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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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TIMBERTIMBER

Lecturer:

Prof. Dr. Mohammad IsmailFaculty of Civil Engineering, UTM-Skudai,

Johor Darul Ta’zim,

MALAYSIA

December 6, 2013

Room : C09-313

Tel : 07 - 5531688

5. Timber Application, Products

and their use

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Department of Structures and Materials2

STRUCTURAL APPLICATION

Marine Work

• Timber use for wharves, piers, sheet piling and cofferdam even though many of these application has been replaced by steel

• For groynes still economic to use timber

• Problem associated with marine work

� Impact, Abrasion, Infestation by marine borers

� Fungal attack, Erosion by chemical action or salt

� Wave action, Dimensional movement caused by differential temperature

• Properties Required

� High density, closeness of grain and resistance to impact, natural durability and wear resistance

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Department of Structures and Materials3

Heavy Construction WorkTimber still used for heavy constructional purposes where availability and cost of materials are favourable. Among others

Pylons, Gantries, Bridges, Shoring and abutments

Main ProblemImpact or accidental loading, infestation, chemical and fungal attack, dimensional movement

Properties RequiredHigh density, closeness of grain and resistance to impact, resistance to acidity, alkalinity and others

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Department of Structures and Materials4

Medium/Light

Construction Work

Roof trusses, partitions,

screens, floors and wall

panels

Properties Required

Reinforced any resistance to fire or rate of flame

Main Problem

Resistance to insect and fungal attack, minimum

dimensional change

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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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Drawback of Solid timber

• Inherent anisotropy

• Many natural defects

• Limited size in (section and length)

• Difficulty of drying

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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SHEET MATERIALS

Range of sheet, board or panel products

includes veneer and core plywoods,

chipboard and flakeboards and a

variety of fibreboards

VERNEER PLYWOOD

• Correct name for plywood defined in BS 6566: Part 2

• All the plies are made of veneers oriented with their plane parallel to the surface of the panel

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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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• Direction of the verneer grain in a ply is at right angles to the direction in the immediately adjacent plies

• There are odd number of plies

• The glues used depend on the intended use of the plywood,

� urea formaldehyde for interior and phenol formaldehyde for exterior

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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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VERNEER PLYWOOD

• Initial cold press may be used before the assembly is put into a hot press, where the glue cures

• Cured panels cooled and trimmed to finished size

• Verneer plywood is generally graded in terms of appearance, durability and bond. According to MS 3.22, 1974, plywood graded to 1, 2 and 3

• Local timber used for plywood:

� Kayu Kapur, Keruing, Mengkulang, Meranti dan Mersawa

• Size (L) 1.8m, 2.4, 2.7 and 3. (W) 600mm, 900 and 1.2m. (T) 2.7-50mm

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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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CORE PLYWOOD

• Commonly referred to as blockboard or laminboard

• Manufactured from strips of solid timber, normally each-glued together to form a solid slab of material

• Normally used in interior applications and have only limited application in construction such as panelling, partitions and door blank

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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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PARTICLEBOARDS

• Commonly referred to wood chipboard or

recently oriented strand board (OSB) and

cement bonded particle board

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FKA –UTM

Department of Structures and Materials, Faculty of Civil Engineering

UTM

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Chipboard

• Raw material may be solid wood, such as sawmill

offcuts, forest thinnings or logging waste

• or wood residues such as planer shavings or sawdust

• Solid wood is fed into a chipper which cuts the required

sizes and shape of particle

• The chips are then mixed with resin, usually urea

formaldehyde and then formed into a mat on a flat plate,

the oriented totally at random

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Department of Structures and Materials, Faculty of Civil Engineering

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Oriented strand board

• Development of waferboard made by cutting small roundwood logs or plywood peeler cores into large flakes which are less than 1 mm thickness

• OSB the flakes are trimmed into rectangular pieces at least twice as long as they are broad, length 75mm or more

• Manufacturing process nearly similar to chipboard

• Application - similar to plywood (wall sheathing) except in highly stressed zones

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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Cement bonded particleboards

� Small particles of wood blended with cement, water and chemical admixtures

� Wet mixture is then spread to thickness and held in a light press until the cement sets

• Cement bonded, wood content quite low

• Density much higher

• High resistance to fire

• Further information in BS 5669

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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FIBREBOARDS

• Wood tissue reduced to the basic fiber, eliminate all trace of structure, defect and anistropy

• The product has exceptionally fine texture throughout, with very smooth surface finish

• According to BS 1142, fiberboard not normally use for structural purpose but for internal fitting and finishing and insulation

• Marketed as a replacement for solid timber mouldings in finishing joinery since its fine texture makes it readily machinable to a range of profiles

• Its smooth surface gives an excellent substrate for painting and it is more stable in changing environments

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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GLUED LAMINATED SECTION

•“Glulam,” or glue-laminated timber, introduced in Europe

in the late nineteenth century, consists of sawn timber

laminations bonded with an adhesive so that the grain of

all laminations runs parallel with the long direction

•BS 4978 for

softwood and

• BS 5756 for

tropical

hardwood

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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“Glulam,” or glue-laminated

timber, introduced in Europe

in the late nineteenth century,

Consists of sawn timber

laminations bonded with an

adhesive so that the grain of

all laminations runs parallel

with the long direction

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Department of Structures and Materials, Faculty of Civil Engineering

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Timber sections are kiln dried

to a moisture content of about

12%, after which they are

finger jointed to a required

lengths

Lamination thickness may

vary from 10 mm – 50 mm

Thinner lamination enabling

tighter bends to be produced

and giving greater strength

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Department of Structures and Materials, Faculty of Civil Engineering

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Manufactured in various sizes and shapes; curved, tapered circular, and spiral-shaped members

Glulam is stronger in longitudinal direction and weaker in the tranverse direction

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Department of Structures and Materials, Faculty of Civil Engineering

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Advantage:

flexibility of shape and size – straight, curved, atches or frame and enabling clear spans in excess of 50m. Appearance warm and attractive

Predictable in fire as solid timber. Additional protection in fire may be obtained by surface treatments, such as clear intumescent varnishes

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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Allowable strength properties superior than those of

sawn timber

Commonly used for purlins, joists, headers, beams,

and truss members. Also in the design of pedestrian

and highway bridges

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Department of Structures and Materials, Faculty of Civil Engineering

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1. Define fiber saturation point and equilibrium

moisture content

2. Explain the effects of moisture content on the

strength characteristics of wood

3. What is clear wood

4. Explain the decay and destruction of wood

5. Define growth ring, check, grain and slope grain

6. Explain seasoning and treatment of timber

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Department of Structures and Materials, Faculty of Civil Engineering

UTM

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