Methods of Assembly & Off-Site Fabrication

Methods of Assembly

• Enclosure construction assembles and joins individual parts into an integrated whole
• Site assembly offers the widest choice of materials, components, sizes, and shapes for a given enclosure
• Basic ingredients of heterogeneous materials are fully processed into the finished product at the site

Materials Processed or Fabricated Offsite and Joined On-Site

• These include masonry units into walls
• Felts and bitumen used for roofing or waterproofing membranes
• Resilient tile or sheets into flooring
• Concrete or wood panels into decking
• Structural steel girders, beams, and columns into framing systems
• Wall panels and wall facing panels

Components Fabricated and Preassembled Off-Site

• Components are self-contained units of diverse complexity and installed in their final location on-site
• Components may include windows, doors, frames, prehung door units, and skylight units
• Moveable partitions and prefabricated modules like shower compartments are included
• Mechanical equipment includes air conditioning units, boilers, heaters, fans, and pumps
• Electrical equipment includes switchgear, lighting fixtures and motors
• Conveying equipment include elevators and escalators

Site Assembled - Pre-Engineered Enclosures

• Pre-engineered enclosures are envelopes and means of support only
• They are assembled on-site, of standardized materials and components
• Forms are generally limited to several types
• Means of support includes standard types like solid girders, open girders, arches, of several standard spans, spaced at several fixed intervals
• Means of support are commonly designed to function under specific loading conditions only
• Envelopes consist of standardized materials supplied as part of the system
• Optional components like doors, windows and louvers are generally available

Prefabricated Enclosures

• Consist of flexible fabric membranes and means of support
• Membranes are shipped to the site completely fabricated, ready to be suspended from or stretched over site-erected supports
• Membranes are custom-made for each specific installations
• The size or span is limited by properties of the membrane itself and or manufacturing processes

Site Erected Prefabricated Enclosures

• Shipped to the site as complete units, ready to be erected
• Site work is commonly limited to anchoring the flexible fabric membrane to the ground or foundation and inflating
• Enclosures are custom-made for each specific installation, and sizes are limited by manufacturing processes
• Components like blowers to maintain pressure or condition the interior and entrance assemblies are generally available

Site-Assembled Enclosures with Rigid Roofs

• Use rigid flat or nearly flat roof decks covering any arrangement of walls
• Area within exterior walls may be of any size and shape
• Parts of the same enclosure may be of varying heights, sizes, and shapes
• May be combined with sections having pitched or curved roofs
• May be constructed to be expanded horizontally and or vertically at a later date
• Pitched roofs either double or single pitch covering various amount of walls
• Area within exterior walls is generally limited in size for double-pitched roofs

Rigid Roof Structures

• Shape of the total enclosure influenced by the shape of the roof, but a diversity of arrangements is possible
• May be used as the top section of a multi-level enclosure
• May be expanded horizontally but generally not vertically.
• Rigid roofs curved in one direction either linear or intersecting covering various square or rectangular arrangements of walls
• Area within exterior walls is generally limited to maximum span of roof assembly
• Shape of enclosure largely determined by shape of roof, limited number of possible arrangements
• May be used as the top section of a multi-level enclosure
• May expand horizontally but not vertically

Rigid Roofs curved in one direction

• Functions as the envelope, defined by walls in the other direction and commonly one story in height, with area limited by span
• Shape is limited to square or rectangular
• Sections may be offset laterally. Roof and walls may also be separate elements, such as in rigid frames

Means of Support Elements

• Columns only for monolithic roof or floor decks
• Columns and girders of either solid or open cross-section for all types of decks
• Girders for roofs may be slightly pitched to provide for positive drainage
• Bearing walls when enclosures are of limited height
• Combination of bearing walls, columns, and girders
• Elements of interior space commonly include floors, partitions, ceilings and means of circulation and conveyance

Curved Monolithic Decks

• Barrel vaults, either single, in series, or intersecting
• Require securing against outward thrust at supports
• Columns and curved girders of solid cross-section
• Generally require securing against outward thrust at supports
• Columns and open cross-section girders with straight bottom cord and curved top cord are commonly referred to as bow string trusses.

Elements of Enclosure

• Roofs are various types of roof decks with built-up, single-ply, or liquid-applied membrane roofing
• Walls: bearing, nonbearing, or curtain.
• Curtain walls may be grid or wall panel types.
• Curved monolithic decks use thin concrete shells
• Curved girders: either solid or open of constant or nearly constant cross section

Rigid Combined Roofs

• Used over circular or modified circular arrangement of walls
• Area within exterior walls limited by maximum span of means of support
• Shape limited to hemispheres with different span-to-rise ratios
• Hemispheres may be modified by slicing off lower portion on three or more sides vertically
• May be raised above ground and supported by columns or bearing walls
• May be incorporated into a flat roof assembly
• Cannot be expanded once constructed

Envelopes

• An enclosure is a continuous air and watertight barrier, maintained in a given form by means of support,to separate the contained environment from that external to it.
• The barrier or envelope consists of a roof assembly and wall assemblies surrounding it.
• Roofs and walls may be separate distinct elements, or essentially one.
• Envelopes may be flexible fabric membrane functioning as a complete enclosure
• Could employ flexible roof assembly and rigid wall assemblies or rigid roof, wall assemblies of components selected to resist environmental factors

Roof Assemblies

• Roofing provides resistance to the effects of environmental factors.
• Deck serves as a substrate for the roofing, carrying it and resisting forces acting on the assembly.
• Means of support for the deck include girders, bearing walls, columns.
• Decking is only a substrate when it can span between widely spaced primary supports without secondary framing

Wall Assemblies

• Structural core: to resist gravity loads of the assembly itself, superimposed loads, and lateral loads
• Exterior facing: resist environmental factors and act as a separate component or integral part of structural core
• Interior facing may be required to complete the wall assembly over framing or to satisfy visual requirements.
• Provide support against lateral forces like wind or seismic activity using columns and pilasters

Types of walls

• Bearing walls: carrying superimposed gravity loads in addition to their own weight.
• Nonbearing walls: not carrying superimposed gravity loads, whether capable of carrying such loads or not, and supported directly on foundations.
• Curtain walls: nonbearing walls secured to, supported by the structural frame of an enclosure.
• Faced walls: functioning as continuous backup, support for various types of facings.

Flat roofs

• Floors are typically horizontal areas within the enclosure, where the floor assemblies resist traffic and decks support all loads imposed on the floor assembly
• Floor decks have decking capable of spanning between primary supports without secondary framing, whether supported the ground, with secondary framing, spanning between primary supports

Elements of Ceilings

• Nonstructural components of an enclosure, depending on their support on floor or roof assemblies.
• Visual screens/functional separation between inhabited space and underside of floor or roof assembly minimizing accumulation
• Integral components of floor or roof assemblies required to be fire-resistant rated

The space within an envelope

• Can be defined or divided vertically by partitions to control movement, provide privacy, enclose different environments, separate activities and prevent the spread of fire.
• May be located across different heights: below eye level, to above eye level or to underside of floor/roof assembly.
• Fixed, relocatable, or operable and supported or suspended from floor or roof assemblies but only capable of carrying their own weight

Means of conveyance or circulation

• May include:ladders (limited) stairs (foot traffic), ramps (foot traffic, handicapped), escalators (continuous, large group)or elevators (intermittent, rapid).

Space Frame Structure

• Consist of 3 classifications based on curvature: Space plane covers, barrel vaults and spherical domes

classification based on curvature

• Spatial structures are made up of planar substructures and are channeled through horizontal bars with diagonals help support shear forces
• Barrel vaults have tetrahedron modules are used are a unit component
• Spherical domes intricate network of steel sections usually tetrahedron modules or pyramids with skin support

classification based on arrangement of dome elements

• Single layer grid all elements approximate position on surface
• Double layer grid elements arranges elements are arranged in two parallel layers that are spaced at a specific distance away from each other.
• Triple layer grid They are often flat and are mainly used in buildings with larger spans
• Most commonly used for commercials, conference rooms, shopping centers, airports, sports stadiums

Benefits

• Sturdy/Lightweight to allow distribution of load
• Prefabricated parts allow ease of installation
• Highly Portable & Manageable
• Good cambering facilities
• Accommodates irregular shapes
• No need of center columns

Disadvantages

• Frame connections such as welding, bolting, or threading can impede space
• require utilization of long spans with bearing interior load

Geodesic Dome

• Meaning "earth dividing" & mathematically means the shortest path between two points
• Formed from straight lines to frame curved shapes on geometry
• Forms include hyperbolic, elliptic and Euclidian

History

• Term first coined by Buckminster Fuller who improved design and material efficiency sufficiently that he patented
• In 1919 the first geometric structure was built by physicist Walther Wilhelm Johannes Bauersfeld using Icosaedron and concrete shell by Dykerhoff and Wydmann.
• The first commercial dome was built for the Ford Motor Company headquarters in Michigan designed by Buckminster Fuller in 1953

First Bucky Dome

• Designed by Buckminster Fuller following World War II because it affordable
• Consisted of framed triangles using limited material, which allowed it was lighter and easily put together
• One of most famous domes bucky domes was installed at International & Universal exposition in Montanel as architectural structure

Climatron (R)

• Bucky inspired and built in 1960 using principles from Buckminster
• It rose 20 metres and supported more than 50 metre spans, covering half an acre of internal space

Efficiency of Geodesic Dome's

• They are based on a network of triangles which are very stable shapes
• Strong and resistant to forces such as those from snow loads, earthquakes and wind
• Require less material to require material that conventional structures
• Enclose a much smaller surface area area
• Construction can be done very fast

What are they suitable for?

• Construction, theater, green houses, halls and emergency centers
• Used for sports and medical structure

Components and uses

• vary widely used to move movable/sturdy
• permanent structures such as Stadiums and exhibits Tensegrity Structure
• The needle tower in Unites States, designed designed by Kennenth Sneslon

Basic features

• Composed of pin joints trusses; compressed or tensile material; compression of elements are disconinous
• Stability of the structure stabilizes for a state of pre-stress is required and tension

They have many advantage

• These materials are always available
• Tuneable & deployed and perform multiple functions Thin Shell Structure
• A three dimensional structure that that consists of more one or more curved fold

Types Of Shell Structures

• Structures such as folded plates, vaults; shells ( revolution or surfaces and surface combinations
• Folded plates used spans that contain 30 meters in length/ 60 millimeters in thickness
• There different types such as prismatic or faceted plates

Cylindrical Vaults

• Deep structures with thin limbs, used as frame elements that are the ends including columns and side beams
• Is assumed more efficient
• Carries and is able to maintain support through shears
• Can be metal framework of enclosure to provide support for all loads, resistance to forces during intended serve life

There are different forms of various means by which deck consist of components

• roof deck
• horizontal pit curves simple floor suspended either above or grade of the earth by piles

Roof/floor decks must provide all loads to resist all forces

• Components are subject to vertical support of those loads

Roof Or Floor Deck Assemblies Will Include Components

• Structural top surface, component of deck of component supports that can be separate by different shapes