TIMBER FOR BIG STRUCTURES

Here are just a number of structures which have employed timber engineering techniques to solve structural problems:

— Hyperbolic paraboloid roof structures covering 406 m².

— Laminated wood curved staircase.

— Plywood barrel vault roof used to construct a 1,800-m² covered area.

— Hardwood surface on timber for a 250-m outdoor banked cycle track.

— Laminated timber telecommunications tower 37 m high.

The solutions of these problems have combined functional requirements with economic considerations.

Timber, and advanced technology in timber engineering is playing a vital role in solving many of the problems encountered in structural engineering. For instance:

Timber is strong for its weight and it is easily workable.

Timber does not plasticise or distort in a fire. Timber in highly resistant to corrosive chemical Timber is one of the few natural resources of the world which will not run out.

A TEST

(The answers are given below.}

1. What is the widest clear span possible with a timber structure? (a) 30 metres, b) 100 metres, c) unlimited)

2. Which of these materials should be used in corrosive conditions? (a) timber, b) steel, c) aluminium)

3. How can the strength grades of timber be assessed? (a) visually, b) mechanically, c) not at all)

4. Why does structural timber perform so well in fire? (a) The loss of strength due to its charring is slow and predictable, b) It will not expand in length, c) It does not plasticise or distort),

5. Can wood products achieve a class "0" spread of flame rating?

6. How long has the oldest timber building in the world been standing? (a) 500 years, b) 800 years, c) over 1,200 years)

7. At the present rate of consumption, world timber supplies will run out in... (a) 50 years, b) 100 years, c) never)

ANSWERS

1. The size of a clear span that can be provided is theoretically unlimited. Practical restrictions are only imposed by road transport regulations.

2. Timber. It is virtually unaffected by chemically polluted atmosphere.

3. Strength grades of timber can be assessed by the supplier either visually or mechanically.

4. All three statements are true and contribute equally to wood's excellent performance.

5. Yes. Newly developed treatment makes it possible to achieve a class "0" rating—the highest possible for any material.

6. The oldest timber building in the world is the Temple in Japan which is more than 1,200 years old. It was constructed between 708 A. D. and 715 A. D.

7. More than a third of the world's land surface is still covered by forests. This, combined with timber's unique self-replacement factor, ensures that timber supplies will never run out.

І.Translate the text using a dictionary:

Asbestos

Asbestos is the only natural, non-combustible fibre known to man. Asbestos insulating boards are used to protect factories, schools, hospitals, ships -and other buildings from danger thatfire presents. It is a lightweight material for fire protection. Added to this, asbestos cement's unique combination of structural strength and weather resistance has long made it a natural choice for specifiers. Asbestos is equally stable in damp and humid conditions. It is immune to vermin, insect and bacteriological attack. It can be used for wall linings partitions ducts, ceilings, soffits, fire stops, beam and column casing. But asbestos dust is hazardous and must be reduced to a minimum. General guidelines for working with asbestos, in both industrial and domestic situations, include these of hand tools rather than power tools which create more dust.

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