and high-strength grout. The depth of the pocket and the length of the dowel are determined by the forces it needs to cater for. In some circumstances this grout may also need to be of the type which hardens quickly, in order to achieve the desired strength in the connection as soon as possible. This is particularly true for high-rise buildings, where the structure needs to take wind and other final loads prior to building completion. In one embodiment, the grout is Sikadur-42 HE high performance epoxy grout, for example. This dowel connection has the same capabilities as the welds between the upper module and the tie plate to cater for all relevant forces.

This arrangement allows a fourth module 1 to be tied in even though access to weld to the plate 30 is not possible after three upper modules have been put in place. Also, it allows at each corner a combination of both welding and dowel pin engagement. By providing four holes 31 in the plate it is possible to choose on site which upper module to lower into position last.

This arrangement is designed to take the static and dynamic forces of a seismic event. Compressive loading is taken primarily by the vertical studs 4. Vertical tension loads are resisted by the corner ties 40 which are specifically designed for such loading. The horizontal forces are transferred via diaphragm action, utilizing the floor slabs and the corner connections, to the reinforced concrete building cores. These corner module connections use welding and/or grouted pins to achieve the structural design requirements. -8Referring to Fig. 6 a non load-bearing internal wall 50 of the module 1 is connected to the structural floor 2 and the ceiling 5 by fastening the structural members. Connection of the internal wall 50 to a structural wall 3 is achieved by a rail 52 of channel configuration in crosssection fastened by screws 53 to the wall 3. Strips 54 of plasterboard are secured to the rail 52. The internal wall 50 is then moved into position butting against the plasterboard 54 at the side edges. The plasterboard 54 fixed to the channel bears onto the first stud of the internal wall panel but is not mechanically fixed to it. A joint 55 of flexible material is then made between the plasterboard strips 54 and the plasterboard panels 56 of the internal wall 50.

In the event of significant seismic activity causing movement of a structural wall 3, the internal wall 50 will not be forced to move with it due to the joint characteristics. The joint may open or become damaged, but all damage will be cosmetic and easily repaired. The main advantage is that the internal wall 50 will maintain its own stability and integrity and will not incur forces which could cause further damage to property or more significantly cause injury to inhabitants.

Figs. 7 to 10 are views showing connection of a module 1 to a reinforced concrete core 61 which had previously been erected on site. The core 61 typically includes a lift shaft and stairwell of the building. A slotted insert 60 is embedded in the core 61 at an exactly vertical orientation and in predetermined locations to coincide with module floor and ceiling levels. The number of inserts is determined by the magnitude of the forces calculated. The slotted insert 60 comprises lateral flanges 62, angled side walls 67 converging to a front wall 63 with a vertical slot 64.

A tie 65 comprises a flat plate with one end notched to provide a head 66 configured to suit the core slotted insert 60. The tie 65 is engaged to the slotted insert 60 in a vertical orientation and is then rotated through about 90° until the tie 65 is in a horizontal orientation. The tie 65 is then slid vertically until it engages either the floor 2 of a module (Figs. 9(a) to 9(c)) or the top of the module I (Figs. 10(a) to 10(c)). The tie 65 is then welded to the module and is free to slide within the core wall slotted insert 60 in a vertical direction only. This enables it to resist both shear and tension forces but cater for any differential settlement between the modules and the core, particularly in multi-storey buildings. It also allows the transfer of horizontal forces from the modules 1 into the core structure 61. This detail is also significant in catering for static and dynamic forces during a seismic event. The extent of differential settlement in a 25-storey building can be in the region of 8mm to 15mm, due to the concrete of the building core shrinking whereas there is no appreciable shrinkage of the modules 1 because of the steel bearing the load. -9As shown in Figs 9 and 10 welding of the tie 65 may involve initially welding a buffer plate (Figs 10(a) to 10(c)) so that the top surface of the tie 65 is brought up to the level of the top surface of the bearing plates 8. Alternatively, the method may involve removing a plate section to create space for the tie (Figs. 9(a) to 9(c)). The latter connection is made between a lateral extension of the floor provided by the inverted U-shaped channel as shown.

It will also be appreciated that the cellular concrete in the module walls 3 adds significantly to its overall stiffness. This in turn improves the capacity of the wall 3 to resist racking forces. This is particularly advantageous in hurricane and seismic zones where braced frames and/or shear walls may otherwise be required to resist such forces.

It will also be appreciated that the modules cater for the avoidance of disproportionate collapse which could occur during an accidental event. The modules have the capacity to deal with the removal of up to 2.25h in metres in length on the long wall of the module at one level without the modules above collapsing ( h = height of module ). Similarly whole short walls of modules can be removed at one level without the danger of collapse of those modules above. This will be appreciated from Fig. 2 The invention is not limited to the embodiments described but may be varied in construction and detail. For example, the wall construction technique of casting in lightweight cellular concrete may also be used for ceilings, roofs and floors. Also, in the embodiments described, there is a cavity between walls of two adjoining modules, however, it is envisaged that a wall such as an internal wall of a single module may incorporate a cavity. If so, there may be a structural frame on both sides of the cavity. Also, the tie arrangement for tying a module to a core may be reversed, with the core having ties which engage slots in the modules.

Claims (20)

Claims

1. A structural module (1) comprising a structural floor (2), load bearing walls (3), and a structural ceiling (5), arranged to support a plurality of other structural modules (1) in a multi-storey building, wherein at least one load bearing wall (3) comprises a structural steel frame (4) and lightweight concrete (20) having a density in the range of 300kg/m 3 and 1200kg/m 3 between frame members of said structural frame, wherein the lightweight concrete is cast into the structural frame, wherein the at least one load bearing wall (3) is lined on at least one side by boards; and wherein the concrete (20) is cast against the structural steel frame and the boards.

2. A structural module as claimed in claim 1, wherein the concrete (20) is cellular, including air entrainment.

3. A structural module as claimed in any preceding claim, wherein the concrete (20) is moulded between the frame members, completely filling voids between the frame members along the plane of the wall.

4. A structural module as claimed in any preceding claim, wherein the wall boards include MgO.

5. A structural module as claimed in any preceding claim, wherein the ceiling includes trusses with structural members, and wherein at least part of the ceiling (5) includes lightweight cellular concrete (20) between said structural members.

6. A structural module as claimed in any preceding claim, wherein the floor (2) includes a perimeter structural steel frame and includes lightweight concrete (20) with reinforcing steel.

7. A structural module as claimed in any preceding claim, wherein the module (1) includes at a comer a vertical dowel pin (33) for engagement in a socket (32) in a comer of another module.

8. A structural module as claimed in claim 7, wherein the module (1) comprises a vertical socket (32) at a comer for engagement with another vertical dowel pin of an upper or lower adjoining module.

9. A structural module as claimed in claims 7 or 8, wherein the module comprises a tie plate (30) for securing to a plurality of other modules at a corner.

10. A structural module as claimed in claim 9, wherein the plate (30) comprises a through hole (31) for receiving a dowel pin (32) of an adjoining module.

11. A structural module as claimed in any preceding claim, wherein the module (1) comprises an internal wall (50) connected to a structural wall (3) by a releasable joint (54, 55).

12. A structural module as claimed in claim 11, wherein the releasable joint comprises a joint of a flexible filler (55) extending in a vertical direction.

13. An assembly of a plurality of modules of any preceding claim mounted one atop another, wherein at least some of the modules adjoin a reinforced concrete core (61) and abut it in a vertical plane, wherein at least one module has a tie (65) with a head (66) engaging behind a vertical slot (64) in the core, and wherein the vertical slot is in an embedded insert (60) within the core.

14. An assembly of a plurality of modules as claimed in claim 13, wherein the insert (60) comprises flanges (62) parallel to the plane of an outer surface of the core facing the module, and side walls (67) connecting the flanges to a front wall (63), and said front wall (63) incorporates the slot (64).

15. An assembly of a plurality of modules as claimed in claims 13 or 14, wherein a plurality of the modules (1) are tied together at adjoining corners by a tie plate (30) and the vertical dowel pin (33) extends through the tie plate (30) and into a vertical socket (32) of an upper or lower module.

16. An assembly of a plurality of modules as claimed in any of claims 13 to 15, wherein there is a cavity formed between two juxtaposed modules.

17. A method of manufacturing a structural module as claimed in claim 1, the method comprising manufacturing the structural floor, the load bearing walls, and the structural ceiling and interconnecting them together, the method including the steps of choosing a 5 concrete composition and/or density for at least one load bearing wall according to intended location and function of said wall in a building to be constructed using the module, and casting in the chosen lightweight concrete into said wall.

18. A method of constructing a building comprising the steps of manufacturing a structural 10 module in a method as claimed in claim 17, transporting the modules to a site with an erected core, placing at least some of the modules in position butting the core (61), and tying at least some of said modules to the core.

19. A method as claimed in claim 18, wherein said modules are tied by engagement of a tie 15 (65) within a vertical slot (64) in the core and securing the tie to the module by welding or fasteners.

20. A method as claimed in claims 18 or 19, wherein a plurality of said modules are tied at adjoining corners by engagement of a vertical dowel pin on a module with a vertical 20 socket in an upper or lower module.