Lect1 material timber_edit-paklan
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Transcript of Lect1 material timber_edit-paklan
TIMBER CONSTRUCTION
Introduction
Introduction Traditional bldg
material
Bldg industry largest consumer
Offer advantages – easy workability + aesthetic appeal + resistance to shocks / vibrations
M’sian usage limited to:- low cost construction- temporary structures- squatters / villages houses- concealed works / formworks
Timber less popular in M’sia Due to prejudice, bad
workmanship, poor detailing.
Difficult to get popular species / higher cost than other materials
Present, Uniform Bldg Bye-Laws (UBBL) classify timber as temporary structures
Insurance companies not willing to insure against fire / premium very high
Difficult to get bank loan
Timber more popular in West Usage in Europe /
N.America / Australia- large + prestigious structures- appreciate timber as bldg materials
Good workmanship / skill
More advanced in timber technology glued laminated beams plywood box beam
Availability + Cost M’sia still has plenty of
timber But only few species
popular – cengal, keruing, meranti
Most timber for export Difficult to get popular
species / higher cost than other materials
Govt, through M’sian Timber Industry Board to encourage other species
Current situation Timber production geared towards export Only leftovers for local Prejudice towards timber – results in less
popular in urban areas Present, Uniform Bldg Bye-Laws (UBBL)
classify timber as temporary structures Insurance companies not willing to insure /
premium very high Difficult to get bank loan
TIMBER AS STRUCTURAL
MATERIAL
Structural Favourable strength to weight ratio “Bending strength” between 1/28 to 1/23
compared to mild steel “Stiffness” is low but compared to its weight, it is
relatively “stiff” (Extra structural members to compensate lack of stiffness will not greatly increase total weight)
Suitable for light to medium loaded low-rise building
Strength Characteristics Strength characteristics indicate ability to
withstand load & potential as engineering an material
Malaysian timber categories into 7 groups:- SG1 to SG7- SG1 the strongest, SG7 the weakest
Strength Group- commercially available M’sian timber
SG1 SG2 SG3 SG4 SG5 SG6 SG7
A) NATURALLY DURABLE
BALAU BELIAN BEKAK GIAM
CENGAL MATA ULAT KERANJI MERBAU
KEKATONG RESAK
B) REQUIRE TREATMENT
KEMPAS RED BALAU KAPUR KEDONDONG DURIAN GERONGGANG
MEMBATU K.SEMANGKOK KASAI KELEDANG JELUTONG PULAI
KULIM MERAWAN KERUING MACANG SESENDOK
TUALANG MEMPAUH RUBBERWOOD MEDANG
PUNAH MERANTI MERSAWA
RENGAS NYATOH TERAP
SIMPOH RAMIN MELANTAI
YELLOWMERANTI
Fire resistance Combustible material
(thin boards easily burnt)
Large size more than 150mm have higher resistance to fire
Smaller sections can be protected with plasterboard, asbestos or fire retardant treatment
Advantages of Timber Environmentally
friendly material Good appearance,
aesthetic appeal Low weight to
strength ratio Light, easy to handle,
easily joined Suitable for
prefabrication of components (reduce amount of site work)
Dry construction, faster completion period
Good sound, thermal and electrical insulation property
Capacity to withstand shock / vibration
Disadvantages Subjected to rot – dry
rot / wet rot Is a combustible
material Being a living
material, it is subjected to attack by insects / termite
Traditional usage of timber Main structure of
Malay house made of “heavy hardwood” – such as “cengal”, “cengal mas”, “cengal batu” and “balau”
Floor of “balau”, “cengal”
Walls made of “medium hardwood” – such as “meranti”
Colonial buildings – other species of timber such as “keruing” and “merbau” for structures
Timber usage in brick buildings FLOOR – floor beams /
bearers, floor joist, floor boards
WALL – studs, wall panel / sheathing
CEILING – beams, ceiling joists
ROOF – beams, rafters, trusses, purlins, battens
DOOR & WINDOW – frames, door panels, window leaves, sills
VERANDA – balusters, handrails, flooring, stairs, columns