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Technical is often in the form of hot rolled steel members, ground floor and below ground levels. This form such as Square Hollow Section (SHS) columns and of construction is very suitable for mixed retail, often Parallel Flange Channel (PFC) edge beams, A commercial and residential developments. Modules shallower PFC section may be used to support the can be set back from the façade line. An example ceiling, but in all cases, the combined depth of the of a mixed development in Manchester is shown in edge beams is greater than for 4 sided modules. Figure 6. The ground floor and below ground car However, modules can be placed side by side to parking is a conventional composite structure. create larger open plan spaces, as required in Alternatively, non load bearing modules can be hospitals and schools etc. supported by a primary frame, and are installed The stability of the building generally relies on a as the construction proceeds. Modules can be Figure 4 – Primary steel separate bracing system in the form of X bracing disassembled in the future to leave the floor cassette frame used in an open sided module (courtesy in the separating walls. For this reason, fully open supported by the beams. An external steel structure, Kingspan). ended modules are not often used for buildings which consists of a façade structure that acts to more than 3 storeys high. Where used, infill walls stabilise the building may also be used. Modules are and partitions within the modules are non load placed internally within the exo skeleton, as shown bearing, except where walls connected to the in Figure 7. columns provide in plane bracing. Lighter wall studs may be used than for load bearing 4 sided modules. Mixed modules and floor cassettes In this ‘hybrid’ or mixed form of construction, long modules may be stacked to form a load bearing serviced core. Floor cassettes span between the modules and load bearing walls, as illustrated in Figure 5. Floor cassettes may be attached to the walls of the module usually at the corner or intermediate posts. Because of the combined depth of the floor and ceiling of the module, it is advantageous to design the floor cassettes to be relatively deep. The form of construction of the modules is similar to that described for open sided modules, but the loading applied to the Figure 5 – Hybrid modular and planar side of the modules is significantly higher. to create open plan space at the lower levelsFigure 8 – Modules supported by long spanning cellular beams construction (courtesy Corus Living Therefore, this form of construction is Solutions). limited to buildings of 4 6 storeys high. A possible example of a podium using cellular beams is shown in Figure 8.The beams are designed Modules supported by a primary steel to align with the ends of the modules i.e. at 3.6 m structure to 4 m spacing, which dictates the grid of columns Modular units may be designed to be supported by (i.e. at 7.2 to 8 m). A grid of 7.2 m is very suitable for a primary structure at a podium or platform level, in below ground car parking. which the supporting columns are positioned at a In the Paragon project in west London for multiple of the width of the modules (normally 2 or Berkeley First, a concrete core was used to stabilise 3 modules). The beams are designed to support the the 17 storey modular building, as illustrated in combined loads from the modules above (normally Figure 9. This is the tallest modular building in the a maximum of 4 6 storeys). World and demonstrates the capabilities of corner The supporting structure is designed supported modules to provide flexible apartment conventionally and provides open plan space at layouts. Figure 6 – Typical podium structure in which seven Figure 7 – Installation of modules behind external Figure 9 – Concrete core used to support 17 stories storeys of residential units are supported on a steel framework at MoHo, Manchester (courtesy of modules, at Paragon, West London (courtesy composite frame below (courtesy The Design Buro, Yorkon and Joule Consulting Engineers). Caledonian Building Systems). Rollalong and Ayrshire Framing). NSC October 2007 29


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