## 9 Building Occupancy and Use
### Module Level  
In the context of structural solutions for prefabricated modules, it is essential to note that there are numerous intersections among them, regardless of the type of material used, whether timber, concrete, or steel. Three generic forms of modular construction exist: continuously supported, four-sided, or panelized/monolithic modules, where vertical loads are transmitted through the walls; open-sided, corner-supported or framed at the edge's modules, where vertical loads are transmitted through corner and intermediate posts; and non-load bearing modules, often called pods, that are supported by the floor or a separate structure. These three construction methods are employed in diverse applications, contingent on the need for cellular spaces, like hotel bedrooms, or open-plan areas [91; 93]:  
* Continuously supported: Continuously supported or four-sided modules are supported on their longitudinal sides, which bear on the walls of the modules below. Continuous-supported modules are divided into a lightweight load-bearing wall system and a massive load-bearing wall system based on the type of sidewall support system [109]. Monolithic load-bearing wall modules are commonly used in concrete buildings, in which the concrete walls are used to transfer gravity loads to the foundation and resist the lateral loads [110]. The end walls are usually highly perforated with large windows at one end and a door and service riser at the other. In some systems, the edge beams in the floor and ceiling provide an indirect means of load transfer by bearing on each other, but in most cases, the side walls provide direct load transfer. The indirect transfer method relies on the resistance of the edge beams to compression across their depth, so this type of modular construction can be more limited in height. The direct transfer of loads through the side walls relies on the compression resistance of the structural elements. In continuously supported modules, corner posts can be incorporated to serve as lifting points and connection points to other modules and structural elements. Stability is provided either by placing X-bracing in the walls of the modules, by the diaphragm action of sheathing boards, or by a separate bracing system [83; 93];
* Open-sided: Corner-supported modules have posts at their corners and sometimes at intermediate points, and edge beams span between them. In this way, the modules may be designed with open sides, although infill walls can be used to form the cellular space. Because of that, this solution usually has more flexibility in architectural design and larger module sizes. This leads to fewer modules and connections [91; 96]. They are generally made of steel in which the gravity loads are transferred to the slab, the edge beams and corner columns, and the foundations [110]. Therefore, frame-supported modular units are employed in high-rise MSBs due to the robust compression, torsional, lateral-torsional, and bending resistance of columns and beams [111]. However, because the beam-to-post connections are relatively weak in terms of their bending resistance, the stability of the group of modules is provided by additional bracing often located around the stair and lift core [93]. The lateral loads due to winds and earthquakes are transferred to shear wall cores and bracing systems via ceilings and floors [93; 111]. These types of open-sided modules are often used in the health and educational sectors [93]. The corner-supported module is commonly used in high-rise buildings due to its high load-carrying capacity [110]. Another variation is the open-ended modules that can be manufactured so full-height glazing can be provided, and modules can also be combined along their length [93];Non-load bearing: The third type is non-load bearing modules, which can only support their weight and crane lifting forces. Simultaneously, relying on adjacent members or modules, such as wall support landings and half-landings of staircase modules, resist externally exerted forces.