Knowledge map Week 6
Roof system: •
Flat roofs: pitch: 1~3 degree, ◦ concrete slabs: precast slabs, waterproof membrane need to applied on the entire roof surface. ◦ flat trusses/ space frames: beams and decking joists and decking/roof sheet • pitched and sloping roof: >3 degree timber or steel or rafters, trusses slops is depends on material, tail need to have higher slop> 15 degree MENTAL-properties often find in steel construction • pure mental can be found in nature, part of minerals • FERROUS: iron is the 4th most common element in the Earth- cheap ◦ non- ferrous: all other metals- generally more expensive and less common. Less likely to react with oxygen and superior working qualities; have different qualities. • ALLOYS: combinations of two or more metals mental-properties • varied hardness, depending on types. Lead is very easy to scratch, gold is not • low fragility, generally not easy shatter or break • high ductility • medium flexibility, high while heated • flashing, preventing water. • Denser than water, good conduction to heat and electricity. • Mental window frame: Ferrous metals and alloys (containing iron) • raw alloys- 19th century and less commonly today NON FERROUS METALS 1. ALUMINIUM -distinctive properties: • very light, < other metals :window framing, balustrades 栏杆 and handrails • non-magnetic & non-sparking • easily formed, machined and cast • pure aluminum is soft and lacks strength, • but alloys with small amount of copper, magnesium, silicon, manganese: useful properties
• costly -uses • ROLLED aluminum: cladding panels, heating and air-conditioning systems • reacts with air: creating very fine layer of oxide: self-protect, keep it aways from further oxidation,give itself natural finish • treatment: POWDER COATING and ANODISATION 阳极氧化 COPPER -distinctive properties: electrical wires • first metal used by humans: 7000BC • reddish with a bright metallic lustre 有光泽的 after polished; turns green when exposed to the weather for times- oxidization • very malleable and ductile • good conductor of heat and electricity -use • roofing materials: natural weathering causes coppers developed green colored • widely used for hot and cold domestic water and heating pipework • electrical cabling • (picture from http://i.huffpost.com/gen/856506/thumbs/o-COPPER-WIRE-facebook.jpg) ZINC
-history: • used to make the zinc-copper alloy BRASS -present use: • plating thin layers of zinc on to iron or steel- galvanizing • protect the iron from corrosion- roofing material • used its own as CLADDING for roofs and walls, expensive -distinctive properties • bluish-white, lustrous • brittle at ambient temperatures • malleable at 100-150degrees • reasonable conductor of electricity LEAD -history • less commonly today: toxic to human, stay in the body • used as drains from the baths -present use • roofs, cornices, tank linings and flashing strips for waterproofing -distinctive properties: • bluish-white, lustrous • very soft, highly malleable, ductile, relatively poor conductor of electricity
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resistant to corrosion BUT tarnishes 暗淡无光的 upon exposure to air.
TIN -history • 3000BC • added to copper to make BRONZE -present use • very rarely nowadays. • Decorative • building for lining lead pipes (TOXIC), cover for small gas pipes -distinctive properties • silvery- white meal • malleable, ductile highly crystalline structure • resists sea and soft tap water, attacked by strong acids • oxygen in solution accelerate the attack TITANUM -history • Cornwall, England 1791 • used for military aviation & high performance jets -present use • used in strong light-weight alloys • very expensive -distinctive properties • excellent corrosion resistance • high strength to weight ratio • light, strong, easily fabricated metal with low density • cladding system BRONZE (copper+tin) -history • small amount of tin + copper -present use • tough and used for bearings, clips, electrical connectors and springs • external application, resistance to corrosion -distinctive properties: • corrosion resistance, • harder used in engineering and marine 船舰 application BRASS (copper +Zinc) -history • 16th century -present use • tough, used in elements where friction is required: locks, gears, screws, valves • fittings: knobs, lamps, taps etc -distinctive properties • malleable, low melting point, easy to cast in to different shapes • not ferromagnetic
Alloys copper
Zin
Lead
Tin
Titanium
Bronze
photo
brass
IRON - PROPERTIES • MANETIC 有磁性的 • reactive chemically- easily corrodes through rusting • good in compression -wrought iron 加工过的 • used from circa 1000bc • formed when iron is heated and hammered into the desired shape, • used in bars for windows and doors, decorative elements. • Still used nowadays but is expensive- labour intensive -cast iron • widely used in 19th century and early 20th • formed when iron is melted and the molten metal is poured into moulds to cool • very high compressive strength • very rarely used in contemporary construction- weight and brittleness 脆度 • generally used for compression element, e.g columns, reproduction work 1iron alloys- steel • steel is an alloy of IRON with CARBON being the primary additional alloy element • others alloying elements: manganese 锰, chromium, boron and titanium • STEEL - distinctive properties • strong and resistant to fracture • transfer heat and electricity • advantages: variability (from wires to panels to beam and columns, tubes, sections) • long lasting and resistant to wear ONLY under good protection 1. structural steels -TWO MAIN TYPES (framing: columns, beams, purlins, stud frames) • hot rolled steel ◦ shaped while metal is hot, more materials need to be used to process. ◦ Used as PRIMARY structural element- need to be protected from rusting and corroding by coatings- JOINTS are WELDED 焊接 or BOLTED 螺旋栓的 • cold formed steel ◦ FOLDED from sheets that have been produced and cooled down. ◦ Used as SECONDARY structure- protected by hot dip processes GALVANISATION 镀
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锌,protected by zinc ◦ joints are bolted or screwed reinforcing bars ◦ good TENSILE 可拉伸的 resistance ◦ used in concrete, ◦ deformations
2. steel sheeting • used for CLADDING 电镀，包材， and ROOFING • corrugated 波纹的 iron • must be protected from weather exposure- paint, enameled finishes 磁漆, galvanization • 3. stainless steel alloys • CHROMIUM – main alloying element, mim 12% • alloy- milled 磨碎 into coils 线圈, sheets, plates, bars, wire and tubing • used in harsh environments,e.g, seaside, polluted environment or inert finises. e.g kitchens benches, operating rooms etc • cavity walls: made from stainless steel- corrosion resistance • rarely used as primary structure- costly SPANNING SPACE- DR. MILES LEWIS • proposition 1: architecture is mainly about enclosing space: how the buildings built inside? • Proposition 2 :Problems- spanning in the buildings; how you use the space efficient to maximum the aims ◦ how do you span space in stone? 1. Build stone beam or slab, natural materials effect how to build 2. the stone corbel 3. arch? Costly and labour expensive ◦ ARCH if the voussoirs 拱石 are strong enough, the arch can only fail by distorting. However, if there is materials surrounded between, it will not break 1. springing failure; loads apply from the middle, causing the arch expend outward from both sides 2. rotational failure load ◦ support it with CENTERING during construction underneath: need to use a lots of empty spaces
Solid wall To keep the sides of the arch Straight
Solid wall To keep the sides of the arch Straight
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FROM CHING'S BOOK arches: curved structures for spanning an opening support a vertical load by axial compression transform the vertical forces into inclined components and transmit them to either side of the archway 1. Masonry arches: individual wedge-shaped stone or brick voussoirs 2. Rigid arches: curved, rigid structures of timber, steel or reinforced concrete capable of carrying some bending stresses 3. Vaults: stone, brick or reinforced concrete, forming a ceiling or roof over a hall. 4. groin vaults: compound vaults formed by the perpendicular intersection of two vaults.
when and where was major interior space invented? ◦ Hypostyle hall: Thick stone columns: could not hold a public meeting because the columns are too thick ◦ building D: stone wall, plants the bottoms, use to support columns then create a huge meeting rooms and open space Square columns used stone to create a space and support the columns above to create a bigger open space(room built: Columnar halls
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Columns
material cultural ◦ one country's new building will bring effects to other countries: fashion, materials cultural influence. 6.2 ROOF SYSTEMS main consideration of construction of roof system: 1. control the passage of moisture vapor, 2. the infiltration of air-condition 3. the flow of heat and solar radiation 4. resist the spread of fire FLAT roof ◦ minimum slope ¼'' per foot ◦ the slope usually leads to interior drains ◦ efficiently cover a building of any horizontal dimension, serves as an outdoor space ◦ consist: ▪ reinforced concrete slabs ▪ flat timber or steel trusses ▪ timber or steel beams ▪ wood or steel joists
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sloping roofs ◦ low-slope roofs up to 3:12 ◦ medium to high -3:12 to 12:12 ◦ the roof slope affects the choice of roofing materials, ◦ low-slope roof require roll or continuous membrane roofing ◦ medium and high slope roofs covered with shingles, tiles or sheet materials ◦ sloping roofs shed rainwater easily to eave gutters ◦ have a structure of : ▪ wood or steel rafters and sheathing ▪ timber or steel beams, purlins, and decking, ▪ timber or steel trusses
source: http://paragoninspects.com/images/roofing/slopediagram.jpg
6.8steel trusses • • • • •
fabricated by welding or bolting structural angles and tees together connections require the use of steel gusset plates heavier steel trusses may utilize wide0flange shapes and structural tubing piping, conduit and ductwork may pass through the web spaces the increased depth of trusses allows them to span greater distances than steel beams and girders
Depth range
Span rage The increased depth of trusses allows them to span greater distance
Glossary – • • • • • • • •
key terms of W06
Rafter: one of a series of sloping parallel beams used to support a roof covering Eave: those portions of a roof that project beyond the outside walls of a building; the bottom edges of a sloping roof Purlin: one of several horizontal structural members that support roof loads and transfer them to roof beams Alloy: a homogeneous 平衡的 mixture of two or more metals developed and used because of its lower cost and the certain desirable properties it exhibits Cantilever: a structural member supported at one end only Soffit : a underside of a part or member of a structure, such as a beam, stairway of arch Portal frame: method of building and designing structures Top Chord: the bottom members of a truss
purlin soffit
rafter