Modular Construction

1

SHARDA SCHOOL OF ARCHITECTURE & PLANNING SHARDA UNIVERSITY UTTAR PRADESH

DISSERTATION ON “MODULAR CONSTRUCTION”

SUBMITTED BY PRANAV NANDA COURSE B.ARCH 6TH SEMISTER : 3RD YEAR ENROLLMENT NO. 2012011804

SUBMITTED IN PARTIAL FULFILLMENT FOR THE DEGREE OF BACHELOR OF ARCHITECTURE BATCH : 2012 – 2017

ACKNOWLEDGEMENT

2

After the successful completion of dissertation schedule, it is the time to acknowledge various people and their unconditional support during this time period. First and farmost I wish to thank Prof. Rakesh Sapra, HOD of Sharda School of Architecture & Planning for his concern, I am grateful to my internal guide Ar. Vineet Garg, Asstt. Prof. for his valuable advices and busy time, for helping me in shaping my project in an effective manner and providing me constructive suggestions to improve the quality of the work. I also take this opportunity to thank all those people who helped me tirelessly during the case studies. The overall staff at SAP, Sharda University, Greater Noida. My Senior batches (2011 – 2016) And last but not the least, I appreciate all the physical, moral and financial support that has been provided by my family members all throughout this time.

(Student’s Signature) Date :

INDEX

Prof. Rakesh Sapra Head of the Dept. School of Architecture & Planning Sharda University

INTERNAL GUIDE : Ar. Vineet Garg

(Assiatant Prof.)

3

CHAPTER 1 - PREAMBLE 1.1 1.2 1.3 1.4 1.5

INTRODUCTION HISTORY AMIS AND OBJECTIVES FUTURISTIC SCOPE METHODOLOGY

Pg 4-5 Pg 6-11 Pg 11 Pg 12-14 Pg 15-16

CHAPTER 2 – LITERATURE STUDY 2.1 SECTORS OF APPLICATION 2.2 ATTRIBUTES OF MODULAR CONSTRUCTION - Advantages - Features of cellular type building - Structural elements used - Types of Module 2.3 KEY TECHNICAL ISSUES 2.4 DIMENTIONAL PLANNING 2.5 DISADVANTAGES 2.6 SUSTAINABILITY 2.7 TYPICAL DETAILS 2.8 FACADES AND INTERFACES

Pg 17 Pg 17-37

Pg 38 Pg 39-47 Pg 48 Pg 48-50 Pg 50-52 Pg 52-54

CHAPTER 3 – CASE STUDIES 3.1 NAKAGIN CAPSULE TOWER 3.2 JAPAN MODULAR HOTEL

Pg 55-58 Pg 59-62

CHAPTER 4 – CONCLUSIONS

Pg 63

BIBLIOGRAPHY

Pg 64

PREAMBLE

4

INTRODUCTION Modular construction is a process in which a building is constructed off-site, under controlled plant conditions, using the same materials and designing to the same codes and standards as conventionally built facilities – but in about half the time. Buildings are produced in “modules” that when put together on site, reflect the identical design intent and specifications of the most sophisticated site-built facility – without compromise. Structurally, modular buildings are generally stronger than conventional construction because each module is engineered to independently withstand the rigors of transportation and craning onto foundations. Once together and sealed, the modules become one integrated wall, floor and roof assembly. Building off site ensures better construction quality management. Materials that are delivered to the plant location are safely and securely stored in the manufacturer’s warehouse to prevent damage or deterioration from moisture and the elements. Manufacturing plants have stringent QA/QC programs with independent inspection and testing protocols that promote superior quality of construction every step of the way. Beyond quality management and improved completion time, modular construction offers numerous other benefits to owners. Removing approximately 80% of the building construction activity from the site location significantly reduces site disruption, vehicular traffic and improves overall safety and security. So, for schools, hospitals, or other active businesses, reducing on-site activity and thereby eliminating a large part of the ongoing construction hazards, is a tremendous advantage. For architects and owners alike, modular construction companies today can work with levels of design and construction sophistication that will exceed all expectations, rivaling their conventional counterparts. It is beneficial that when exploring the various project delivery

5

methods, off-site construction is chosen early in the design development process, and the project built around that methodology, to avoid redesigning. Most modular companies, however, can take a stick built design and create a modular version when required, so it’s never too late to explore the possibilities! As owners and designers look for more sustainable designs for improved environmental impact, modular construction is inherently a natural fit. Building in a controlled environment reduces wastethrough avoidance upstream rather than diversion downstream. This, along with improved quality management throughout the construction process and significantly less on-site activity and disturbance, inherently promotes sustainability.

HISTORY Colonialism through the 19th Century

6

Prefabricated construction stretches back to 1624 when a disassembled house was shipped from England to Cape Ann, Massachusetts to house a fishing fleet using readymade and trusted English building techniques, familiar to settlers who had just arrived in America in 1620. Twenty-five years later, in about 1650, the domestic shipment of precut wood for a house from Plymouth Colony to southern Connecticut eased the settlement of new land by providing immediate shelter and negating the need to gather and fit lumber onsite. Though neither of these examples conforms to the current view of a modern, industrial solution to building, it is clear that a sense of the convenience of assembling building materials offsite predates many of the technologies and much of the development with which these techniques have become synonymous. In 1833, Chicago saw the first “balloon frame” building, St. Mary’s Church, erected on Lake Street. Credited to, alternately, a man named George W. Snow and a carpenter named Augustine Deodat Taylor, the innovation of the balloon frame involved using uniform, slender wood studs held together with newly mass-produced nails, rather than with more complex joinery. The technique, so called due to its lightness and precarious appearance, proved to be an expedient way of creating much-needed housing in burgeoning urban centers. By 1834, a simple balloon frame “shack” would take no more than a week to construct. Within a decade, the new mode of construction had spread from the Midwest throughout the nation. By 1849 railroads carried prefabricated housing “kits” to California to provide expedient shelter for prospectors during the gold rush. The Industrial Revolution and World War I England’s industrial revolution, beginning in the mid-eighteenth century, also expanded to America, ushering in factory production powered by new machines. Companies subsequently began offering homes through catalogs to be assembled by the client onsite. While Aladdin Readi-Cut Houses was the first company to offer prefabricated houses on the market in 1906, Sears, Roebuck & Co.’s

7

mail-order houses proved the best-known example. The company’s designs, sold between 1908 and 1940, offered designs to suit nearly all aesthetic sensibilities, and the homes came complete with all necessary materials including nails and house paint. The cost of assembling one’s home from a box was significantly lower than the custom-built alternative, and there was little need to fear one’s neighbor might end up with the same house; nearly 450 different Sears home types have been identified. Sears houses were particularly popular due to their lack of iconography though many of the houses’ floor plans are the same, there was little to betray the origins of the “factory made” house to the untrained eye. Many of the designs evoked classic Americana and would not be out of place on any suburban street. In the early twentieth century, both domestically and abroad, architects and engineers were grappling with the question of how to efficiently and simply house a rapidly growing population. At the onset of World War I, well-known modernist Le Corbusier’s Dom-ino House of 1914 proposed a simple reinforced concrete structure supported by slender beams. Cheaply and easily reproducible, the project explored simple housing concepts, though it was never built.

World War II and Postwar Housing During World War II, prefabricated sheet-metal construction achieved widespread use in the form of military barracks and mobile trailers. In The Science Newsletter, an anonymous author lauded the mobility of trailer housing and the usefulness of temporary housing: “No ghost town will be left after the war,” states the author, “for the entire community can be folded up and moved elsewhere.” Cornell University professor Svend Riemer wrote in 1945 that “on the basis of mass production and backed up by experiences with large scale industrial conversions during the war, the fateful dilemma of modern residential housing may finally come to a solution.” Referring to trailer homes, he spoke conservatively regarding the future of American housing: “These family homes…will

8

be of extremely limited size. This differs from our expectations… Today, we know that (trailers) are here to stay, whether we like it or not.” By the end of the war, Sears, Roebuck & Co. had ceased production on homes and the notion of prefabrication had lost its charm. By 1946, a Fortune magazine survey indicated a sharp turn against prefabricated houses, with only 16% of respondents saying they would choose to live in one. With the subsequent postwar housing shortage, the use of prefabricated materials was necessary to shelter a severely underhoused population. Modularity and prefabrication were not wholly ignored or criticized after the war; the suburban boom relied heavily on precut, standardized housing designs and economies of scale. Levittown, perhaps the bestknown example of the American postwar suburb, thrived on the replicability of house after house. William J. Levitt, the town’s namesake, even graced the cover of Time Magazine on June 3, 1950.15 The production was so streamlined that Time reported a house rose from the ground every fifteen minutes: “Every 100 feet, (the) trucks stopped and dumped identical bundles of lumber, pipes, bricks, shingles and copper tubing… Near the bundles, giant machines with an endless chain of buckets ate into the earth, taking just 13 minutes to dig a narrow, four-foot trench around a 25-by-32 ft. rectangle. Then came more trucks, loaded with cement, and laid a four-inch foundation for a house…” Moving from site to site, a team of two or three workers would then quickly assemble the house from its component parts. The developments—three Levittowns in all—are still inhabited today. But suburban tract homes, though often relying on prefabricated techniques, did not become emblematic of the concept of modular or manufactured housing. During the 1950s and 1960s, a public pushback against the aesthetics of “trailers” along with the complex legislative practices barring the housing type from certain areas, spoke to a narrow view of manufactured housing. Perhaps as a holdover from earlier war efforts, when soldiers lived in mobile homes as emergency shelters, the concept of modularity seemed to evoke inexpensive, shoddy, and most importantly, impermanent housing.

1960-1990

9

By 1967, modularity was once again thrust into public consciousness with Moshe Safdie’s Habitat ’67, constructed for the Montreal World’s Fair. The large apartment building consisted of individual “modules” made from precast concrete and fitted together like a puzzle. The fully-assembled structure was well-received critically, and is considered a Canadian landmark. Safdie’s Habitat design was meant to be easily duplicated as the modules could be assembled anywhere, regardless of location. In spite of the architect’s plans for additional such structures, the project was never built elsewhere, but prefabrication and modularity were garnering renewed interest—and a new found association with high art—after images of the war had faded. The 1960s also brought a growing trend of mobile home purchases as well as advocacy for modular housing to accommodate the needs of lower-income families. In 1970, economist Daniel A. Hodes noted that “There (is) a large number of people now occupying mobile homes on a temporary basis, even though they could afford more costly housing, simply because they can't find suitable shelter in their price range. Very little conventionally-built housing is being produced today in the $12.000 to $25,000 price range. This segment of the market is, essentially, wide open to the modular housing industry.” Hodes also, however, noted the lingering bias against modular design: “For years, the greatest barrier to the growth of modular housing has been a negative attitude on the part of the consumer toward prefabrication and factory-assembly of housing.” While modularity touched both ends of the housing spectrum—that of high design and that of low-income necessity—the general pushback against it, the 1980s brought a renewed interest in urban applications for modular and prefabricated building practices. One of the greatest obstacles to widespread modular design, though, was the challenge of disassociating it with the unappealing image of the trailer, and instead expanding the concept to include large, well-constructed, and attractive spaces.

10

By 1985, modular housing became an attractive option for rebuilding much of the blighted urban areas that had been abandoned in the 1960s and 1970s. Even New York City embraced modular construction for low-income, single family structures in Brooklyn and the Bronx, in some cases mimicking the suburban tract home aesthetic rather than an urban one. Writing for the New York Times in 1986, Betsy Brown discussed the need for affordable housing and the surprise of New York State legislators who visited a manufactured housing factory; “Sandra R. Galef, Democratic legislator from Ossining and New Castle, said that ‘people think of trailers when they think of modular, and these aren't that - these are attractive, made well, and fairly large.’ Robert Sawyer, director of housing for Mount Vernon, said modular housing had ‘a sort of stigma, as something that wasn't permanent,’ and he added that the visit had changed his outlook.” By the late 1980s, modular homes were modifying their designs to enable spatial configurations untethered to the width and length restrictions on modules in order to allow for highway transport; the single-story structures associated with manufactured housing were no longer the only option. As builders became more creative, design options followed, allowing for large, even sprawling, structures on multiple levels.

11

In the 1990s, consumers and even developers began to take to modular construction for its convenience, low cost, and efficiency. In 1999, Lisa Prevost wrote about a modular Georgian-style mansion in Greenwich, Connecticut that sprawled to 8,900 square feet. The house used

AIMS AND OBJECTIVES modular components for the exterior framing while adding custom, opulent detail to the interior. Seemingly at odds with the concept, modular companies were now offering the option of customization: traditional “stick-built” home design could now be mimicked using modules. Still, modular and prefabricated housing struggled with the image of the mobile home and trailer and of assumed inferior construction; though modular housing companies could build mansions and large single family split-levels, the same factories also continued to produce mobile homes, thus making conflation nearly inevitable.

TO CHANGE THE WAY THE WORLD BUILDS -

12

FUTURISTIC SCOPE IN INDIA India has the second fastest growing economy in the world and a lot of it, is attributed to its construction industry which figures just next to agriculture in its economic contribution to the nation. In its steadfast development, the construction industry has discovered, invented and developed a number of technologies, systems and products; one of them being the concept of Pre-engineered Buildings (PEBs). As opposed to being on-site fabricated, PEBs are delivered as a complete finished product to the site from a single supplier with a basic structural steel framework with attached factory finished cladding and roofing components. The structure is erected on the site by bolting the various building components together as per specifications. PEBs are developed using potential design software. The onset of technological advancement enabling 3d modelling and detailing of the proposed structure and coordination has revolutionised conventional building construction. PEBs have hit the construction market in a major way owing to the many benefits they possess. They exemplify the rising global construction, technology and while they oppose the practice of conventional building construction they simultaneously have taken it to a higher level too. Worldwide, they are a much used concept with studies revealing that 60% of the non-residential low-rise building in USA are pre-engineered; for India the concept has been gaining momentum and the scope of growth is guaranteed looking at India's huge infrastructural requirements. Studies already validate that India has the fastest growing market in the PEB construction segment. The scope of using PEBs ranges from showrooms, low height commercial

13

complexes, industrial building and workshops, stadiums, schools, bridges, fuel stations to aircraft hangers, exhibition centres, railway stations and metro applications. While we are still to see PEBs being used in residences in India, one can see their optimal use in warehouses, industrial sheds, sports facilities etc. The Delhi Airport and the metro projects of Delhi, Bengaluru and Mumbai are also examples of PEB applications. Pune based Tata BlueScope Building Solutions: a division of Tata BlueScope Steel Limited (an equal joint-venture between Tata Steel and BlueScope Steel (Australia) supplies PEB solutions and takes single source responsibility for their design, manufacture, shipment and erection. With developing structures conforming to AISC, MBMA or IS standards, Mr Rohit Ranjan, General Manager, Marketing adds, "Steel construction is evolving from boxlike steel structures to aesthetically pleasing designs. Initial acceptance of metal building systems has been high in industrial applications, followed by infrastructure and commercial structures. However as awareness is growing, metal buildings are being considered for residential applications as well." Interarch Building Products Pvt Ltd with headquarter in Noida is India's leading turnkey pre-engineered metal building company and has myriad construction solutions including advanced Preengineered Steel Buildings. Specialising in airport roofing and ceilings for over two decades, one of their coveted projects is DIAL Terminal 3 (Terminal 3, IGI Airport at Delhi) with a seven-layer roof installed over 2,00,000sqm roof area covering the entire airport. On the absence of PEB's in the residential sector in India, Mr Gautam Suri, the firm's CTO & Founder Director notes, "In India, modular construction is still the preferred choice over PEB systems for the residential sector which is mostly due to lack of awareness about the benefits of PEB with the general perception being that they are expensive. Having said that, I would also like to mention that the PEB industry is slowly and steadily gaining its hold in the commercial /residential sector and will certainly see widespread application soon."

14

15

METHODOLOGY How Are Modular Units Constructed ?

1

16

2

3

17

4

LITERATURE STUDY Main Sectors of Applications of Modular Constructon : 1. 2. 3. 4. 5. 6. 7. 8.

Private housing Social housing Apartments and mixed use buildings Educational sector and student residences Key worker accommodation and sheltered housing Public sector buildings, such as prisons and MoD buildings Health sector buildings Hotels.

ATTRIBUTES OF MODULAR CONSTRUCTION

18

Advantages : 1. Economy of scale through repetitive manufacture 2. Rapid installation on site (6-8 units per day) 3. High level of quality control in factory production 4. Low selfweight leading to foundation savings 5. Suitable for projects with site constraints and where methods of working require more off-site manufacture 6. Limited disruption in the vicinity of the construction site 7. Useful in building renovation projects, such as roof top extensions 8. Excellent acoustic insulation due to double layer construction 9. Adaptable for future extensions, and ability to be dismantled easily and moved if required 10. Robustness can be achieved by attaching the units together at their corners 11. Stability of tall buildings can be provided by a braced steel core.

Features of cellular type building such as student residences and key worker accommodation : 1. Suitable for buildings with multiple repeated units 2. Size of units is limited by transport (3.6m x 8m is typical) 3. Open sided units can be created (by changing the floor orientation) 4. Modules are stacked with usually no independent structure 5. Self weight of 1.5 to 2 kN/m2 6. 4 to 10 storeys (6 is usually the optimum) 7. Fire resistance of 30 to 60 minutes provided 8. Acoustic insulation is provided through double layer walls and floors.

19

Structural elements used in walls and floors of modular modules :

TYPES OF MODULES The following types of modules may be used in the design of buildings using either fully modular construction or mixed forms of steel construction : 1. 4-sided modules 2. Partially open-sided modules 3. Open-sided (corner-supported) modules 4. Modules supported by a primary structural frame 5. Non-load bearing modules

20

6. Mixed modules and planar floor cassettes 7. Special stair or lift modules.

1. 4 – SIDED MODULES In this form of construction, modules are manufactured with four closed sides to create cellular type spaces designed to transfer the combined vertical load of the modules above and in-plane loads (due to wind action) through their longitudinal walls. The cellular space provided is limited by the transportation and installation requirements. Depending on location and exposure to wind action, the height of buildings in fully modular construction is in the range of 6 to 10 storeys. Modules are manufactured from a series of 2D panels, beginning with the floor cassette, to which the four wall panels and ceiling panel are attached generally by screws. The walls transfer vertical loads and therefore the longitudinal walls of the upper module are designed to sit on the walls of the module below. Additional steel angles may be introduced in the recessed corners of the modules for lifting and for improved stability. Module to-module connections are usually in the form of plates that are bolted on site. Special lifting frames are used that allow the modules to be unhooked safely at height.

21

Details of 4 sided modules showing recessed corners with additional angle sections

Module being lifted in the factory

22

Modules can be manufactured with integral balconies and a range of cladding materials can be pre attached or installed on site. All walls are insulated, and are usually boarded externally for weather protection. Additional external insulation can be attached on site. For low rise buildings, in plane bracing or diaphragm action of the board materials within the modules provides shear resistance, assisted by the module to module connections, which transfer the applied wind forces to the group of modules. For buildings of 6 to 10 storeys height, a vertical bracing system is often located around an access core, and assisted by horizontal bracing in the corridor floor between the modules. For taller buildings, a steel podium frame may be provided on which the modules are stacked and supplemented by a concrete or steel core. The maximum height of a group of modules is dependent on the stability provided under wind action. Various cases are presented in the table for scheme design (based on wind loading in the Midlands of England).

23

2. PARTIALLY OPEN SIDED MODULES 4 sided modules can be designed with partially open sides by the introduction of corner and intermediate posts and by using a stiff continuous edge beam in the floor cassette. The maximum width of opening is limited by the bending resistance and stiffness of the edge member in the floor cassette. Additional intermediate posts are usually square hollow sections (SHS), so that they can fit within the wall width. Two modules can be placed together to create wider spaces. The compression resistance of the corner or internal posts controls the maximum height of the building, but 6 to 10 storeys can be achieved, as for fully modular construction. Long modules can also be designed to include an integral corridor, as shown below. The length of the module may be limited by transport and site access but a length of up to 12m is normally practical. Use of modules with integral corridors can improve the speed of construction by avoiding weather tightness problems during installation and finishing work.

24

25

The form of construction is similar to that of 4 sided modules, except for the use of additional posts, generally in the form of 70 x 70 to 100 x 100 SHS members. Balconies or other components can be attached to the corner or internal posts. Overall stability is provided by additional bracing located in the walls of the modules.

26

Stability of the modules is affected by their partially open sides; additional temporary bracing during lifting and installation may be necessary. A separate bracing system may also be required, as the partially open-sided modules may not possess sufficient shear resistance in certain applications. A typical building form in which larger apartments are created using partially open sided units is shown right.

3. OPEN SIDED (CORNER SUPPORTED) MODULE

Modules may be designed to provide fully open sides by transfer of loads through the longitudinal edge beams to the corner posts. The

27

framework of the module is often in the form of hot rolled steel members, such as Square Hollow Section (SHS) columns and Parallel Flange Channel (PFC) edge beams, that are bolted together. A shallower parallel flange channel (PFC) section may be used to support the ceiling, but in all cases, the combined depth of the edge beams is greater than for 4 sided modules. Modules can be placed side by side to create larger open plan spaces, as required inhospitals and schools, etc. The stability of the building generally relies on a separate bracing system in the form of X bracing in the separating walls. For this reason, fully open ended modules are not often used for buildings more than three storeys high. Where used, infill walls and partitions within the modules are non load bearing, except where walls connected to the columnsprovide in plane bracing. The corner posts provide the compression resistance and are typically 100 x 100 SHS members. The edge beams may be connected to these posts by fin plates, which provide nominal bending resistance. End plates and Hollo-bolts to the SHS members may also be used. The corner posts possess sufficient compression resistance for use in buildings at least up to 10 storeys. As open sided modules are only stable on their own for one or two storeys, additional vertical and horizontal bracing is usually introduced. In plane forces can be transferred by suitable connections at the corners of the modules. An open ended module is a variant of a 4 sided module in which a rigid end frame is provided, usually consisting of welded or rigidly connected Rectangular Hollow Sections (RHS). The rigid end frames are manufactured as part of the module or can be assembled as separate components.

28

A steel external framework comprising walkways or balconies may be also designed to provide stability. Modules using hot rolled

29

steelframework can be designed to support concrete floors for use in medical and other applications, where strict control of vibrations is required.

4. MIXED MODULE AND FLOOR CASSETTES In this ‘hybrid’ or mixed form of construction, long modules may be stacked to form a load-bearing serviced core and floor cassettes span between the modules and load-bearing walls. The modules are constructed in a similar way to that described for opensided modules, but the loading applied to the side of the modules is significantly higher. Therefore, this mixed modular and panel form of construction is limited to buildings of 4 to 6 storey height. It is typically used in residential buildings, particularly of terraced form, comprising modular ‘cores’ for stairs, and highly serviced areas. The modules are arranged in a ‘spine’ through the building and the floors are attached to it. An example of this hybrid form of construction is shown on the next page.

30

31

5. MODULES SUPPORTED BY A PRIMARY STRUCTURE Modular units may be designed to be supported by a primary structure at a podium or platform level. In this case, the supporting columns are positioned at a multiple of the width of the modules (normally 2 or 3 modules). The beams are designed to support the combined loads from the modules above (normally a maximum of 4 6 storeys). The supporting structure is designed conventionally as a steel framework withbeams and columns that align with multiples of the module width, and provides open plan space at ground floor and below ground levels. This form of construction is very suitable for mixed retail, commercial and residentialdevelopments, especially for residential units above commercial areas or car parking, etc, particularly in urban projects. Modules can be set back from the façade line. An example of a mixed development in Manchester is shown. The ground floor and belowground car parking is a conventional composite structure.

32

Where the 4 sided modules are designed to be supported by steel or composite beams and the typical line load per supported floor is 15kN/m,columns are placed at 6 to 8m spacing. A column spacing of 7.2m is suitable for below ground car parking. The depth of the podium type structure is 800 to 1000mm, and spans of 10 to 18m can be created below the podium, which are suitable for commercial applications and car parking. The podium structure is generally braced to resist wind loads and a separate braced core is often used to stabilise the group of modules above the podium level. The module design is similar to that described for 4 sided modules. Wind loads can be transferred horizontally through the corridor floors.

33

Alternatively, non load bearing modules can be supported by a primary frame, and are installed as the construction proceeds. Modules can be disassembled in the future to leave the floor cassette supported by the beams. An example of the mixed use of modules and primary steel frame is shown below. The modules are shown shaded and floor spans indicated. An external steel structure, consisting of a façade structure that acts to stabilise the building, may also be used. Modules are placed internally within the braced steel frame, as shown in the MoHo project in Manchester (below).

34

6. OTHER TYPES OF MODULES STAIR MODULE Modular stairs may be designed as fully modular units and generally comprise landings and half landings with two flights of stairs. The landings and half landings are supported by longitudinal walls with additional angles or SHS members to provide local strengthening, if necessary. The stair modules rely for their stability on a base and top, which leads to use of a false landing. The open top and base of the wall may be strengthened by a T, L or similar members to transfer out of plane loads to the landing. SHS posts and bracing can be introduced in the walls to provide for overall stability.

35

36

NON LOAD – BEARING MODULES Non load bearing modules are of similar form to fully modular units, but are not designed to resist external loads, other than their own weight and the forces during lifting. They are used as toilet/bathroom units, plant rooms or other serviced units and are supported directly on a floor or by a separate structure. The walls and floor of these ‘pods’ are relatively thin (typically <100mm). The units are designed to be installed either as the construction proceeds or slid into place on the completed floor. Compatibility of the floor depth in the module and in the floor elsewhere is achieved by one of four methods: Designing the depth of the floor of the module to be the same as the raised floor or acoustic layer elsewhere.  Placing the module in a recess in the floor of the main structure.  Designing the module without a floor (possible in small modules in which fitments are attached to the walls).  Designing the modules to be supported on the bottom flange of Slim floor beams. 

37

BALCONIES AND ATRIA Balconies may be attached to modules in various ways: Balconies supported by a self standing steel structure that is ground supported  Balconies attached between adjacent modules  Balconies that are attached to corner posts in the modules  Integrated balconies within an open sided module. 

Atria may be created by attaching a lightweight steel roof to the upper modules or by by spanning the roof between the modules as shown on the next page.

38

KEY TECHNICAL ISSUES The following general design issues are reviewed below:  Dimensional planning  Stability and structural integrity  Service interfaces  Acoustic performance  Fire safety.

39

DIMENSIONAL PLANNING The factors that influence the dimensional planning of modular systems in general building design may be summarised as:  Cladding requirements, including alignment with external dimensions of cladding.  Planning grid for internal fit out, such as kitchens  Transportation requirements, including access to the site  Building form, as influenced by its functionality  Repeatability in modular manufacture.

CLADDING Brickwork design is based on a standard unit of 225mm width and 75mm depth. Therefore, it may be important to design a floor depth to a multiple of 75mm in order to avoid non standard coursing of bricks.

Other types of cladding, such as clay tiles or metallic finishes, have their own dimensional requirements, but generally they can be designed and manufactured to fit with window dimensions etc.

Many types of lightweight cladding can be pre attached to the modules, but it is generally necessary to install a cover piece over the joints between the modules on site, to cater for geometrical tolerances and misalignments.

STANDARDISATION OF PLANNING GRID

40

Standardisation of the planning grid is important at the scheme design stage, as the planning grid will be controlled by other building components and fitments. A dimensional unit of 300mm may be adopted as standard for vertical and horizontal dimensions, reducing to 150mm as a second level for vertical dimensions. External walls are detailed according to the type of cladding, but a 300mm total wall width may be adopted as a guide for most cladding materials. The actual width will vary between 200mm for insulated render and board materials to 320mm for brickwork.

41

TRANSPORTATION Guidance on transportation on major roads is given by the Road Haulage Association, based on the Road Vehicles (Construction and Use) Regulations. The following basic requirements for transportation should be considered when designing the sizes of modular units:  Modules exceeding 2.9m external width require 2 days notice to the police  Modules exceeding 3.5m width require a driver’s mate and 2 days police notice  Modules exceeding 4.3m width require additional speed restrictions and may require police escort. Stricter limits may be required for local roads, particularly in urban areas. In all cases, the maximum height of the load is 4.95m for motorway bridges. Standard container vehicles can deliver one large or two smaller units.

INTERNAL WALLS

42

Internal walls comprising the walls of adjacent modules may be designed for a standard 300mm face face overall width, incorporating the sheathing boards, internal plasterboards and insulation between the C sections. The gap between the walls is a variable, depending on the number and thickness of boards and size of the wall studs.

FLOOR ZONE Floors and ceilings in modular construction are deeper than in more traditional construction. The three structural cases of side supported (4-sided modules), corner supported (open sided) and frame supported modules require different overall ceiling floor dimensions for planning purposes, as follows:   

Continuously supported or 4-sided modules: 300 or 450mm Corner supported or open-sided modules: 450 to 600mm Frame supported modules: 750 to 900mm.

In most cases, 450mm may be adopted as a standard for the floor-toceiling dimension, although many systems provide shallower depths. Forcorner supported modules, a standard overall floor and ceiling depth of 600mm may be used. The gap between the floor and ceiling is a variable depending on the number of boards and the joist size.

43

STABILITY AND STRUCTURAL INTEGRITY Overall stability is provided by the modules themselves, or by an external structure. The load path is through the walls of the 3-D units, and so removal of this load path means that the walls should be designed to either: Span horizontally over a damaged area by acting as a deep beam or  Be supported by tie forces to the adjacent units. 

The latter means that the units should be tied both horizontally and vertically. Robustness is provided by the ties between the modules with a normally assumed minimum tying force equivalent to half the loaded weight of the module (minimum value of 30kN).

44

SERVICE INTERFACES The installation of electrical, plumbing and heating services in modular buildings can be largely carried out in the factory with final connections made on-site. In traditional construction, such activities are labour intensive on-site and are often on the critical path, so that

45

any difficulties can cause delays. Service strategies that have been used in modular buildings include: Use of communal spaces for distribution of services Use of the floor or ceiling zone within each module for service distribution  Installation of services within each module in the factory with site work involving only connection of modules  Drainage connections of modules connected to vertical risers in the corner of the modules  Wet areas are connected back to back to concentrate service zones.  

A vertical service duct is usually incorporated in the corner of each unit to accommodate the vertical drainage and pipework. The services in each module are installed in the factory and terminate in the vertical duct. Access to the service duct is generally only possible from circulation areas outside the modular unit. The horizontal distribution of services between modules varies, depending on the building type. For most types of residential buildings and hotels, the corridor ceiling and floor voids act as service zones. Vertical drainage stacks are also installed in the factory and a removable floor panel is provided to allow the final connection to the drains installed in the ground on-site. This requires a high degree of accuracy in setting out service inlets on-site.

46

ACOUSTIC PERFORMANCE Modular construction provides a high level of acoustic separation because each module has separate floor, ceiling and wall elements, which prevents direct transfer of sound along the members.

Modular unit manufacturers use various methods to further improve sound reduction between units – two overlapping layers of plasterboard fixed inside each module, oriented strand board (OSB) or plasterboard fixed as external sheeting or quilt insulation between steel members.

47

Special care needs to be taken around openings for service pipes or other penetrations, because sound attenuation is particularly affected by air pathways between spaces. Electrical sockets penetrate the plasterboard layer, so they should be carefully insulated using quilt at their rear.

FIRE SAFETY

Fire safety is related to provision of adequate means of escape, to ensuring structural integrity, and controlling spread of fire across compartment boundaries. In England, minimum periods of fire resistance are given in Approved Document B. Modular construction generally achieves these requirements by the use of fire resistant plasterboard conforming to BS EN 520, Type F. Alternative materials, such as cement particle board and gypsum fibre board may also be used in combination with plasterboard as the facing layer.

Each module is lined internally with one or two layers of fire resistant plasterboard as follows: For walls: 30 minutes fire resistance is achieved by a single layer of 12.5mm fire resistant plasterboard on each face of a steel stud wall  For walls: 60 minutes fire resistance is achieved by one layer of 12.5mm fire resistant plasterboard on a layer of 12.5 mm wallboard with staggered joints on each face of a steel stud wall  For floors: 30 minutes fire resistance is achieved with 18mm tongue and groove boarding on light steel joists and 12.5mm fire resistant plasterboard beneath with joints taped and filled  For floors: 60 minutes fire resistance is achieved with at least 18mm T&G board floor finish and one layer of 12.5mm fire 

48

resistant plasterboard on a layer of 12.5mm wallboard with staggered joints beneath the steel joists.

In residential construction, each dwelling usually forms a separate fire compartment. All walls and floors that provide a separating function between compartments require 60 minutes fire resistance. In hotels and other residential buildings, each bedroom may form its own compartment.

In general, a compartment floor will also act as a separating floor for acoustic purposes, as the same measures will also achieve excellent acoustic insulation between rooms.

49

Disadvantages : • Volumetric – Transporting the completed modular building sections take up a lot of space. This is balanced with the speed of construction once arrived on site.

50

• Flexibility – Due to transport and sometimes manufacturing restrictions, module size can be limited, affecting room sizes. Panelized forms and flat pack versions can provide easier shipment, and most manufacturers have flexibility in their processes to cope with the majority of size requirements.

SUSTAINABILITY The concept of using sustainability indicators is becoming accepted as part of the environmental assessment of building construction. For modular construction, it is appropriate to include whole life measures, such as potential re-use, or re-location which are not properly reflected in conventional measures of sustainability.

The sustainability indicators relevant to modular construction are listed below. Comments on how modular construction contributes to these indicators are given against each indicator.

51

52

TYPICAL DETAILS CONNECTIONS : Guidance on the design and detailing of the most common connection types is given in BS EN 1993-1-8. Manufacturers use the method which best suits their manufacturing process and for which appropriate test data are available.

53

Structural connections between modules are required for integrity and robustness but details vary depending on the form of the module and the particular application. Floor boarding, plasterboard and sheathing boards are attached using self drilling, self-tapping screws. Manufacturers of light steel framed modules have prepared their own details of horizontal attachments that satisfy robustness requirements.

ATTACHMENT POINTS

Attachments between modules are made in both horizontal and vertical directions, primarily to transfer in plane forces, but also for structured integrity.

54

SHS provide the highest compressive resistance and may be used as the corner posts for open sided modules. However, although these sections are compact, their connections can be more complex. A welded fin plate to which the edge beams are bolted is shown. Access holes in the SHS allow bolts to be inserted through end plates to provide for vertical and horizontal attachments.

55

FACADES AND INTERFACES Various interfaces between modular units and other components in the building may not be under the control of the modular manufacturer. The responsibility for design and coordination usually lies with the building designer.

FOUNDATION INTERFACES A variety of foundations can be used, including strip, trench-fill, pad and piled foundations. Further information on pile foundations is given in SCI P299. Strip or trench-fill foundations are most common.

Modular units are lightweight and therefore foundations may be smaller than in traditional construction. Nevertheless, the cladding options and building height may dictate the foundation design. With strips, rafts or ground beams, the modular units can be designed to be continuously supported around the perimeter of each unit.

56

The levelling of the foundations or ground beams is crucial to the subsequent installation and alignment of the modular units. The modular manufacturers have developed their own proprietary locating and fixing mechanisms to aid the positioning of units on the foundations

WALL CLADDING INTERFACES

57

Claddings for modular buildings can be self supporting vertically and only supported laterally by the units. Alternatively, they can be supported entirely by the modular structure. Two generic systems of facade construction may be considered: Cladding that is placed entirely on-site using conventional techniques.  Cladding that is completely or partially attached in the factory; infill pieces or secondary cladding may be fixed on-site. 

Cavity barriers must also be incorporated into any cavity that occurs between the external cladding and the modular structure. These must resist the spread of smoke and flame and are required between all separate dwellings or fire compartments. Mineral wool is generally used.

ROOFING INTERFACES Roofing materials for modular buildings generally comprise tiles supported on battens, or roof sheeting on purlins. Modern roofs may comprise tiles supported on roof sheeting or structural liner trays. Flat roofs can also be constructed with a variety of weatherproof finishes. Insulation in the line of the roof pitch is used where a ‘warm roof’ is created. However, in most cases, the roof space is ‘cold’, and insulation is placed directly on the upper surface of the modular units.

Roofs are generally designed as separate structures that are supported either continuously by the internal walls of the modular units, or as free spanning roofs between the outer walls. Roofs may also be designed as modular units for habitable space, and ease of installation, especially in taller buildings. However, conventional trussed rafter or purlin roofs are mostly used.

58

Roofs are designed to support the weight of the roof covering, snow loads, services and tanks stored on the roof space, and occupancy loads from habitable use. The interface between the roof and the modular units is designed to resist both compression and tension due to wind uplift. In some cases, the roof can be designed to be detachable so that the building can be extended later. Shallow pitch roofs can be designed to be supported directly by the modular units and are easily dismantled.

CASE STUDIES

1.) NAKAGIN CAPSULE TOWER

LOCATION - TOKYO, JAPAN

59

ARCHITECT – KISHO KUROKAWA ARCHITECT & ASSOCIATES CONSTRUCTION STARTED – 1970 CONSTRUCTION COMPLETED – 1972 NO. OF FLOORS – 13 PROGRAM – RESIDENCIAL/OFFICE TOWER OF 140 CAPSULE UNITS AREA – 3,091 SQ M SIZE OF SINGLE UNIT – 2.3 m X 3.8 m X 2.1 m



The building is a rare remaining example of Japanese Metabolism, an architectural movement emblematic of Japan's postwar cultural resurgence.



The building was the world's first example of capsule architecture built for permanent and practical use.



The building still exists but has fallen into disrepair. As of October 2012, around thirty of the 140 capsules remained in use as apartments, while others were used for storage or office space, or simply abandoned and allowed to deteriorate.

 

The building is actually composed of two interconnected concrete towers, respectively eleven and thirteen floors, which house 140 prefabricated modules (or "capsules") which are each self-contained units.  Each capsule measures 2.3 m (7.5 ft) × 3.8 m (12 ft) × 2.1 m (6.9 ft) and functions as a small living or office space.



Capsules can be connected and combined to create larger spaces.



Each capsule is connected to one of the two main shafts only by four high-tension bolts and is designed to be replaceable.

60



No units have been replaced since the original construction.

61

PLAN

62

2.) JAPAN MODULAR HOTEL

ELEVATION

ARCHITECT : YASUTAKA YOSHIMURA

63

The group of Japanese architects YASUTAKA YOSHIMURA ARCHITECTS has designed and implemented a modular apartment complex on the coast of Yokohama. The last winners of the architectural competitions, Mr. Tomáš Henel and Mr. Ondřej Fiala, have independly designed a similar apartment complex. This shows the creativity of young Czech and Slovak architects and the using of modular construction in practise. We believe that we will see the similar designes in the 5th annual of architectural competition that will end on February 28, 2011. The apartment complex on the coast of Yokohama was built up from modules that were produced in Thailand, transported to Japan and than assembled there. The each dwelling unit is made up of two modules that are placed upon themself. There are a kitchen and a living room on the ground floor. These two modules are connected with minimalist interior stairs.

64

On the first floor there is a bedroom with ceiling-window to the living room. A large bathroom is located on the ground floor under the bedroom. The natural lighting in each module is ensured by windows placed across the front side of each module.

INTERIORS

VIEW FROM OTHER SIDE OF THE ROAD

65

SECTION

66

SITE PLAN

67

CONCLUSIONS PEBs have a lot of advantages and some challenges that are being confronted successfully. It is important to realise that in their case whatever can be done in advance should be done in advance. Efforts should be made to reduce the number of parts and material and use light weight elements to save on the transportations costs. However, the most important step is to increase the awareness amongst people so that there can be a shift from conventional structures to PEBs. Firms like Tata BlueScope Building Solutions are focusing on training and development of their partners and vendors as well – the industry is hoping to see a wider application of PEBs.

68

BIBLIOGRAPHY www.nbmcw.com www.modular.org www.nyc.gov www.steelconstruction.info www.architonic.com www.koma-modular.cz www.wikipedia.org www.designboom.com