Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 6 views

    RCC Chapter 9

    Uploaded by

    uniqueacharya8

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    RCC Chapter 9

    Uploaded by

    uniqueacharya8
    6 views21 pages

    Original Title

    Rcc Chapter 9

    Copyright

    © © All Rights Reserved

    Available Formats

    PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    6 views21 pages

    RCC Chapter 9

    Uploaded by

    uniqueacharya8

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    You are on page 1of 21

    CHAPTER: nine

    TIMBER STRUCTURE

    2 MARKS

    ER. NABIN TIWARI


    INTRODUCTION:
    ❖ Timber is a type of wood which has been
    processed into beams and planks.
    ❖ Words derive from old English world
    “timbrian” which means to build.
    ❖ Timbers are used for structural purposes.
    ❖ Those woods which are adapted for
    building purposes are timbers. Finished
    timber is supplied in standard sizes for the
    industry. Timber is used for building
    houses and making furniture.

    Thi s Photo by Unknown Author i s licensed under CC BY-SA

    ER. NABIN TIWARI


    Classification of Tree

    ER. NABIN TIWARI


    Structure of Tree

    ER. NABIN TIWARI


    Pith
    The innermost central portion or core of the tree is called the pith or
    medulla. It varies in size and shape for different types of trees. It
    consists entirely of cellular tissues and it nourishes the plant in its
    young age. When the plant becomes old, the pith dies up and decays
    and the sap is then transmitted by the woody fibres deposited round
    the pith. The pith of branches is nothing but merely a prolongation of
    the pith of stem.
    • Heart wood
    The inner annual rings surrounding the pith constitute the heart wood.
    It is usually dark in colour. As a matter of fact, it indicates dead portion
    of tree and as such, it does not take active part in the growth of tree.
    But it imparts rigidity to the tree and hence it provides strong and
    durable timber for various engineering purposes.

    ER. NABIN TIWARI


    • Sap wood
    • The outer annual rings between heart wood and cambium layer is known as the sap
    wood. It is usually light in colour and weight. It indicates recent growth and it contains
    sap. The annual rings of sap wood are less sharply defined than those of heart wood.
    It takes active part in the growth of tree and the sap moves in an upward direction
    through it.
    • Cambium layer
    • Thethin layer of sap between sap wood and inner bark is known as the cambium layer. It indicates
    sap which has yet not been converted into sap wood. If the bark is removed for any reason, the
    cambium layer gets exposed and the cells cease to be active resulting in the death of tree.
    •

    ER. NABIN TIWARI


    • Inner bark
    • The inner skin or layer covering the cambium layer is known
    as the inner bark. It gives protection to the cambium layer
    from any injury.

    • Outer bark
    • The outer skin or cover of the tree is known as the outer
    bark. It is the outermost protective layer and it sometimes
    contains cracks and fissures. It consists of cells of wood fibre
    and is also known as the cortex.

    ER. NABIN TIWARI


    • Medullary rays
    • The thin radial fibres extending from pith to cambium layer are
    known as the medullary rays. The function of these rays is to hold
    together the annual rings of heart wood and sap wood. These rays
    are sometimes broken and in some varieties of trees, they are not
    very prominent.

    ER. NABIN TIWARI


    Seasoning of Timber
    • Reduction of moisture content along with improving some
    qualities before the use of woods is called seasoning of timber.
    By seasoning, generally, the moisture is reduced to about 15%
    whereas new-cut woods bear about 50%.
    Reasons for Seasoning
    1.To change and improve the properties of wood.
    2.To make a correct percentage of shrinking of woods.
    3.To make confident use of wood.
    4.To reduce the adverse behavior of woods.
    5.To get the proper working condition of woods.

    ER. NABIN TIWARI


    ER. NABIN TIWARI
    USES OF TIMBER
    1. For heavy construction works like columns, trusses, piles.
    2. For light construction works like doors, windows, flooring and
    roofing.
    3. For other permanent works like for railway sleepers, fencing poles,
    electric poles and gates.
    4. For temporary works in construction like scaffolding, centering,
    shoring and strutting, packing of materials.
    5. For decorative works like showcases and furnitures.
    6. For body works of buses, lorries, trains and boats
    7. For industrial uses like pulps (used in making papers), card boards,
    wall papers
    8. For making sports goods and musical instruments

    ER. NABIN TIWARI


    REQUIREMENT OF GOOD TIMBER
    1. Have uniform colour, and regular annual ring
    2. Bright appearance and silky lusture
    3. Well seasoned
    4. Free from natural defects
    5. Shouldn’t be affectef by fungi,wood rooting
    6. Hard, durable and tough
    7. Sweet smell when freshly out
    8. Clear sound when struck

    ER. NABIN TIWARI


    Properties Of Timber

    • Toughness
    • Elasticity •Colour
    •Appearance
    • Warping •Hardness
    • Durability •Specific Gravity
    • Defectless •Moisture Content
    • Workability •Grain
    •Shrinkage and Swelling
    • Soundness •Strength
    • Free of •Density
    abrasion

    ER. NABIN TIWARI


    Advantage of timber

    • Excellent insulator
    • Elastic material
    • Easy and fast to build
    • Sustainable
    • Reusabale
    • Price
    • Weight
    • Strength
    • Asethitic appeal

    ER. NABIN TIWARI


    Dis advanatages of Timber
    • Shrinkage and sweeling
    • Fire resistance
    • Dis colaration
    • Mouldiness
    • Deterioration of wood

    ER. NABIN TIWARI


    Defects in Timber

    • A Defect is taken to be any irregularity occurring in or on the


    timber which may lower its strength, durability, utility value or
    diminish its appearance. Defects may be 'natural' which occur
    while the tree is growing, or 'artificial' as a result of poor
    conversion, seasoning or handling after felling.
    •

    ER. NABIN TIWARI


    1. KNOTS.
    A knot marks the position of growth of a branch
    on the tree. On the cut board, it is most easily
    marked by its conspicuously darker appearance
    and harder character.
    A knot is essentially a discontinuity in the timber
    and hence a place of weakness.

    2. SHAKES.
    After knots, shakes are more serious and common
    defects in timber.
    In simple language, they are also called cracks or
    fissures. These natural cracks may result from:
    Shrinkage on aging of the tree;
    due to movement caused by wind action in the
    growing tree;
    ER. NABIN TIWARI
    3. Rind Galls:
    Rind means bark, and gall implies abnormal growth. These are
    peculiar curved swellings appear on the body of a tree. These rind
    galls are caused due to the growth of layers over the wounds left over
    after abnormal felling of trees which makes them weak and not
    durable.

    ER. NABIN TIWARI


    4. Wind Cracks
    • The exterior surface of a tree shrinks when it is exposed to
    atmospheric agencies results in cracks known as wind cracks. A long
    thin crack is called a steak.

    5. Foxiness:
    Due to poor ventilation during storage or by commencement of decay
    due to over maturity indicated by red or yellow tinge in wood

    ER. NABIN TIWARI


    6. Twisted fibres/Wandering hearts:
    caused by twisting of young trees by fast blowing wind.

    7. Upsets or ruptures:
    Indicate wood fibres which are injured by crushing or compression as
    shown in fig.

    ER. NABIN TIWARI


    6. Burls
    Burls are uneven projections on the body of the tree during its growth.
    These are mainly due to the effect of shocks and injuries received by the
    tree during its young age.

    7. Dead Wood:
    A standing aged tree contain dead wood. This portion is light in weight
    and reddish in colour

    ER. NABIN TIWARI

    You might also like