Timber

5 Key excerpts on "Timber"

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  eBook - PDF

  An Introduction to Timber Engineering

  Pergamon Series of Monographs on Furniture and Timber

  • H. J. Andrews, Jack Kape(Authors)
  • 2014(Publication Date)
  • Pergamon

    (Publisher)

  CHAPTER 2 Timber as a Structural Material Timber is one of the very few living natural materials found widely distributed throughout the World, and in such vast quantities in many cases that its potential is not fully appreciated. If Timber had resulted from a recent scientific discovery possessing all its natural characteristics, it would have a resounding effect in the construction industry, and in fact may well have delayed the advances made by other materials in this field. This new material can be made available in vast quantities and is able to reproduce each year more than that extracted for normal usage. It is competitive in cost and possesses unique strength characteristics in its ability to withstand shock treatment and retain permanent resilience. It is a natural insulating material, can be obtained in large sizes, and is readily worked into items of unique and exceptional beauty. Timber will stand up to considerable abuse and when properly used has an indefinite life. Left in its natural state, it possesses a wide variety of unique grain designs which when treated result in natural and enduring patterns. It can be painted and for this purpose provides a smooth surface; it is a material which can be worked with the simplest of tools; and its scrap value' is directly related to the size of pieces remaining after completing its first use. It possesses a useful weight-strength ratio superior to steel and concrete and is 9 A N I N T R O D U C T I O N T O T I M B E R E N G I N E E R I N G 10 more versatile in its application than any other known form of structural material. Timber has remained a primary construction material for thousands of years and the simple reason for this is that no other competitive material is as versatile or possesses all the advantages to be found in Timber. Physical Properties A tree grows in size by the growth and development of new cells —myriads of new cells —direcdy under the bark and at the tips of the branches and roots.

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  eBook - PDF

  N1 Woodworker's Theory

  • E Ebrahim(Author)
  • 2013(Publication Date)
  • Future Managers

    (Publisher)

  MODULE In this module we will discuss some of the more common materials used in any form of construction. We will first look at the characteristics of solid wood, which are obtained from the vast forests in our country. This ranges from the felling of the tree to the final building product. Timber is both renewable and recyclable material; for every tree that is felled, another is planted. We continue with Timber moving to the various types of Timber products, including laminated boards, chipboards and hardboards as well many other types of boards. We will also look at the various types of metals used in construction, including ferrous and non-ferrous metals. Finally, we will discuss the handling and uses of glass, fibreglass and plastics. Wood is the product of a class of plants called ‘exogens’ ( characterised by the addition of layers of woody tissue ) which grows adding new wood on the outside of the trunk and branches. It is composed of minute, tube-like cells packed closely together and joined end-to-end or overlapping obliquely. The cells are made up of cellulose or lignin, a combination of carbon, hydrogen and oxygen. Inside the cells is a watery composition of starches, sugars, minerals, gums and resins. As the cells age, the complicated organic material called ‘lignin’ is deposited in and between the cell walls, making the walls more rigid and the wood more durable. Timber, Timber products, metal and glass 3 Module 3 • Timber, Timber products, metal and glass 52 3.1 Differences between hardwoods and softwoods A tree consists of a trunk, roots, branches and leaves. In the construction industry we are only interested in the trunk from which we receive our Timber. We start our journey into the world of Timber by looking at the two main types of trees from which we obtain our building construction Timber. These are known by their botanical terms as hardwoods and softwoods. Hardwood trees are identified by their broad leaves which they shed during autumn.

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  Structures and Architecture

  New concepts, applications and challenges

  • Paulo J. Cruz(Author)
  • 2013(Publication Date)
  • CRC Press

    (Publisher)

  This m akes the dialog between the structural engineer and t he architect or general designer more fluid and fruitful, as long as designers tend to immediately become famil- iar with the “new” material. Detailing became comparatively easy, and this is a huge innovative step in Timber engineering (even in general high demanding structural engineering). In the future, as I see from my experience, we’ll need to address two main innovation areas: - New species based CLT (poplar, eucalyptus, chestnut, other hardwoods, bam boo, locally grown coniferous trees…). The presented buil ding process is so “obvious” that, as long as it will expand more and more in the future, we must use it to help us to equili brate the management of the different forestry resources. - Incorporation of t he latest developm ents on aircraft and ship buil ding structur al design concepts. There’re two main subject areas: post-critical behavior and reliability based ap- proaches. The current si mplified approach we use regarding instabilit y analysis and code verification leads to too conservative results: in fact, they’ re not consistent with historical reality. Furthermore, results in both areas will help us to a more efficient use of the mate- rial under fire, as long as we end up designing with dramatically thin structural sheets. 510 1 INTRODUCTION Timber as a structural material has historically provided an easily accessible, workable source in the forested areas of the world. In all forested regions, ti mber has appeared in basic structures built for sheltering needs and it has through histor y been utilised in all types of structures. In ar- eas with less Timber supply the material has been combined with other materials providing struc- tural techniques like ti mber framed brick structures to decrease the volume of Timber by replac- ing non-load carry ing parts with non-t imber in-fills.

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  Timber

  Structure, Properties, Conversion and Use

  • H.E. Desch, J.M. Dinwoodie(Authors)
  • 2016(Publication Date)
  • Red Globe Press

    (Publisher)

  Part 4 UTILISATION OF Timber -HOW, WHY AND WHERE IS IT USED? 179 16 Utilisation of Timber The competent and efficient use of Timber either in the production of manufactured items or in the wide area of Timber construction depends on two important criteria: (1) the selection of the most suitable Timber for the task, and (2) the choice of the most appropriate method of joining together the different pieces of Timber. This chapter therefore discusses the criteria to be considered when choosing Timber for a parti-cular end use, and then proceeds to the selection of the mode of assembly, whether by adhesives or mechanical fixings: the final section of the chapter is devoted to examples of Timber in use, illustrating the combination of Timber selec-tion and mode of assembly. 16.1 Choice of Timber Basically there are two aspects to the choice of Timber: the first relates to the selection of the most appropriate species for the given set of environmental and stress conditions; the second aspect is concerned with obtaining the correct grade or selecting the appropriate specification for the wood of any one species. 16. 1. 1 Selection of species The selection of a Timber for a particular purpose depends not only on its technical performance, but also on such factors as cost, size and avail-ability; these four factors are closely interrelated and differ in their relative importance dependent upon the particular species and the purpose for which it is being used. The technical performance of a Timber em-braces such properties as its durability, movement, strength, stiffness and toughness, permeability and ease of processing; not all these properties will be important for any one end use and the order of their relative importance will vary with the task the Timber has to perform.

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  Testing of Construction Materials

  • Bahurudeen A, P.V.P. Moorthi(Authors)
  • 2020(Publication Date)
  • CRC Press

    (Publisher)

  8 Timber

  8.1 Introduction

  Wood is one of the widely used materials for construction. Wood generally has a high strength-to-mass ratio. Based on the engineering applications Timber can be obtained from different trees.

  8.2 Classification of trees

  Trees can be classified into exogenous and endogenous based on their mode of growth. If the mode of growth is in the outward direction, then the trees are said to be exogenous. Exogenous trees find numerous applications in case of construction. They are further subdivided into conifers and deciduous. Some of the examples include oak, teak, deodar, chir, etc. On the other hand, if the mode of growth is in the inward direction, then the trees are said to endogenous and consist of fibrous mass in their longitudinal direction. Some of the examples include palm, cane, bamboo, etc.

  8.3 Macrostructure of Timber

  A cross-section of Timber consists of following essential parts.

  1. 1. Pith – Innermost central part of the tree cross-section is called as pith.
  2. 2. Annual ring of heartwood – This wood covers the innermost portion surrounding the pith of the annual ring. They are highly rigid and strong, enabling their usage as a construction material.
  3. 3. Annual ring of sapwood – The annual rings that are located in between the heartwood and vascular cambium is called as sapwood.
  4. 4. Vascular cambium – Cambium layers are responsible for the production of new cells in the trees. They produce both xylem and phloem. These layers are later converted into the sapwood.
  5. 5. Medullar rays – These rays start from the pith and extend towards outward direction until the cambium layers. These rays extend in the transverse direction such a way that they impart strength to the Timber and hold the cross-section of Timber intact.
  6. 6. Barks – This protects the vascular cambium and phloem layer and safeguards the tree for its future growth.

  8.4 Timber testing

  Timber is generally identified by their species and defects present by visual examination. However, some of the essential tests are conducted in the laboratory. (1) Moisture content determination; (2) Tensile strength parallel to grains; (3) Tensile strength perpendicular to grains; and (4) Brittleness measurement by Charpy test.

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